The effects of age and gender on parathyroid hormone dynamics

The association of milk and multiple food avoidance with growth parameters in infants and children

BACKGROUND

Recent studies reported that strict avoidance of milk products in cow's milk allergy (CMA) affects growth and bone turnover, causing negative calcium balance and changes in bone metabolism.

OBJECTIVE

To investigate biochemical parameters to predict bone turnover and its relations with height and weight measurements and nutritional intake.

METHODS

Height, weight, and body mass index z scores were plotted for age according to the World Health Organization. A 3-consecutive day food record was analyzed for nutritional values of foods. The blood levels of calcium, phosphorus, alkaline phosphatase, vitamin D, and parathyroid hormone (PTH) were determined.

RESULTS

The study included 69 controls, 66 children with isolated CMA, and 59 children with multiple food allergy (FA). The z scores for weight, height, and body mass index were lower in isolated CMA and multiple FA groups than controls (P < .001, P = .004, and P = .002, respectively). The nutritional intakes of protein, fat, carbohydrates, vitamins B2 and B12, niacin, calcium, and phosphorus were significantly lower in isolated CMA and multiple FA than controls. In infants (≤2 years of age), although blood calcium level was in normal range, it was significantly lower in isolated CMA and multiple FA than in controls (P < .001). In children older than 2 years, PTH level was significantly higher in isolated CMA and multiple FA groups than in controls (P = .003).

CONCLUSION

Our study revealed that children with isolated CMA and multiple FA had a high nutrition gap, growth deceleration, and unbalanced bone metabolism, as illustrated by low blood calcium and elevated PTH levels.

Leg restlessness and hyperparathyroidism in Parkinson's disease, a further clue to RLS pathogenesis?

Background

Non-motor manifestations are the main features of Parkinson's disease (PD). These have been associated with vitamin D abnormalities, but the role of parathormone (PTH) is still obscure. Among the non-motor symptoms of PD, the pathogenesis of restless leg syndrome (RLS) is still debated, but it has been associated with the vitamin D/PTH axis in other disease models. Our study deepens the association between vitamin D and PTH with the prevalence of non-motor symptoms of PD and explores such a relationship in patients reporting leg restlessness.

Methods

Fifty patients with PD were extensively investigated with motor and non-motor scales. Data on serum levels of vitamin D, PTH, and related metabolites were obtained, and patients were stratified as having vitamin D deficiency or hyperparathyroidism according to standardized criteria.

Results

Overall, 80% of patients with PD exhibited low vitamin D levels, and hyperparathyroidism was diagnosed in 45%. The analysis of the non-motor symptoms profile using the non-motor symptom questionnaire (NMSQ) revealed 36% of leg restlessness, a main feature of RLS. This was significantly associated with worse motor symptoms, quality of sleep, and quality of life. Moreover, it was associated with hyperparathyroidism (OR: 3.48) and with PTH levels, independent of vitamin D, calcium/phosphate levels, and motor status.

Conclusion

Our results suggest a significant association between the vitamin D/PTH axis and leg restlessness in PD. PTH has a putative role in nociceptive modulation, and previous evidence on hyperparathyroidism has suggested a possible interrelation with RLS. Further investigations are necessary to add PTH to the non-dopaminergic non-motor landscape of PD.

Primary hyperparathyroidism in the geriatric population: A case report and mini literature review

We report a case of a 93‐year‐old woman with PHPT secondary to a left inferior parathyroid adenoma. The patient met criteria to be a surgical candidate; however, literature about parathyroidectomy in the elderly was limited and controversial. The patient remained stable through medical management for the next 5 years.

Diagnosis and management of PHPT in the geriatric population remains challenging. Although parathyroidectomy is the definitive treatment in the general population, medical management can be strongly considered in the geriatric population with PHPT.

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.

A Clinical Review of the Psychiatric Sequelae of Primary Hyperparathyroidism

Despite one-quarter of patients with primary hyperparathyroidism (PHPT) experiencing psychiatric symptoms, there remains a dearth of literature regarding the diagnosis and further management of psychiatric sequelae in PHPT. We aim to review the literature pertaining to the epidemiology, disease presentation, pathophysiology, diagnostics, and therapeutics regarding psychiatric sequelae of PHPT with an emphasis on clinical pearls for practicing psychiatrists. A literature search was conducted using the US National Library of Medicine’s PubMed resource using the following keywords in various combinations: primary hyperparathyroidism, neuropsychiatric, calcium, psychosis, mania, depression, catatonia, delirium, parathyroidectomy, and psychotropic medication. We discuss in depth all aspects of the diagnosis and management of psychiatric sequela in PHPT. We have also identified epidemiological trends, discussed the most common clinical presentations, and postulated possible mechanisms for psychiatric symptoms in PHPT. Psychiatrists should maintain diagnostic suspicion for PHPT in older adult female patients presenting with new-onset psychiatric illness. Several mechanisms involving the following may explain the variety of psychiatric symptoms in PHPT: tyrosine hydroxylase, parathyroid hormone, interleukin-6, monoamine oxidase, calcium, and the sodium-potassium adenosine triphosphatase transporter. We recommend psychiatrists take a symptom-oriented approach to management. Treating a patient’s psychosis, mania, depression, catatonia, delirium, or eating disorder pathology via conventional therapeutics seems like a rational approach despite the underlying medical etiology. Only parathyroidectomy has been proven to be definitive in the complete amelioration of psychiatric symptoms.

Molecular Interactions between Dietary Lipids and Bone Tissue during Aging

Age-related bone disorders such as osteoporosis or osteoarthritis are a major public health problem due to the functional disability for millions of people worldwide. Furthermore, fractures are associated with a higher degree of morbidity and mortality in the long term, which generates greater financial and health costs. As the world population becomes older, the incidence of this type of disease increases and this effect seems notably greater in those countries that present a more westernized lifestyle. Thus, increased efforts are directed toward reducing risks that need to focus not only on the prevention of bone diseases, but also on the treatment of persons already afflicted. Evidence is accumulating that dietary lipids play an important role in bone health which results relevant to develop effective interventions for prevent bone diseases or alterations, especially in the elderly segment of the population. This review focuses on evidence about the effects of dietary lipids on bone health and describes possible mechanisms to explain how lipids act on bone metabolism during aging. Little work, however, has been accomplished in humans, so this is a challenge for future research.

Sex-Specific Relationship Between Parathyroid Hormone and Platelet Indices in Phenotypes of Heart Failure-Results From the MyoVasc Study

Background: Heart failure (HF) is a multifactorial syndrome with pathophysiological complexities still not fully understood. Higher mean platelet volume (MPV), a potential marker of platelet activation, and high concentrations of parathyroid hormone (PTH) have been implicated in the pathogenesis of HF.

Aim: This study aims to investigate sex-specifically the association between PTH concentrations and platelet indices in phenotypes of HF.

Methods and Results: PTH and platelet indices (MPV and platelet count) were available in 1,896 participants from the MyoVasc study in Mainz, Germany. Multivariable linear regression models, adjusted for age, sex, season, vitamin D status, cardiovascular risk factors, comorbidities, estimated glomerular filtration rate, and medication, were used to assess the associations between platelet indices and PTH. The results showed distinct sex-specific associations between PTH and platelet indices. A positive association between PTH and MPV was found in females with symptomatic HF with reduced ejection fraction (HFrEF) only [β = 0.60 (0.19; 1.00)]. Platelet count was inversely associated with PTH in male HFrEF individuals [β = −7.6 (−15; −0.30)] and in both males and females with HF with preserved ejection fraction (HFpEF).

