Vitamin D insufficiency and the blunted PTH response in established osteoporosis: the role of magnesium deficiency

Lower serum magnesium levels are associated with a higher risk of fractures and vascular calcifications in hemodialysis patients

Background

Magnesium (Mg) deficiency seems to be associated with altered bone metabolism and vascular calcifications (VC). This study aimed to evaluate the association between serum Mg levels and incident bone fragility fractures and VC in a cohort of prevalent hemodialysis (HD) patients.

Methods

We performed a retrospective study of 206 patients, with a mean age of 68.3 ± 13.1 years; 121 (59%) were male, and the median follow-up time was 58 months.

Results

Thirty-seven episodes of fragility fractures were identified with a median HD vintage of 42 months-an incidence rate of 29 per 1000 person-years. Patients with fractures showed lower Mg levels compared with those without fractures (P < .001) and more VC (P = .01). In a Cox regression analysis, time to fragility fracture was independently associated with serum Mg <2.2 mg/dL (P < .001), in a model adjusted to age, female gender, HD vintage, diabetes mellitus, body mass index, albumin, parathyroid hormone, active vitamin D therapy and the presence of VC. Patients with Mg serum levels <2.2 mg/dL had a 1.32-fold higher risk of fragility fractures (P < .001).

Conclusions

This study showed that the incidence of bone fragility fractures in HD patients is high and is significantly associated with lower Mg levels and with the presence of more VC.

The Biological Effects of Magnesium-Based Implants on the Skeleton and Their Clinical Implications in Orthopedic Trauma Surgery

Magnesium (Mg)-based implants have evolved as a promising innovation in orthopedic trauma surgery, with the potential to revolutionize the treatment of bone diseases, including osteoporotic fractures and bone defects. Available clinical studies mostly show excellent patient outcomes of resorbable Mg-based implants, without the need for subsequent implant removal. However, the occurrence of radiolucent zones around Mg-based implants seems to be a noticeable drawback for a more widespread clinical use. Mechanistically, both in vivo and in vitro studies demonstrated beneficial effects on the formation of new bone, a unique characteristic of Mg-based implants. In this regard, Mg has been shown to exert pleiotropic functions on osteogenic differentiation and migration of osteoblasts and their precursors. Additionally, collective evidence suggests that Mg-based implants promote angiogenesis in newly formed bone and exert immunomodulatory effects in the bone microenvironment. Likewise, Mg-based implants and their degradation products were shown to inhibit bone resorption by impairing osteoclastogenesis. The purpose of this review is to provide a state-of-the-art summary of the clinical and basic science evidence regarding the performance of currently used Mg-based implants. In addition to the status of in vivo and in vitro research and clinical applications, future challenges and perspectives of Mg-based orthopedic implants are discussed.

Challenges and Pitfalls of Research Designs Involving Magnesium-Based Biomaterials: An Overview

Magnesium-based biomaterials hold remarkable promise for various clinical applications, offering advantages such as reduced stress-shielding and enhanced bone strengthening and vascular remodeling compared to traditional materials. However, ensuring the quality of preclinical research is crucial for the development of these implants. To achieve implant success, an understanding of the cellular responses post-implantation, proper model selection, and good study design are crucial. There are several challenges to reaching a safe and effective translation of laboratory findings into clinical practice. The utilization of Mg-based biomedical devices eliminates the need for biomaterial removal surgery post-healing and mitigates adverse effects associated with permanent biomaterial implantation. However, the high corrosion rate of Mg-based implants poses challenges such as unexpected degradation, structural failure, hydrogen evolution, alkalization, and cytotoxicity. The biocompatibility and degradability of materials based on magnesium have been studied by many researchers in vitro; however, evaluations addressing the impact of the material in vivo still need to be improved. Several animal models, including rats, rabbits, dogs, and pigs, have been explored to assess the potential of magnesium-based materials. Moreover, strategies such as alloying and coating have been identified to enhance the degradation rate of magnesium-based materials in vivo to transform these challenges into opportunities. This review aims to explore the utilization of Mg implants across various biomedical applications within cellular (in vitro) and animal (in vivo) models.

Hypomagnesemia: a potential underlooked cause of persistent vitamin D deficiency in chronic kidney disease

Magnesium and vitamin D play important roles in most cells of the body. These nutrients act in a coordinated fashion to maintain physiologic functions of various organs, and their abnormal balance could adversely affect these functions. Therefore, deficient states of both nutrients may lead to several chronic medical conditions and increased cardiovascular and all-cause mortality. Chronic kidney disease (CKD) patients have altered metabolism of both magnesium and vitamin D. Some studies indicate that magnesium could have a role in the synthesis and metabolism of vitamin D, and that magnesium supplementation substantially reversed the resistance to vitamin D treatment in some clinical situations. Recent observational studies also found that magnesium intake significantly interacted with vitamin D status and, particularly with the risk of cardiovascular mortality. It is therefore essential to ensure adequate levels of magnesium to obtain the optimal benefits of vitamin D supplementation in CKD patients. In this review, we discuss magnesium physiology, magnesium and vitamin D metabolism in CKD, potential metabolic interactions between magnesium and vitamin D and its clinical relevance, as well as the possible role of magnesium supplementation to assure adequate vitamin D levels.

An Overview of Scaffolds and Biomaterials for Skin Expansion and Soft Tissue Regeneration: Insights on Zinc and Magnesium as New Potential Key Elements

The utilization of materials in medical implants, serving as substitutes for non-functional biological structures, supporting damaged tissues, or reinforcing active organs, holds significant importance in modern healthcare, positively impacting the quality of life for millions of individuals worldwide. However, certain implants may only be required temporarily to aid in the healing process of diseased or injured tissues and tissue expansion. Biodegradable metals, including zinc (Zn), magnesium (Mg), iron, and others, present a new paradigm in the realm of implant materials. Ongoing research focuses on developing optimized materials that meet medical standards, encompassing controllable corrosion rates, sustained mechanical stability, and favorable biocompatibility. Achieving these objectives involves refining alloy compositions and tailoring processing techniques to carefully control microstructures and mechanical properties. Among the materials under investigation, Mg- and Zn-based biodegradable materials and their alloys demonstrate the ability to provide necessary support during tissue regeneration while gradually degrading over time. Furthermore, as essential elements in the human body, Mg and Zn offer additional benefits, including promoting wound healing, facilitating cell growth, and participating in gene generation while interacting with various vital biological functions. This review provides an overview of the physiological function and significance for human health of Mg and Zn and their usage as implants in tissue regeneration using tissue scaffolds. The scaffold qualities, such as biodegradation, mechanical characteristics, and biocompatibility, are also discussed.

Nutrition, Physical Activity, and Dietary Supplementation to Prevent Bone Mineral Density Loss: A Food Pyramid

Bone is a nutritionally modulated tissue. Given this background, aim of this review is to evaluate the latest data regarding ideal dietary approach in order to reduce bone mineral density loss and to construct a food pyramid that allows osteopenia/osteoporosis patients to easily figure out what to eat. The pyramid shows that carbohydrates should be consumed every day (3 portions of whole grains), together with fruits and vegetables (5 portions; orange-colored fruits and vegetables and green leafy vegetables are to be preferred), light yogurt (125 mL), skim milk (200 mL,) extra virgin olive oil (almost 20 mg/day), and calcium water (almost 1 l/day); weekly portions should include fish (4 portions), white meat (3 portions), legumes (2 portions), eggs (2 portions), cheeses (2 portions), and red or processed meats (once/week). At the top of the pyramid, there are two pennants: one green means that osteopenia/osteoporosis subjects need some personalized supplementation (if daily requirements cannot be satisfied through diet, calcium, vitamin D, boron, omega 3, and isoflavones supplementation could be an effective strategy with a great benefit/cost ratio), and one red means that there are some foods that are banned (salt, sugar, inorganic phosphate additives). Finally, three to four times per week of 30-40 min of aerobic and resistance exercises must be performed.

Environmental Factors That Affect Parathyroid Hormone and Calcitonin Levels

Calciotropic hormones, parathyroid hormone (PTH) and calcitonin are involved in the regulation of bone mineral metabolism and maintenance of calcium and phosphate homeostasis in the body. Therefore, an understanding of environmental and genetic factors influencing PTH and calcitonin levels is crucial. Genetic factors are estimated to account for 60% of variations in PTH levels, while the genetic background of interindividual calcitonin variations has not yet been studied. In this review, we analyzed the literature discussing the influence of environmental factors (lifestyle factors and pollutants) on PTH and calcitonin levels. Among lifestyle factors, smoking, body mass index (BMI), diet, alcohol, and exercise were analyzed; among pollutants, heavy metals and chemicals were analyzed. Lifestyle factors that showed the clearest association with PTH levels were smoking, BMI, exercise, and micronutrients taken from the diet (vitamin D and calcium). Smoking, vitamin D, and calcium intake led to a decrease in PTH levels, while higher BMI and exercise led to an increase in PTH levels. In terms of pollutants, exposure to cadmium led to a decrease in PTH levels, while exposure to lead increased PTH levels. Several studies have investigated the effect of chemicals on PTH levels in humans. Compared to PTH studies, a smaller number of studies analyzed the influence of environmental factors on calcitonin levels, which gives great variability in results. Only a few studies have analyzed the influence of pollutants on calcitonin levels in humans. The lifestyle factor with the clearest relationship with calcitonin was smoking (smokers had increased calcitonin levels). Given the importance of PTH and calcitonin in maintaining calcium and phosphate homeostasis and bone mineral metabolism, additional studies on the influence of environmental factors that could affect PTH and calcitonin levels are crucial.

