Vitamin D status in relation to obesity, bone mineral density, bone turnover markers and vitamin D receptor genotypes in healthy Saudi pre- and postmenopausal women

Summary

The various factors that may contribute to vitamin D deficiency or insufficiency were examined among healthy Saudi pre- and postmenopausal women. Vitamin D deficiency was highly prevalent among studied Saudi women with obesity, poor sunlight exposure, poor dietary vitamin D supplementation and age as the main risk factors.

Introduction

The various factors that may contribute to vitamin D deficiency or insufficiency in relation to bone health among Saudi women are not known. The main objectives of the present study were to determine the factors influencing vitamin D status in relation to serum 25-hydroxyvitamin D (25(OH)D), intact parathyroid hormone (PTH), bone turnover markers (BTMs), bone mineral density (BMD), and vitamin D receptor genotype (VDR) in healthy Saudi pre- and postmenopausal women.

Methods

A total number of 1,172 healthy Saudi women living in the Jeddah area were randomly selected and studied. Anthropometric parameters, socioeconomic status, sun exposure index together with serum levels of 25(OH)D, calcitriol, intact PTH, Ca, PO4, Mg, creatinine, albumin, and biochemical BTMs were measured. BMD was measured by a dual energy X-ray absorptiometry and VDR genotypes were also determined.

Results

About 80.0% of Saudi women studied exhibited vitamin D deficiency (serum 25(OH)D?<?50.0?nmol/L) with only 11.8% of all women were considered with adequate vitamin D status (serum 25(OH)D?>?75?nmol/L). Secondary hyperparathyroidism was evident in 18.5% and 24.6% in pre- and postmenopausal women with 25(OH)D?<?50?nmol/L. Serum 25(OH)D was lower (P?<?0.001) and intact PTH higher (P?<?0.001) in the upper quintiles of body mass index (BMI) and waist-to-hip ratio (WHR). Multiple linear regression analysis showed that BMI, sun exposure index, poor dietary vitamin D supplementation, WHR, and age were independent positive predictors of serum 25(OH)D values.

Conclusions

Vitamin D deficiency is highly prevalent among healthy Saudi pre-and postmenopausal women and largely attributed to obesity, poor exposure to sunlight, poor dietary vitamin D supplementation, and age.     

Vitamin D Supplementation Efficacy: Sleeve Gastrectomy Versus Gastric Bypass Surgery

Background

Vitamin D deficiency is common with bariatric surgery, and few prospective studies comparing different surgical procedures have evaluated appropriate vitamin D supplementation levels. Therefore, vitamin D₃ and calcium supplementation were evaluated following gastric bypass and sleeve gastrectomy.

Methods

Women consumed 2,000 international units (IU) of vitamin D₃ and 1,500 mg calcium citrate daily for 3 months following gastric bypass (n?=?11) and sleeve gastrectomy (n?=?12). Height, weight, body mass index (BMI), serum 25-hydroxyvitamin D [25(OH)D], and serum PTH concentrations were measured preoperatively and at 3 months. Wilcoxon signed rank analyses compared body weight parameters, serum 25(OH)D and PTH concentrations, and dietary intakes of vitamin D and calcium preoperatively and at 3 months. Vitamin D deficiency was defined as a serum 25(OH)D concentration <20 ng/mL (50 nmol/L).

Results

Vitamin D deficiency decreased from 60.6 % preoperatively to 26.1 % after 3 months (P?P?Conclusions Reduced food intake increased the risk of vitamin D deficiency following bariatric surgery. However, daily supplementation with 2,000 IU of vitamin D₃ and 1,500 mg calcium citrate significantly increased 25(OH)D concentrations and reduced the percent of women who were vitamin D deficient. Although serum 25(OH)D concentrations did not reach levels associated with detrimental health effects, several women remained vitamin D deficient and more aggressive supplementation may be indicated.     

Is high-dose cholecalciferol justified in children with chronic kidney disease who failed low-dose maintenance therapy?