Conclusion: This study reports differential, sex-specific relationships between PTH and platelet indices in HF individuals independent of vitamin D status and clinical profile. Particularly in phenotypes of symptomatic HF, distinct associations were observed, suggesting a sex-specific mechanism involved in the interaction between PTH and platelets.

Association between Vitamin D and Heart Failure Mortality in 10,974 Hospitalized Individuals

A broad range of chronic conditions, including heart failure (HF), have been associated with vitamin D deficiency. Existing clinical trials involving vitamin D supplementation in chronic HF patients have been inconclusive. We sought to evaluate the outcomes of patients with vitamin D supplementation, compared with a matched cohort using real-world big data of HF hospitalization. This study was based on the Diagnosis Procedure Combination database in the Japanese Registry of All Cardiac and Vascular Datasets (JROAD-DPC). After exclusion criteria, we identified 93,692 patients who were first hospitalized with HF between April 2012 and March 2017 (mean age was 79 ± 12 years, and 52.2% were male). Propensity score (PS) was estimated with logistic regression model, with vitamin D supplementation as the dependent variable and clinically relevant covariates. On PS-matched analysis with 10,974 patients, patients with vitamin D supplementation had lower total in-hospital mortality (6.5 vs. 9.4%, odds ratio: 0.67, p < 0.001) and in-hospital mortality within 7 days and 30 days (0.9 vs. 2.5%, OR, 0.34, and 3.8 vs. 6.5%, OR: 0.56, both p < 0.001). In the sub-group analysis, mortalities in patients with age < 75, diabetes, dyslipidemia, atrial arrhythmia, cancer, renin-angiotensin system blocker, and β-blocker were not affected by vitamin D supplementation. Patients with vitamin D supplementation had a lower in-hospital mortality for HF than patients without vitamin D supplementation in the propensity matched cohort. The identification of specific clinical characteristics in patients benefitting from vitamin D may be useful for determining targets of future randomized control trials.

Tiempo óptimo para medición de paratohormona como predictor de hipocalcemia en pacientes posterior a tiroidectomía total

Introducción. La hipocalcemia posterior a tiroidectomía total es una complicación frecuente en la cirugía de tiroides. La hormona paratiroidea ha demostrado ser un predictor confiable para detectar los pacientes con alto riesgo de hipocalcemia significativa y la consecuente necesidad de administrar suplemento de calcio. El objetivo de este estudio fue determinar el tiempo óptimo de medición de la paratohormona para dicho fin. Métodos. Estudio prospectivo realizado en dos instituciones de nivel III en Popayán, Colombia, entre abril de 2016 y febrero de 2018, en el cual se midieron niveles de paratohormona prequirúrgico, a las 0, 2, 4 y 12 horas del postoperatorio, y se compararon con los valores obtenidos a los 3 meses de seguimiento en pacientes sometidos a tiroidectomía total. Se consideró como grupos de riesgo y con necesidad de suplemento de calcio un valor de paratohormona menor de 10 pg/ml o una disminución mayor del 80 % con respecto al valor prequirúrgico. Resultados. Se incluyeron 34 pacientes intervenidos. Tomando como umbral un valor menor de 10 pg/ml, la medición de paratohormona a las 4 horas fue sensible y específica (60 y 93,1 % respectivamente). Para una disminución mayor del 80 % con respecto al valor prequirúrgico, la sensibilidad fue del 60 % y la especificidad del 96,5 %, presentando un valor predictivo positivo de 75 % y negativo del 93,3 %, con una p < 0,001. Discusión. Una disminución mayor del 80 % del valor de paratohormona prequirúrgico medida a las 4 horas después de la tiroidectomía total permite identificar aquellos pacientes con alto riesgo de hipocalcemia significativa, que requieren administración temprana de suplementos de calcio, comparado con la determinación de la disminución a las 0, 2 y 12 horas postoperatorias.

Physical Activity-Dependent Regulation of Parathyroid Hormone and Calcium-Phosphorous Metabolism

Exercise perturbs homeostasis, alters the levels of circulating mediators and hormones, and increases the demand by skeletal muscles and other vital organs for energy substrates. Exercise also affects bone and mineral metabolism, particularly calcium and phosphate, both of which are essential for muscle contraction, neuromuscular signaling, biosynthesis of adenosine triphosphate (ATP), and other energy substrates. Parathyroid hormone (PTH) is involved in the regulation of calcium and phosphate homeostasis. Understanding the effects of exercise on PTH secretion is fundamental for appreciating how the body adapts to exercise. Altered PTH metabolism underlies hyperparathyroidism and hypoparathyroidism, the complications of which affect the organs involved in calcium and phosphorous metabolism (bone and kidney) and other body systems as well. Exercise affects PTH expression and secretion by altering the circulating levels of calcium and phosphate. In turn, PTH responds directly to exercise and exercise-induced myokines. Here, we review the main concepts of the regulation of PTH expression and secretion under physiological conditions, in acute and chronic exercise, and in relation to PTH-related disorders.

A 39 year-old woman with milk-alkali syndrome complicated by posterior reversible encephalopathy syndrome

Milk-alkali syndrome (MAS) is characterized by the triad of hypercalcemia, metabolic alkalosis, and acute kidney injury. Once thought to be a rare condition, there has been a resurgence of cases due to the consumption of calcium-containing supplements for osteoporosis prevention and dyspepsia in the general population. We describe the case of a female who presented with acute encephalopathy, hypercalcemia, and new-onset seizure. An extensive hypercalcemia workup and ruling out of other causes led to the diagnosis of MAS from excessive intake of calcium carbonate. Brain magnetic resonance imaging revealed signal abnormalities in the occipital and posterior parietal lobes that were indicative of posterior reversible encephalopathy syndrome. The patient's encephalopathy resolved after treatment of her hypercalcemia with fluid resuscitation and cessation of her calcium supplements. We present our case to highlight this unusual presentation of MAS, challenges in diagnosis, and briefly discuss the pathophysiology underlying hypercalcemia-induced encephalopathy.

Serum parathyroid hormone levels in patients with chronic right heart failure

Parathyroid hormone (PTH) is a novel cardiovascular biomarker which is particularly useful for detection and assessment of heart failure (HF). However, previous studies examining PTH in heart failure have primarily focused on left HF; thus, the relationship between PTH and right HF remains unclear. The aim of the present study was to evaluate the serum PTH levels in patients with chronic right HF. A total of 154 patients with chronic right HF were enrolled in the present study. A binary logistic regression analysis model was used to assess the independent predictive value of PTH levels in chronic right HF. Partial correlative analysis was used to demonstrate the relevance of PTH levels on the parameters of assessment of right heart function. A multiple linear regression analysis model was used to evaluate the independent factors of PTH levels in patients with right HF. The results showed that the serum PTH levels in the right HF group were significantly higher compared with the control group. After adjusting for predictors of right HF, serum PTH levels were associated with right HF with an odds ratio of 1.066 (95% confidence interval: 1.030-1.102, P<0.001. Serum PTH levels were independently correlated with plasma N-terminal pro-B-type natriuretic peptide levels, right ventricular end-diastolic diameter and severity of lower extremity edema (all P<0.05). Therefore, based on the results of the present study, PTH may be a useful biomarker for detection and assessment of right HF.