Serum 25(OH)D Concentration and Cardiovascular Disease Risk Markers Among Middle-Aged Healthy and Type 2 Diabetic Subjects

Vitamin D deficiency is a major widespread health concern and is linked to a high risk of cardiovascular disease (CVD). Thus, we have investigated the association of vitamin D with various CVD risk markers. The present study comprises 90 control and 90 type 2 diabetes mellitus (T2DM) subjects of both sexes (age range, 30-50 years). The 25 hydroxyvitamin D [25(OH)D] and CVD risk markers including high sensitive C-reactive protein (hs-CRP), monocyte chemoattractant protein-1 (MCP-1), intact parathyroid hormone (I-PTH), fibroblast growth factor (FGF)-23, erythrocyte sedimentation rate (ESR), and fibrinogen were measured by using standard assays. Blood viscosity and atherogenic index of plasma calculated using standard formulae. The ten-year cardiovascular risk was assessed using the Framingham risk score (FRS). 25(OH)D, hs-CRP, MCP-1, FGF-23, ESR, fibrinogen, atherogenic index of plasma and FRS were significantly different between control and T2DM groups (p<0.05). 25(OH)D showed a significant negative correlation with MCP-1, ESR, blood viscosity, atherogenic index of plasma and FRS among total study subjects. Further, logistics regression analysis showed an association of 25(OH)D with MCP-1, hematocrit, fibrinogen, and blood viscosity. The association between 25(OH)D and various CVD risk markers suggests that 25(OH)D might help in the prediction of CVD risk.

Magnesium Depletion Score (MDS) Predicts Risk of Systemic Inflammation and Cardiovascular Mortality among US Adults

BACKGROUND

Kidney reabsorption of magnesium (Mg) is essential for homeostasis.

OBJECTIVES

We developed and validated models with the kidney reabsorption-related magnesium depletion score (MDS) to predict states of magnesium deficiency and disease outcomes.

METHODS

MDS was validated in predicting body magnesium status among 77 adults (aged 62 ± 8 y, 51% men) at high risk of magnesium deficiency in the Personalized Prevention of Colorectal Cancer Trial (PPCCT) (registered at clinicaltrials.gov as NCT01105169) using the magnesium tolerance test (MTT). We then validated MDS for risk stratification and for associations with inflammation and mortality among >10,000 US adults (weighted: aged 48 ± 0.3 y, 47% men) in the NHANES, a nationally representative study. A proportional hazards regression model was used for associations between magnesium intake and the MDS with risks of total and cardiovascular disease (CVD) mortality.

RESULTS

In the PPCCT, the area under the receiver operating characteristic (ROC) curve (AUC) for magnesium deficiency was 0.63 (95% CI: 0.50, 0.76) for the model incorporating the MDS with sex and age compared with 0.53 (95% CI: 0.40, 0.67) for the model with serum magnesium alone. In the NHANES, mean serum C-reactive protein significantly increased with increasing MDS (P-trend < 0.01) after adjusting for age and sex and other covariates, primarily among individuals with magnesium intake less than the Estimated Average Requirement (EAR; P-trend < 0.05). Further, we found that low magnesium intake was longitudinally associated with increased risks of total and CVD mortality only among those with magnesium deficiency predicted by MDS. MDS was associated with increased risks of total and CVD mortality in a dose-response manner only among those with magnesium intake less than the EAR.

CONCLUSIONS

The MDS serves as a promising measure in identifying individuals with magnesium deficiency who may benefit from increased intake of magnesium to reduce risks of systemic inflammation and CVD mortality. This lays a foundation for precision-based nutritional interventions.

Blunted PTH response to vitamin D insufficiency/deficiency and colorectal neoplasia risk

BACKGROUND & AIMS

In contrast to many observational studies, large-scale randomized trials do not support the protective role of vitamin D for the prevention of colorectal neoplasia. However, in previous studies, individuals with blunted parathyroid hormone (PTH) response to vitamin D insufficiency/deficiency (BPRVID), were not differentiated from those with high PTH response to vitamin D insufficiency/deficiency (HPRVID). Individuals with BPRVID are responsive to magnesium treatment, particularly treatment of magnesium plus vitamin D while those with HPRVID are responsive to vitamin D treatment. We prospectively compared these two distinct groups (i.e. BPRVID and HPRVID) for risk of incident adenoma, metachronous adenoma, and incident colorectal cancer (CRC) METHODS: Three nested case-control studies in the Prostate, Lung, Colorectal and Ovarian Cancer (PLCO) Screening Trial.

RESULTS

We found optimal 25(OH)D levels were associated with a significantly reduced risk of CRC, primarily among women. The associations between 25(OH)D and CRC risk significantly differed by PTH levels, particularly among women. Compared to individuals with optimal levels for both 25(OH)D and PTH, all others were at an elevated risk of incident CRC, primarily in women. We found those with BPRVID had 2.56-fold significantly increased risk of CRC compared to 1.65-fold non-significantly increased risk for those with HPRVID. Among women, we observed those with BPRVID had 4.79-6.25-fold significantly increased risks of incident CRC and adenoma whereas those with HPRVID had 3.65-fold significantly increased risk of CRC.

CONCLUSIONS

Individuals with BPRVID are at higher risks of incident adenoma and CRC compared to those with HPRVID, particularly among women.

Evaluation of Serum 25-Hydroxyvitamin D3 and Bone Mineral Density in 268 Patients with Hip Fractures

Objective

The aim of the present study was to evaluate the relationship among vitamin D nutritional status, bone mineral density, and other factors in elderly patients with brittle hip fractures.

Methods

The present study was a retrospective analysis of 268 patients, 102 men (38.06%) and 166 women (61.94%), with brittle hip fractures admitted to the Hip Joint Center of Tianjin Hospital from February 2016 to June 2018. The median age of the patients was 74 years (range, 50–93 years). The patients were divided into three groups based on age: ≤69 years, 70–79 years, and ≥80 years. Serum 25‐hydroxyvitamin D₃ (25(OH) D₃), parathyroid hormone (PTH), body mass index (BMI), and bone mineral density (BMD) of the lumbar spine, femoral neck, and hip were measured and statistically analyzed.

Results

The median serum 25(OH)D₃ level of patients was 9.90 (range, 2.60–42.70) ng/mL; the proportion of deficiency was 89.18% and the deficiency was severe in 136 cases (49.25%). The proportion of vitamin D deficiency was significantly lower in men than in women (P = 0.013). With the increase of age, 25(OH)D₃ levels gradually decreased (P = 0.044) and PTH levels gradually increased (P < 0.001). There was significantly negative correlation (P < 0.001) between the levels of serum 25(OH)D₃ and PTH. There were 200 cases (74.63%) in which T‐values of BMD were less than −2.5 in any part of the lumbar vertebrae, femoral neck, and hip. T‐values in 74 cases (27.61%) were less than −2.5 in all three parts. The T‐values of BMD in men were significantly higher than those in men (P < 0.001). With the increase of age, the femoral neck BMD in men gradually decreased (P = 0.016), and the femoral neck and hip BMD in female gradually decreased (P‐value was 0.001 and 0.003, respectively). Multivariate analysis suggested that gender and BMI were independent risk factors for BMD, and vitamin D deficiency affected BMD.

Conclusion

Vitamin D deficiency is common in patients with brittle hip fractures, especially in women. With the increase of age, vitamin D continues to decrease and PTH increases. The decrease of BMD in patients with hip fractures is the result of a combination of age, gender, BMI, and vitamin D content.

The Effects of Calcium, Magnesium, Phosphorus, Fluoride, and Lead on Bone Tissue

Bones are metabolically active organs. Their reconstruction is crucial for the proper functioning of the skeletal system during bone growth and remodeling, fracture healing, and maintaining calcium-phosphorus homeostasis. The bone metabolism and tissue properties are influenced by trace elements that may act either indirectly through the regulation of macromineral metabolism, or directly by affecting osteoblast and osteoclast proliferation or activity, or through becoming part of the bone mineral matrix. This study analyzes the skeletal impact of macroelements (calcium, magnesium, phosphorus), microelements (fluorine), and heavy metals (lead), and discusses the concentration of each of these elements in the various bone tissues.

