Vitamin D Insufficiency is Associated With Reduced Parasympathetic Nerve Fiber Function in Type 2 Diabetes

ObjectiveVitamin D insufficiency is prevalent in subjects with type 2 diabetes mellitus (T2DM) and is associated with peripheral neuropathy. However, there are little data regarding vitamin D status in patients with cardiovascular autonomic neuropathy. Our objective was to evaluate the association of cardiovascular autonomic function, 25-hydroxyvitamin D (25[OH]D) insufficiency (i.e., levels < 30 ng/mL), and multiple metabolic parameters in subjects with T2DM.MethodsWe examined 50 individuals with T2DM. Cardiovascular autonomic function (i.e., parasympathetic function) was assessed by RR-variation during deep breathing (i.e., mean circular resultant [MCR] and expiration/inspiration [E/I] ratio). Metabolic parameters included measures of adiposity, glycemic control, insulin resistance, calcium metabolism, and 25(OH)D.ResultsParticipants with 25(OH)D insufficiency (n = 26) were younger (66 ± 9 vs. 60 ± 10 years, P < .05), more insulin resistant, had a higher body mass index (BMI) and lower adiponectin levels. The MCR (39.5 ± 26.3 vs. 27.6 ± 17.2, P < .01) and E/I ratio (1.21 ± 0.17 vs. 1.15 ± 0.09, P < .01) were lower for those with 25(OH)D insufficiency after controlling for age. A stepwise selection procedure regressing MCR and E/I ratio on a number of metabolic parameters resulted in a model identifying age and 25(OH)D insufficiency as significant determinants for both measures. The interaction of age × 25(OH)D insufficiency was also included (MCR model, R² = 0.491, P < .001; E/I ratio, R² = 0.455, P < .001). Neither glycemic control nor other metabolic parameters were selected.ConclusionOur results suggest that 25(OH)D insufficiency is associated with reduced parasympathetic function, with a stronger association in younger persons with T2DM. Studies are needed to determine if vitamin D supplementation into the sufficient range could prevent or delay the onset of cardiovascular autonomic dysfunction. (Endocr Pract. 2015;21:174-181)     

Evaluation of Vitamin D Repletion Regimens to Correct Vitamin D Status in Adults

ObjectiveTo determine the efficacy and safety of commonly prescribed regimens for the treatment of vitamin D insufficiency.MethodsWe performed a retrospective analysis of 306 consecutive patients who were prescribed ergocalciferol (vitamin D₂) for correction of vitamin D insufficiency at the Atlanta Veterans Affairs Medical Center between February 2003 and May 2006. Serum levels of parathyroid hormone, 25-hydroxyvitamin D (25-OHD), and calcium were compared before and after treatment with ergocalciferol. Patients who did not have a 25-OHD determination (n = 41) were excluded from analysis. Vitamin D deficiency, insufficiency, and sufficiency were defined as a serum 25-OHD level of < 20 ng/mL, 21 to 29 ng/mL, and > 30 ng/mL, respectively.ResultsWe identified 36 discrete prescribing regimens. The 3 most common regimens were ergocalciferol 50,000 IU once weekly for 4 weeks followed by 50,000 IU once monthly for 5 months (n = 48); ergocalciferol 50,000 IU once monthly for 6 months (n = 80); and ergocalciferol 50,000 IU 3 times weekly for 6 weeks (n = 27). Each of these 3 treatments significantly increased serum 25-OHD (P < .01), but vitamin D sufficiency was achieved in only 38%, 42%, and 82% of study subjects, respectively. Regimens with > 600,000 IU of ergocalciferol given for a mean of 60 ± 40 days achieved sufficiency in 64% of cases, without vitamin D toxicity.ConclusionIn this study, regimens that contained at least 600,000 IU of ergocalciferol appeared to be the most effective in achieving vitamin D sufficiency. Guidelines for the treatment of vitamin D insufficiency in healthy adults should be developed. (Endocr Pract. 2009;15:95-103)     