Background

We aimed to investigate the effect of single, high-dose intramuscular cholecalciferol on vitamin D3 and intact parathyroid hormone (iPTH) levels in children with chronic kidney disease (CKD).

Methods

Between January 2012 and June 2012, we conducted a prospective, uncontrolled study at the Pediatric Nephrology Unit of King Abdulaziz University Hospital, Jeddah, to investigate the effect of single, high-dose intramuscular vitamin D3 on 25(OH)D3 and iPTH levels in vitamin D insufficient/deficient children with CKD. Serum vitamin D3, iPTH, calcium, phosphate, alkaline phosphatase (ALP), and creatinine levels were measured before intramuscular vitamin D3 (300,000 IU) administration, and these were subsequently repeated at 1 and 3 months after treatment. Statistical analysis was performed with the Statistical Package for the Social Sciences (SPSS Inc., Chicago, IL, USA).

Results

Nineteen children fulfilled the criteria. At 3 months after treatment, vitamin D3 levels were significantly higher than at baseline (p?<?0.001) but lower than the levels at 1 month. iPTH levels decreased significantly at 3 months (p?=?0.01); however, the drop in iPTH levels was not significant at 1 month (p?=?0.447). There were no changes in calcium, phosphate, ALP, or creatinine levels after treatment.

Conclusions

Single-dose intramuscular vitamin D3 (300,000 IU) resulted in significant improvement of vitamin D3 and iPTH levels in children with CKD.     

Ergocalciferol decreases erythropoietin resistance in children with chronic kidney disease stage 5

Background

Vitamin D insufficiency is related to erythropoietin resistance in chronic kidney disease (CKD). This study was conducted to evaluate the effect of ergocalciferol on the dose of erythrocyte-stimulating agent (ESA) administered to children with CKD stage 5 and vitamin D insufficiency.

Methods

Twenty patients aged <18 years with CKD stages 5 or 5D and vitamin D insufficiency were divided into two groups. During the 12-week study, ten patients received oral ergocalciferol (treatment) whereas the other ten patients did not (control). The ESA dosage was recorded monthly.

Results

There were no significant differences in demographic data, ESA dosages, and laboratory data, including corrected calcium, phosphorus, parathyroid hormone, hemoglobin, ferritin, 25-hydroxyvitamin D (25D), and transferrin saturation levels, between the two groups at baseline. At the completion of the study, serum 25D levels in the treatment group were significantly increased from baseline (p?=?0.02) and were significantly higher than the serum 25D levels in the controls (p?<?0.005). The ESA dosage in the treatment group was significantly decreased when compared to baseline (p?=?0.04).

Conclusions

Vitamin D deficiency should be routinely detected and treated. Our results show that the administration of ergocalciferol in conjunction with 1,25-dihydroxyvitamin D3 reduced the dose of ESA required to treat children with CKD stages 5 and 5D and may decrease erythropoietin resistance.     

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

Summary

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.     

Effect of concomitant vitamin D deficiency or insufficiency on lumbar spine volumetric bone mineral density and trabecular bone score in primary hyperparathyroidism

Summary

Lower vitamin D and higher parathyroid hormone (PTH) levels are associated with higher volumetric BMD and bone strength at the lumbar spine as measured by central quantitative computed tomography in primary hyperparathyroidism (PHPT), but there are no differences in bone microarchitecture as measured by trabecular bone score (TBS).

Introduction

The purpose of this study was to evaluate the association between 25-hydroxyvitamin D (25OHD) and volumetric bone mineral density (vBMD) and the TBS at the lumbar spine (LS) in PHPT.

Methods

This is a cross-sectional analysis of PHPT patients with and without low 25OHD. We measured vBMD with quantitative computed tomography (cQCT) and TBS by dual-energy X-ray absorptiometry (DXA) at the LS in 52 and 88 participants, respectively.

