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Open access

Vitamin D supplementation does not improve CVD risk factors in vitamin D-insufficient subjects

Julia Kubiak, Per Medbøe Thorsby, Elena Kamycheva, and Rolf Jorde

Objective

Low serum 25(OH)D levels are associated with cardiovascular disease (CVD) and some of its risk factors. However, in interventional studies, the effects of vitamin D supplementation have been uncertain, possibly due to inclusion of vitamin D-sufficient subjects. Our aim was therefore to examine effects of vitamin D supplementation on CVD risk factors in vitamin D-insufficient subjects.

Design

Double-blinded randomized controlled trial.

Methods

A 4-month interventional study with high-dose vitamin D (100,000 IU loading dose, followed by 20,000 IU/week) or placebo with measurements of blood pressure, lipids (total-, LDL- and HDL-cholesterol, triglycerides, apolipoproteins A1 and B), and glucose metabolism parameters (blood glucose, HbA1c, serum human receptors for advanced glycation end products (sRAGE), insulin, C-peptide and HOMA-IR).

Results

A total of 422 subjects with mean serum 25(OH)D level 34 nmol/L were included, with 411 subjects completing the study. Serum 25(OH)D levels increased with 56 nmol/L and decreased with 4 nmol/L in the vitamin D and placebo group, respectively. We found no statistically significant differences between the two groups in any of the measured CVD risk factors, except for a minor increase in sRAGE in the vitamin D group. Stratified analyses of subjects with low baseline serum 25(OH)D levels alone, or combined with blood pressure, lipid and HOMA-IR values above the median for the cohort, did not skew the results in favour of vitamin D supplementation.

Conclusion

Supplementation with vitamin D in subjects with baseline vitamin D insufficiency does not improve CVD risk factor profile.

DOI:
https://doi.org/10.1530/EC-18-0144
Volume 7: Issue 6,
Pages:
840–849 (10 total)
Open access

Impact of intercurrent illness on calcium homeostasis in children with hypoparathyroidism: a case series

A Chinoy, M Skae, A Babiker, D Kendall, M Z Mughal, and R Padidela

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.

DOI:
https://doi.org/10.1530/EC-17-0234
Volume 6: Issue 8,
Pages:
589–594 (6 total)
Open access

Lean mass, magnesium, faecal calprotectin and glucocorticoid exposure as risk factors for low bone mineral density in inflammatory bowel disease patients

Iulia Soare, Anca Sirbu, Mihai Mircea Diculescu, Bogdan Radu Mateescu, Cristian Tieranu, Sorina Martin, Carmen Gabriela Barbu, Mirela Ionescu, and Simona Fica

Background and aim

Low bone mineral density (BMD) is a common complication in patients with inflammatory bowel disease (IBD). However, debates are ongoing with regard to the other involved factors, especially in younger patients. This study aimed to evaluate the parameters that contribute to decreased BMD, focusing on premenopausal women and men aged <50 years.

Methods

This study included 81 patients with IBD and 81 age-, sex- and BMI-matched controls. Blood tests were conducted on IBD patients, and a dual-energy X-ray absorptiometry (DXA) scan was performed on both groups.

Results

Low BMD and fragility fracture were found to be more prevalent in IBD patients than in healthy subjects (49.3% vs 23.4%, P = 0.001 and 9.8% vs 1.2%, P = 0.01, respectively). Patients with low BMD were older, with a longer disease duration, higher faecal calprotectin (FC) levels and lower magnesium and lean mass (appreciated as appendicular skeletal muscle index (ASMI)). Multiple regression analysis revealed that ASMI, age and use of glucocorticoids were the independent parameters for decreased BMD. Although 91.3% of the patients had a 25-hydroxy vitamin D level of <30 ng/mL, it was not a statistically significant factor for decreased BMD.

Conclusion

In our study, the levels of vitamin D did not seem to have an important impact on BMD. Conversely, FC, magnesium and lean mass are important factors, suggesting that good control of disease, adequate magnesium intake and increased lean mass can have a good impact on bone metabolism in patients with IBD.

DOI:
https://doi.org/10.1530/EC-21-0138
Volume 10: Issue 8,
Pages:
918–925 (8 total)
Open access

Serum PTH is not a good marker for defining a threshold for vitamin D deficiency

Rolf Jorde and Guri Grimnes

Objective

In addition to its skeletal effects, vitamin D may also be important for health in general. It is uncertain what level of serum 25-hydroxyvitamin D (25(OH)D), marker of vitamin D status, is sufficient for these effects. With decreasing serum 25(OH)D levels there is an increase in serum PTH. The point at which this occurs has been considered as a threshold for vitamin D sufficiency. The thresholds found have varied widely and have mainly been based on observational studies. However, to truly establish a threshold for vitamin D effects, this has to be based on randomized controlled trials (RCTs).

Methods

The study included 2803 subjects from a general health survey, the Tromsø study, and pooled individual person data from five vitamin D intervention studies (n = 1544). Serum parathyroid hormone (PTH) and change in PTH after vitamin D supplementation were related to serum 25(OH)D levels in steps of 25 nmol/L (<24, 25–49, 50–74, 75–99, and >99 nmol/L).