Increase in Bone Mass After Correction of Vitamin D Insufficiency in Bisphosphonate-Treated Patients

ObjectiveTo assess the relative contribution of vitamin D insufficiency to loss of bone mineral density (BMD) in patients taking bisphosphonates.MethodsPatients were eligible for inclusion if they had osteoporosis or osteopenia and demonstrated a decline in BMD during the preceding year while taking stable doses of alendronate or risedronate, plus supplemental calcium and vitamin D. Patients with previously known secondary causes of osteoporosis were excluded from the study. Eligible patients underwent prospective measurement of bilateral hip and lumbar spine BMD by dual-energy x-ray absorptiometry, serum 25-hydroxyvitamin D (25-OHD), 1,25-dihydroxyvitamin D, intact parathyroid hormone, osteocalcin, and thyroid-stimulating hormone (thyrotropin), and urinary calcium:creatinine ratio.ResultsAnnual BMD was assessed in 175 previously bisphosphonate-responsive patients with low BMD. Of the 175 patients, 136 (78%) had either a significant interval increase or no change in BMD, whereas 39 (22%) had a significant decrease. Of the 39 patients who lost BMD, 20 (51%) had vitamin D insufficiency (25-OHD < 30 ng/mL). After a single course of orally administered vitamin D₂ (500,000 IU during a 5-week period), the 25-OHD level returned to normal in 17 of the 20 vitamin D-insufficient patients and was associated with significant (P < .02) 3.0% and 2.7% increases in BMD at the lumbar spine and the femoral neck, respectively. Failure to normalize the serum 25-OHD level was associated with further loss of BMD.ConclusionVitamin D insufficiency was the most frequently identified cause of bone loss in patients with declining BMD during bisphosphonate therapy. Correction of vitamin D insufficiency in these patients led to a significant rebound in BMD. (Endocr Pract. 2008; 14:293-297)     

Determinants of Circulating 25-Hydroxyvitamin D and bone Mineral Density in Young Physicians

ObjectiveTo examine determinants of serum 25-hydroxyvitamin D [25(OH)D] and bone mineral density (BMD) in young physicians, a group not well studied previously.MethodsWe analyzed data from a questionnaire completed by young physicians as well as results of serum 25(OH)D, serum parathyroid hormone, and BMD measurements.ResultsAmong 104 study subjects, 42% were white, 46% were Asian, 12% were “other” (10 Hispanic and 2 African American subjects), and 75% were women. The mean age and body mass index (BMI) were 28.1 years and 23.0 kg/m², respectively. White subjects had a higher mean serum 25(OH)D level (27.3 ng/mL) than did Asian subjects (15.9 ng/mL) and other subjects (22.3 ng/mL) (P < .0001). White subjects tended to have higher Z-scores than Asian subjects and other subjects for the hip (P = .06), trochanter (P = .08), and lumbar spine (P = .08). The serum 25(OH)D level was negatively associated with serum parathyroid hormone (r = -0.44; P < .01) but not with BMD. The prevalence of vitamin D insufficiency [serum 25(OH)D < 30 ng/mL, 77% for the entire group] was higher (P < .01) in Asian subjects (93%) than in white subjects (61%) and other subjects (73%). Significant determinants of serum 25(OH)D included age, ethnicity, exposure to sunlight, use of vitamin D supplements, and family history of osteoporosis (P < .05 for all), and together with sex, calcium supplements, exercise, and BMI, these factors explained 49% of serum 25(OH)D level variability. Significant determinants of low BMD (osteopenia plus osteoporosis, prevalence 37.5%) included sex (P = .002) and BMI (P < .0001) but not serum 25(OH)D; Asian ethnicity reached borderline significance (P = .088). Age, sex, ethnicity, smoking, and BMI explained 20% to 30% of the Z-score variations.ConclusionIn young physicians with a healthful lifestyle, determinants of low serum 25(OH)D and BMD included modifiable risk factors. Vitamin D insufficiency and low BMD could be important contributors to future osteoporotic fractures in this population. (Endocr Pract. 2012;18:219-226)     