Older Age Is Associated with Decreased Levels of VDR, CYP27B1, and CYP24A1 and Increased Levels of PTH in Human Parathyroid Glands

Parathyroid glands contain the vitamin D receptor (VDR) and 25-hydroxyvitamin D-1α-hydroxylase (CYP27B1) and 24-hydroxylase (CYP24A1), which catalyze the production and degradation of 1,25-dihydroxyvitamin D [1,25(OH)₂D], respectively. Previous studies have shown that the serum level of intact parathyroid hormone (iPTH) increases with age. We hypothesized that the expression of CYP27B1 or VDR in parathyroid glands decreases with age, which might account for the increased serum levels of iPTH due to decreased suppression of parathyroid hormone (PTH) secretion by 1,25(OH)₂D in older people. To test this hypothesis, we examined relative expression levels of VDR, CYP27B1, CYP24A1, and PTH in specimens from parathyroid glands unintentionally removed during thyroidectomy for 70 patients varying in age from 10 to 70 years. The results showed that there was an inverse correlation between age and VDR, CYP27B1, and CYP24A1 expression (p < 0.05). A significant positive correlation between PTH expression levels and age was also observed (p < 0.05). These data indicate that older age is associated with decreased levels of VDR, CYP27B1, and CYP24A1 and increased levels of PTH in human parathyroid glands.

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.

EFFECT OF AGE AND GENDER ON FASTING AND FOOD-STIMULATED LEVELS OF CALCITONIN, PARATHYROID, AND GASTRIN HORMONES IN HEALTHY ADULTS

Objective: To investigate the effect of age and gender on basal and food-stimulated serum calcitonin (CT), parathyroid hormone (PTH), and gastrin levels among healthy adults. Methods: Ninety-six healthy adults (76 men and 20 women) aged between 21 and 43 years were recruited. Serum CT, PTH, and gastrin levels were measured after a 9-hour overnight fast, and 1 and 3 hours postprandially. Results: PTH levels decreased early and increased late after feeding. This change was significant in men but not in women. CT levels increased in response to food intake in men but not in women. Gastrin levels were significantly increased after feeding in both men and women. Mean basal and food stimulated CT, PTH, and gastrin levels did not significantly differ between genders. Fasting and post-prandial PTH levels were higher while gastrin levels were lower in older subjects (>30 years old) compared to younger subjects (≤30 years old). Fasting and postprandial CT levels were not significantly different between age groups. Conclusion: Age had a significant effect on fasting and food-stimulated PTH and gastrin hormone levels. The effect of age on PTH levels was independent of baseline vitamin D levels. Men showed significant changes in CT and PTH levels in response to feeding compared to women, although the mean hormone levels were not significantly different between men and women. Abbreviations: CT = calcitonin; MTC = medullary thyroid carcinoma; PTH = parathyroid hormone; SD = standard deviation.

A Just-in-Time Learning Based Monitoring and Classification Method for Hyper/Hypocalcemia Diagnosis

This study focuses on the classification and pathological status monitoring of hyper/hypo-calcemia in the calcium regulatory system. By utilizing the Independent Component Analysis (ICA) mixture model, samples from healthy patients are collected, diagnosed, and subsequently classified according to their underlying behaviors, characteristics, and mechanisms. Then, a Just-in-Time Learning (JITL) has been employed in order to estimate the diseased status dynamically. In terms of JITL, for the purpose of the construction of an appropriate similarity index to identify relevant datasets, a novel similarity index based on the ICA mixture model is proposed in this paper to improve online model quality. The validity and effectiveness of the proposed approach have been demonstrated by applying it to the calcium regulatory system under various hypocalcemic and hypercalcemic diseased conditions.

Parathyroid hormone: Data mining for age-related reference intervals in adults

OBJECTIVE

Age-related changes in parathyroid hormone (PTH) have been previously documented in adults. However, because of the limitations of traditional approaches to establishing reference intervals, age-related reference intervals have not been defined. We sought to use a data mining approach to derive age-related PTH reference intervals.

DESIGN AND PARTICIPANTS

Results from patients undergoing PTH testing over a 4-year period were extracted from the database of a private pathology laboratory in New South Wales, Australia. Patients were included in the study if they were 18 years or older and had simultaneous determination of PTH, serum calcium, estimated glomerular filtration rate and 25-hydroxyvitamin D (25-OHD). Patients with abnormalities of serum calcium or renal function were excluded.

MEASUREMENTS

Bhattacharya analysis of log-transformed data was used to derive age-related PTH reference intervals across adulthood.

RESULTS

Results were available for 33 652 subjects. Among patients with optimal 25-OHD status, older age was associated with higher PTH concentrations. Age-related reference intervals were derived and showed a 63% increase in the upper and lower reference limits between the youngest (18-29 years of age) and the oldest (80 years of age or older) age partitions. The appropriateness of using a single reference interval for patients of all ages was evaluated against objective criteria and was found to be unsatisfactory.

CONCLUSIONS

Data mining was demonstrated to be a useful tool for establishing age-related PTH reference intervals. The technique demonstrated that increasing age is associated with higher PTH concentrations and that age-related reference intervals are important for accurate result interpretation.

Hypercalcemic pancreatitis a rare presentation of sarcoidosis: A case report

RATIONALE

The usual presentation of sarcoidosis is hilar adenopathy, pulmonary reticular opacities, skin, joint, or eye lesions. Pancreatic involvement is unusual and hypercalcemic pancreatitis as initial manifestation is very rare.

PATIENT CONCERNS

We present a case that presented with 1-day history of vomiting, diffuse abdominal pain, and altered mental status.

DIAGNOSES

Initial investigations showed highly elevated calcium levels, acute pancreatitis, and kidney failure. Possible causes entertained were malignancy, hyperparathyroidism, hypervitaminosis D, and granulomatous diseases. Full work-up including a hilar lymph node biopsy revealed noncaseating granuloma. After excluding other diseases capable of producing a similar picture, a diagnosis of sarcoidosis was made.

INTERVENTIONS AND OUTCOMES

The patient was started on aggressive intravenous fluid hydration and intravenous calcitonin, after which her altered mental status resolved and both kidney function and hypercalcemia improved. The patient was discharged on oral prednisone and serum calcium level normalized with progressive improvement of kidney function at follow-up.

LESSONS

The current case highlights the need for a high index of suspicion for this condition in patients who present with acute pancreatitis, as steroids are the treatment of choice. Thus, prompt recognition of this entity is of therapeutic significance.

Biochemistry of the menopause

The life of a human female is characterized from teenage years by monthly menstruation which ceases (the menopause) typically between the age of 40 and 60 years. The potential for reproduction declines and ceases as the ovaries become depleted of follicles. A transition period in mid-life, for 2 to 10 years, when menstruation is less regular is called the perimenopause. The menopause is associated with a significant decline in plasma concentrations of sex hormones, an increase in the concentrations of the gonadotrophins and changes in other hormones such as the inhibins. These changes are superimposed with effects of aging, social and metabolic factors, daily activity and well-being. Although the menopause is entirely natural, in some cases ovarian failure can occur earlier than usual; this is pathological and warrants careful biochemical investigations to distinguish it from conditions causing infertility. Elderly females are affected by a range of clinical disorders including endocrine, cardiovascular, skeletal, urogenital tract and immunological systems, body mass, vasomotor tone, mood and sleep pattern. Reference intervals for many diagnostic biochemical tests for the menopause need to be used when interpreting results in clinical investigations for patient management. The standardization and harmonization of assays are being addressed. Many women now choose to develop their career before bearing children, and the health service has had to change services around this. This review does not cover screening for and tests during pregnancy. The review is timely since the population is aging and there will be more demand on healthcare services.

