The role of the gastrointestinal tract in calcium homeostasis and bone remodeling

Effects of the Interaction between Dietary Vitamin D3 and Vitamin K3 on Growth, Skeletal Anomalies, and Expression of Bone and Calcium Metabolism-Related Genes in Juvenile Gilthead Seabream (Sparus aurata)

The interaction between vitamin D and vitamin K is crucial for regulating bone metabolism and maintaining calcium homeostasis across diverse animal species due to their complementary roles in calcium metabolism and bone health. However, research on this interaction of vitamin D and K in fish, particularly Mediterranean species like gilthead seabream, is limited or not studied. This study aimed to understand the effects of different dietary combinations of vitamin D3 and K3 on juvenile gilthead seabream. Accordingly, seabream juveniles were fed with varying combinations of vitamin D3/vitamin K3 (mg/kg diet) for 3 months: (0.07/0.01), (0.20/0.58), (0.19/1.65), (0.51/0.74), (0.56/1.00). At the end of the trial, survival, growth, body morphology, serum calcitriol, and vertebral mineral composition remained unaffected by varying vitamin levels, while gene expression patterns related to bone formation, resorption, and calcium regulation in various tissues were significantly influenced by both vitamins and their interaction. Gilthead seabream juveniles fed the 0.07/0.01 mg/kg diet upregulated calcium-regulating genes in the gills, indicating an effort to enhance calcium absorption to compensate for dietary deficiencies. Conversely, an increase in vitamin D3 and K3 up to 0.19 and 1.65 mg/kg, respectively, upregulated bone formation, bone remodeling, and calcium homeostasis-related gene expression in vertebra and other tissues. On the contrary, a dietary increase in these vitamins up to 0.56 mg/kg vitamin D3 and 1.00 mg/kg vitamin K3 downregulated calcium metabolism-related genes in tissues, suggesting an adverse interaction resulting from elevated levels of these vitamins in the diet. Hence, sustaining an equilibrium in the dietary intake of vitamin D3 and vitamin K3, in an appropriately combined form, may potentially induce interactions between the vitamins, contributing to favorable effects on bone development and calcium regulation in gilthead seabream juveniles.

Bariatric surgery and secondary hyperparathyroidism: a meta-analysis

BACKGROUND

Obesity increases the risk of obesity-related medical problems. Weight loss after metabolic and bariatric surgery (MBS) has been well studied. However, the effects of MBS on parathyroid function remain unclear.

OBJECTIVE

The objective of this study was to perform a meta-analysis to examine the impact of MBS on the risk of secondary hyperparathyroidism (SHPT).

SETTING

The Second Xiangya Hospital, Central South University, Changsha, Hunan, China.

METHODS

The PubMed, Embase, Web of Science, and the Cochrane Library databases were systematically reviewed from inception to May 2022 to identify studies reporting quantitative measurements of SHPT risk pre-MBS and post-MBS. Odds ratios (ORs) with 95% confidence intervals (95% CIs) were estimated and compared. Effects were pooled using a random-effects or fixed-effects model. Subgroup analyses were performed according to the follow-up time and surgical procedure.

RESULTS

The final meta-analysis included 9 studies with a total of 5585 patients. The mean follow-up time was 3.5 years (range 0.25-5). Overall, MBS appears to does not affect SHPT risk (OR = 1.34, 95% CI 0.81-2.20, I² = 95%). Follow-up data showed no evidence of SHPT within 2 years following gastric bypass (GB) and sleeve gastrectomy procedures (OR = 1.42, 95% CI 0.66-3.07 for GB, OR = 0.39, 95% CI 0.09-1.62 for sleeve gastrectomy ). At the 2-year and long-term follow-up intervals, a marked increase in SHPT was detected for GB (OR = 6.06, 95% CI 3.39-10.85 for GB). In addition, the surgical procedure for GB decreased the likelihood of SHPT compared with the surgical procedure for biliopancreatic diversion with duodenal switch (OR = 0.29, 95% CI 0.17-0.49).

CONCLUSIONS

Our meta-analysis indicated that GB appears to increase SHPT risk. Patients undergoing MBS should be aware of the risk of SHPT. Larger studies are needed to evaluate the outcomes and side effects and may eventually provide a better and more comprehensive understanding of the risks.

