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Department of Clinical Chemistry, Amsterdam Gastroenterology & Metabolism, Amsterdam UMC, University of Amsterdam, Endocrine Laboratory, Amsterdam, Netherlands
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Objective
PTH can be oxidised in vivo, rendering it biologically inactive. Non-oxidised PTH (n-oxPTH) may therefore give a better image of the hormonal status of the patient. While vitamin D supplementation decreases total PTH (tPTH) concentration, the effect on n-oxPTH concentration is unexplored. We investigated the effect of vitamin D on n-oxPTH concentration in comparison to tPTH and compared the correlations between parameters of calcium, bone and lipid metabolism with n-oxPTH and tPTH.
Methods
N-oxPTH was measured in 108 vitamin D-insufficient (25(OH)D <75 nmol/L) hypertensive patients, treated with vitamin D (2800 IE daily) or placebo for 8 weeks in the Styrian Vitamin D Hypertension Trial (NCT02136771). We calculated the treatment effect and performed correlation analyses of n-oxPTH and tPTH with parameters of calcium, bone and lipid metabolism and oxidative stress.
Results
After treatment, compared to placebo, 25(OH)D concentrations increased, tPTH decreased by 9% (P < 0.001), n-oxPTH by 7% (P = 0.025) and the ratio of n-oxPTH/tPTH increased (P = 0.027). Changes in phosphate and HDL concentration correlated with changes in n-oxPTH, but not tPTH.
Conclusions
tPTH and n-oxPTH decrease upon vitamin D supplementation. Our study suggests that vitamin D supplementation reduces the oxidation of PTH, as we observed a small but significant increase in the non-oxidised proportion of PTH upon treatment. In addition, we found that changes in phosphate and HDL concentration showed a relationship with changes in n-oxPTH, but not tPTH. This may be explained by the biological activity of n-oxPTH. Further research should be carried out to establish the clinical relevance of n-oxPTH.
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Fundación Santa Fe de Bogotá, Section of Endocrinology, Bogotá, Colombia
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Data on dietary calcium and vitamin D intake from Latin America are scarce. We explored the main correlates and dietary sources of calcium and vitamin D in a probabilistic, population-based sample from Colombia. We studied 1554 participants aged 18–75 from five different geographical regions. Dietary intake was assessed by employing a 157-item semi-quantitative food frequency questionnaire and national and international food composition tables. Daily vitamin D intake decreased with increasing age, from 230 IU/day in the 18–39 age group to 184 IU/day in the 60–75 age group (P -trend < 0.001). Vitamin D intake was positively associated with socioeconomic status (SES) (196 IU/day in lowest vs 234 in highest SES, P-trend < 0.001), and with educational level (176 IU/day in lowest vs 226 in highest education level, P-trend < 0.001). Daily calcium intake also decreased with age, from 1376 mg/day in the 18–39 age group to 1120 mg/day in the 60–75 age group (P -trend < 0.001). Calcium intake was lowest among participants with only elementary education, but the absolute difference in calcium intake between extreme education categories was smaller than for vitamin D (1107 vs 1274 mg/day, P-trend = 0.023). Daily calcium intake did not correlate with SES (P -trend = 0.74). Eggs were the main source of overall vitamin D, albeit their contribution decreased with increasing age. Dairy products contributed at least 48% of dietary calcium in all subgroups, mostly from cheese-containing traditional foods. SES and education were the key correlates of vitamin D and calcium intake. These findings may contribute to shape public health interventions in Latin American countries.
Department of Clinical Chemistry, Hematology and Immunology, Noordwest Ziekenhuis, Alkmaar, The Netherlands
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Amsterdam Gastroenterology, Endocrinology & Metabolism, Amsterdam, The Netherlands
Amsterdam UMC location University of Amsterdam, Department of Clinical Chemistry, Endocrine Laboratory, Amsterdam, The Netherlands
Amsterdam Reproduction & Development Research Institute, Amsterdam, The Netherlands
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The measurement of vitamin D metabolites aids in assessing vitamin D status and in diagnosing disorders of calcium homeostasis. Most laboratories measure total 25-hydroxyvitamin D (25(OH)D), while others have taken the extra effort to measure 25(OH)D2 and 25(OH)D3 separately and additional metabolites such as 1,25-dihydroxyvitamin D and 24,25-dihydroxyvitamin D. The aim of this review is to provide an updated overview of the main markers of vitamin D metabolism, define the intended measurands, and discuss the advantages and disadvantages of the two most widely used assays, automated assays and liquid chromatography–tandem mass spectrometry (LC-MS/MS). Whether using the easy and fast automated assays or the more complex LC-MS/MS, one should know the pitfalls of the used technique in order to interpret the measurements. In conclusion, automated assays are unable to accurately measure 25(OH)D in all patient groups, including persons using D2. In these cases, an LC-MS/MS method, when appropriately developed and standardized, produces a more reliable measurement.
Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
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Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
Laboratory of Experimental Intensive Care and Anesthesiology, Academic Medical Center, University of Amsterdam, the Netherlands
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Department of Plasma Proteins, Sanquin Research, Amsterdam, the Netherlands
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Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
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Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
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Introduction
Abnormal coagulation tests have been observed in patients with primary hyperparathyroidism (HPT) suggesting a prothrombotic effect of parathyroid hormone (PTH). Vitamin D deficiency (VIDD) is the most frequent cause of secondary HPT. Aim of our study was to investigate the influence of HPT secondary to moderate-to-severe VIDD and vitamin D replacement on the coagulation and fibrinolysis system.
Subjects and methods
Prospective cohort study of patients with vitamin D <25 nmol/L with and without HPT, and a control group of patients on vitamin D suppletion. At baseline and after 2 months of vitamin D suppletion (900,000 IU in 2 months), endocrine and coagulation markers were measured.
Results
59 patients with VIDD of which 34 had secondary HPT and 36 controls were included. After 2 months of suppletion, vitamin D increased by 399% (VIDD with HPT), 442% (all patients with VIDD) and 6% (controls). PTH decreased by 34% (VIDD with HPT, P < 0.01 for decrease), 32% (all VIDD, P < 0.01) and increased by 8% in the controls (P-values: <0.01 for relative changes between VIDD with HPT or all VIDD patients vs controls). Relative changes in PT, aPTT, fibrinogen, Von Willebrand factor, factors VII, VIII and X, thrombin generation, TAFI, clot-lysis time and d-dimer were not different between patients with VIDD with HPT or all VIDD vs controls.
Discussion
Secondary HPT due to VIDD does not have a prothrombotic effect. In contrast with previous reports, PTH does not seem to influence coagulation or fibrinolysis, which is relevant because of the high prevalence of VIDD.
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Department of Health & Life Sciences, Charles R. Drew University of Medicine and Science, Los Angeles, California, USA
Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
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Department of Health & Life Sciences, Charles R. Drew University of Medicine and Science, Los Angeles, California, USA
Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
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Skeletal muscle wasting is a serious disorder associated with health conditions such as aging, chronic kidney disease and AIDS. Vitamin D is most widely recognized for its regulation of calcium and phosphate homeostasis in relation to bone development and maintenance. Recently, vitamin D supplementation has been shown to improve muscle performance and reduce the risk of falls in vitamin D deficient older adults. However, little is known of the underlying molecular mechanism(s) or the role it plays in myogenic differentiation. We examined the effect of 1,25-D3 on myogenic cell differentiation in skeletal muscle derived stem cells. Primary cultures of skeletal muscle satellite cells were isolated from the tibialis anterior, soleus and gastrocnemius muscles of 8-week-old C57/BL6 male mice and then treated with 1,25-D3. The efficiency of satellite cells isolation determined by PAX7+ cells was 81%, and they expressed VDR. Incubation of satellite cells with 1,25-D3 induces increased expression of: (i) MYOD, (ii) MYOG, (iii) MYC2, (iv) skeletal muscle fast troponin I and T, (v) MYH1, (vi) IGF1 and 2, (vii) FGF1 and 2, (viii) BMP4, (ix) MMP9 and (x) FST. It also promotes myotube formation and decreases the expression of MSTN. In conclusion, 1,25-D3 promoted a robust myogenic effect on satellite cells responsible for the regeneration of muscle after injury or muscle waste. This study provides a mechanistic justification for vitamin D supplementation in conditions characterized by loss of muscle mass and also in vitamin D deficient older adults with reduced muscle mass and strength, and increased risk of falls.