Elderly patients with chronic kidney disease have higher risk of hyperparathyroidism

PURPOSE

As the world's population ages, the incidence of chronic kidney disease (CKD) is growing. There is ongoing debate regarding whether high levels of parathyroid hormone (PTH) would be more common in elderly than young patients, and which factors are driven the risk of secondary hyperparathyroidism (SHPT), independent of renal function.

METHODS

Elderly patients (age ≥ 65 years, N = 518) were compared to a 1:1 sex- and estimated glomerular filtration rate (eGFR)-matched sample of young patients (age < 65 years), in a cross-sectional analysis. Demographic, biochemical and drug prescription data were collected from electronic charts. The main outcome measure was the prevalence of SHPT, defined as PTH > 65 pg/mL.

RESULTS

Elderly patients presented higher serum calcium and PTH levels and lower serum phosphate, and were taking more diuretics than young patients. SHPT was more frequent among elderly patients (49.4 vs. 38.6%, p = 0.005), and it was associated with lower eGFR, low levels of 25(OH) vitamin D and with furosemide therapy, while thiazide use was a protector factor. Elderly patients with 25(OH) vitamin D > 40 ng/mL were protected against SHPT. The Ca/PTH ratio was lower in elderly than in young patients [0.15 (0.10, 0.20) vs. 0.16 (0.11, 0.23), respectively, p = 0.003].

CONCLUSION

CKD elderly patients have higher risk of SHPT than young, which cannot be explained solely by renal function. Besides low levels of vitamin D, furosemide therapy and a distinct relationship between calcium and PTH are possible factors contributing to SHPT. Whether this is a result of renal resistance to PTH or an altered set point to calcium deserves further investigation.

No association between frequent apheresis donation and risk of fractures: a retrospective cohort analysis from Sweden

BACKGROUND

Citrate anticoagulation during apheresis induces transient alterations in calcium homeostasis. It is unknown whether the repeated, transient alterations in calcium homeostasis experienced by repeated apheresis donors affects bone turnover to increase fracture risk. Our aim was to investigate the risk of osteoporotic and nonosteoporotic fracture among voluntary, frequent apheresis donors.

STUDY DESIGN AND METHODS

All apheresis donors were identified from the Scandinavian Donations and Transfusions database (SCANDAT2), which includes information on over 1.6 million blood donors from Sweden and Denmark from the years 1968 and 1981, respectively. Only data from Sweden were used for these analyses. Information on fractures was obtained by linking SCANDAT2 to hospital registers. Poisson regression was used to compute incidence rate ratios of fractures in relation to the cumulative number of apheresis donations, both overall and in fixed time windows.

RESULTS

In total, 140,289 apheresis donors (67,970 women and 72,319 men) were identified from the SCANDAT2 database and were followed for up to 23 years. We observed no association between the frequency of apheresis donation and the risk of fracture either in the overall study period or during fixed-length time windows. The incidence rate ratio of fractures in donors who had made 100 or more cumulative apheresis donations was 0.99 (95% confidence interval, 0.92-1.06) compared with donors who had made from 9 to 24 donations. The results were similar in analyses stratified by sex and restricted to postmenopausal women.

CONCLUSIONS

The absence of an association between repeated apheresis donation and fracture risk indicates that apheresis collection is safe with regard to bone health.

Effect of oral versus intramuscular Vitamin D replacement in apparently healthy adults with Vitamin D deficiency

CONTEXT

A number of controversies exist regarding appropriate treatment strategy for Vitamin D deficiency.

AIMS

The aim of this study was to investigate the efficacy of equivalent doses of oral cholecalciferol (60,000 IU weekly for 5 weeks) versus intramuscular (IM) cholecalciferol (300,000 IU) in correcting Vitamin D deficiency in apparently healthy volunteers working in a hospital.

SETTINGS AND DESIGN

Prospective randomized open-label single institution study.

SUBJECTS AND METHODS

This study enrolled 40 apparently healthy adults with Vitamin D deficiency into 2 arms. The oral cholecalciferol group (n = 20) received oral cholecalciferol 60,000 IU weekly for 5 weeks while the IM cholecalciferol group (n = 20) received a single injection of cholecalciferol 300,000 IU. The main outcome measure was serum 25-hydroxyvitamin D (25OHD) levels at baseline, 6 and 12 weeks after the intervention.

STATISTICAL ANALYSIS USED

Differences in serum 25OHD and other biochemical parameters at baseline and follow-up were analyzed using general linear model.

RESULTS

Mean 25OHD level at baseline was 5.99 ± 1.07 ng/mL and 7.40 ± 1.13 ng/mL (P = 0.332) in the oral cholecalciferol and IM cholecalciferol group, respectively. In the oral cholecalciferol group, serum 25OHD level was 20.20 ± 1.65 ng/mL at 6 weeks and 16.66 ± 1.36 ng/mL at 12 weeks. The corresponding serum 25OHD levels in the IM cholecalciferol group were 20.74 ± 1.81 ng/mL and 25.46 ± 1.37 ng/mL at 6 and 12 weeks, respectively. At 12 weeks, the mean 25OHD levels in IM cholecalciferol group was higher as compared to the oral cholecalciferol group (25.46 ± 1.37 vs. 16.66 ± 1.36 ng/mL; P < 0.001).

CONCLUSIONS

Both oral and IM routes are effective for the treatment of Vitamin D deficiency. 25-hydroxyvitamin D levels in the IM cholecalciferol group showed a sustained increase from baseline.

The effect of experimental osteoporosis on bone regeneration: Part 1, histology findings

OBJECTIVES

To histologically define the healing events occurring in calvarial critical size defects (CSDs) following treatment with a collagen barrier for guided bone regeneration (GBR) and a particulate graft in healthy and osteoporotic conditions.

MATERIAL AND METHODS

Thirty-six 10-month-old, female, Wistar rats were used in this study. Half of them were ovariectomized (OVX) and fed with a low-calcium diet to induce an osteoporotic-like status. In each animal of both groups, two 5-mm CSDs were created, one in the centre of each parietal bone, and they were treated with a deproteinized bovine bone mineral (DBBM) particulate graft and a bi-layer collagen membrane. Six OVX and six healthy control rats were randomly euthanized at 7, 14 and 30 days. One defect per animal was randomly processed for decalcified histology. Three central sections were used for qualitative histology and histomorphometric analysis.

RESULTS

No significant difference in terms of percentage of newly formed bone was detected between the two groups at the different healing periods. However, a trend towards less bone formation and of poorer quality, expressed as reduced bone maturation, was detected in the OVX animals at 30 days.

DISCUSSION

According to this study, GBR with a collagen barrier and a DBBM graft can be successfully obtained also in osteoporotic-like conditions. Future studies considering longer healing periods and controlling for the confounding factors arising from the use of a particulate graft are needed to confirm these data.