The predictive role of parathyroid hormone for non-alcoholic fatty liver disease based on invasive and non-invasive findings in candidates of bariatric surgery

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH) and hepatic fibrosis are the most detrimental hepatic abnormalities associated with increased body weight with devastating clinical outcomes. Therefore, there is a substantial necessity for efficient management strategies, including significant weight reduction. Bariatric surgery has been used as a therapeutic approach in a selected obese patient with NAFLD/NASH and other cardiometabolic comorbidities.

PURPOSE

The study is focused on the predictive role of PTH with the indices of hepatic steatosis/NAFLD and NASH based on liver biopsy, elastography, and sonography in morbidly obese patients.

METHODS

Ninety patients with BMI between 35 and 40 kg/m2 with more than two comorbidities who referred to Imam Reza outpatient clinic from December 2016 to September 2017 were recruited and underwent initial assessments, including demographic profiles, psychological assessment, anthropometric measurements, hepatic biopsy, and basic laboratory tests. Liver stiffness was evaluated using two-dimensional shear wave elastography (2D-SWE) at least two weeks before liver biopsy. The histological analysis of the liver was performed using biopsy samples which obtained from left hepatic lobe during bariatric surgery under direct surgeon observation using a 16-gauge Tru-cut needle. The study was approved by the ethical committee (IR.MUMS.fm.REC.1396.312).

RESULTS

The level of PTH was significantly high in patients with positive histology for hepatic fibrosis, steatosis, and NASH/NAFLD compared to patients with negative histology (p = 0.005, p = 0.009, and p = 0.013, respectively). Also, patients with liver fibrosis confirmed by elastography had significantly higher serum PTH concentration than patients without fibrosis (p = 0.011). PTH was also positively correlated with hepatic fibrosis, NASH, and steatosis (p = 0.007, p = 0.012, p = 0.023, respectively).

CONCLUSION

High levels of PTH was significantly associated with histological indices of (hepatic fibrosis, steatosis, NAFLD and NASH) and elasticity indices. Therefore, it is imperative to assess for high levels of PTH in the morbidly obese population pre-and post-bariatric surgery. However, for a more robust and comprehensive assessment, a randomized controlled trial is needed. The study was conducted in accordance with the practice guidance in the diagnosis and management of NAFLD from the American association for the study of liver disease (AASLD) 2018.

LEVEL III

Evidence obtained from well-designed cohort or case-control analytic studies.

Investigating the Effects of Diet-Induced Pre-Diabetes on the Functioning of Calcium-Regulating Organs in Male Sprague Dawley Rats: Effects on Selected Markers

Derangements to the functioning of calcium-regulating organs have been associated with type 2 diabetes mellitus (T2DM), a condition preceded by pre-diabetes. Type 2 diabetes has shown to promote renal calcium wastage, intestinal calcium malabsorption and increased bone resorption. However, the changes to the functioning of calcium-regulating organs in pre-diabetes are not known. Subsequently, the effects of diet-induced pre-diabetes on the functioning of calcium-regulating organs in a rat model for pre-diabetes was investigated in this study. Male Sprague Dawley rats were separated into two groups (n=6, each group): non-pre-diabetic (NPD) group and a diet-induced pre-diabetic (DIPD) group for 20 weeks. After the experimental period, postprandial glucose and HOMA-IR were analysed in addition to plasma and urinary calcium concentrations. Gene expressions of intestinal vitamin D (VDR), intestinal calbindin-D9k, renal 1-alpha hydroxylase and renal transient receptor potential vanilloid 5 (TRPV5) expressions in addition to plasma osteocalcin and urinary deoxypyridinoline concentrations were analysed at week 20. The results demonstrated significantly increased concentrations of postprandial glucose, HOMA-IR and urinary calcium in addition to unchanged plasma calcium levels in the DIPD group by comparison to NPD. Renal TRPV5, renal 1-alpha hydroxylase, intestinal VDR and intestinal calbindin-D9k expressions were increased in the DIPD group by comparison to NPD. Furthermore, plasma osteocalcin levels were increased and urine deoxypyridinoline levels were decreased in the DIPD group by comparison to NPD. These observations may suggest that calcium-regulating organs compensate for the changes to calcium homeostasis by inducing increased renal calcium reabsorption, increased intestinal calcium absorption and decreased bone resorption followed by increased bone formation.