Metabolism Laboratory, Department of Endocrinology, School of Medicine and Medical Sciences, St Vincent's University Hospital, Elm Park, Dublin 4, Ireland
Metabolism Laboratory, Department of Endocrinology, School of Medicine and Medical Sciences, St Vincent's University Hospital, Elm Park, Dublin 4, Ireland
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Background
The Institute of Medicine 2011 Report on Dietary Reference Intakes for Calcium and Vitamin D specified higher intakes for all age groups compared to the 1997 report, but also cautioned against spurious claims about an epidemic of vitamin D deficiency and against advocates of higher intake requirements. Over 40 years, we have noted marked improvement in vitamin D status but we are concerned about hypervitaminosis D.
Objective
We sought to evaluate the 25-hydroxyvitamin D (25OHD) trend over 20 years.
Design
We retrieved all results of serum 25OHD from 1993 to 2013 (n=69 012) that was trimmed to one sample per person (n=43 782). We conducted a time series analysis of the monthly averages for 25OHD using a simple sequence chart and a running median smoothing function. We modelled the data using univariate auto-regressive integrated moving average (ARIMA) and forecast 25OHD levels up to 2016.
Results
The time series sequence chart and smoother function demonstrated a steady upward trend with seasonality. The yearly average 25OHD increased from 36.1 nmol/l in 1993 to 57.3 nmol/l in 2013. The ARIMA model was a good fit for the 25OHD time series; it forecasted monthly average 25OHD up to the end of 2016 with a positive stationary R 2 of 0.377.
Conclusions
Vitamin D status improved over the past 40 years, but there remains a dual problem: there are groups at risk of vitamin D deficiency who need public health preventative measures; on the other hand, random members of the population are taking unnecessarily high vitamin D intakes for unsubstantiated claims.
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Background
Hypoparathyroidism is characterised by hypocalcaemia, and standard management is with an active vitamin D analogue and adequate oral calcium intake (dietary and/or supplements). Little is described in the literature about the impact of intercurrent illnesses on calcium homeostasis in children with hypoparathyroidism.
Methods
We describe three children with hypoparathyroidism in whom intercurrent illnesses led to hypocalcaemia and escalation of treatment with alfacalcidol (1-hydroxycholecalciferol) and calcium supplements.
Results
Three infants managed with standard treatment for hypoparathyroidism (two with homozygous mutations in GCMB2 gene and one with Sanjad-Sakati syndrome) developed symptomatic hypocalcaemia (two infants developed seizures) following respiratory or gastrointestinal illnesses. Substantial increases in alfacalcidol doses (up to three times their pre-illness doses) and calcium supplementation were required to achieve acceptable serum calcium concentrations. However, following resolution of illness, these children developed an increase in serum calcium and hypercalciuria, necessitating rapid reduction to pre-illness dosages of alfacalcidol and oral calcium supplementation.
Conclusion
Intercurrent illness may precipitate symptomatic hypocalcaemia in children with hypoparathyroidism, necessitating increase in dosages of alfacalcidol and calcium supplements. Close monitoring is required on resolution of the intercurrent illness, with timely reduction of dosages of active analogues of vitamin D and calcium supplements to prevent hypercalcaemia, hypercalciuria and nephrocalcinosis.
Regenerative Medicine Institute at CÚRAM SFI Research Centre, School of Medicine, National University of Ireland Galway (NUIG), Galway, Ireland
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Department of Clinical Biochemistry, SUHCG, GUH, Galway, Ireland
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Lambe Institute for Translational Research, School of Medicine, NUIG, Galway, Ireland
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Regenerative Medicine Institute at CÚRAM SFI Research Centre, School of Medicine, National University of Ireland Galway (NUIG), Galway, Ireland
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Newcastle upon Tyne NHS Hospitals Foundation Trust, Newcastle upon Tyne, UK
NIHR Newcastle Biomedical Research Centre, Newcastle upon Tyne, UK
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Introduction
Inactivating mutations in CYP24A1, encoding vitamin D-24-hydroxylase, can lead to an accumulation of active vitamin D metabolites and consequent hypercalcaemia. Patient (infantile and adult) presentation is varied and includes mild-severe hypercalcaemia, hypercalciuria, nephrocalcinosis and nephrolithiasis. This study aimed to characterize the clinical and biochemical phenotypes of a family with two CYP24A1 missense variants.
Methods
The proband and seven family members underwent detailed clinical and biochemical evaluation. Laboratory measurements included serum calcium, intact parathyroid hormone (iPTH), vitamin D metabolites and urine calcium and creatinine.