Effect of Vitamin D Therapy on Bone Turnover Markers in Postmenopausal Women with Osteoporosis and Osteopenia

ObjectiveTo (7) assess the rate of reduction in bone turnover with vitamin D and bisphosphonate therapies and (2) evaluate the clinical utility of bone-specific alkaline phosphatase (BSAP) in monitoring treatment response.MethodsWe retrospectively reviewed medical records of patients with newly diagnosed osteopenia and osteoporosis from 2002 to 2009 at Loyola University Medical Center. A cohort of postmenopausal women with hip or spine T-scores of less than -1, normal serum creatinine, and no prior vitamin D or bisphosphonate therapy was divided into vitamin D-deficient (n = 29) and vitamin D-sufficient (n = 13) groups. Vitamin D-deficient patients received high-dose vitamin D, whereas vitamin D-sufficient patients received orally administered bisphosphonates. BSAP levels at baseline and 1 year were compared.Resultsvitamin D therapy in the group with vitamin D deficiency led to a 26.7% decrease in BSAP (P < .01). Bisphosphonate therapy in the vitamin D-sufficient group led to a 32.7% decrease in BSAP (P = .01). The magnitude of BSAP change in the 2 study groups (6.74 ± 6.48 μg ∕ L and 8.72 ± 9.94 μgZL) did not differ significantly (P = .45).ConclusionThe results of this study suggest that correction of vitamin D deficiency in patients with osteopenia and osteoporosis can lead to a decrease in bone turnover as measured by BSAP and that the magnitude of this reduction is similar to that achieved with orally administered bisphosphonates. (Endocr Pract. 2011;17:873-879)     

La vitamine D : effets « classiques », « non classiques » et évaluation du statut du patient

Knowledge about vitamin D has greatly improved during the last few years. Vitamin D cannot any more be considered as exclusively necessary to prevent ricket/osteomalacia. Its role in the prevention of some osteoporotic fractures in the elderly (in association with calcium nutrition) is now well-demonstrated and many epidemiologic and laboratory data argue for a role in the prevention of several diseases or anomalies (cancer, auto-immune diseases, cardiovascular events, sarcopenia…). A few intervention studies confirming some of these effects also exist. Vitamin D status can easily be assessed by measuring serum 25-OH vitamin D level. However, many experts have claimed that the population-based reference values for 25OHD are too low and that the cut-off value below which vitamin D insufficiency can be present is somewhere between 20 and 40 ng/mL with a clear tendency to target values above 30 ng/mL (75 nmol/L). The main consequences are that vitamin D insufficiency is highly frequent whereas the currently recommended supplementation doses are not sufficient.     

Influencia del inmunoensayo empleado en la determinación de vitamina D sérica

IntroductionSerum 25-hydroxyvitamin D [25(OH)D] levels are the best indicator of vitamin D levels in the body. Precision, reproducibility, and lack of standardization are the main problems in such measurements. The aim of this study was to compare the 25(OH)D levels measured using Elecsys Vitamin D Total (Roche) and ADVIA Centaur Vitamin D Total (Siemens).Material and methods25(OH)D levels were tested in 166 patients using both methods. Patients were subsequently divided into two groups: a «supplemented group» consisting of patients receiving vitamin D supplements, and an «untreated group» consisting of the rest of patients.Results25(OH)D mean levels measured by the Roche and Siemens methods in the overall group were 33.6 ± 16.0 and 19.8 ± 12.4 ng/mL respectively. 54.2% of patients were receiving vitamin D supplements. In this group, mean 25(OH)D levels measured by the Roche and Siemens methods were 40.6 ± 14.5 and 25.4 ± 13.1 ng/mL respectively. In the untreated group, the respective values were 24.9 ± 13.2 and 12.8 ± 6.6 ng/mL. Prevalence of vitamin D deficiency (serum 25(OH)D levels less than 20 ng/mL) was higher in samples analyzed using the Siemens method (60.2%) as compared to those tested using the Roche method (23.5%).ConclusionThe assays evaluated are not comparable to each other. Laboratory specialists should inform clinicians of the features of the method used for measuring 25(OH)D because this will have a direct impact on interpretation of the results and medical decisions.     