[Musculoskeletal laboratory diagnostics in competitive sport]

Hintergrund

Die labordiagnostische Untersuchung stellt eine wichtige Möglichkeit zur Beurteilung und Optimierung der Leistungs- und Regenerationsfähigkeit professioneller Athleten dar. Ferner ist sie für die Prävention, Diagnostik und Rehabilitation von Verletzungen und Überbelastungen von Bedeutung.

Fragestellung

Ziel dieser Arbeit ist die Darstellung muskuloskelettaler laborchemischer Parameter, die relevante Erkenntnisse für die medizinische Betreuung von Leistungssportlern liefern.

Material und Methoden

Literaturrecherche und narratives Review.

Ergebnisse

Die Bestimmung des Vitamin-D-, Calcium- und Knochenstoffwechsels stellt die laborchemische Basisdiagnostik im Rahmen der Beurteilung des Skelettstatus mit zusätzlichem präventivem Nutzen bezüglich muskuloskelettaler Verletzungen dar. Ferner können muskuläre Serummarker, z. B. Laktatdehydrogenase (LDH), Kreatinkinase (CK), Myoglobin und Aspartat-Aminotransferase (ASAT), helfen, eine metabolische Adaptation an das physische Training festzustellen und Aussagen über die muskuläre Arbeitslast und mögliche Schädigungen zu gewinnen. Die Energieverfügbarkeit kann durch eine entsprechende Bilanzierung sowie die laborchemische Bestimmung der Makro- und Mikronährstoffe eingeschätzt und optimiert werden.

Schlussfolgerungen

Die labordiagnostische Untersuchung besitzt in der Betreuung von Athleten eine sportartenübergreifende klinische Relevanz. Sie dient der Erreichung einer höchstmöglichen Leistungsfähigkeit sowie optimalen Prävention von Knochen- und Muskelverletzungen, wobei sämtliche Mangelzustände (z. B. Vitamin D) ausgeglichen werden sollten. Durch eine Periodisierung der laborchemischen Untersuchungen, mit zumindest zwei Labordiagnostiken im Jahr, und Aufstellung individueller Variabilitäts- und Referenzbereiche kann ferner eine bessere Beurteilbarkeit erreicht werden.

Strategy for achieving standardized bone models

Reliably producing functional in vitro organ models, such as organ-on-chip systems, has the potential to considerably advance biology research, drug development time, and resource efficiency. However, despite the ongoing major progress in the field, three-dimensional bone tissue models remain elusive. In this review, we specifically investigate the control of perfusion flow effects as the missing link between isolated culture systems and scientifically exploitable bone models and propose a roadmap toward this goal.

Absorption Characteristics of Novel Compound Calcium Carbonate Granules: Effects of Gastric Acid Deficiency and Exogenous Weak Acids

Calcium carbonates are commonly administered as supplements for conditions of calcium deficiency. We report here pharmacokinetic characteristics of a novel formulation, calcium carbonate compound granules (CCCGs), forming complexes of calcium carbonate and calcium citrate in water. CCCGs were compared to a kind of commonly-used calcium carbonate D3 preparation (CC) in the market in 5-week-old mice that had been treated with omeprazole, to suppress gastric acid secretion, and in untreated control mice. The results showed that: (1) CCCGs had better water solubility than CC in vitro; (2) In control mice, calcium absorption rates after CCCGs administration were comparable to those after CC administration; (3) Inhibition of gastric acid secretion did not affect calcium absorption after CCCGs, but moderately decreased it after CC; (4) The presence of phytic acid or tannin did not affect calcium absorption rates after CCCGs but did for CC; and (5) In normal mice, CCCGs did not inhibit gastric emptying and intestinal propulsion, and did not alter the gastrointestinal hormones. The results suggest that CCCGs may be therapeutically advantageous over more commonly used calcium supplement formulations, particularly for adolescents, because of their stable calcium absorption characteristics and their relatively favorable adverse effect profile.

High Incidence of Secondary Hyperparathyroidism in Bariatric Patients: Comparing Different Procedures

BACKGROUND

Bariatric surgery is an effective therapy for morbid obesity but may reduce calcium absorption and significantly decrease the bone mineral density. This study examined the prevalence of secondary hyperparathyroidism (SHPT) in obese subjects during follow-up after different bariatric surgeries. We investigated predictors of SHPT.