Results

In the cQCT cohort, those with lower vitamin D (<20 vs. 20-29 vs. ≥30 ng/ml) tended to be younger (p?=?0.05), were less likely to use vitamin D supplementation (p?<?0.01), and had better renal function (p?=?0.03). Those with 25OHD <20 ng/ml had 80 and 126 % higher serum PTH levels respectively vs. those with 25OHD 20–29 ng/ml (p?=?0.002) and 25OHD ≥30 ng/ml (p?<?0.0001). Covariate-adjusted integral and trabecular vBMD were higher in those with 25OHD 20–29 vs. those with 25OHD ≥30 ng/ml, but those with 25OHD <20 did not differ. Because there were few participants with 25OHD deficiency, we also compared those with vitamin D <30 vs. ≥30 ng/ml. Covariate-adjusted integral and trabecular vBMD were 23 and 30 % higher respectively (both p?<?0.05) in those with vitamin D <30 vs. ≥30 ng/ml. TBS was in the partially degraded range but did not differ by vitamin D status.

Conclusion

In mild PHPT, lower 25OHD is associated with higher PTH, but vitamin D deficiency and insufficiency using current clinical thresholds did not adversely affect lumbar spine skeletal health in PHPT. Further work is needed to determine if higher vBMD in those with lower vitamin D is due to an anabolic effect of PTH.

     

Vitamin D status in children with chronic kidney disease

Background

The role of vitamin D status in patients with renal insufficiency and its relation to dietary intake and parathyroid hormone (PTH) secretion is of utmost interest given the morbidity and mortality associated with the disordered mineral metabolism seen in chronic kidney disease (CKD).

Methods

We conducted a cross-sectional study of 100 pediatric patients with a diagnosis of CKD stage 1–5 at Children's Hospital Boston, measuring blood levels of 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D [1,25(OH)₂D], and parathyroid hormone and obtaining data on nutrient intake and other variables related to vitamin D status.

Results

Subjects ranged in age from 6 months to 18?years, and 60 were male, 40 female. Of the 100 patients, 16 % were deficient in 25(OH)D (≤20?ng/mL) and another 24 % were insufficient (≤30?ng/mL), with 40 % in the suboptimal range. Serum 25(OH)D and dietary vitamin D intake were not correlated.

Conclusions

We found a high prevalence of hyperparathyroidism in early-stage CKD and a significant relationship between 25(OH)D and PTH regardless of calcitriol level. Our study results support the suggestion that optimization of vitamin D levels may provide additional benefit in preventing or improving hyperparathyroidism in patients with early CKD and likely remains important as an adjunctive therapy in children with advanced CKD.     

The Value of Postoperative Parathyroid Hormone Levels in Predicting the Need for Long-Term Vitamin D Supplementation after Total Thyroidectomy

Background

Few studies have examined the need for vitamin D supplementation after total thyroidectomy. This study examines the role of postoperative day (POD) 1 serum calcium and parathyroid hormone (PTH) levels in predicting the need for long-term vitamin D supplementation after total thyroidectomy.

Methods

A retrospective, single institutional study of patients who underwent total thyroidectomy between January 2007 and December 2008 was performed. Data collected included extent of surgery, final pathology, postoperative calcium (mg/dl) and PTH (pg/ml) values, and duration of vitamin D supplementation. Patients were divided into 4 groups based on POD1 PTH values: group 1 (<5.0); group 2 (5.0–10); group 3 (10.1–20); and group 4 (>20).

Results

Of the 104 patients, 26 were in group 1, 12 in group 2, 18 in group 3, and 48 in group 4, with median PTH values of <2.5, 8.2, 14.1, and 30 pg/ml, respectively. All 7 (7%) patients who required vitamin D supplementation >1 month were in group 1. The positive predictive value of POD1 PTH <5.0 in predicting supplementation >1 month was 27% (sensitivity 100%, specificity 80%). Seventy-eight patients had a POD1 PTH level ≥5, and none required vitamin D supplementation >1 month (100% negative predictive value). The positive predictive value of various POD1 calcium thresholds (<7.5, <8.0, and <8.5 mg/dl) was 17, 14, and 15%, respectively.