Prevalence and Determinants of a Blunted Parathyroid Hormone Response in Young Saudi Women with Vitamin D Deficiency: A Cross-Sectional Study

Vitamin D deficiency is highly prevalent among the Saudi population. Increased parathyroid hormone (PTH) secretion is an appropriate homeostatic response to correct the resultant hypocalcemia. However, not all vitamin D deficiency patients have increased PTH levels. This study determined the prevalence of a blunted PTH response to vitamin D deficiency among apparently healthy young Saudi women and assessed anthropometric and biochemical factors associated with this response by performing a secondary analysis of data obtained from a cross-sectional study conducted at the "Center of Excellence for Osteoporosis research." Overall, 315 women (aged 20-45 years) with vitamin D deficiency (serum 25-hydroxyvitamin D (25(OH)D) levels <30 nmol/L) were included. They were divided into two groups according to the laboratory cutoff value of PTH (<7 or ≥7 pmol/L), and anthropometric and biochemical characteristics of both groups were compared. Women with a blunted PTH response (n = 62, 19.7%) had a significantly lower body mass index (BMI) (P < 0.001) and smaller waist circumference (P=0.001). They also had significantly higher serum 25(OH)D (P=0.001), corrected serum calcium (P < 0.001), and phosphate (P=0.003) levels than those with an elevated PTH response (n = 253, 80.3%). Multiple logistic regression analysis showed that lower BMI (OR = 0.925; 95% CI: 0.949-0.987) and higher 25(OH)D (OR = 1.068; 95% CI: 1.014-1.124) and serum calcium (OR = 8.600; 95% CI: 1.614-45.809) levels were significantly associated with a blunted PTH response (R ² = 0.178). A blunted PTH response to vitamin D deficiency is mainly observed among women with lower BMI. Higher serum calcium and 25(OH)D levels and lower BMI were significant predictors of a blunted PTH response, which may indicate that these subjects are adapting to lower 25(OH)D levels and maintaining normal calcium levels without the need to increase PTH secretion. The mechanisms underlying this adaptation are unclear, and future studies to explore these mechanisms are warranted.

Application of nutrient essentiality criteria to dietary carbohydrates

The purpose of the present review is to describe how human physiology at very low carbohydrate intakes relates to the criteria for nutritional essentiality. Although we did not limit ourselves to one particular type or function of carbohydrates, we did primarily focus on glucose utilisation as that function was used to determine the recommended daily allowance. In the general population, the human body is able to endogenously synthesise carbohydrates, and does not show signs of deficiency in the absence of dietary carbohydrates. However, in certain genetic defects, such as glycogen storage disease type I, absence of dietary carbohydrates causes abnormalities that are resolved with dietary supplementation of carbohydrates. Therefore, dietary carbohydrates may be defined as conditionally essential nutrients because they are nutrients that are not required in the diet for the general population but are required for specific subpopulations. Ketosis may be considered a physiological normal state due to its occurrence in infants in addition to at very low carbohydrate intakes. Although sources of dietary carbohydrates can provide beneficial micronutrients, no signs of micronutrient deficiencies have been reported in clinical trials of low-carbohydrate ketogenic diets. Nonetheless, more research is needed on how micronutrient requirements can change depending on the dietary and metabolic context. More research is also needed on the role of dietary fibre during a low-carbohydrate ketogenic diet as the beneficial effects of dietary fibre were determined on a standard diet and several studies have shown beneficial effects of decreasing non-digestible carbohydrates.

Low PTH Levels in Adolescents With Anorexia Nervosa

Introduction: Patients with anorexia nervosa (AN) experience medical complications including impaired bone metabolism, increased fracture rate, kidney stones and chronic renal failure. However, the mechanisms of such complications are not fully understood. Healthy adolescents have been shown to have higher PTH levels when compared with pre-pubertal children and adults. Given the importance of central measures of calcium and vitamin D metabolism in bone and kidney health, 25-hydroxyvitamin D (25OHD) and parathyroid hormone (PTH) have been extensively investigated in patients with AN, however none of the previous studies accounted for age-specific reference ranges for PTH. The aim of this study was to investigate central measures of calcium and vitamin D metabolism in adolescents with newly diagnosed AN using age-specific reference ranges and to determine whether any significant abnormalities required further study. Methods: This was a cross-sectional study of 61 adolescents (mean age = aged 15.2 ± 1.56 years) with newly diagnosed AN, referred to a tertiary center over a period of 2 years. Demographic, auxiological, and nutrient (vitamin D and calcium) intake data was obtained. Central measures of calcium and vitamin D metabolism in blood and urine were investigated. PTH results were compared with age-specific reference ranges from the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER). Descriptive statistics and correlation analysis were performed. Results: Low PTH levels were observed in 35% of the cohort. Overall, serum calcium, phosphate and 25OHD were within the reference range. Using loess curves, PTH had a significant negative and non-linear correlation with 25OHD with an inflection point at a 25OHD level of 100 nmol/l, above which the association was no longer present. Correlation analysis did not show a significant association between PTH and total or corrected serum calcium, urine calcium/creatinine (Ca/Cr) ratio, total dietary calcium intake, magnesium or Tanner staging. Conclusion: PTH levels were reduced in approximately a third of adolescents with AN. This observation has not been reported given the universal usage of reference ranges that covers all ages. This finding may unmask a potential role for reduced PTH levels in the pathogenesis of kidney stones and bone phenotype in patients with AN.

Parathyroid hormone response to different vitamin D levels in population-based old and very-old Polish cohorts

BACKGROUND

Low vitamin D (VD) is not always followed by the development of secondary hyperparathyroidism (SHPT). The study aimed to assess the prevalence of SHPT and functional hypoparathyroidism (FHPT) in relation to VD deficiency/insufficiency and factors predisposing to parathyroid hormone (PTH) response in old and very-old Caucasians.

METHODS

A sub-study of the cross-sectional PolSenior project analyzed serum 25(OH)D, intact PTH (iPTH) and C-terminal fibroblast growth factor 23 (cFGF23) concentrations in 3472 (1658 women) individuals aged ≥65 years. SHPT was defined as iPTH concentration > 65 pg/mL, while FHPT as iPTH within the reference range in the presence of 25(OH)D < 30 ng/mL.

RESULTS

SHPT was diagnosed in 426 participants (14%) and was more frequent in very-old (≥ 80 years) than in the old (65-79 years) subgroup (18.8 vs 9.8%; OR = 2.12; 95% CI: 1.72-2.62). While, FHPT was found in 2269 subjects (85.2%) with 25(OH)D < 30 ng/mL, and was more prevalent in the old than very-old subgroup (89.3 vs 80.1%; OR = 2.03; 95% CI: 1.63-2.52). Multiple regression analysis showed that age ≥ 80 years, use of loop diuretics, decreased glomerular filtration rate, higher cFGF23 level but lower calcium and phosphate concentrations, predispose for the occurrence of SHPT.

CONCLUSIONS

The interrelation between 25(OH)D deficiency and PTH response is complex. In older adults, PTH response is related to VD deficiency, age, impaired kidney function, the use of loop diuretics and the levels of calcium, phosphate, and cFGF23.

Anabolic effects of vitamin D and magnesium in aging bone

Decreased bone mass and an increased risk of bone fractures become more common with age. This condition is often associated with osteoporosis and is caused by an imbalance of bone resorption and new bone formation. Lifestyle factors that affect the risk of osteoporosis include alcohol, diet, hormones, physical activity, and smoking. Calcium and vitamin D are particularly important for the age-related loss of bone density and skeletal muscle mass, but other minerals, such as magnesium, also have an important role. Here, we summarize how optimal magnesium and vitamin D balance improve health outcomes in the elderly, the role of magnesium and vitamin D on bone formation, and the implications of widespread deficiency of these factors in the United States and worldwide, particularly in the elderly population.

The relative influence of serum ionized calcium and 25-hydroxyvitamin D in regulating PTH secretion in healthy subjects

BACKGROUND

While the inverse relationship between serum ionized calcium (Ca²⁺) and PTH is well-established, the relationship between 25(OH)D and PTH showed conflicting results. The study aimed to evaluate the relative contributions of age, sex, serum Ca²⁺, ionized magnesium (Mg²⁺), 25(OH)D and 1,25(OH)₂D in regulating PTH secretion in healthy subjects.

METHODS

This is a secondary analysis of an observational study performed from March 2014 to July 2015 carried out in 2259 blood donors (1652 men and 607 women, age range 18-68 years). Subjects with parathyroid disorders and taking drugs that affect mineral metabolism were excluded.

RESULTS

Significant correlations [between Ca²⁺ and PTH (r = -0.223, p < 0.001), 25(OH)D and PTH (r = -0.178, p < 0.001) and between PTH and age (r = 0.322, p < 0.001)] were found. As a preliminary step to multivariate analysis, a regression tree analysis was performed using PTH as response variable and age, Ca²⁺, Mg²⁺, 25(OH)D, 1,25(OH)₂D and sex as explanatory variables to determine the effect of each covariate on the response variable. For subjects <38 years, 25(OH)D was the most important parameter in regulating PTH. For subjects ≥38 both 25(OH)D and Ca²⁺ levels regulated PTH secretion. Subjects with 25(OH)D < 13 ng/mL had average higher PTH; in this group only, subjects with Ca²⁺ ≥ 1.30 mmol/L had average lower PTH compared to subjects with Ca²⁺ < 1.30. The multivariate analysis showed that all variables had a significant effect (p < 0.001) on PTH. Anova Type III errors c indicated that 25(OH)D accounted for 32.1% of the total variance in PTH, Ca²⁺ accounted for 18% of the total variance, BMI for 14.3%, and 1,25(OH)₂D for 11.1%. The remaining percentage was attributable to age and sex. This was confirmed by the regression tree approach, where 25(OH)D and Ca²⁺ accounted for the largest variation in the average levels of PTH.

DISCUSSION

Under stable conditions 25(OH)D plays a significant role in regulating PTH secretion. Under conditions of relative vitamin D sufficiency, Ca²⁺ also plays an important role.