METHODS

We enrolled 1470 obese subjects undergoing bariatric/metabolic surgery with at least 1-year follow-up, including 322 patients undergoing Roux-en-Y gastric bypass (RYGB), 695 undergoing single anastomosis (mini-) gastric bypass (SAGB), 93 undergoing laparoscopic adjustable gastric banding (LAGB), and 360 undergoing sleeve gastrectomy (SG). Five years of data were available for 215 patients. Patients were instructed to supplement their diet according to the guideline. Calcium, parathyroid hormone (PTH), and vitamin D levels were measured before surgery and at 1 and 5 years after surgery. SHPT was defined as PTH > 69 pg/mL.

RESULTS

The overall prevalence of SHPT was high, 21.0% before surgery and was not different between patients with different bariatric procedures. Pre-operative PTH correlated with age, BMI, and vitamin D levels. Multi-variate analysis confirmed that vitamin D level was the only independent predictor of SHPT before surgery. The prevalence of SHPT increased to 35.4% at 1 year after surgery and 63.3% at 5 years after surgery. SAGB had the highest prevalence of SHPT (50.6%) followed by RYGB (33.2%), LAGB (25.8%), and SG (17.8%) at 1 year after surgery. At 5 years after surgery, SAGB still had the highest prevalence of SHPT (73.6%), followed by RYGB (56.6%), LAGB (38.5%), and SG (41.7%). Serum PTH at 1 year after surgery correlated with decreased BMI and weight loss. Multi-variate analysis confirmed that age, sex, calcium level, and bypass procedure were independent predictor of SHPT after surgery.

CONCLUSIONS

The prevalence of SHPT is high in morbidly obese patients before bariatric surgery which is related to vitamin D deficiency. The prevalence of SHPT increased continually along with the time after bariatric surgery, especially in patients receiving SAGB, followed by RYGB. The supplementation of vitamin D and calcium have to be higher in bypass procedure, especially in malabsorptive procedure.

[Calcium and vitamin D in bone metabolism: Clinical importance for fracture treatment]

A balanced calcium homeostasis is of critical importance not only for bone remodeling, the physiological process of bone resorption and bone formation that constantly renews bone throughout life but also for normal fracture healing. Given that disturbances of calcium homeostasis are present in 50 % of the German population and that this might result in delayed fracture healing after correct surgical treatment, this paper focusses on calcium and vitamin D in the daily practice in orthopedics and trauma surgery. To ensure the required enteral calcium uptake the following three conditions are required: (1) sufficient calcium intake via the nutrition, (2) a 25-hydroxyvitamin D serum level > 30 µg/l and (3) the presence of sufficient gastric acidification. Given the endemic vitamin D deficiency in Germany as well as the constantly increasing number of people using proton pump inhibitors on a regular basis, it is necessary to closely connect trauma orthopedic surgery and osteological treatment. The first issue to be dealt with is to control and if needed normalize calcium homeostasis in order to allow a normal undisturbed fracture healing process after both conservative as well as operative treatment of fractures.

Bone biology in the elderly: clinical importance for fracture treatment

Age-related bone impairment often leads to fragility fractures in the elderly. Although excellent surgical care is widely provided, diagnosis and treatment of the underlying bone disorder are often not kept in mind. The interplay of the three major bone cells – osteoblasts, osteoclasts, and osteocytes – is normally well regulated via the secretion of messengers to control bone remodeling. Possible imbalances that might occur in the elderly are partly due to age, genetic risk factors, and adverse lifestyle factors but importantly also due to imbalances in calcium homeostasis (mostly due to vitamin D deficiency or hypochlorhydria), which have to be eliminated. Therefore, the cooperation between the trauma surgeon and the osteologist is of major importance to diagnose and treat the respective patients at risk. We propose that any patient suffering from fragility fractures is rigorously screened for osteoporosis and metabolic bone diseases. This includes bone density measurement by dual-energy X-ray absorptiometry, laboratory tests for calcium, phosphate, vitamin D, and bone turnover markers, as well as additional diagnostic modalities if needed. Thereby, most risk factors, including vitamin D deficiency, can be identified and treated while patients who meet the criteria for a specific therapy (i.e. antiresorptive and osteoanabolic) receive such. If local health systems succeed to manage this process of secondary fracture prevention, morbidity and mortality of fragility fractures will decline to a minimum level.