Results
The proband presented during the second trimester of a planned pregnancy with flu-like symptoms. Laboratory tests showed elevated adjusted calcium of 3.27 (upper reference limit (URL: 2.30) mmol/L), suppressed iPTH (<6 ng/L), elevated 25(OH)D (264 (URL: 55) nmol/L) and elevated 1,25(OH)D (293 (URL: <280) pmol/L). Ionized calcium was 1.55 (URL: 1.28) mmol/L. Sanger sequencing revealed two heterozygous missense variants in the CYP24A1: p.(Arg439Cys), R439C and p.(Trp275Arg), W275R. The proband’s brother and sister had the same genotype. The brother had intermittent hypercalcaemia and hypervitaminosis D. Only the sister had a history of nephrolithiasis. The proband’s daughter and two nephews were heterozygous for the R439C variant. The proband and her brother frequently had elevated 25(OH)D:24,25(OH)2D ratios (>50) during follow-up.
Conclusions
W275R is a new pathogenic CYP24A1 mutation in compound heterozygotic form with R439C in this family.
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Department of General Surgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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Department of General Surgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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Department of General Surgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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Objective
The aim was to explore the effects of preoperative calcium and activated vitamin D3 supplementation on post-thyroidectomy hypocalcemia and hypo-parathyroid hormone-emia (hypo-PTHemia).
Methods
A total of 209 patients were randomly divided into control group (CG) and experimental group (EG). Oral calcium and activated vitamin D3 supplementation were preoperatively administered to EG, whereas a placebo was administered to CG. Data on serum calcium, phosphorus, and PTH concentrations before operation, on postoperative day 1 (POPD1), at postoperative week 3 (POPW3), and on the length of postoperative hospitalization were collected.
Results
The serum calcium, phosphorus, and PTH concentrations, as well as the incidence of postoperative hypocalcemia and hypo-PTHemia, did not significantly differ between EG and CG. Subgroup analysis revealed that the serum calcium concentrations of the experimental bilateral thyroidectomy subgroup (eBTS) on POPD1 and POPW3 were higher than that of the control bilateral thyroidectomy subgroup (cBTS) (P < 0.05); the reduction of serum calcium in eBTS on POPD1 and POPW3 was less than those in cBTS (P < 0.05). However, significant differences were not observed between the unilateral thyroidectomy subgroups (UTS) (P > 0.05). Moreover, the incidence of postoperative hypocalcemia in cBTS on POPD1 was significantly higher than that in eBTS (65.9% vs 41.7%) (P < 0.05). The length of hospitalization in cBTS (3.55 ± 1.89 days) was significantly longer than that (2.79 ± 1.15 days) in eBTS (P < 0.05).
Conclusion
Short-term preoperative prophylactic oral calcium and activated vitamin D3 supplementation could effectively reduce the incidence of postoperative hypocalcemia and decrease the length of postoperative hospitalization in patients who have undergone bilateral thyroidectomy.
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Medical Clinic V (Nephrology, Hypertensiology, Rheumatology, Endocrinology, Diabetology), Medical Faculty Mannheim, Ruperto-Carola University of Heidelberg, Heidelberg, Germany
Synlab Medical Center of Human Genetics Mannheim, Mannheim, Germany
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Vitamin D testing and treatment is a subject of controversial scientific discussions, and it is challenging to navigate through the expanding vitamin D literature with heterogeneous and partially opposed opinions and recommendations. In this narrative review, we aim to provide an update on vitamin D guidelines and the current evidence on the role of vitamin D for human health with its subsequent implications for patient care and public health issues. Vitamin D is critical for bone and mineral metabolism, and it is established that vitamin D deficiency can cause rickets and osteomalacia. While many guidelines recommend target serum 25-hydroxyvitamin D (25[OH]D) concentrations of ≥50 nmol/L (20 ng/mL), the minimum consensus in the scientific community is that serum 25(OH)D concentrations below 25–30 nmol/L (10–12 ng/mL) must be prevented and treated. Using this latter threshold of serum 25(OH)D concentrations, it has been documented that there is a high worldwide prevalence of vitamin D deficiency that may require public health actions such as vitamin D food fortification. On the other hand, there is also reason for concern that an exploding rate of vitamin D testing and supplementation increases costs and might potentially be harmful. In the scientific debate on vitamin D, we should consider that nutrient trials differ from drug trials and that apart from the opposed positions regarding indications for vitamin D treatment we still have to better characterize the precise role of vitamin D for human health.