Retinopathy is a Strong Determinant of Atherosclerosis in Type 2 Diabetes: Correlation with Carotid Intima Media Thickness

ObjectiveWe investigated the correlation between the severity of diabetic retinopathy (DR) and carotid intima media thickness (IMT) as a marker of atherosclerosis in patients with type 2 diabetes.MethodsThe study group consisted of 140 normo-tensive Egyptian patients (68 males and 72 females) with type 2 diabetes and DR. Carotid IMT was evaluated using high-resolution B-mode ultrasonography. DR was assessed and graded using colored fundus photography and fundus fluorescein angiography, as either nonproliferative DR (NPDR) or proliferative DR (PDR).ResultsCarotid IMT was greater in patients with PDR compared to those with NPDR (1.094 ± 0.142 mm vs. 0.842 ± 0.134 mm; P < .001). Carotid IMT showed positive correlation with diabetes duration (P < .01), systolic blood pressure (P < .001), diastolic blood pressure (P < .01), fasting blood glucose (P < .01), postprandial blood glucose (PPBG) (P < .001), glycated hemoglobin (P < .01), total cholesterol (P < .01), triglycerides (TGs) (P < .001), and DR (P < .0001). No significant difference was found between males and females in any of the studied parameters. Multiple regression analysis revealed that the determinants of carotid IMT in the studied group were age (P < .01), PPBG (P < .01), TGs (P < .001), and DR (P < .0001).ConclusionOur study proves that both NPDR and PDR are strong determinants of carotid IMT and atherosclerosis in patients with type 2 diabetes. (Endocr Pract. 2015;21:226-230)     

Supplemental vitamin D increases serum cytokines in those with initially low 25-hydroxyvitamin D: A randomized,double blind,placebo-controlled study

The purpose of this study was to determine if vitamin D status before supplementation influences the cytokine response after supplemental vitamin D. Forty-six reportedly healthy adults (mean(SD); age, 32(7) y; body mass index (BMI), 25.3(4.5) kg/m²; serum 25-hydroxyvitamin D (25(OH)D), 34.8(12.2) ng/mL) were randomly assigned (double blind) to one of three groups: (1) placebo (n = 15), or supplemental vitamin D (cholecalciferol) at (2) 4000 (n = 14) or (3) 8000 IU (n = 17). Supplements were taken daily for 35 days. Fasting blood samples were obtained before (Baseline, Bsl) and 35-days after (35-d) supplementation. Serum 25(OH)D, 1,25-dihydroxyvitamin D (1,25(OH)D), cytokines, and intact parathyroid hormone with calcium were measured in each blood sample. Supplemental vitamin D increased serum 25(OH)D (4000 IU, ≈29%; 8000 IU, ≈57%) and 1,25(OH)D (4000 IU, ≈12%; 8000 IU, ≈38%) without altering intact parathyroid hormone or calcium. The vitamin D metabolite increases in the supplemental vitamin D groups (n = 31) were dependent on initial levels as serum 25(OH)D (r = −0.63, p < 0.05) and 1,25(OH)D (r = −0.45, p < 0.05) at Bsl correlated with their increases after supplementation. Supplemental vitamin D increased interferon (IFN)-γ and interleukin (IL)-10 in subjects that were vitamin D insufficient (serum 25(OH)D < 29 ng/mL) compared to sufficient (serum 25(OH)D ⩾ 30 ng/mL) at Bsl. We conclude that supplemental vitamin D increase a pro- and anti-inflammatory cytokine in those with initially low serum 25(OH)D.     