Analysis of Patients with Helicobacter pylori Infection and the Subsequent Risk of Developing Osteoporosis after Eradication Therapy: A Nationwide Population-Based Cohort Study

Purpose

Previous studies have reported conflicting results on the association between Helicobacter pylori infection and osteoporosis. A few studies have discussed the influence of H. pylori eradication therapy on bone mineral density.

Methods

We assessed the prevalence of osteoporosis among the H. pylori-infected population in Taiwan and the influence of early and late H. pylori eradication therapy on bone mineral density.

Results

Using data from Taiwan's National Health Insurance Research Database, we identified 5,447 patients who received H. pylori eradication therapy from 2000 to 2010 and 21,788 controls, frequency-matched according to age, sex, and year of receiving H. pylori eradication therapy. Those who received H. pylori eradication therapy were divided into two groups based on the time interval between the diagnosis of a peptic ulcer and commencement of eradication therapy. The risk of developing osteoporosis was higher in the early H. pylori treatment cohort (hazard ratio [HR] = 1.52, 95% confidence interval [CI] = 1.23–1.89) and late H. pylori treatment cohort (HR = 1.69, 95% CI = 1.39–2.05), compared with the risk in the control cohort. When followed for less than 5 years, both the early and late cohorts had a higher risk of developing osteoporosis (HR = 1.69, 95% CI = 1.32–2.16 and HR = 1.72, 95% CI = 1.38–2.14). However, when the follow-up period was over 5 years, only the late eradication group exhibited a higher incidence of osteoporosis (HR = 1.62, 95% CI = 1.06–2.47).

Conclusion

The development of osteoporosis is complex and multi-factorial. Via this population-based cohort study and adjustment of possible confounding variables, we found H. pylori infection may be associated with an increased risk of developing osteoporosis in Taiwan. Early eradication could reduce the influence of H. pylori infection on osteoporosis when the follow-up period is greater than 5 years. Further prospective studies are necessary to discover the connection of H. pylori and osteoporosis.

[Vitamin D metabolism of the bone]

BACKGROUND

Bone health is a crucial requirement for individual mobility. Preventive, diagnostic, and therapeutic actions to preserve or restore bone health are major tasks for orthopedic surgeons and health practitioners in musculoskeletal medicine.

RESULTS

In the context of the widespread vitamin D deficiency in Germany, it is relevant to keep in mind thatserum calcitriol levels above > 30 µg/l are necessary for optimal bone metabolism and bone health. In particular, because vitamin D deficiency not only increases the amount of non-mineralized bone matrix (osteoid), but it can also cause negative changes in the mineralized bone tissue. Widening of the osteons and osteocyte lacunae, together with increased bone aging under the osteoid layer, can lead to reduced fracture resistance.

CONCLUSION

Integration of bone metabolism into the orthopedic strategy is an important concept for optimizing treatment in modern musculoskeletal medicine.

Use of proton pump inhibitors is associated with fractures in young adults: a population-based study

Proton pump inhibitors (PPIs) are associated with risk for fracture in osteoporotic adults. In this population-based study, we found a significant association between PPIs and fracture in young adults, with evidence of a dose-response effect. Young adults who use PPIs should be cautioned regarding risk for fracture.

INTRODUCTION

Proton pump inhibitors (PPIs) are associated with fracture in adults with osteoporosis. Because PPI therapy may interfere with bone accrual and attainment of peak bone mineral density, we studied the association between use of PPIs and fracture in children and young adults.

METHODS

We conducted a population-based, case-control study nested within records from general medical practices from 1994 to 2013. Participants were 4-29 years old with ≥ 1 year of follow-up who lacked chronic conditions associated with use of long-term acid suppression. Cases of fracture were defined as the first incident fracture at any site. Using incidence density sampling, cases were matched with up to five controls by age, sex, medical practice, and start of follow-up. PPI exposure was defined as 180 or more cumulative doses of PPIs. Conditional logistic regression was used to estimate the odds ratio and confidence interval for use of PPIs and fracture.

RESULTS

We identified 124,799 cases and 605,643 controls. The adjusted odds ratio for the risk of fracture associated with PPI exposure was 1.13 (95% CI 0.92 to 1.39) among children aged < 18 years old and 1.39 (95% CI 1.26 to 1.53) among young adults aged 18-29 years old. In young adults but not children, we observed a dose-response effect with increased total exposure to PPIs (p for trend <0.001).