Conclusions

Postoperative PTH levels better predict long-term hypocalcemia requiring vitamin D supplementation than serum calcium levels. A PTH level ≥5.0 may identify patients who can be safely discharged without routine vitamin D supplementation.     

Vitamin D Status 10 Years After Primary Gastric Bypass: Gravely High Prevalence of Hypovitaminosis D and Raised PTH Levels

Background

The primary aim of this study was to evaluate the prevalence of vitamin D deficiency and secondary hyperparathyroidism after Roux-en-Y gastric bypass. Secondly, we have tried to assess predictors for vitamin D deficiency.

Methods

Five hundred thirty-seven patients who underwent primary Roux-en-Y gastric bypass surgery between 1993 and 2003 at the Örebro University Hospital and Uppsala University Hospital were eligible for the study. Patients were asked to provide a blood sample between November 2009 and June 2010 and to complete a questionnaire about their postoperative health status. Serum values of 25-OH vitamin D, parathyroid hormone (PTH), alkaline phosphatase (ALP) and calcium were determined.

Results

Follow-up was completed in 293 patients, of which 83 % were female, with an age of 49?±?9.9 years after a median time of 11?±?2.8 years. Vitamin D, PTH and albumin-corrected calcium values were 42?±?20.4 nmol/L, 89.1?±?52.7 ng/L and 2.3?±?0.1 mmol/L, respectively. Of all patients, 65 % were vitamin D deficient, i.e. 25-OH vitamin D <50 nmol/L, and 69 % had PTH above the upper normal reference range, i.e. >73 ng/L. Vitamin D was inversely correlated with PTH levels (p?<?0.001) and positively correlated with calcium (p?=?0.016). Vitamin D did not correlate with ALP. The only factor found to predict vitamin D deficiency was high preoperative body mass index (BMI) (p?=?0.008), whereas gender, age, time after surgery and BMI at follow-up did not.

Conclusions

Vitamin D deficiency and secondary hyperparathyroidism after Roux-en-Y gastric bypass (RYGB) were confirmed in our study because 65 % of patients had vitamin D deficiency, and 69 % had increased PTH levels more than 10 years after surgery. These data are alarming and highlight the need for improved long-term follow-up. Vitamin D deficiency does not seem to progress with time after surgery, possibly due to weight loss. Only preoperative BMI, cutoff point 43 kg/m², was a predictor of vitamin D deficiency at follow-up. Improved long-term follow-up of patients that undergo RYGB is needed.     

Effect of vitamin D supplementation on bone health parameters of healthy young Indian women

Summary

There is a huge prevalence of hypovitaminosis D in the Indian population. We studied the efficacy and safety of oral vitamin D supplementation in apparently healthy adult women. Monthly cholecalciferol given orally, 60,000 IU/month during summers and 120,000 IU/month during winters, safely increases 25-hydroxyvitamin D (25(OH)D) levels to near normal levels.

Introduction

There is a huge burden of hypovitaminosis D in the Indian population. The current recommendation for vitamin D supplementation is not supported by sufficient evidence.

Methods

Study subjects included 100 healthy adult women of reproductive age group from hospital staff. They were randomized into group A (control) and group B (supplement) by simple randomization. Group B received 60,000 IU of cholecalciferol/month administered orally for 3 months, and then group A received 60,000 IU and group B 120,000 IU/month for 6 months.

Results

Mean baseline 25(OH)D level was 4.5?±?3.1 ng/ml and parathyroid hormone level was 50?±?25 pg/ml. In group B, 25(OH)D levels increased from 4.8?±?3.5 to 31.6?±?15.5 ng/ml (P?<?0.001) in 3 months. Interestingly, the increase, although of lower magnitude, was also observed in control group A, from 4.5?±?3.4 ng/ml (in spring) to 10.8?±?7.2 ng/ml (in summer; P?<?0.001). In group A (60,000 IU/month), mean 25(OH)D level had increased to 22.3?±?12.4 ng/ml (P?<?0.001) at 9 months (winter). In group B (120,000 IU/month), 25(OH)D levels were maintained at 30.7?±?12.8 ng/ml at 9 months (winter).