Effects of vitamin D supplementation on bone turnover markers and other bone-related substances in subjects with vitamin D deficiency

In observational studies, vitamin D deficiency is a risk factor for low bone density and future fractures, whereas a causal relation has been difficult to show in randomized controlled trials (RCTs). Similarly, vitamin D deficiency has been associated with increased bone turnover, but RCTs with vitamin D have not shown conclusive effects. This could be due to inclusion of vitamin D sufficient subjects and low vitamin D doses. In the present study 399 subjects with mean baseline serum 25-hydroxyvitamin D (25(OH)D) 34.0 nmol/L completed a four months intervention with vitamin D₃ 20,000 IU per week versus placebo. Mean serum 25(OH)D increased to 89.0 nmol/L in the vitamin D group and decreased slightly in the placebo group. A small, but significant, decrease in the bone formation marker procollagen of type 1 amino-terminal propeptide (P1NP) was seen in the vitamin D group as compared to the placebo group (mean delta P1NP -1.2 pg/mL and 1.5 ng/mL, respectively, P < 0.01). No significant effects were seen on serum carboxyl-terminal telopeptide of type 1 collagen (CTX-1), Dickkopf-1, sclerostin, tumor necrosis factor-alpha, osteoprotegerin, receptor activator of nuclear factor ĸB ligand, or leptin. Subgroup analyses on subjects with low baseline serum 25(OH)D did not yield additional, significant results. In subjects with high baseline serum parathyroid hormone (PTH) > 6.5 pmol/L and post-intervention decrease in PTH, the decrease in P1NP was more pronounced, they also exhibited significantly reduced serum CTX-1 and increased serum sclerostin. In conclusion, supplementation with vitamin D appears to suppress bone turnover, possibly mediated by PTH reduction. Our findings need to be confirmed in even larger cohorts with vitamin D insufficient subjects.

Celiac disease and severe vitamin D deficiency: the case for anti-tissue transglutaminase antibody screening

Vitamin D-deficient Saudi adolescent girls were screened for anti-tissue transglutaminase (IgA-tTG) antibodies to determine whether the presence of severe vitamin D deficiency was associated with celiac disease. All 9 participants who were positive for IgA-tTG antibodies had severe vitamin D deficiency (25(OH)D < 12.5 nmol/l), suggesting that this population should be screened for celiac disease.

PURPOSE

The current cross-sectional study aimed to see if severe vitamin D deficiency is associated with celiac disease (CD) among Saudi adolescent girls.

METHODS

A total 200 adolescent females aged 13-19 years old with vitamin D deficiency (serum 25(OH)D < 50 nmol/l) were screened for IgA tTG (anti-tissue transglutaminase antibodies).

RESULTS

Of the 200 girls, 9 (4.5%) were positive for IgA tTG antibodies; all of whom had serum 25(OH)D < 12.5 nmol/l. A strong significant inverse association was observed between tTG antibody levels and serum 25(OH)D (R = - 0.53; p < 0.001) among antibody negative participants. Finally, participants with positive IgA tTG antibodies was 37.2 times higher for participants with 25(OH)D < 12.5 nmol/l than those whose vitamin D status was higher [OR = 37.2 (95% CI 4.6-299.7) (p = 0.0002)].

CONCLUSION

The data suggests that CD maybe a risk factor for severe vitamin D deficiency and that patients presenting with very low levels of 25(OH)D of less than 12.5 nmol/l-in the absence of an obvious cause-may need to be screened for CD.

Parathyroid Gland Response to Vitamin D Deficiency in Type 2 Diabetes Mellitus: An Observational Study

Background

Studies have linked vitamin D deficiency with the risk of type 2 diabetes mellitus (T2DM) and to the development of chronic complication of diabetes. Vitamin D receptors (VDR) have been found in many tissues in the body including the pancreas, a finding that indicates its role in insulin secretion. In addition, many studies have demonstrated the role of vitamin D and its receptor in insulin sensitivity and signal transduction. Vitamin D deficiency is common throughout the world, but not all vitamin D deficiencies are accompanied by a rise in parathyroid hormone (PTH). The present study was conducted to assess vitamin D deficiency in type 2 diabetic patients in comparison to healthy control and to determine parathyroid gland response to vitamin D deficiency in both groups.

Methods

This observational study was performed during a period from January to October 2018. The study included 151 type 2 diabetic patients selected from three diabetes clinics and 43 age and sex-matched healthy subjects. Informed consent and clinical information were obtained from all participants before the study. Results of the laboratory analysis for serum 25-hydroxyvitamin D (25-OHD), PTH, calcium, and phosphorous were recorded. The data was analyzed using the statistical package for the social sciences (SPSS) Statistics 17.

Results

The results showed low vitamin D concentration in both groups; however, there was no significant difference in vitamin D concentration between diabetic patients and the control patients. A high percentage of PTH level was found in severe vitamin D deficient diabetic patients and healthy controls. The higher percentage of diabetic and normal subjects with mild vitamin D deficiency had a normal PTH level. All healthy subjects with vitamin D insufficiency showed normal PTH concentration. About 10% of diabetic patients with severe vitamin D deficiency had a low PTH level.

Conclusion

The population in our study was generally deficient in 25-OHD irrespective of diabetes mellitus, indicating a greater need for vitamin D supplementation. Not all vitamin D deficient patients have high PTH levels, a finding that supports the emergence of new criteria for vitamin D deficiency, diagnosis and treatment, and highlights the importance of testing PTH in this regard.

Bone metabolism, density, and geometry in postmenopausal women with vitamin D insufficiency: a cross-sectional comparison of the effects of elevated parathyroid levels

Increased levels of parathyroid hormone (PTH) may have adverse effects on bone health. In a cross-sectional design, we investigated this hypothesis among 102 postmenopausal vitamin D insufficient women. Elevated PTH was associated with altered bone geometry, decreased bone mineral density in the spine, and increased bone turnover.

INTRODUCTION

In vitamin D insufficiency, elevated parathyroid hormone (PTH) levels may contribute to adverse effect on bone. We assessed effects of PTH responses to vitamin D insufficiency on bone metabolism, density, and geometry.

METHODS

Using a cross-sectional design, we investigated 102 healthy postmenopausal women with low 25-hydroxy-vitamin D (< 50 nmol/L) levels, who had either secondary hyperparathyroidism with elevated PTH levels (> 6.9 pmol/L, N = 51) or normal PTH levels (N = 51). Bone mineral density (BMD) and bone geometry were assessed by Dual-Energy X-ray absorptiometry (DXA), quantitative computed tomography (QCT) and high-resolution peripheral QCT (HRpQCT) scans. Bone metabolism was assessed by biochemistry including bone turnover markers.

RESULTS

Levels of 25(OH)D were 38 (IQR 31-45) nmol/L with no differences between groups. PTH levels were 8.5 (IQR 7.5-9.5) in women with SHPT and 5.2 (4.4-6.6) pmol/L in women with normal PTH (p < 0.001). BMI and eGFR did not differ between groups. SHPT was associated with lower total- and trabecular bone area, lower cortical perimeter, and increased cortical area in tibia and radius. SHPT was associated with a lower weight-adjusted BMD at the lumbar spine (p < 0.05). High compared to normal PTH levels were associated with significantly lower plasma levels of 1,25(OH)₂D, phosphate, but higher levels of osteocalcin and borderline higher levels of CTx. PTH correlated to osteocalcin and CTx.

CONCLUSIONS

High PTH levels are associated with altered bone geometry, increased bone turnover, and reduced BMD at the spine. Whether an increased cortical thickness with a lower trabecular volume is an effect of PTH or not needs further elucidations.

Vitamin D and Ageing

One hundred years has passed since the discovery of vitamin D as the active component of cod-liver oil which cured the bone disease rickets. Since then our knowledge of vitamin D has expanded tremendously and has included recognition of the importance of UV radiation as a source of the vitamin as well as the discovery of the vitamin as a nutrient, a pro-hormone and a potent steroid hormone with a major role in calcium and bone metabolism. In the last 25 years or so, the discovery of the vitamin D receptor in over 30 different body tissues together with the existence of the alpha-1-hydroxylase enzyme in these tissues provided evidence of a pleiotropic role of vitamin D outside its classical role in the skeleton. These important discoveries have provided the basis for the increasing interest in vitamin D in the context of nutritional requirements for health including the prevention of chronic diseases of ageing. The recent publication of the Dietary Reference Intake report on vitamin D and calcium by the North American Institute of Medicine (IOM) is the most comprehensive report to date on the basis for setting nutritional requirements for vitamin D. This chapter will summarize the nutritional aspects of vitamin D and discuss the changes in vitamin D metabolism and requirements with ageing. It will summarize key evidence on the relationship between vitamin D status and some of the main ageing related health outcomes including bone, muscle and cognitive health as well as survival focusing on the published literature in very-old adults (those >= 85 years of age).

Vitamin D deficiency and biochemical variations among urban Saudi adolescent girls according to season

Objectives:

To determine seasonal variations in the vitamin D status of Saudi adolescent girls in Riyadh, Kingdom of Saudi Arabia (KSA) and its effect in biochemical and clinical characteristics.

Methods:

In this prospective study, a total of 2000 Saudi females aged 12-18 years from different schools in Riyadh, KSA participated and submitted a generalized questionnaire with clinical information. Fasting blood samples were obtained in 1618 subjects for the winter season (December to February) and only 499 subjects returned to submit fasting blood samples for the summer season (June-August). Circulating serum 25(OH)D, parathyroid hormone (PTH), and other biomarkers of bone remodeling were measured during both seasons.