A model of calcium homeostasis in the rat

We developed a model of calcium homeostasis in the rat to better understand the impact of dysfunctions such as primary hyperparathyroidism and vitamin D deficiency on calcium balance. The model accounts for the regulation of calcium intestinal uptake, bone resorption, and renal reabsorption by parathyroid hormone (PTH), vitamin D₃, and Ca²⁺ itself. It is the first such model to incorporate recent findings regarding the role of the calcium-sensing receptor (CaSR) in the kidney, the presence of a rapidly exchangeable pool in bone, and the delayed response of vitamin D₃ synthesis. Accounting for two (fast and slow) calcium storage compartments in bone allows the model to properly predict the effects of bisphophonates on the plasma levels of Ca²⁺ ([Ca²⁺]_p), PTH, and vitamin D₃ Our model also suggests that Ca²⁺ exchange rates between plasma and the fast pool vary with both sex and age, allowing [Ca²⁺]_p to remain constant in spite of sex- and age-based hormonal and other differences. Our results suggest that the inconstant hypercalciuria that is observed in primary hyperparathyroidism can be attributed in part to counterbalancing effects of PTH and CaSR in the kidney. Our model also correctly predicts that calcimimetic agents such as cinacalcet bring down [Ca²⁺]_p to within its normal range in primary hyperparathyroidism. In addition, the model provides a simulation of CYP24A1 inactivation that leads to a situation reminiscent of infantile hypercalcemia. In summary, our model of calcium handling can be used to decipher the complex regulation of calcium homeostasis.

Constitutively Elevated Blood Serotonin Is Associated with Bone Loss and Type 2 Diabetes in Rats

Reduced peripheral serotonin (5HT) in mice lacking tryptophan hydroxylase (TPH1), the rate limiting enzyme for 5HT synthesis, was reported to be anabolic to the skeleton. However, in other studies TPH1 deletion either had no bone effect or an age dependent inhibition of osteoclastic bone resorption. The role of 5HT in bone therefore remains poorly understood. To address this issue, we used selective breeding to create rat sublines with constitutively high (high-5HT) and low (low-5HT) platelet 5HT level (PSL) and platelet 5HT uptake (PSU). High-5HT rats had decreased bone volume due to increased bone turnover characterized by increased bone formation and mineral apposition rate, increased osteoclast number and serum C-telopeptide level. Daily oral administration of the TPH1 inhibitor (LX1032) for 6 weeks reduced PSL and increased the trabecular bone volume and trabecular number of the spine and femur in high-5HT rats. High-5HT animals also developed a type 2 diabetes (T2D) phenotype with increased: plasma insulin, glucose, hemoglobin A1c, body weight, visceral fat, β-cell pancreatic islets size, serum cholesterol, and decreased muscle strength. Serum calcium accretion mediated by parathyroid hormone slightly increased, whereas treatment with 1,25(OH)2D3 decreased PSL. Insulin reduction was paralleled by a drop in PSL in high-5HT rats. In vitro, insulin and 5HT synergistically up-regulated osteoblast differentiation isolated from high-5HT rats, whereas TPH1 inhibition decreased the number of bone marrow-derived osteoclasts. These results suggest that constitutively elevated PSL is associated with bone loss and T2D via a homeostatic interplay between the peripheral 5HT, bone and insulin.

Dynamic modeling of bone metastasis, microenvironment and therapy: Integrating parathyroid hormone (PTH) effect, anti-resorptive and anti-cancer therapy

Bone is a common site for the development of metastasis, as its microenvironment provides the necessary conditions for the growth and proliferation of cancer cells. Several mathematical models to describe the bone remodeling process and how osteoclasts and osteoblasts coupled action ensures bone homeostasis have been proposed and further extended to include the effect of cancer cells. The model proposed here includes the influence of the parathyroid hormone (PTH) as capable of triggering and regulating the bone remodeling cycle. It also considers the secretion of PTH-related protein (PTHrP) by cancer cells, which stimulates the production of receptor activator of nuclear factor kappa-B ligand (RANKL) by osteoblasts that activates osteoclasts, increasing bone resorption and the subsequent release of growth factors entrapped in the bone matrix, which induce tumor growth, giving rise to a self-perpetuating cycle known as the vicious cycle of bone metastases. The model additionally describes how the presence of metastases contributes to the decoupling between bone resorption and formation. Moreover, the effects of anti-cancer and anti-resorptive treatments, through chemotherapy and the administration of bisphosphonates or denosumab, are also included, along with their corresponding pharmacokinetics (PK) and pharmacodynamics (PD). The simulated models, available at http://sels.tecnico.ulisboa.pt/software/, are able to describe bone remodeling cycles, the growth of bone metastases and how treatment can effectively reduce tumor burden on bone and prevent loss of bone strength.

The effect of leptin replacement on parathyroid hormone, RANKL-osteoprotegerin axis, and Wnt inhibitors in young women with hypothalamic amenorrhea

CONTEXT

Recombinant leptin (metreleptin) treatment restores bone mineral density in women with hypothalamic amenorrhea (HA), a condition characterized by hypoleptinemia, which has adverse impact on bone health.

OBJECTIVE

The objective of the study was to investigate how metreleptin exerts its positive effect on bone metabolism in humans.

DESIGN

This was a randomized, double-blinded, placebo-controlled study.

SETTING

The study was conducted at Beth Israel Deaconess Medical Center (Boston, Massachusetts).

PATIENTS AND INTERVENTIONS

Women (n = 18) with HA and hypoleptinemia for at least 6 months were randomized to receive either metreleptin or placebo for 36 weeks. Serum samples were obtained at baseline and 12, 24, and 36 weeks of treatment.

MAIN OUTCOME MEASURES

Circulating levels of leptin, intact PTH (iPTH), receptor activator of nuclear factor-κB ligand (RANKL), osteoprotegerin (OPG), sclerostin, dickkopf-1, and fibroblast growth factor-23.

RESULTS

Metreleptin administration significantly increased leptin levels throughout the treatment period (P = .001). iPTH decreased over the 36 weeks of treatment (P = .01). There was a trend toward a decrease in serum RANKL and increase in serum OPG in the metreleptin-treated group. The RANKL to OPG ratio was significantly decreased within the metreleptin (P = .04) but not the placebo group. Metreleptin had no effect on serum sclerostin, dickkopf-1, and fibroblast growth factor-23.

CONCLUSIONS

Metreleptin treatment over 36 weeks decreases iPTH and RANKL to OPG ratio levels in hypoleptinemic women with HA.

Achievement of NKF/K-DOQI recommended target values for bone and mineral metabolism in incident hemodialysis patients: results of the FARO-2 cohort

BACKGROUND

Mineral Bone Disorders (MBD) is prevalent in hemodialysis (HD) patients and associated with increased cardiovascular mortality. The FARO-2 study evaluated the achievement of the NKF/K-DOQI guidelines on recommended target values for serum calcium (Ca), phosphorous (P) and intact parathyroid hormone (PTH) levels on survival in incident HD patients.

METHODS

Data were collected by questionnaire from 568 incident HD patients followed prospectively over a 3-year period from 26 Italian dialysis units. The cumulative probability of time-to-death for CKD-MBD treatment characteristics was determined by the Kaplan-Meier curves.