Conclusion

Our data show that monthly administration of 60,000 IU cholecalciferol in healthy subjects with hypovitaminosis D may suffice in summer months, but higher doses may be more appropriate during winter months.     

Vitamin D deficiency, insulin resistance, serum adipokine, and leptin levels in peritoneal dialysis patients

Objective

Associations between 25 hydroxy vitamin D [25(OH)D], adipokines levels, and insulin resistance have been reported. The aim of this study was to explore the effects of cholecalciferol supplementation on vitamin D levels, insulin resistance, leptin, and adiponectin levels in vitamin D-deficient peritoneal dialysis (PD) patients.

Methods

In nineteen vitamin D-deficient PD patients, who were treated with cholecalciferol, fasting serum glucose, insulin, adiponectin, leptin, 25(OH)D and parathyroid hormone (PTH) were measured before and after cholecalciferol replacement therapy. Eighteen (94.7 %) PD patients with vitamin D deficiency were receiving active vitamin D compounds (alphacalciferol) for PTH control. Alphacalciferol dosing was kept constant during treatment with cholecalciferol.

Results

While mean 25(OH)D significantly increased from (10.2 ± 4.9 ng/ml) to (82.9 ± 56.5 ng/ml) (p < 0.05), mean homeostatic model assessment-insulin resistance index significantly decreased from (4.6 ± 3.6) to (2.8 ± 2.0) after cholecalciferol replacement therapy (p < 0.05). Serum leptin levels (12.9 ± 17.6 ng/ml) significantly increased (18.1 ± 19.5 ng/ml) (p < 0.05), while there was no change in serum adiponectin, calcium, and phosphate after vitamin D replacement. Serum PTH levels significantly decreased from 551.9 ± 276.6 pg/ml to 434.0 ± 273.4 ng/ml.

Conclusions

Cholecalciferol replacement therapy significantly decreases PTH levels and insulin resistance. The results of this study need to be confirmed in larger clinical trials.     

Secondary Hyperparathyroidism, Vitamin D Sufficiency, and Serum Calcium 5 Years After Gastric Bypass and Duodenal Switch

Background

The prevalence of secondary hyperparathyroidism (SHPT) is high after bariatric surgery. Vitamin D is supplied to counteract SHPT and bone disease, and we studied vitamin D associations with SHPT.

Methods

We measured serum levels of 25-OH vitamin D and parathyroid hormone (PTH) 5 years after gastric bypass and duodenal switch. One hundred twenty-five patients were included, of whom 114 (91 %) had undergone gastric bypass and 11 (9 %) had undergone duodenal switch. SHPT was defined as PTH?>?7.0 pmol/l in the absence of hypercalcemia. 25-OH vitamin D levels were divided into three categories: <50, 50–74, and ≥75 nmol/l. Serum ionized calcium, magnesium, phosphate, and creatinine were divided into tertiles.

Results

Mean age?±?SD was 44?±?9 years at 5 years follow-up. Ninety out of 125 (72 %) patients were women. SHPT was present in 45 out of 114 (40 %) gastric bypass patients and in 11 out of 11 (100 %) duodenal switch patients. The prevalence was high in all vitamin D categories studied. An inverse association between ionized calcium and PTH was found. For the gastric bypass patients, the odds ratio for SHPT in the upper two tertiles of ionized calcium was 0.35; 95 % CI, 0.15–0.79; p?=?0.011, compared with the lowest tertile. Supplements of vitamin D and calcium were not associated with a lower prevalence of SHPT at 5 years follow-up.

Conclusions

The prevalence of SHPT was high 5 years after gastric bypass and duodenal switch. SHPT was inversely associated with serum ionized calcium, but not with vitamin D. The supplementation used was insufficient to compensate for the impaired calcium absorption after surgery.     

Vitamin D supplementation improves endothelial dysfunction in patients with non-dialysis chronic kidney disease

Purpose

Hypovitaminosis D is common in chronic kidney disease (CKD) and is associated with endothelial dysfunction and cardiovascular events. This study aimed to investigate the effects of vitamin D supplementation on endothelial dysfunction in non-dialysis CKD patients.