Urinary Calcium Excretion in Primary Hyperparathyroidism: Relationship to 25-Hydroxyvitamin D Status

ObjectiveTo determine the prevalence of vitamin D deficiency in patients with primary hyperparathyroidism (PHPT) and evaluate the relationship between urinary calcium excretion and serum 25-hydroxyvitamin D (25-OH-D) levels in patients with PHPT.MethodsWe present a case report and a review of the medical records of patients with PHPT. Of 75 patients with PHPT substantiated by hypercalcemia and increased levels of intact parathyroid hormone (iPTH), 35 were identified with laboratory evaluation of vitamin D levels and 24-hour urinary calcium excretion. These study subjects were stratified as 25-OH-D deficient, insufficient, or replete (on the basis of serum values of < 15, 15 to 25, or > 25 ng/mL, respectively). Total 24-hour urinary calcium excretion and the fractional excretion of calcium (FECa) were analyzed as a function of 25-OH-D status.ResultsOf the 35 study subjects, 14 (40%) and 13 (37%) had 25-OH-D deficiency or insufficiency, respectively. Those patients with a 25-OH-D level < 15 ng/mL had higher serum iPTH concentrations as well as lower urinary calcium excretion and FECa. No significant correlations were found, however, between 25-OH-D status and iPTH concentrations (r = -0.21; P = 0.23), total 24-hour urinary calcium excretion (r = 0.07; P = 0.7), or FECa (r = 0.04; P = 0.8).ConclusionVitamin D deficiency (25-OH-D levels < 15 ng/mL) was common in our population of patients with PHPT. Urinary calcium excretion was not significantly altered by 25-OH-D deficiency in patients with newly recognized PHPT. Measurements of total urinary calcium excretion and FECa can be reliably used to rule out familial benign hypocalciuric hypercalcemia in the initial evaluation of PHPT, regardless of 25-OH-D status. Determining 25-OH-D concentrations best assesses the vitamin D status. (Endocr Pract. 2005;11:37-42)     

The effect of adding zinc to vitamin A on IGF-1, bone age and linear growth in stunted children

A randomized, double-blind, placebo controlled trial of a single dose of 200,000 I.U. of vitamin A with daily zinc supplementation was conducted with children in Mojo village, Surabaya City. Children aged 48 to 60 months were randomized to receive a single dose of 200,000 I.U. of vitamin A plus zinc sulfate (n = 12) or a single dose of 200,000 I.U. of vitamin A (n = 12) plus placebo six days a week for six months. Children were evaluated weekly for nutrient intake and for IGF-1, C-reactive protein levels, gamma globulin levels, serum zinc, serum retinol, bone age and the index height for age at six months.At the end of the study, there was a significant increase in the serum retinol level (p < 0.03), serum zinc level (p < 0.03), IGF-1 hormone (p < 0.04) and Z-score height for age (p < 0.001), bone age (p < 0.01), and gamma globulin level (p < 0.04) and a significant decrease in the amount of infection/inflammation measured by CRP level (p < 0.001). There was also a significant correlation between CRP level and height for age (p < 0.01), and between gamma level and height for age (p < 0.01).These results suggest that combined vitamin A and zinc supplementation reduces the risk of infection and increases linear growth among children, and thus may play a key role in controlling infection and stunted growth for children under five years old.     

Hiperparatiroidismo secundario en el cáncer de próstata avanzado

Background and ObjectiveHigh parathyroid hormone (PTH) concentrations are associated with increased bone resorption and bone matrix degradation. Some studies show elevated PTH concentrations and hypocalcemia in patients with advanced prostate carcinoma, although the pathophysiological significance of these findings is not well defined.Materials and methodsWe performed a retrospective study of 60 patients diagnosed with advanced prostate cancer (44 nonmetastatic and 16 metastatic) treated with androgen deprivation. In all patients, PTH, calcium, phosphorus, 25 (OH) vitamin D and prostate-specific antigen (PSA) were determined. Bone scintigraphy had previously been performed.ResultsIn patients with bone metastases, mean concentrations were as follows: calcium 9.19 mg/dl, phosphorus 3.47 mg/dl, 25 (OH) vitamin D 13.85 ng/ml, PTH 66.8 pg/ml and total PSA 101.27 ng/ml. For those without bone metastases, the results were calcium 9.39 mg/dl, phosphorus 3.38 mg/dl, 25 (OH) vitamin D 20.50 ng/ml, PTH 52.23 pg/ml and total PSA 2.52 ng/ml. PTH levels were significantly higher in patients with prostate cancer and bone metastases than in those without metastases (p=0.03). Vitamin D levels were also significantly lower in this group (p=0.03). There were no differences in other values.ConclusionsThe present study found increased PTH concentrations in patients with advanced prostate cancer. This finding could be useful to predict disease progression.     