RESULTS

Serum PTH levels (median values at 6 months vs. 36 months; 225 vs. 254 pg/ml), Ca (8.8 vs. 8.9 g/dl) and P (5.1 vs. 4.8 mg/dl) were not significantly different at 6 months versus follow-up. The majority of incident HD patients (60-70%) who were followed up for 36 months did not achieve the NKF/K-DOQI recommended target values. Survival rates were higher in patients on target for three parameters versus patients off target (survival at 24 months: at target 95.7% (95% CI: 84.0-98.9) versus not on target 71.1% (95% CI: 66.3-75.4, p < 0.01)). The 30.1% of patients on target for three MBD parameters at least once during the follow-up period had better survival rates compared to those not reaching these targets (survival at 24 months: at least once 88.0% (95% CI: 81.9-92.1); 67.7% (95% CI: 61.9-72.8, p < 0.01)).

CONCLUSION

Our findings indicate that incident HD patients who achieved target levels (for three MBD parameters) for at least one visit have a lower risk of mortality.

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.

A control engineering model of calcium regulation

CONTEXT

A control engineering perspective provides a framework for representing important mechanistic details of the calcium (Ca) regulatory system efficiently. The resulting model facilitates the testing of hypotheses about mechanisms underlying the emergence of known Ca-related pathologies.

OBJECTIVE

The objective of this work is to develop a comprehensive computational model that will enable quantitative understanding of plasma Ca regulation under normal and pathological conditions.

DESIGN

Ca regulation is represented as an engineering control system where physiological subprocesses are mapped onto corresponding block components (sensor, controller, actuator, and process), and underlying mechanisms are represented by differential equations. The resulting model is validated with clinical observations of induced hypo- or hypercalcemia in healthy subjects, and its applicability is demonstrated by comparing model predictions of Ca-related pathologies to corresponding clinical data.

RESULTS

Our model accurately predicts clinical responses to induced hypo- and hypercalcemia in healthy subjects within a framework that facilitates the representation of Ca-related pathologies in terms of control system component defects. The model also enables a deeper understanding of the emergence of pathologies and the testing of hypotheses about related features of Ca regulation-for example, why primary hyperparathyroidism and hypoparathyroidism arise from "controller defects."

CONCLUSIONS

The control engineering framework provides an efficient means of organizing the subprocesses constituting Ca regulation, thereby facilitating a fundamental understanding of this complex process. The resulting validated model's predictions are consistent with clinically observed short- and long-term dynamic characteristics of the Ca regulatory system in both healthy and diseased patients. The model also enables simulation of currently infeasible clinical tests and generates predictions of physiological variables that are currently not measurable.

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.

Relationship between insulin resistance and plasma vitamin D in adults

A recent relationship between vitamin D deficiency and the risk of type 2 diabetes mellitus (T2DM) and insulin resistance has been established through several studies. Research suggests a correlation between serum vitamin D and glycemic status measures. The aim of this study was to investigate the relationship between the plasma vitamin D levels (25[OH]D) and the factors linked to insulin resistance in a representative sample of Canadians ranging in age from 16-79 years. Data were used from the Canadian Health Measures Survey where direct measures of health and wellness were reported from 1,928 subjects. These data were gathered from March 2007-February 2009 at 15 sites selected through a multistage sampling strategy. An inverse relationship between insulin resistance and plasma vitamin D level in both men and women was observed. This study provides additional evidence for the role of vitamin D in T2DM. If causally associated, the supplementation of vitamin D may help in preventing insulin resistance and subsequent T2DM.

Maintaining normal levels of ionized calcium during citrate-based renal replacement therapy is associated with stable parathyroid hormone levels

BACKGROUND/AIMS

Citrate is an effective anticoagulant during continuous renal replacement therapy (CRRT). Previous studies showed raised parathyroid hormone (PTH) levels when aiming for serum ionized calcium [Cai] between 0.8 and 1.1 mmol/l. Our objective was to assess whether citrate-based CRRT with physiologic target systemic [Ca(i)] between 1.12 and 1.20 mmol/l could maintain stable PTH levels.

METHODS

Measurement of intact PTH (PTHi) in 30 consecutive critically ill patients treated with citrate-based CRRT.

RESULTS

Thirty patients [mean age: 70.4 (SD 11.3) years; 56.7% males] were enrolled. Mean serum [Ca(i)] was 1.16 mmol/l (SD 0.09), 1.13 mmol/l (SD 0.09), 1.17 mmol/l (SD 0.05) and 1.16 mmol/l (SD 0.04) at baseline, 12, 24 and 48 h, respectively (p = 0.29). Median PTHi levels (interquartile range) at baseline, 12, 24 and 48 h were 66.5 (43-111), 109 (59.5-151.5), 88.5 (47-133) and 85 pg/ml (53-140), respectively. The differences between baseline and 12 h and across all time points were statistically not significant (p = 0.16 and p = 0.49, respectively). In a mixed-effects model, each 0.1 mmol/l increase in serum [Ca(i)] was associated with a 31.2% decrease in PTHi (p < 0.001). Results were unchanged after adjustment for age, gender, magnesium, phosphate, arterial pH and time spent on CRRT.

CONCLUSIONS

Maintaining systemic [Ca(i)] within the physiologic range was associated with stable PTHi levels.

Lithium-associated hypercalcemia and hyperparathyroidism in the elderly: what do we know?

BACKGROUND

Lithium has been reported to induce hypercalcemia and hyperparathyroidism, yet few studies have examined the impact on older patients. We therefore undertook this review and report our findings.

METHOD

We undertook a systematic review of articles on lithium-associated hypercalcemia and/or hyperparathyroidism that were identified via electronic English language database searches through PubMed.

RESULTS

Among reported cases and case series of lithium-associated hyperparathyroidism in which ages of specific subjects were provided, 40% of affected individuals were over age 60. Mean serum calcium levels are reported to be higher in lithium treated patients over age 60 compared with younger patients. While many patients who develop lithium-associated hypercalcemia and hyperparathyroidism are asymptomatic, symptomatic complications may be more of a concern in older patients, especially in those with co-morbid renal disease.

LIMITATIONS

To date, all cross-sectional studies of lithium-associated hypercalcemia and hyperparathyroidism are of mixed age group cohorts and more specific studies focused on older patients have yet to be performed.

CONCLUSIONS

Lithium-induced hypercalcemia and hyperparathyroidism are under-recognized potential complications of lithium therapy which may occur more frequently in older patients. Psychiatrists should be vigilant in screening for hypercalcemia and hyperparathyroidism in their older patients receiving lithium, both prior to starting treatment and at least annually thereafter.

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.

Demographic, dietary, and serum factors and parathyroid hormone in the National Health and Nutrition Examination Survey

Many determinants of parathyroid hormone (PTH) are unknown. In the National Health and Nutrition Examination Survey (NHANES), numerous factors not classically associated with calcium-phosphorus homeostasis, such as uric acid and smoking, are independently associated with PTH in adults without chronic kidney disease. Associations between serum phosphorus and PTH may vary by race.

INTRODUCTION

Although PTH may be an important biomarker for osteoporosis and cardiovascular disease, many determinants of PTH are unknown. We investigated associations between demographic, dietary, and serum factors and PTH level.

METHODS

We studied 4,026 white, 1,792 black, and 1,834 Mexican-American adult participants without chronic kidney disease from the 2003-2004 and 2005-2006 NHANES.