Results:

Vitamin D deficiency (serum 25(OH)D <25 nmol/L) was significantly higher during summer than winter (63.5% versus 40.8%; p<0.001). Mean serum PTH was also significantly higher during summer than winter (p<0.01). In all subjects, serum PTH showed a significant inverse association with 25(OH)D at levels below 40 nmol/L (r=-0.21; p<0.001). The prevalence of subjects having clinical and metabolic manifestations suggestive of osteomalacia was 2.1% (N=33 out of 1548).

Conclusion:

Seasonal variations in the vitamin D status of Saudi adolescent females significantly modifies biochemical parameters as response to vitamin D status change. In the meantime, heightened public health awareness should be given to populations at higher risk for vitamin D deficiency.

Attenuated PTH responsiveness to vitamin D deficiency among patients with type 2 diabetes and chronic hyperglycemia

BACKGROUND

The short and long-term relationship between hyperglycemia and PTH level among patients suffering from both diabetes type 2 and vitamin D deficiency were evaluated.

METHODS

This was a cross sectional study performed at Dubai Diabetes Center, UAE. To demonstrate the relationship between hyperglycemia and PTH level, subjects with type 2 diabetes and vitamin D deficiency (124 adults) were divided into 4 groups based on their FPG and HbA1c levels.

RESULTS

Mean vitamin D and PTH levels among subjects with HbA1c≤7% (53mmol/mol) were 14.05ng/ml and 19.51pg/ml respectively. On the other hand, mean vitamin D and PTH levels among subjects with HbA1c≥10% (86mmol/mol) were significantly lower at 11.77ng/ml and 17.75pg/ml respectively. The product of vitamin D and PTH among subjects with an HbA1c≤7% (53mmol/mol) was 250.380, compared with only 197.710 among subjects with HbA1c≥10 (86mmol/mol). Regression analysis for subjects older than 50years shows a significant negative effect of HbA1c on the PTH level. Mean calcium level among subjects with HbA1c≤7% (53mmol/mol) was 8.80mg/dl compared with 8.94mg/dl when HbA1c is ≥10% (86mmol/mol) with no statistical difference. Although high FPG was associated with a lower PTH level, such association was not statistically significant.

CONCLUSIONS

Chronic hyperglycemia, as assessed by A1C level, is associated with a significantly attenuated PTH responsiveness to vitamin D deficiency without a significant change in calcium level. On the other hand, there was no significant association between FPG and PTH level.

Parameters of Calcium Metabolism Fluctuated during Initiation or Changing of Antipsychotic Drugs

OBJECTIVE

Serum parameters of calcium homeostasis were measured based on previously published evidence linking osteoporotic fractures and/or bone/mineral loss with antipsychotics.

METHODS

Prospective, four-week, time-series trial was conducted and study population consisted of patients of both genders, aged 35-85 years, admitted within the routine practice, with acute psychotic symptoms, to whom an antipsychotic drug was either introduced or substituted. Serial measurements of serum calcium, phosphorous, magnesium, 25(OH)D, parathyroid hormone, calcitonin, osteocalcin and C-telopeptide were made from patient venous blood samples.

RESULTS

Calcium serum concentrations significantly decreased from baseline to the fourth week (2.42±0.12 vs. 2.33±0.16 mmol/L, p=0.022, n=25). The mean of all calcemia changes from the baseline was -2.6±5.7% (-24.1 to 7.7) with more decreases than increases (78 vs. 49, p=0.010) and more patents having negative sum of calcemia changes from baseline (n=28) than positive ones (n=10) (p=0.004). There were simultaneous falls of calcium and magnesium from baseline (63/15 vs. 23/26, p<0.001; OR=4.75, 95% CI 2.14-10.51), phosphorous (45/33 vs. 9/40, p<0.001; 6.06, 2.59-14.20) and 25(OH)D concentrations (57/21 vs. 13/35, p<0.001; 7.31, 3.25-16.42), respectively. Calcemia positively correlated with magnesemia, phosphatemia and 25(OH)D values. Parathyroid hormone and C-telopeptide showed only subtle oscillations of their absolute concentrations or changes from baseline; calcitonin and osteocalcin did not change. Adjustment of final calcemia trend (depletion/accumulation) for relevant risk factors, generally, did not change the results.

CONCLUSION

In patients with psychotic disorders and several risks for bone metabolism disturbances antipsychotic treatment was associated with the decrease of calcemia and changes in levels of the associated ions.

High prevalence of vitamin D deficiency in patients with xeroderma pigmetosum-A under strict sun protection

BACKGROUND/OBJECTIVES

Xeroderma pigmentosum (XP) is a rare autosomal recessive disease characterized by defective repair of ultraviolet (UV) irradiation-induced DNA damage and high risk of skin cancer. Thus, these patients require strict photoprotection. Considering the importance of UV-mediated cutaneous vitamin D production, such rigorous photoprotection would cause vitamin D deficiency. Then, we have studied the vitamin D status in patients with XP-A, a group requiring the most strict photoprotection.

SUBJECTS/METHODS

Twenty-one patients with XP-A (aged 6-25) were evaluated for their vitamin D intake, serum levels of 25-hydroxy-vitamin D (25OHD) and parathyroid hormone (PTH). Vitamin D intake was assessed by a 2-day food weighing method.

RESULTS

Median dietary intake of vitamin D was 4.1 μg/day, and the median concentrations of serum 25OHD and PTH were 7.7 and 49.9 pg/ml, respectively. In 76% of the patients, serum 25OHD level was lower than 10 ng/ml, indicating vitamin D deficiency. Vitamin D intake and serum 25OHD level were significantly lower in patients under enteral nutrition (EN) than those with oral intake (OI). Multivariate analyses revealed that EN was a significant predictor of decreased serum 25OHD level (β coefficient=-0.59, P=0.03).

CONCLUSIONS

Vitamin D deficiency is highly prevalent in XP-A patients, and supplementation should be considered to avoid unfavorable skeletal consequences in these patients. In addition, determination of dietary vitamin D requirement has been a difficult work issue in the decision of dietary reference intakes (DRIs) because of its cutaneous production. Data from XP patients would yield useful information for the determination of DRIs for vitamin D.

Estimation of magnesium in patients with functional hypoparathyroidism

CONTEXT

It is evident that about 30-50% of patients with Vitamin D deficiency (VDD) do not manifest develop secondary hyperparathyroidism (SHPT). A number of theories have been proposed to explain this lack of SHPT, including hypomagnesemia.

SETTINGS AND DESIGN

Retrospective review of laboratory database.

MATERIALS AND METHODS

We evaluated the differences in serum magnesium (Mg) levels among those with VDD with or without SHPT. A retrospective review of 6255 laboratory data of bone mineral profiles performed in the period of 2007-2013. After excluding patients with hypercalcemia, renal dysfunction/unknown kidney function and primary hypothyroidism, the remaining 1323 patient data were analyzed. SHPT was defined as serum parathyroid hormone >65 in those with VDD.

STATISTICAL ANALYSIS USED

ANOVA and Wilcoxon tests as appropriate to compare means. Multivariate logistic regression to analyze relation between variables and outcome of SHPT.

RESULTS

We noted that 55% patients (n = 727) had VDD, and among those who had VDD, 23% (n = 170) were hypocalcemic (corrected serum calcium <8.5). Patients with VDD who did not exhibit SHPT were 56% (n = 407). The mean (±standard deviation) serum Mg levels in the entire cohort (n = 1323) was 1.94 ± 0.26 mg/dl and 1.95 ± 0.26 mg/dl in VDD cohort and 2 ± 0.31 mg/dl in the VDD-hypocalcemic cohort. There was no statistical difference in the Mg levels among those with SHPT compared to those without SHPT (P = 0.14). Serum calcium and phosphorus were lower in those with SHPT (P = 0.06 and P < 0.001, respectively). In multivariate logistic regression, serum calcium (P = 0.043), phosphorus (P < 0.001) and severe VDD (P < 0.001) independently correlated with occurrence of SHPT in VDD.

CONCLUSIONS

Serum Mg levels did not explain the functional hypoparathyroidism seen in about half of the patients with VDD. A low normal serum calcium and phosphorus levels are more likely to be associated with VDD patients who develop SHPT.

Prognostic value of serum parathyroid hormone level in acute decompensated heart failure

BACKGROUND

Secondary hyperparathyroidism develops as a compensatory response to chronic heart failure (HF) and renal failure. The role of parathyroid hormone (PTH) level in acute decompensated HF remains unclear. The aim of this study was therefore to investigate the relationships among mortality, renal function, and serum PTH level in acute decompensated HF patients. METHODS AND RESULTS: A total of 266 consecutive patients admitted for acute decompensated HF without acute coronary syndrome (78±12 years; 48% male) were enrolled. Demographic, clinical, and laboratory characteristics were obtained on admission.During 1-year follow-up, 65 patients (24%) died. Serum PTH level on admission was within the normal range (10-65 pg/ml) in 108 patients (41%), of whom 39 (15%) had low-normal PTH (10-40 pg/ml). On Kaplan-Meier analysis all-cause mortality was significantly higher in patients with low-normal PTH than in those with high-normal (40-65 pg/ml) or high (>65 pg/ml) PTH (log-rank test). On univariate and multivariate Cox regression analysis, low-normal PTH was significantly associated with increased all-cause mortality (unadjusted HR, 2.88; 95% CI: 1.69-4.91; P<0.001; adjusted HR, 3.84; 95% CI: 1.54-9.57; P=0.004).