Differencesin-Vitamin-D3-Dosing-Regimens in a Geriatric Community-Dwelling Population

ObjectiveThe adequate dose of vitamin D supple mentation for community-dwelling elderly people has not been thoroughly investigated. This study aims to determine the efficacy of a low-dose and a higher dose of vitamin D₃ in maintaining 25-hydroxyvitamin D [25(OH)D] levels at or above 30 ng/mL.MethodsThis was a single site, double-blind, ran domized exploratory clinical trial that enrolled adults 65 years of age and older. Within strata of baseline 25(OH) D levels (< 30 versus ≥ 30 ng/mL) subjects were random ized in a 1:2 ratio to receive either 400 or 2,000 IU vitamin D₃ daily for 6 months. The main outcome measures were changes in serum 25(OH)D levels according to baseline 25(OH)D levels and dose of vitamin D3.ResultsAt baseline, 41 of 105 participants (39%) had low 25(OH)D levels (< 30 ng/mL). After 6 months of vitamin D₃ supplementation, 21 of 32 participants (66%) receiving 400 IU and 14 of 59 participants (24%) receiving 2,000 IU of vitamin D₃ still had low 25(OH)D levels. Thelargest increases in serum 25(OH)D levels were observed in subjects with baseline levels < 30 ng/mL who received 2,000 IU of vitamin D daily.ConclusionRegardless of baseline 25(OH)D level, in persons 65 years of age and older, 6-month vitamin D₃ supplementation with 400 IU daily resulted in low 25(OH) D in most individuals, while 2,000 IU daily maintained 25(OH)D levels within an acceptable range in most people on this regimen. (Endocr Pract. 2012;18:847-854)     

Prevalence and Predictors Ofvitamin D Deficiency in Healthy Adults

ObjectiveVitamin D deficiency is highly prevalent in high-risk patient populations, but the prevalence among otherwise healthy adults is less well-defined. The goal of this study was to determine the prevalence and predictors of low 25-hydroxyvitamin D [25(OH)D] levels in healthy younger adults.MethodsThis was a cross-sectional study of 634 healthy volunteers aged 18-50 years performed between January, 2006 and May, 2008. We measured serum 25(OH) D and parathyroid hormone and recorded demographic variables including age, sex, race, and use of multivitamin supplements.ResultsThirty-nine percent of subjects had 25(OH)D ≤ 20 ng/mL and 64% had 25(OH)D ≤ 30 ng/mL. Predictors of lower 25(OH)D levels included male sex, black or Asian race, and lack of multivitamin use (P < 0.001 for each pre dictor). Seasonal variation in 25(OH)D levels was present in the overall cohort but was not observed in multivita min users. Lower 25(OH)D levels were associated with increased risk of elevated parathyroid hormone. Regression models predicted 25(OH)D levels ≤ 20 or ≤ 30 ng/mL with areas under the receiver operating characteristic curves of 0.76 and 0.80, respectively.ConclusionLow 25(OH)D levels are prevalent in healthy adults and may confer risk of skeletal disease. Black and Asian adults are at increased risk of deficiency and multivitamin use appears partially protective. Our models predicting low 25(OH)D levels may guide decision-making regarding whom to screen for vitamin D defi ciency. (Endocr Pract. 2012;18:914-923)     

Improvement in Pancreatic β-Cell Function with Vitamin D and Calcium Supplementation in Vitamin D-Deficient Nondiabetic Subjects