Materials and methods

Seventy-one non-dialysis CKD patients with low vitamin D (serum 25(OH)D < 30 ng/mL) were recruited. Patients received oral cholecalciferol 50,000 units once a week for 12 weeks. Changes in endothelial function by brachial artery flow-mediated dilation (FMD), soluble vascular cell adhesion molecule-1 (sVCAM-1), and sE-selectin were studied.

Results

There was a significant increase in serum levels of 25(OH)D after cholecalciferol supplementation (33.7 ± 12.1 vs. 13.2 ± 5.4 ng/mL, P < 0.001). Multivariable regression analysis showed that higher proteinuria (β = ? 0.548, P < 0.001) and lower levels of 25(OH)D (β = 0.360, P < 0.001) at baseline were related to lower 25(OH)D level after supplementation. FMD increased significantly from 4.4 ± 1.3 to 5.1 ± 1.5% (P < 0.001), and soluble endothelial biomarkers decreased: sVCAM-1 from 926.9 ± 158.0 to 867.0 ± 129.0 ng/mL (P < 0.001), and sE-selectin 69.7 ± 15.8 to 63.3 ± 14.7 ng/mL (P < 0.001).

Conclusions

Vitamin D supplementation can improve endothelial dysfunction in pre-dialysis CKD patients.

     

Vitamin D deficiency in HIV-infected postmenopausal Hispanic and African-American women

Summary

We evaluated vitamin D status in HIV+ and HIV? postmenopausal African-American (AA) and Hispanic women. Most women (74-78%) had insufficient 25-hydroxyvitamin D (25OHD) levels, regardless of HIV status. 25OHD was lower in AA women and women lacking supplement use, providing support for screening and supplementation. Among HIV+ women, 25OHD was associated with current CD4 but not type of antiretroviral therapy.

Introduction

To evaluate vitamin D status and factors associated with vitamin D deficiency and insufficiency in HIV-infected (HIV+) postmenopausal minority women.

Methods

In this cross-sectional study, 89 HIV+ and 95 HIV? postmenopausal women (33% AA and 67% Hispanic) underwent assessment of 25OHD, 1,25-dihydroxyvitamin D, parathyroid hormone, markers of bone turnover and bone mineral density by dual energy X-ray absorptiometry.

Results

The prevalence of low 25OHD did not differ by HIV status; the majority of both HIV+ and HIV? women (74-78%) had insufficient levels (<30?ng/ml). Regardless of HIV status, 25OHD was significantly lower in AA subjects, and higher in subjects who used both calcium and multivitamins. In HIV+ women on antiretroviral therapy (ART), 25OHD was directly associated with current CD4 count (r?=?0.32; p?<?0.01) independent of age, ethnicity, BMI, or history of AIDS-defining illness. No association was observed between 1,25(OH)₂D and CD4 count or between serum 25OHD, 1,25(OH)₂D or PTH and type of ART.

Conclusions

In postmenopausal minority women, vitamin D deficiency was highly prevalent and associated with AA race and lack of supplement use, as well as lower current CD4 cell count. These results provide support for screening and repletion of vitamin D in HIV+ patients.     

Hypocalcaemia after total thyroidectomy for Graves' disease and for benign atoxic multinodular goitre

Purpose

Postoperative hypocalcaemia has been reported to be more common after total thyroidectomy (TT) for Graves' disease than after TT for benign atoxic multinodular goitre (MNG). The reasons for this potential association are not clear. In the present study, the frequency and risk factors of hypocalcaemia after TT for Graves' vs MNG were compared.

Methods

Between January 1999 and October 2009, patients with first-time surgery for Graves' disease or MNG treated with a TT were included in the study. Postoperative hypocalcaemia was defined by symptoms, calcium levels and treatment with calcium and/or vitamin D analogues during postoperative hospital stay, at discharge, and at the 6-week and 6-month follow-ups. Outcomes were compared with Mann–Whitney, chi² and Fishers' exact test where appropriate and by multivariable logistic regression analysis.