CONCLUSIONS

In patients with acute decompensated HF resulting in hospitalization, low-normal PTH on admission is associated with increased all-cause mortality, regardless of renal function.

Parathyroid-hormone variance is only marginally explained by a panel of determinants: a cross-sectional study of 909 hip-fracture patients

Several factors affect the levels of parathyroid hormone (PTH) in hip-fracture patients. We hypothesized that a panel of easily assessable determinants could account for both a substantial proportion of PTH variance and the occurrence of secondary hyperparathyroidism. We evaluated 909 of 981 hip-fracture inpatients admitted consecutively to our Rehabilitation division. In each patient we assessed PTH, 25-hydroxyvitamin D, albumin-adjusted total calcium, phosphate, magnesium, and creatinine on a fasting blood sample 21.3 ± 6.1 (mean ± SD) days after fracture occurrence. Glomerular filtration rate (GFR) was estimated by the 4-variable Modification of Diet in Renal Disease Study equation. Functional level was assessed using the Barthel index. On multivariate analysis, six factors (phosphate, albumin-adjusted total calcium, estimated GFR (eGFR), 25-hydroxyvitamin D, age, and magnesium) were significantly associated with PTH levels. Overall, the panel of variables accounted for 23.7 % of PTH variance. Among the 909 patients, 304 (33.4 %) had PTH levels exceeding the normal range. Six factors (phosphate, albumin-adjusted total calcium, eGFR, 25-hydroxyvitamin D, age, and Barthel index scores) were significantly associated with the category of PTH level (either normal or elevated). The model correctly classified 70.4 % of cases. For the optimal cut-off point, sensitivity was 80 % and specificity was 61 %. Data shows that six factors were significantly associated with PTH levels in hip-fracture inpatients. However, the six factors accounted for only 23.7 % of PTH variance and the presence or absence of secondary hyperparathyroidism was correctly categorized in a modest proportion of cases. We conclude that more knowledge is needed on the factors affecting PTH levels after hip fracture.

Variations in parathyroid hormone concentration in patients with low 25 hydroxyvitamin D

Although 25 hydroxyvitamin D (25OHD) and parathyroid hormone (PTH) levels are inversely related, less than half of the patients with a low vitamin D level have an elevated PTH, and, in most of these patients, the PTH does not immediately normalize with correction of the vitamin D.

INTRODUCTION

Despite the inverse relationship between 25OHD and PTH, patients with vitamin D deficiency seen in clinical practice do not always have an elevated PTH, and, in those with secondary hyperparathyroidism, the PTH does not always normalize with correction of vitamin D deficiency. We examined variations in PTH concentrations in patients with low 25OHD and studied changes in the PTH concentration with restoration of vitamin D sufficiency.

METHODS

This was a retrospective cohort study of patients with a 25OHD < 30 ng/mL and a concomitant PTH measurement seen at the Metabolic Bone Disease Clinic at a tertiary care center between July 1, 2007 and May 31, 2011. Patients with conditions associated with alterations in PTH were excluded.

RESULTS

The study population consisted of 104 patients. The mean age was 55.5 years, and 83 % were female. The 25OHD and PTH were negatively correlated, but only 30 % of patients with a 25OHD < 30 ng/mL and 40 % of those with a 25OHD < 20 ng/mL had an elevated PTH. As the 25OHD increased to 30 ng/mL or higher, the PTH decreased significantly in the group of patients who had an elevated PTH at baseline, but only 44 % reached a normal PTH. Of patients with a normal PTH at baseline, 59 % experienced a drop in their PTH while the PTH remained unchanged or increased in 41 %.

CONCLUSIONS

PTH has a limited role in defining vitamin D status in individual patients and in guiding vitamin D therapy in clinical practice.

Association between serum level of magnesium and postmenopausal osteoporosis: a meta-analysis

There are conflicting reports as to the association between serum level of magnesium (Mg) and postmenopausal osteoporosis (OP). The purpose of the present study is to clarify the association between serum level of Mg and postmenopausal OP using a meta-analysis approach. We searched articles indexed in Pubmed and the Chinese Journal Full-text Database (CJFD) published as of October 2013 that met our predefined criteria. Seven eligible studies involving 1,349 postmenopausal women from 12 case-control study arms were identified. Overall, pooled analysis indicated that postmenopausal osteoporotic women had a lower serum level of Mg than the healthy controls (standardized mean difference [SMD]=-0.55, 95 % confidence interval [CI]=-0.83 to -0.26). Further subgroup analysis found a similar pattern in Turkey (SMD=-0.66, 95% CI=-0.99 to -0.32) and Belgium (SMD=-0.98, 95% CI=-1.91 to -0.05), but not in China (SMD=0.02, 95% CI=-0.21 to 0.26). And the difference of serum level of Mg between postmenopausal osteoporotic women and healthy controls below the age of 60 years (SMD=-0.61, 95% CI=-1.09 to -0.13) was similar to that among the population over 60 years (SMD=-0.49, 95% CI=-0.80 to -0.18).In conclusion, this meta-analysis suggests that the low serum level of Mg seems to be a risk factor for OP among the postmenopausal women. However, the subgroup analysis found that there was contradiction regarding races and geography, like China and Turkey. Thus, this finding needs further confirmation by trans-regional multicenter study to obtain better understanding of causal relationships between serum Mg and postmenopausal OP.

Osteoporosis in men

Osteoporosis in men causes significant morbidity and mortality. Bone health declines gradually, often insidiously; and in light of the advancing aging population poses a serious public health issue that is not well recognized. Studies of the past decade have expanded our understanding of the events within, as well as the regulation of, bone remodeling and provided better insight into the physiology and pathophysiology specific to the adult male skeleton. The clinical measurement of bone mineral density using dual-energy X-ray absorptiometry remains the gold standard for diagnosis of osteoporosis in males; and fracture risk assessment is now recognized as a preferred approach to guide treatment decisions. Utilizing surrogate end-points such as increasing bone mineral density and decreasing concentrations of bone resorption markers, clinical trials have demonstrated efficacy in pharmacological treatment of osteoporosis in the adult male. Unfortunately, few studies have evaluated the anti-fracture benefits in this population. Measurement of bone turnover markers may be an additional tool to monitor therapeutic responsiveness in addition to the measurement of bone mineral density.

Isotope concentrations from 24-h urine and 3-h serum samples can be used to measure intestinal magnesium absorption in postmenopausal women

Studies suggest a link between magnesium status and osteoporosis. One barrier to more conclusive research on the potential relation is measuring intestinal magnesium absorption (MgA), which requires the use of stable isotopes and a ≥6-d stool or 3-d urine collection. We evaluated alternative methods of measuring MgA. We administered 2 stable magnesium isotopes to 15 postmenopausal women (cohort 1) aged 62 ± 8 y with a dietary magnesium intake of 345 ± 72 mg/d. Participants fasted from 1200 h to 0700 h and then consumed breakfast with ∼23 mg of oral ²⁶Mg and ∼11 mg of i.v. ²⁵Mg. We measured magnesium isotope concentrations in 72-h urine, spot urine (36, 48, 60, and 72 h), and spot serum (1, 3, and 5 h) samples collected after isotope dosing. We calculated MgA using the dose-corrected fraction of isotope concentrations from the 72-h urine collection. We validated new methods in 10 postmenopausal women (cohort 2) aged 59 ± 5 y with a dietary magnesium intake of 325 ± 122 mg/d. In cohort 1, MgA based on the 72-h urine collection was 0.28 ± 0.08. The 72-h MgA correlated most highly with 0-24 h urine MgA value alone (ρ = 0.95, P < 0.001) or the mean of the 0-24 h urine and the 3-h (ρ = 0.93, P < 0.001) or 5-h (ρ = 0.96, P < 0.001) serum MgA values. In cohort 2, Bland-Altman bias was lowest (-0.003, P = 0.82) using means of the 0-24 h urine and 3-h serum MgA values. We conclude that means of 0-24 h urine and 3-h serum MgA provide a reasonable estimate of 72-h MgA. However, if researchers seek to identify small changes in MgA, we recommend a 3-d urine or extended stool collection.

Bone and mineral metabolism in patients undergoing Roux-en-Y gastric bypass

Despite effective weight reduction, the impact of bariatric surgery on bone is a major concern. Mechanisms include decreased mechanical loading, calcium and vitamin D malabsorption, deficiency in other nutrients, and alterations in fat- and gut-derived hormones. The evidence to support clinical care pathways to prevent bone loss and fractures is at this point weak.

INTRODUCTION

There is a growing concern regarding the potential deleterious impact of bariatric surgery on bone metabolism. This comprehensive review addresses this controversial topic.

METHODS

We reviewed and analyzed articles evaluating bone metabolism and mechanisms for the ensuing putative bone loss in adult patients exclusively undergoing Roux-en-Y gastric bypass (RYGB) surgery, for the period spanning 1942 till September 2012.