ObjectiveThere are varied reports on the effect of vitamin D supplementation on β-cell function and plasma glucose levels. The objective of this study was to examine the effect of vitamin D and calcium supplementation on β-cell function and plasma glucose levels in subjects with vitamin D deficiency.MethodsNondiabetic subjects (N = 48) were screened for their serum 25-hydroxyvitamin D (25-OHD), albumin, creatinine, calcium, phosphorus, alkaline phosphatase, and intact parathyroid hormone (PTH) status. Subjects with 25-OHD deficiency underwent a 2-hour oral glucose tolerance test. Cholecalciferol (9,570 international units [IU]/day; tolerable upper intake level, 10,000 IU/day; according to the Endocrine Society guidelines for vitamin D supplementation) and calcium (1 g/day) were supplemented.ResultsThirty-seven patients with 25-OHD deficiency participated in the study. The baseline and postvitamin D/calcium supplementation and the difference (corrected) were: serum calcium, 9 ± 0.33 and 8.33 ± 1.09 mg/dL (− 0.66 ± 1.11 mg/dL); 25-OHD, 8.75 ± 4.75 and 36.83 ± 18.68 ng/mL (28.00 ± 18.33 ng/mL); PTH, 57.9 ± 29.3 and 36.33 ± 22.48 pg/mL (− 20.25 ± 22.45 pg/mL); fasting plasma glucose, 78.23 ± 7.60 and 73.47 ± 9.82 mg/dL (− 4.88 ± 10.65 mg/dL); and homeostasis model assessment-2–percent β-cell function C-peptide secretion (HOMA-2–%B C-PEP), 183.17 ± 88.74 and 194.67 ± 54.71 (11.38 ± 94.27). Significant differences were observed between baseline and post-vitamin D/calcium supplementation serum levels of corrected calcium (Z, − 3.751; P < .0001), 25-OHD (Z, − 4.9; P < .0001), intact PTH (Z, − 4.04; P < .0001), fasting plasma glucose (Z, − 2.7; P < .007), and HOMA-2–%B C-PEP (Z, − 1.923; P < .05) as determined by Wilcoxon signed rank test. Insulin resistance as measured by HOMA was unchanged.ConclusionOptimizing serum 25-OHD concentrations and supplementation with calcium improves fasting plasma glucose levels and β-cell secretory reserve. Larger randomized control studies are needed to determine if correction of 25-OHD deficiency will improve insulin secretion and prevent abnormalities of glucose homeostasis. (Endocr Pract. 2014;20:129-138)     

Vitamin A deficiency suppresses high fructose-induced triglyceride synthesis and elevates resolvin D1 levels

Background/AimsVitamin A and its metabolites are known to regulate lipid metabolism. However so far, no study has assessed, whether vitamin A deficiency per se aggravates or attenuates the development of non-alcoholic fatty liver disease (NAFLD). Therefore, here, we tested the impact of vitamin A deficiency on the development of NAFLD.MethodsMale weanling Wistar rats were fed one of the following diets; control, vitamin A-deficient (VAD), high fructose (HFr) and VAD with HFr (VADHFr) of AIN93G composition, for 16 weeks, except half of the VAD diet-fed rats were shifted to HFr diet (VAD(s)HFr), at the end of 8^th week.ResultsAnimals fed on VAD diet with HFr displayed hypotriglyceridemia (33.5 mg/dL) with attenuated hepatic triglyceride accumulation (8.2 mg/g), compared with HFr diet (89.5 mg/dL and 20.6 mg/g respectively). These changes could be partly explained by the decreased activity of glycerol 3-phosphate dehydrogenase (GPDH) and the down-regulation of stearoyl CoA desaturase 1 (SCD1), both at gene and protein levels, the key determinants of triglyceride biosynthesis. On the other hand, n-3 long chain polyunsaturated fatty acid, docosahexaenoic acid and its active metabolite; resolvin D1 (RvD1) levels were elevated in the liver and plasma of VAD diet-fed groups, which was negatively associated with triglyceride levels. All these factors confer vitamin A deficiency-mediated protection against the development of hepatic steatosis, which was also evident from the group shifted from VAD to HFr diet.ConclusionsVitamin A deficiency attenuates high fructose-induced hepatic steatosis, by regulating triglyceride synthesis, possibly through GPDH, SCD1 and RvD1.     