Results

There were 128 patients with Graves' disease and 81 patients with MNG. Patients with Graves' disease were younger than patients with MNG (median age, 35 vs 51?years, p?<?0.001). Symptoms of hypocalcaemia were more common in patients with Graves' disease (p?<?0.001; OR, 95?% CI 3.26, 1.48–7.14), but the frequency of biochemical hypocalcaemia, postoperative levels of parathyroid hormone (PTH) and treatment with calcium and vitamin D did not differ between groups of patients.

Conclusion

Apart from more frequent symptoms of hypocalcaemia in patients with Graves' disease, there was no difference in the overall frequency of biochemical hypocalcaemia, low levels of PTH and/or treatment with calcium and vitamin D.     

Vitamin D bioavailability and catabolism in pediatric chronic kidney disease

Background

Vitamin D-binding protein (DBP) and catabolism have not been examined in the clinical setting of childhood chronic kidney disease (CKD).

Methods

The concentrations of serum vitamin D {25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D [1,25(OH)₂D], 24,25-dihydroxyvitamin D [24,25(OH)₂D]}, DBP, intact parathyroid hormone (iPTH), and fibroblast growth factor-23 (FGF23) were measured in 148 participants with CKD stages 2–5D secondary to congenital anomalies of the kidney/urinary tract (CAKUT), glomerulonephritis (GN), or focal segmental glomerulosclerosis (FSGS). Free and bioavailable 25(OH)D concentrations were calculated using total 25(OH)D, albumin, and DBP concentrations.

Results

The concentrations of all vitamin D metabolites were lower with more advanced CKD (p?<?0.001) and glomerular diagnoses (p?≤?0.002). Among non-dialysis participants, DBP was lower in FSGS versus other diagnoses (FSGS–dialysis interaction p?=?0.02). Winter season, older age, FSGS and GN, and higher FGF23 concentrations were independently associated with lower concentrations of free and bioavailable 25(OH)D. Black race was associated with lower total 25(OH)D and DBP, but not free or bioavailable 25(OH)D. 24,25(OH)₂D was the vitamin D metabolite most strongly associated with iPTH. Lower 25(OH)D and higher iPTH concentrations, black race, and greater CKD severity were independently associated with lower levels of 24,25(OH)₂D, while higher FGF23 concentrations and GN were associated with higher levels of 24,25(OH)₂D.

Conclusions

Children with CKD exhibit altered catabolism and concentrations of DBP and free and bioavailable 25(OH)D, and there is an important impact of their underlying disease.     

Vitamin D status and parathyroid hormone relationship in adolescents and its association with bone health parameters: analysis of the Northern Ireland Young Heart’s Project

Summary

In girls, a plateau in parathyroid hormone (PTH) was observed at a 25-hydroxyvitamin D (25(OH)D) concentration of approximately 60 nmol/l. In boys, there was no plateau in PTH concentrations as 25(OH)D concentration increased. A 25(OH)D threshold of 60 nmol/l appears to have implications for bone health outcomes in both girls and boys.

Introduction

Our objective was to investigate if there is a threshold 25(OH)D concentration where a plateau in PTH concentration is evident and to examine the impact of this relationship on bone mineral density (BMD) and bone turnover in a representative sample of adolescents.

Methods

We conducted a cross-sectional analysis among 1,015 Northern Irish adolescents aged 12 and 15 years. Serum 25(OH)D, PTH, osteocalcin, type 1 collagen cross-linked C-telopeptide (CTx), and BMD of the nondominant forearm and heel were measured. Nonlinear regression analysis was used to model the association between 25(OH)D and PTH.