RESULTS

Mechanisms identified to contribute to alterations in bone metabolism after bypass surgery include: decreased mechanical loading, calcium and vitamin D malabsorption with secondary hyperparathyroidism, deficiency in other nutrients, in addition to alterations in adipokines, gonadal steroids, and gut-derived hormones favoring bone loss, with the exception of serotonin and glucagon-like peptide-1. The relative contribution of each of these hormones to changes in bone homeostasis after bypass surgery remains undefined. Bone loss reflected by a decline in bone mineral density (BMD) and an increase in bone turnover markers have been reported in many studies, limited for the most part by the exclusive use of dual energy X-ray absorptiometry. Well-designed long-term prospective trials with fractures as an outcome, and studies investigating the magnitude, reversibility, and impact of the observed metabolic changes on fracture outcomes are lacking.

CONCLUSION

Robust conclusions regarding bone loss and fracture outcome after RYGB surgery cannot be drawn at this time. Although not evidence based, baseline evaluation and sequential monitoring with measurement of BMD and calciotropic hormones seem appropriate, with adequate calcium and vitamin D replacement. Beneficial interventions remain unclear.

Guidelines for optimizing design and analysis of clinical studies of nutrient effects

Presented here is a system to standardize clinical studies of nutrient effects, using nutrient-specific physiological criteria. These guidelines are based mainly on analysis of the typical sigmoid curve of biological response to nutrients and are intended for design, interpretation, and pooling of studies of nutrient effects. Five rules have been articulated for individual studies of nutrients, and six for systematic reviews and/or meta-analyses.

Hormonal relationships to bone mass in elderly Spanish men as influenced by dietary calcium and vitamin D

We aim to evaluate whether calcium and vitamin D intake is associated with 25-hydroxyvitamin D (25-OH-Vitamin D₃) and parathyroid hormone (PTH) serum concentrations or is associated with either the phalangeal dual energy X-ray absorptiometry (pDXA) or the quantitative bone ultrasound (QUS) in independent elderly men. Serum PTH and 25-OH-Vitamin D₃ were measured in 195 healthy elderly men (mean age: 73.31 ± 5.10 year). Food intake was quantified using a dietetic scale. Participants with 25-OH-Vitamin D₃ levels ≥ 30 ng/mL (75 nmol/L) and a calcium intake of 800–1200 mg/day exhibited the lowest PTH levels (41.49 ± 16.72 ng/mL). The highest PTH levels (75.60 ± 14.16 ng/mL) were observed in the <30 ng/mL group 25-OH-Vitamin D₃ with a calcium intake >1200 mg/day. No significant differences in the serum PTH levels based on the serum 25-OH-Vitamin D3 levels were observed among participants with a calcium intake of 800–1200 mg/day. Serum PTH was inversely correlated with serum 25-OH-Vitamin D₃ in the entire patient sample (r = −0.288, p = 0.019). No differences in any of the three densitometry techniques were observed between any of the age groups in the 800–1200 mg/day and >1200 mg/day calcium intake groups. PTH levels correlate negatively with serum 25-OH-Vitamin D₃ levels, and neither calcium nor vitamin D intake exert a strong influence on either of the two parameters.

Vitamin D supplementation in older people (VDOP): Study protocol for a randomised controlled intervention trial with monthly oral dosing with 12,000 IU, 24,000 IU or 48,000 IU of vitamin D₃

The randomised, double blind intervention trial ‘Optimising Vitamin D Status in Older People’ (VDOP) will test the effect of three oral dosages of vitamin D given for one year on bone mineral density (BMD) and biochemical markers of vitamin D metabolism, bone turnover and safety in older people. VDOP is funded by Arthritis Research UK, supported through Newcastle University and MRC Human Nutrition Research and sponsored by the Newcastle upon Tyne Hospitals NHS Foundation Trust.^a

Vitamin D and bone health outcomes in older age

The aim of this review is to summarise the evidence linking vitamin D to bone health outcomes in older adults. A plethora of scientific evidence globally suggests that large proportions of people have vitamin D deficiency and are not meeting recommended intakes. Older adults are at particular risk of the consequences of vitamin D deficiency owing to a combination of physiological and behavioural factors. Epidemiological studies show that low vitamin D status is associated with a variety of negative skeletal consequences in older adults including osteomalacia, reduced bone mineral density, impaired Ca absorption and secondary hyperparathyroidism. There seems to be inconsistent evidence for a protective role of vitamin D supplementation alone on bone mass. However, it is generally accepted that vitamin D (17·5 μg/d) in combination with Ca (1200 mg/d) reduces bone loss among older white subjects. Evidence for a benefit of vitamin D supplementation alone on reducing fracture risk is varied. According to a recent Agency for Healthcare Research and Quality review in the USA the evidence base shows mixed results for a beneficial effect of vitamin D on decreasing overall fracture risk. Limitations such as poor compliance with treatment, incomplete assessment of vitamin D status and large drop-out rates however, have been highlighted within some studies. In conclusion, it is generally accepted that vitamin D in combination with Ca reduces the risk of non-vertebral fractures particularly those in institutional care. The lack of data on vitamin D and bone health outcomes in certain population groups such as diverse racial groups warrants attention.

Magnesium, vitamin D status and mortality: results from US National Health and Nutrition Examination Survey (NHANES) 2001 to 2006 and NHANES III

BACKGROUND

Magnesium plays an essential role in the synthesis and metabolism of vitamin D and magnesium supplementation substantially reversed the resistance to vitamin D treatment in patients with magnesium-dependent vitamin-D-resistant rickets. We hypothesized that dietary magnesium alone, particularly its interaction with vitamin D intake, contributes to serum 25-hydroxyvitamin D (25(OH)D) levels, and the associations between serum 25(OH)D and risk of mortality may be modified by magnesium intake level.

METHODS

We tested these novel hypotheses utilizing data from the National Health and Nutrition Examination Survey (NHANES) 2001 to 2006, a population-based cross-sectional study, and the NHANES III cohort, a population-based cohort study. Serum 25(OH)D was used to define vitamin D status. Mortality outcomes in the NHANES III cohort were determined by using probabilistic linkage with the National Death Index (NDI).

RESULTS

High intake of total, dietary or supplemental magnesium was independently associated with significantly reduced risks of vitamin D deficiency and insufficiency respectively. Intake of magnesium significantly interacted with intake of vitamin D in relation to risk of both vitamin D deficiency and insufficiency. Additionally, the inverse association between total magnesium intake and vitamin D insufficiency primarily appeared among populations at high risk of vitamin D insufficiency. Furthermore, the associations of serum 25(OH)D with mortality, particularly due to cardiovascular disease (CVD) and colorectal cancer, were modified by magnesium intake, and the inverse associations were primarily present among those with magnesium intake above the median.

CONCLUSIONS

Our preliminary findings indicate it is possible that magnesium intake alone or its interaction with vitamin D intake may contribute to vitamin D status. The associations between serum 25(OH)D and risk of mortality may be modified by the intake level of magnesium. Future studies, including cohort studies and clinical trials, are necessary to confirm the findings.

Magnesium and osteoporosis: current state of knowledge and future research directions

A tight control of magnesium homeostasis seems to be crucial for bone health. On the basis of experimental and epidemiological studies, both low and high magnesium have harmful effects on the bones. Magnesium deficiency contributes to osteoporosis directly by acting on crystal formation and on bone cells and indirectly by impacting on the secretion and the activity of parathyroid hormone and by promoting low grade inflammation. Less is known about the mechanisms responsible for the mineralization defects observed when magnesium is elevated. Overall, controlling and maintaining magnesium homeostasis represents a helpful intervention to maintain bone integrity.

Parathyroid hormone response to severe vitamin D deficiency is sex associated: an observational study of 571 hip fracture inpatients

OBJECTIVES

To investigate the association between sex and parathyroid hormone response to severe vitamin D deficiency after hip fracture.

DESIGN

Cross-sectional study.

SETTING

Rehabilitation hospital in Italy.

PARTICIPANTS

571 consecutive inpatients with hip fracture and severe vitamin D deficiency (serum 25-hydroxyvitamin D < 12ng/ml), without hypercalcemia or estimated glomerular filtration rate (GFR) < 15ml/min.

MEASUREMENTS

In each patient we assessed PTH (by two-site chemiluminescent enzyme-labelled immunometric assay), 25-hydroxyvitamin D (by immunoenzymatic assay), albumin-adjusted total calcium, phosphate, magnesium, and creatinine 21.3 ± 6.1 (mean ± SD) days after fracture occurrence. Functional level was assessed using the Barthel index. PTH response to vitamin D deficiency was classified as either secondary hyperparathyroidism (serum PTH >75pg/ml) or functional hypoparathyroidism, i.e., inappropriate normal levels of PTH (≤75pg/ml).

RESULTS

Among the 571 patients, 336 (59%) had functional hypoparathyroidism, whereas 235 (41%) had secondary hyperparathyroidism. PTH status was significantly different between sexes (p=0.003): we found functional hypoparathyroidism in 61% of women and 43% of men (secondary hyperparathyroidism in 39% of women and 57% of men). The significance of the between-sex difference was maintained after adjustment for age, estimated GFR, phosphate, albumin-adjusted total calcium, albumin, Barthel index scores, 25-hydroxyvitamin D, and hip fracture type (either cervical or trochanteric). The adjusted odds ratio was 1.85 (95%CI from 1.09 to 3.13; p=0.023).