Measurement of 25-OH-vitamin D in human serum using liquid chromatography tandem-mass spectrometry with comparison to radioimmunoassay and automated immunoassay

The plasma 25-OH vitamin D concentration is a reliable biomarker for vitamin D status but assay's variability makes adequate monitoring of vitamin D status difficult. We employed isotope-dilution liquid chromatography (LC) tandem-mass spectrometry (MS/MS) for the measurement of both 25-OH vitamin D₃ and 25-OH vitamin D₂ in human serum. Hexadeuterium labelled 25-OH vitamin D₃ internal standard (IS) was added to calibrators (prepared in phosphate-buffered saline with 60 g/L albumin), controls or patient sera and 25-OH vitamin D metabolites were released from vitamin D binding protein by adding sodium hydroxide prior to protein precipitation by acetonitrile/methanol (9:1, v/v). Subsequent off-line solid-phase extraction was followed by chromatographic separation on a C-18 column using a water/methanol/ammonium acetate gradient. Detection was by Atmospheric Pressure Electrospray Ionisation (AP-EI) followed by selected reaction monitoring. We compared the LC-MS/MS assay to the DiaSorin radioimmunoassay (RIA) and a recently re-standardised version of an automated electrochemiluminescent immunoassay (ECLIA) from Roche Diagnostics. We also analysed external quality control samples from the International Vitamin D External Quality Assessment Scheme (DEQAS) for comparison with other participating laboratories using LC-MS. The method was linear from 5 to at least 550 nmol/L with intra- and interday CV's ≤6% for both 25-OH vitamin D₃ and 25-OH vitamin D₂. Recoveries ranged between 94.9 and 106.9% for 25-OH vitamin D₃ and 82.7 and 100.3% for 25-OH vitamin D₂. Our results for the DEQAS serum pools averaged ?7.2% from the overall LC-MS method mean. The DiaSorin RIA agreed well with the LC-MS/MS method (r² = 0.90; average bias 1.61 nmol/L), the Roche ECLIA considerably disagreed (r² = 0.58; bias 10.13 nmol/L). This LC-MS/MS method is reliable and robust for the measurement of both 25-OH vitamin D₃ and 25-OH vitamin D₂ in human serum.     

Body mass index,iron absorption and iron status in childbearing age women

BackgroundThe prevalence of obesity has increased at an alarming rate worldwide. Some studies have observed an association between iron (Fe) deficiency (ID) and obesity, however more research is needed.ObjectiveTo assess whether body mass index (BMI) is associated with both Fe absorption and Fe status.MethodsA cross sectional sample of 318 Chilean childbearing age women was studied. The women received either a single dose of 0.5 mg of Fe (n = 137, group 1) or 3 mg of Fe plus ascorbic acid (1:2 molar ratio) (n = 181, group 2), both as FeSO₄ with labeled radioisotopes. Fe absorption was assessed through radio Fe erythrocyte incorporation. Fe status was determined by hemoglobin (Hb), mean corpuscular volume, serum Fe, total iron binding capacity, transferrin saturation, erythrocyte Zn protoporphyrin and serum ferritin (SF).Results29%, 47% and 24% of the women were classified as normal, overweight or obese, respectively. Fe absorption was significantly lower in obese women (p < 0.05). In group 1, the geometric mean and range ±1 SD of the percentage of Fe absorption for normal-weight women was 32.9% vs. 19.7% in obese. For group 2, this percentage was 36% vs. 30%, respectively (2-way ANOVA: BMI classification and Fe dose p < 0.05; interaction p = 0.34). Although Fe absorption was lower in obese women, they had higher SF (p < 0.01) and Hb (p < 0.05) concentrations.ConclusionAlthough we did not observe a relationship between BMI and Fe status, obese women displayed lower Fe absorption compared with overweight and normal weight women, possibly due to subclinical inflammation associated with obesity.