CONCLUSIONS

PPI use was associated with fracture in young adults, but overall evidence did not support a PPI-fracture relationship in children. Young adults who use PPIs should be cautioned regarding potentially increased risk for fracture, even if they lack traditional fracture risk factors.

Hyperparathyroidism Associated with Long-Term Proton Pump Inhibitors Independent of Concurrent Bisphosphonate Therapy in Elderly Adults

OBJECTIVES

To measure the effect of proton pump inhibitors (PPIs), with and without concurrent bisphosphonates, on parathyroid hormone (PTH), vitamin D, and calcium.

DESIGN

Retrospective chart review of individuals 60 years and older. Subjects with reduced renal function (creatinine >1.3 mg/dL) and low vitamin D (<30 ng/mL) were excluded.

SETTING

Academic geriatric outpatient center in southern midwest.

PARTICIPANTS

Individuals aged 60 and older with concurrent calcium, PTH, vitamin D, and creatinine laboratory measurements (N = 80) meeting labeled criteria.

MEASUREMENTS

Serum calcium, PTH, vitamin D, and creatinine.

RESULTS

Chronic PPI exposure was associated with statistically significantly higher PTH (65.5 vs 30.3 pg/mL, P < .001; normal range 10-55 pg/mL) and lower calcium (9.1 vs 9.4 mg/dL, P = .02; normal range 8.5-10.5 mg/dL) than no PPI exposure. Chronic PPI exposure with concurrent BP therapy was associated with statistically significantly higher PTH (65.2 vs 43.4 pg/mL, P = .05) and lower calcium (9.2 vs 9.6 mg/dL, P = .04) than BP therapy only.

CONCLUSION

Based on the present study, chronic PPI exposure in elderly adults is associated with mild hyperparathyroidism regardless of concurrent oral BP administration.

Serologically Determined Gastric Mucosal Condition Is a Predictive Factor for Osteoporosis in Japanese Men

BACKGROUND

There are few reports about the influence of Helicobacter pylori infection and/or atrophic gastritis on bone conditions in Japan.

AIMS

To assess whether the combination of serologically determined Helicobacter pylori infection and atrophic gastritis is available as a biomarker for bone conditions.

METHODS

We studied 230 men in their 50s and 60s. Helicobacter pylori infection was determined using serum antibody to this bacterium. Atrophic gastritis was diagnosed on the basis of the serum pepsinogen I and II criteria. The characteristics of the participants' bone were measured at the radius using an ultrasonic bone densitometry system. The risks of low trabecular bone density, low elastic modulus of trabecular bone, and low cortical thickness among subjects who were positive for Helicobacter pylori infection and/or atrophic gastritis relative to those who were not were calculated.

RESULTS

Helicobacter pylori infection significantly increased the risk of low trabecular bone density (odds ratio 1.83, 95 % confidence interval 1.04-3.21, P = 0.03). Atrophic gastritis significantly increased the risk of low trabecular bone density (2.22, 1.17-4.22, 0.01). Compared with anti-Helicobacter pylori antibody (-) and atrophic gastritis (-) subjects, anti-Helicobacter pylori antibody (+) and atrophic gastritis (+) subjects were a significant high-risk group for low trabecular bone density (2.65, 1.27-5.55, 0.01).

CONCLUSIONS

A serological diagnosis of Helicobacter pylori infection and atrophic gastritis, which is utilized for risk assessment of gastric cancer, was suggested to be useful for risk assessment of osteoporosis.

Calcium gluconate supplementation is effective to balance calcium homeostasis in patients with gastrectomy

We demonstrate histological evidence for hyperparathyroidism in patients with gastrectomy. This is, at least in part, explained by impaired calcium absorption, resulting in mineralization defects and secondary hyperparathyroidism. Additionally, we demonstrate improved bone mineralization in patients with gastrectomy after gluconate therapy and showed the effectiveness of calcium gluconate over carbonate to balance impaired calcium hemostasis in mice.

INTRODUCTION

Gastrectomy and hypochlorhydria due to long-term proton pump inhibitor therapy are associated with increased fracture risk because of intestinal calcium malabsorption. Hence, our objectives were to histologically investigate bone metabolism in patients with gastrectomy and to analyze the impact of calcium gluconate supplementation on skeletal integrity in the setting of impaired gastric acidification.