Results

In girls, a plateau in PTH was observed at a 25(OH)D concentration of approximately 60 nmol/l (PTH?=?47.146?+?370.314?×?exp^{(?0.092?×?25(OH)D)}) while no plateau in PTH was observed in boys (PTH?=?42.144?+?56.366?×?exp^{(?0.022?×?25(OH)D)}). Subjects with 25(OH)D levels <60 nmol/l had significantly higher osteocalcin concentrations (P?<?0.05) compared with those who had ≥60 nmol/l, while no significant (P?>?0.05) differences were noted for CTx concentrations. In girls only, nondominant forearm BMD but not heel BMD was significantly higher (P?=?0.046) in those with 25(OH)D concentrations?≥?60 nmol/l.

Conclusions

Serum 25(OH)D levels above 60 nmol/l in Northern Irish adolescent girls prevent an increase in serum PTH levels and maintaining 25(OH)D >60 nmol/l in both girls and boys may lead to improved bone health outcomes.     

Serum Vitamin D Increases with Weight Loss in Obese Subjects 6 Months After Roux-en-Y Gastric Bypass

Background

Malabsorptive surgical procedures lead to deficiencies in fat-soluble vitamins. However, results concerning serum vitamin D (25OHD) after gastric bypass (GBP) are controversial. The aim of the study was to assess the influence of GBP on 25OHD and calcium metabolism.

Methods

Parameters of calcium metabolism were evaluated in 202 obese subjects before and 6 months after GBP. Thirty of them were matched for age, gender, weight, skin color, and season with 30 subjects who underwent sleeve gastrectomy (SG). A multivitamin preparation that provides 200 to 500 IU vitamin D3 per day was systematically prescribed after surgery.

Results

In the 202 patients after GBP, serum 25OHD significantly increased from 13.4?±?9.1 to 22.8?±?11.3 ng/ml (p?<?0.0001), whereas parathyroid hormone (PTH) did not change. Despite a decrease in calcium intake (p?<?0.0001) and urinary calcium/creatinine ratio (p?=?0.015), serum calcium increased after GBP (p?<?0.0001). Preoperatively, 91 % of patients had 25OHD insufficiency (<30 ng/ml), 80 % deficiency (<20 ng/ml), and 19 % secondary hyperparathyroidism (>65 pg/ml) vs. 76, 44, and 17 %, respectively, following GBP. Serum 25OHD was negatively correlated with BMI at 6 months after GBP (R?=??0.299, p?<?0.0001). In the two groups of 30 subjects, serum 25OHD and PTH did not differ at 6 months after GBP or SG.

Conclusions

At 6 months after GBP, serum 25OHD significantly increased in subjects supplemented with multivitamins containing low doses of vitamin D. These data suggest that weight loss at 6 months after surgery has a greater influence on vitamin D status than malabsorption induced by GBP.     

Ethnic differences in 25-hydroxyvitamin D levels and response to treatment in CKD

Aim

Nutritional vitamin D [25(OH)D] deficiency is common in patients with chronic kidney disease (CKD). No studies have specifically examined the differences between ethnic groups in response to ergocalciferol (“D2”) therapy.

Methods

A retrospective analysis was performed to evaluate the effectiveness of D2 therapy as recommended by the KDOQI guidelines in 184 Hispanic and Caucasian nondialysis CKD patients.

Results

Low 25(OH)D levels (<75 nmol/L) were found in 89.4 % of Hispanics versus 61.4 % of Caucasians, despite similar degrees of CKD. Treatment per KDOQI guidelines resulted in 85.5 % of treated Hispanics and 66.7 % of treated Caucasians remaining vitamin D-deficient. Although both Hispanics and Caucasians had significant (P < 0.0001) changes in 25(OH)D levels, absolute changes were modest (12.5 ± 2.0 nmol/mL in Hispanics, 20.0 ± 3.5 nmol/L in Caucasians). The increase seen in Caucasians was significantly greater than in Hispanics (P < 0.0001). In multiple logistic regression modeling, Hispanic ethnicity remained independently associated with poorer response to therapy (P = 0.0055), even after adjustment for other factors.

Conclusions

While both Hispanics and Caucasians demonstrated suboptimal response to the KDOQI-guided vitamin D repletion strategy, Hispanic ethnicity was significantly associated with poorer response. Our findings may have implications for other darker-skinned populations, even in solar-rich environments.