CONCLUSIONS

Data shows that PTH response to vitamin D deficiency was sex-associated following a fracture of the hip. The higher prevalence of secondary hyperparathyroidism may play a role in the known prognostic disadvantage found in hip-fracture men.

Osteoporosis in chronic inflammatory disease: the role of malnutrition

Osteoporosis is a metabolic bone disorder affecting million of people worldwide. Increased understanding of bone disease has led to a greater recognition of factors affecting bones, and consequently many secondary causes of osteoporosis were demonstrated. In this study, we aim to explore possible causes of bone loss and fractures in subjects affected by chronic inflammatory disease and to suggest new targets for intervention. In fact several studies, evaluated to perform this study, suggest that the patients with chronic inflammatory disease could be at high risk for fractures due to bone loss as consequence of malnutrition, caused by inflammation and hormonal change. Consequently, some actions could derive from the considerations of these mechanisms: a change in actual approach of chronic patients, that may include the investigation on the possible presence of osteoporosis, as well as further research on this topic to find a better therapy to prevent osteoporosis considering all the mechanisms described.

Modifying effect of calcium/magnesium intake ratio and mortality: a population-based cohort study

OBJECTIVES

Magnesium (Mg) and calcium (Ca) antagonise each other in (re)absorption, inflammation and many other physiological activities. Based on mathematical estimation, the absorbed number of Ca or Mg depends on the dietary ratio of Ca to Mg intake. We hypothesise that the dietary Ca/Mg ratio modifies the effects of Ca and Mg on mortality due to gastrointestinal tract cancer and, perhaps, mortality due to diseases occurring in other organs or systems.

DESIGN

Prospective studies.

SETTING

Population-based cohort studies (The Shanghai Women's Health Study and the Shanghai Men's Health Study) conducted in Shanghai, China.

PARTICIPANTS

74 942 Chinese women aged 40-70 years and 61 500 Chinese men aged 40-74 years participated in the study.

PRIMARY OUTCOME MEASURES

All-cause mortality and disease-specific mortality.

RESULTS

In this Chinese population with a low Ca/Mg intake ratio (a median of 1.7 vs around 3.0 in US populations), intakes of Mg greater than US Recommended Daily Allowance (RDA) levels (320 mg/day among women and 420 mg/day among men) were related to increased risks of total mortality for both women and men. Consistent with our hypothesis, the Ca/Mg intake ratio significantly modified the associations of intakes of Ca and Mg with mortality risk, whereas no significant interactions between Ca and Mg in relation to outcome were found. The associations differed by gender. Among men with a Ca/Mg ratio >1.7, increased intakes of Ca and Mg were associated with reduced risks of total mortality, and mortality due to coronary heart diseases. In the same group, intake of Ca was associated with a reduced risk of mortality due to cancer. Among women with a Ca/Mg ratio ≤1.7, intake of Mg was associated with increased risks of total mortality, and mortality due to cardiovascular diseases and colorectal cancer.

CONCLUSIONS

These results, if confirmed, may help to understand the optimal balance between Ca and Mg in the aetiology and prevention of these common diseases and reduction in mortality.

Effects of age and serum 25-OH-vitamin D on serum parathyroid hormone levels

CONTEXT

Several studies define optimal serum 25-hydroxyvitamin D (25-OHD) levels based on serum PTH level reaching an asymptote. However, results differ widely, ranging from 25-OHD levels of 12-44 ng/ml: many studies are constrained by small sample size.

OBJECTIVE

The objective of the study was to determine the relationship between serum PTH and 25-OHD levels and age in a very large reference laboratory database.

DESIGN

This was a detailed cross-sectional analysis of 312,962 paired serum PTH and 25-OHD levels measured from July 2010 to June 2011.

RESULTS

Median PTH levels and the proportion of patients (PTH > 65 pg/ml), from 63 successive 25-OHD frequency classes of 5000 patients, provide smooth, exceptionally well-fitted curves (R(2) = 0.994 and R(2) = 0.995, respectively) without discernible inflection points or asymptotes but with striking age dependencies. Serum 25-OHD was below the recent Institute of Medicine sufficiency guidance of 20 ng/ml in 27% (85,000) of the subjects. More importantly, 40 and 51% of subjects (serum 25-OHD <20 and 10 ng/ml, respectively) had biochemical hyperparathyroidism (PTH > 65 pg/ml).

CONCLUSIONS

This analysis, despite inevitable inherent limitations, introduces several clinical implications. First, median 25-OHD-dependent PTH levels revealed no threshold above which increasing 25-OHD fails to further suppress PTH. Second, the large number of subjects with 25-OHD deficiency and hyperparathyroidism reinforces the Third International Workshop on Asymptomatic Primary Hyper parathyroidism's recommendations to test for, and replete, vitamin D depletion before considering parathyroidectomy. Third, strong age dependency of the PTH-25-OHD relationship likely reflects the composite effects of age-related decline in calcium absorption and renal function. Finally, this unselected large population database study could guide clinical management of patients based on an age-dependent, PTH-25-OHD continuum.

Bone health status of premenopausal healthy adult females in Pakistani females

Bone health status in healthy premenopausal females was assessed. We found high bone turnover in 36.8 % and vitamin D deficiency and insufficiency in 82.8 and 16.1 %, respectively, and secondary hyperparathyroidism in 25.9 % of the subjects. This is alarming as there is inability to achieve peak bone mass and predisposes to osteoporosis risk.

PURPOSE

This study aimed to assess bone health status in healthy females by using biochemical markers of bone metabolism in blood [N-telopeptide of type I collagen (NTx), 25-hydroxyvitamin D (25OHD), and plasma intact parathyroid hormone (iPTH)].

MATERIAL AND METHODS

One hundred and seventy-four healthy premenopausal female volunteers were recruited from an urban residential area in Karachi. Demographic details were collected on a preformed questionnaire. Blood samples for the estimation of serum NTx, 25OHD, and plasma iPTH were taken in a fasting state. Data were analyzed using Statistical Package for Social Sciences 16.0. A p value of <0.05 was considered as significant.

RESULTS

High bone turnover, as depicted by NTx, was seen in 36.8 % cases. Vitamin D deficiency, insufficiency, and sufficiency were seen in 82.8, 16.1, and 1.1 % respectively. Secondary hyperparathyroidism was present in 25.9 % of the subjects, while others had blunted PTH response. Significant correlates of bone health were serum 25OHD levels, duration of sun exposure, and the practice of wearing veil (p value < 0.001).

CONCLUSION

Bone turnover is high with high prevalence of vitamin D deficiency in apparently healthy premenopausal females predisposing them to higher risk for development of osteoporosis.

The association of bone mineral density and parathyroid hormone with serum magnesium in adult patients with sickle-cell anaemia

INTRODUCTION

Bone disorders including osteopenia and osteoporosis are a frequent cause of morbidity in sickle-cell disease (SCD). Magnesium (Mg) regulates some biological processes important in bone remodelling. We aimed to investigate whether serum Mg levels (sMg) may have an impact on bone mineral density (BMD) in sickle-cell anaemia (SCA).

MATERIAL AND METHODS

Sixty adults with SCA in steady-state and 20 age- and race-matched healthy blood donors were included in the study. The BMD was evaluated with respect to minerals and biochemical indices of bone metabolism. Multivariate analysis was performed to determine the factors influencing BMD.

RESULTS

The mean sMg concentration was 0.64 ±0.06 (reference range 0.7-1.2 mmol/l) for 34% of the population, and 0.86 ±0.08 mmol/l for 66%. There were significant differences between Mg groups and controls in BMD, phosphorus (PO(4)), parathyroid hormone (PTH) (p = 0.011, p = 0.011 and p = 0.0001 respectively) and osteocalcin (OC) (p = 0.030) levels. The sMg was found to be associated positively with serum calcium (Ca), PTH and OC (r = 0.585; r = 0.436; r = 0.351 respectively, all at p < 0.05), and negatively with PO(4) (r = -0.312; p < 0.05). Multivariate analysis demonstrated that only PTH (p < 0.05) was an independent factor for BMD. Moreover, it identified sMg, OC, and CTX as independent factors for PTH (all p < 0.05).

CONCLUSIONS

These results indicate that serum Mg may be a co-contributing factor in causing low BMD. However, other possible aetiologies including decreased PTH and increased bone turnover certainly play a role. Based on the present data, it is prudent to monitor sMg routinely in this patient population and treat the condition whenever possible.

Osteoporosis related to disease or therapy in patients with cancer

Osteoporosis is a major public health issue in the general population, particularly in postmenopausal women. Patients with cancer may not only be at risk for primary osteoporosis, but for secondary osteoporosis related to cancer therapies-particularly therapies that impair gonadal function, lead to loss of serum estrogen, and negatively affect bone turnover. Normal bone remodeling is influenced by the receptor activator for nuclear kappa-B ligand pathway, calcium, vitamin D, and other nutrition factors, as well as modifiable and nonmodifiable factors. Identifying which patients with cancer are at risk for bone mineral density loss is important and may include patients with breast or prostate cancer, some survivors of pediatric malignancies, and adults with other tumors. Nurses play a major role in identifying those patients and their risk for low-impact fractures, which can have a significant effect on patient morbidity and mortality. Counseling and teaching are central nursing functions, as well as safely administering therapies, particularly bisphosphonates and denosumab.