METHODS

Undecalcified bone biopsies of 26 gastrectomized individuals were histologically analyzed. In the clinical setting, we retrospectively identified 5 gastrectomized patients with sufficient vitamin D level, who were additionally supplemented with calcium gluconate and had a real bone mineral density (aBMD) follow-up assessments. A mouse model of achlorhydria (ATP4b-/-) was used to compare the effect of calcium gluconate and calcium carbonate supplementation on bone metabolism.

RESULTS

Biopsies from gastrectomized individuals showed significantly increased osteoid, osteoclast, and osteoblast indices and fibroosteoclasia (p < 0.05) as well as impaired calcium distribution in mineralized bone matrix compared to healthy controls. Five gastrectomized patients with sufficient vitamin D level demonstrated a significant increase in aBMD after a treatment with calcium gluconate alone for at least 6 months (p < 0.05). Calcium gluconate was superior to calcium carbonate in maintaining calcium metabolism in a mouse model of achlorhydria.

CONCLUSION

Gastrectomy is associated with severe osteomalacia, marrow fibrosis, and impaired calcium distribution within the mineralized matrix. We show that calcium gluconate supplementation can increase bone mineral density in gastrectomized individuals and performs superior to calcium carbonate in restoring calcium/skeletal homoeostasis in a mouse model of achlorhydria.

Determinants of Secondary Hyperparathyroidism in Bariatric Patients after Roux-en-Y Gastric Bypass or Sleeve Gastrectomy: A Pilot Study

Objective. Nutritional deficiencies are common after bariatric surgery. We aimed to assess the prevalence and possible predictors of secondary hyperparathyroidism (SHPT) in bariatric patients. Methods. A total of 95 patients who had undergone Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) were assessed after a median of 3 years after surgery. Anthropometric/demographic and weight-loss parameters were compared according to the presence of SHPT, independently for men/premenopausal women and postmenopausal women. Results. SHPT was highly prevalent (men/premenopausal women, 52.1%; postmenopausal women, 31.9%). Among men/premenopausal women, multivariate analysis indicated that SHPT was predicted by (a) 25-hydroxyvitamin D levels (Exp(B) = 0.869, P-value = 0.037), independently of age, sex, smoking; (b) calcium (Exp(B) = 0.159, P-value = 0.033) and smoking, independently of age and sex; (c) magnesium (Exp(B) = 0.026, P-value = 0.046) and smoking, independently of age and sex. Among postmenopausal women, SHPT was predicted by menopausal age independently of age, smoking, and levels of 25-hydroxyvitamin D or calcium. The development of SHPT was not associated with the type of surgery. Conclusions. RYGB and SG exhibited similar effects regarding the regulation of the hypothalamus-pituitary-parathyroid axis after surgery. Vitamin D status and menopausal age appear to determine SHPT on the long term. SHPT should be sought and vigorously treated with calcium and vitamin D supplementation.

Renal control of calcium, phosphate, and magnesium homeostasis

Calcium, phosphate, and magnesium are multivalent cations that are important for many biologic and cellular functions. The kidneys play a central role in the homeostasis of these ions. Gastrointestinal absorption is balanced by renal excretion. When body stores of these ions decline significantly, gastrointestinal absorption, bone resorption, and renal tubular reabsorption increase to normalize their levels. Renal regulation of these ions occurs through glomerular filtration and tubular reabsorption and/or secretion and is therefore an important determinant of plasma ion concentration. Under physiologic conditions, the whole body balance of calcium, phosphate, and magnesium is maintained by fine adjustments of urinary excretion to equal the net intake. This review discusses how calcium, phosphate, and magnesium are handled by the kidneys.

A holistic hip fracture approach: individualized diagnosis and treatment after surgery

Secondary fracture prevention is of paramount importance in the clinical management of patients with hip fractures. However, in contrast to the excellent surgical care provided to these patients in the Western hemisphere and despite good medical options, causative treatment of the underlying osteopathy causing skeletal fragility remains an unmet medical need that urgently needs to be improved. This calls for a concerted action between orthopedic/trauma surgeons and osteologists, as outstanding hospitals not only treat fragility fractures, but also prevent fractures from recurring. Aiming for a holistic hip fracture approach, in this work we highlight aspects of (a) improved risk assessment and differential diagnosis, (b) optimized basic medical care, and