RESULTS

The mean serum PTH level was 38.3 pg/ml for whites, 42.6 pg/ml for blacks, and 41.3 pg/ml for Mexican-Americans. After adjusting for diet, body mass index, serum levels of calcium, phosphorus, 25-hydroxyvitamin D, creatinine, and other factors, smokers compared to non-smokers had lower PTH, ranging from -4.2 pg/ml (95% confidence interval (CI) -7.3 to -1.1) in Mexican-Americans to -6.1 pg/ml (95% CI -8.7 to -3.5) in blacks. After multivariate adjustment, PTH was higher in females compared to males, ranging from 1.1 pg/ml (95% CI -1.2 to 3.4) in Mexican-Americans to 4.5 pg/ml (95% CI 1.9 to 7.0) in blacks, and in older (>60 years) compared to younger participants (<30 years), ranging from 3.7 pg/ml (95% CI 1.3 to 6.1) in Mexican-Americans to 8.0 pg/ml (95% CI 5.4 to 10.7) in blacks. Higher uric acid was associated with higher PTH. In whites only, lower serum phosphorus and lower serum retinol were associated with higher PTH.

CONCLUSIONS

Numerous factors not classically associated with calcium-phosphorus homeostasis are independently associated with PTH and should be considered in future studies of PTH and chronic disease. Additional research is needed to elucidate mechanisms underlying identified associations with PTH and to explore possible racial differences in phosphorus handling.

Age-specific associations of reduced estimated glomerular filtration rate with concurrent chronic kidney disease complications

BACKGROUND AND OBJECTIVES

It has been suggested that moderate reductions in estimated GFR (eGFR) among older adults may not reflect chronic kidney disease (CKD).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We examined age-specific (<60, 60 to 69, 70 to 79, and ≥80 years) associations between eGFR level and six concurrent CKD complications among 30,528 participants from the National Health and Nutrition Examination Survey (NHANES) 1988 to 1994 and 1999 to 2006 (n = 8242 from NHANES 2003 to 2006 for hyperparathyroidism). Complications included anemia (hemoglobin <12 g/dl women, <13.5 g/dl men), acidosis (bicarbonate <22 mEq/L), hyperphosphatemia (phosphorus ≥4.5 mg/dl), hypoalbuminemia (albumin <3.5 mg/dl), hyperparathyroidism (intact parathyroid hormone ≥70 pg/ml), and hypertension (systolic/diastolic BP ≥140/90 mmHg or antihypertensive use).

RESULTS

Among participants ≥80 years old, compared with those with estimated GFR (eGFR) ≥60 ml/min per 1.73 m(2), the multivariable adjusted prevalence ratios (95% confidence interval) associated with eGFR levels of 45 to 59 and <45 ml/min per 1.73 m(2) were 1.39 (1.11 to1.73) and 2.06 (1.59 to 2.67) for anemia, 1.33 (0.89 to 1.98) and 2.47 (1.52 to 4.00) for acidosis, 1.11 (0.70 to 1.76) and 2.16 (1.36 to 3.42) for hyperphosphatemia, 2.04 (1.39 to 3.00) and 2.83 (1.76 to 4.53) for hyperparathyroidism and 1.09 (1.03 to 1.14), and 1.12 (1.05 to 1.19) for hypertension, respectively. Higher prevalence ratios for these complications at lower eGFR levels were also present at younger ages. Reduced eGFR was associated with hypoalbuminemia only for adults <70.

CONCLUSIONS

Reduced eGFR was associated with a higher prevalence of several concurrent CKD complications, regardless of age.

Comparative 25-OH-vitamin D level in institutionalized women older than 65 years from two cities in Spain and Argentina having a similar solar radiation index

OBJECTIVE

The present study evaluated and compared vitamin D nutritional status and calcium-phosphorus metabolism in institutionalized women >65 y from two cities that have a similar sun irradiation index (heliophany).

METHODS

The study was carried out in women living in similar social-status institutions from geographic cities having a similar solar radiation index (Lleida, Spain, n=49, and suburban Buenos Aires, Argentina [BA], n=48) at the end of summer.

RESULTS

Fish consumption was higher in the Lleida group, as was red-meat consumption in the BA group. In both groups mean calcium intake was 800 mg/d. The daily intake of vitamin D was higher in the BA group (P<0.001). A total of 90% in Lleida and 86% in BA had 25-hydroxyvitamin D (25OHD) levels <20 ng/mL. A significant inverse correlation between individual 25OHD and parathyroid hormone (PTH) levels was observed in the two groups of women (r=-0.329, P=0.035). PTH levels >100 pg/mL were found in 24% and 20% of women in Lleida and BA, respectively. There was a marked increase in carboxy-terminal telopeptide cross-links of type I collagen levels and a decrease in 25OHD with an increase in PTH levels (P<0.05). Conversely, bone alkaline phosphatase increased significantly only when the PTH concentration duplicated the reference range.

CONCLUSION

Even at the end of summer, vitamin D deficiency/insufficiency was prevalent in the two studied institutionalized elderly women. In the narrow range of the dietary calcium intake (close to 800 mg/d) of both studied groups, secondary hyperparathyroidism was absent when 25OHD levels were >17 ng/dL, indicating changes in the regulation control of serum PTH and consequently the changes in this threshold. As a result, vitamin D deficiency must be reversed to avoid the increment in bone turnover and to ensure the endocrine and paracrine functions of vitamin D for overall health and well-being.

Dynamics of parathyroid hormone secretion in health and secondary hyperparathyroidism

This review examines the dynamics of parathyroid hormone secretion in health and in various causes of secondary hyperparathyroidism. Although most studies of parathyroid hormone and calcium have focused on the modification of parathyroid hormone secretion by serum calcium, the relationship between parathyroid hormone and serum calcium is bifunctional because parathyroid hormone also modifies serum calcium. In normal animals and humans, factors such as phosphorus and vitamin D modify the basal parathyroid hormone level and the maximal parathyroid hormone response to hypocalcemia. Certain medications, such as lithium and estrogen, in normal individuals and sustained changes in the serum calcium concentration in hemodialysis patients change the set point of calcium, which reflects the serum calcium concentration at which parathyroid hormone secretion responds. Hypocalcemia increases the basal/maximal parathyroid hormone ratio, a measure of the relative degree of parathyroid hormone stimulation. The phenomenon of hysteresis, defined as a different parathyroid hormone value for the same serum calcium concentration during the induction of and recovery from hypo- and hypercalcemia, is discussed because it provides important insights into factors that affect parathyroid hormone secretion. In three causes of secondary hyperparathyroidism--chronic kidney disease, vitamin D deficiency, and aging--factors that affect the dynamics of parathyroid hormone secretion are evaluated in detail. During recovery from vitamin D deficiency, the maximal parathyroid hormone remains elevated while the basal parathyroid hormone value rapidly becomes normal because of a shift in the set point of calcium. Much remains to be learned about the dynamics of parathyroid hormone secretion in health and secondary hyperparathyroidism.

Molecular backgrounds of age-related osteoporosis from mouse genetics approaches

Backgrounds underlying age-related bone loss can be classified into two categories: systemic abnormality and osteoblast dysfunction. The former includes insufficiency of vitamin D or estrogen, causing a negative balance of calcium metabolism. We propose the contribution of an aging-suppressing gene, klotho, as a novel systemic factor, as a mouse deficient in the klotho gene exhibits multiple aging phenotypes including osteopenia with a low bone turnover. As a factor intrinsic to osteoblasts, we investigated the role of PPARgamma, a key regulator of adipocyte differentiation, based on the facts that osteoblasts and adipocytes share a common progenitor. Heterozygous PPARgamma-deficient mice exhibited high bone mass by stimulating osteoblastogenesis from bone marrow progenitors, and this effect became prominent with aging, indicating involvement of PPARgamma-dependent bone formation in the pathophysiology of age-related bone loss. The local environment of osteoblasts is mainly controlled by cytokines/growth factors, among which insulin-like growth factor-I (IGF-I) is the most possible candidate whose production and activity are decreased with aging. Bone phenotypes of deficient mice of insulin receptor substrates (IRS-1 and IRS-2), essential molecules for intracellular signaling of IGF-I, revealed that IRS-1 is essential to maintain bone turnover by up-regulating anabolic and catabolic functions of osteoblasts, while IRS-2 is needed to keep the predominance of the anabolic function over the catabolic function. A next task ahead of us will be to elucidate the network system of these factors underlying age-related osteoporosis.

Effect of active acromegaly and its treatment on parathyroid circadian rhythmicity and parathyroid target-organ sensitivity

CONTEXT

Patients with active acromegaly have increased bone turnover and skeletal abnormalities. Biochemical cure of acromegaly may represent a functional GH-deficient state and result in cortical bone loss. Reduced PTH target-organ sensitivity occurs in adult GH deficiency and may underlie the associated development of osteoporosis.

OBJECTIVE

We examined the effect of active and treated acromegaly on PTH concentration and target-organ sensitivity.

PATIENTS

Ten active acromegalic subjects (GH nadir > 0.3 mug/liter after 75-g oral glucose load and IGF-I above age-related reference range) and 10 matched controls participated in the study.

DESIGN

Half-hourly blood and 3-h urine samples were collected on patients and controls for 24 h. Samples were analyzed for PTH, calcium (Ca), nephrogenous cAMP (NcAMP, a marker of PTH renal activity), beta C-telopeptide (bone resorption marker), and procollagen type-I amino-terminal propeptide (bone formation marker). Serum calcium was adjusted for albumin (ACa). Eight acromegalic subjects who achieved biochemical cure (GH nadir < 0.3 mug/liter after 75-g oral glucose load and IGF-I within reference range) after standard surgical and/or medical treatment reattended and the protocol repeated.

RESULTS

Active acromegalic subjects had higher 24-h mean PTH, NcAMP, ACa, urine Ca, beta C-telopeptide, and procollagen type I amino-terminal propeptide (P < 0.05), compared with controls. Twenty-four-hour mean PTH increased (P < 0.001) in the acromegalic subjects after treatment, whereas NcAMP and ACa decreased (P < 0.05).

CONCLUSION

Increased bone turnover associated with active acromegaly may result from increased PTH concentration and action. Biochemical cure of acromegaly results in reduced PTH target-organ sensitivity indicated by increased PTH with decreased NcAMP and ACa concentrations. PTH target-organ sensitivity does not appear to return to normal after successful treatment of acromegaly in the short term and may reflect functional GH deficiency.

The relationship between vitamin D and parathyroid hormone: calcium homeostasis, bone turnover, and bone mineral density in postmenopausal women with established osteoporosis

It is evident from several studies that not all patients with hypovitaminosis D develop secondary hyperparathyroidism. What this means for bone biochemistry and bone mineral density (BMD) remains unclear. The aim of this study was to investigate the effects of hypovitaminosis D (defined as a 25OHD < or = 30 nmol/l) and patients with a blunted PTH response (defined arbitrarily as a PTH within the standard laboratory reference range in the presence of a 25OHD < or = 30 nmol/l) in comparison to patients with hypovitaminosis D and secondary hyperparathyroidism (defined arbitrarily as a PTH above the standard laboratory reference range in the presence of a 25OHD < or = 30 nmol/l) and vitamin D-replete subjects (25OHD > 30 nmol/l). Four hundred twenty-one postmenopausal women (mean age: 71.2 years) with established vertebral osteoporosis were evaluated by assessing mean serum calcium, 25OHD, 1,25(OH)2D, bone turnover markers, and BMD. The prevalence of hypovitaminosis D was 39%. Secondary hyperparathyroidism was found in only one-third of these patients who maintained calcium homeostasis at the expense of increased bone turnover relative to the vitamin D-replete subjects (bone ALP mean difference: 43.9 IU/l [95% CI: 24.8, 59.1], osteocalcin: 1.3 ng/ml [95% CI: 1.1, 2.5], free deoxypyridinoline mean difference: 2.6 nmol/nmol creatinine [95% CI: 2.5, 4.8]) and bone loss (total hip BMD mean difference: 0.11 g/cm2 [95% CI: 0.09, 0.12]). Patients with hypovitaminosis D and a blunted PTH response were characterized by a lower serum calcium (mean difference: 0.07 mmol/l [95% CI: 0.08, 0.2]), a reduction in bone turnover (bone ALP mean difference: 42.4 IU/l [95% CI: 27.8, 61.9], osteocalcin: 1.6 ng/ml [95% CI: 0.3, 3.1], free-deoxypyridinoline mean difference: 3.0 nmol/nmol creatinine [95% CI: 1.9, 5.9]), but protection in bone density (total hip BMD mean difference: 0.10 g/cm2, [95% CI: 0.08, 0.11]) as compared to those with hypovitaminosis D and secondary hyperparathyroidism. This study identifies a distinct group of patients with hypovitaminosis D and a blunted PTH response who show a disruption in calcium homeostasis but protected against PTH-mediated bone loss. This has clinical implications with respect to disease definition and may be important in deciding the optimal replacement therapy in patients with hypovitaminosis D but a blunted PTH response.

Gender variation in PTH sensitivity and rhythmicity following growth hormone replacement in adult growth hormone-deficient patients

BACKGROUND

Adult GH deficiency (AGHD) is associated with osteoporosis and reduced bone turnover; factors improved by GH replacement (GHR), with men gaining greater benefit than women. Reduction in sensitivity of bone and kidney to the effects of PTH may underlie AGHD changes in bone turnover. We determined the gender difference in PTH target-organ sensitivity following GHR in AGHD patients.

DESIGN, PATIENTS AND MEASUREMENTS

Twenty AGHD patients (10 men) were admitted to hospital before and after GHR initiation. Half-hourly blood samples were collected for PTH, calcium, nephrogenous cyclic AMP (NcAMP, marker of PTH activity), type-I collagen C-telopeptide (CTX, bone resorption marker) and procollagen type-I amino-terminal propeptide (PINP, bone formation marker).

RESULTS

The 24-h mean PTH concentration decreased in both genders (P < 0.001), with maximal changes seen 6 and 12 months following GHR in men and women, respectively. Increases in 24-h mean NcAMP (P < 0.05), calcium (P < 0.001) and bone turnover markers (P < 0.001) occurred in both genders following GHR, with maximal changes at 1 month in men, but at 3 months for NcAMP, calcium and CTX and 12 months for PINP in women. Maximal NcAMP increase was higher in men (P = 0.009).

CONCLUSIONS

Following GHR, PTH target-organ sensitivity increased in both genders, demonstrated by simultaneous reduction in PTH concentration and increase in NcAMP, calcium and bone turnover. In women, improvement in renal PTH sensitivity was delayed and reduced, and changes in bone turnover were delayed, with increase in bone resorption preceding bone formation. Both factors may contribute to the reduced bone mineral density (BMD) response to GHR observed in women.