Results

In the Tromsø study, in the females there was a gradual decrease in serum PTH with increasing serum 25(OH)D with no apparent plateau, whereas in the males the decrease in PTH in subjects with serum 25(OH)D >74 nmol/l was marginal. In pooled RCTs, there was a significant reduction in serum PTH by vitamin D supplementation regardless of baseline serum 25(OH)D level.

Conclusions

The use of the serum PTH–25(OH)D relation from observational studies to determine a threshold for vitamin D sufficiency is highly questionable.

DOI:
https://doi.org/10.1530/EC-20-0067
Volume 9: Issue 5,
Pages:
396–404 (9 total)
Open access

Vitamin D and critical illness: what endocrinology can learn from intensive care and vice versa

K Amrein, A Papinutti, E Mathew, G Vila, and D Parekh

The prevalence of vitamin D deficiency in intensive care units ranges typically between 40 and 70%. There are many reasons for being or becoming deficient in the ICU. Hepatic, parathyroid and renal dysfunction additionally increases the risk for developing vitamin D deficiency. Moreover, therapeutic interventions like fluid resuscitation, dialysis, surgery, extracorporeal membrane oxygenation, cardiopulmonary bypass and plasma exchange may significantly reduce vitamin D levels. Many observational studies have consistently shown an association between low vitamin D levels and poor clinical outcomes in critically ill adults and children, including excess mortality and morbidity such as acute kidney injury, acute respiratory failure, duration of mechanical ventilation and sepsis. It is biologically plausible that vitamin D deficiency is an important and modifiable contributor to poor prognosis during and after critical illness. Although vitamin D supplementation is inexpensive, simple and has an excellent safety profile, testing for and treating vitamin D deficiency is currently not routinely performed. Overall, less than 800 patients have been included in RCTs worldwide, but the available data suggest that high-dose vitamin D supplementation could be beneficial. Two large RCTs in Europe and the United States, together aiming to recruit >5000 patients, have started in 2017, and will greatly improve our knowledge in this field. This review aims to summarize current knowledge in this interdisciplinary topic and give an outlook on its highly dynamic future.

DOI:
https://doi.org/10.1530/EC-18-0184
Volume 7: Issue 12,
Pages:
R304–R315
Open access

Serum and urine vitamin D metabolite analysis in early preeclampsia

J A Tamblyn, C Jenkinson, D P Larner, M Hewison, and M D Kilby

Vitamin D deficiency is common in pregnant women and may contribute to adverse events in pregnancy such as preeclampsia (PET). To date, studies of vitamin D and PET have focused primarily on serum concentrations vitamin D, 25-hydroxyvitamin D3 (25(OH)D3) later in pregnancy. The aim here was to determine whether a more comprehensive analysis of vitamin D metabolites earlier in pregnancy could provide predictors of PET. Using samples from the SCOPE pregnancy cohort, multiple vitamin D metabolites were quantified by liquid chromatography–tandem mass spectrometry in paired serum and urine prior to the onset of PET symptoms. Samples from 50 women at pregnancy week 15 were analysed, with 25 (50%) developing PET by the end of the pregnancy and 25 continuing with uncomplicated pregnancy. Paired serum and urine from non-pregnant women (n = 9) of reproductive age were also used as a control. Serum concentrations of 25(OH)D3, 25(OH)D2, 1,25(OH)2D3, 24,25(OH)2D3 and 3-epi-25(OH)D3 were measured and showed no significant difference between women with uncomplicated pregnancies and those developing PET. As previously reported, serum 1,25(OH)2D3 was higher in all pregnant women (in the second trimester), but serum 25(OH)D2 was also higher compared to non-pregnant women. In urine, 25(OH)D3 and 24,25(OH)2D3 were quantifiable, with both metabolites demonstrating significantly lower (P < 0.05) concentrations of both of these metabolites in those destined to develop PET. These data indicate that analysis of urinary metabolites provides an additional insight into vitamin D and the kidney, with lower urinary 25(OH)D3 and 24,25(OH)2D3 excretion being an early indicator of a predisposition towards developing PET.

DOI:
https://doi.org/10.1530/EC-17-0308
Volume 7: Issue 1,
Pages:
199–210 (12 total)
Open access

25-hydroxyvitamin D level is associated with greater grip strength across adult life span: a population-based cohort study

Fabienne A U Fox, Lennart Koch, Monique M B Breteler, and N Ahmad Aziz

Objective

Maintaining muscle function throughout life is critical for healthy ageing. Although in vitro studies consistently indicate beneficial effects of 25-hydroxyvitamin D (25-OHD) on muscle function, findings from population-based studies remain inconclusive. We therefore aimed to examine the association between 25-OHD concentration and handgrip strength across a wide age range and assess potential modifying effects of age, sex and season.

Methods

We analysed cross-sectional baseline data of 2576 eligible participants out of the first 3000 participants (recruited from March 2016 to March 2019) of the Rhineland Study, a community-based cohort study in Bonn, Germany. Multivariate linear regression models were used to assess the relation between 25-OHD levels and grip strength while adjusting for age, sex, education, smoking, season, body mass index, physical activity levels, osteoporosis and vitamin D supplementation.

Results

Compared to participants with deficient 25-OHD levels (<30 nmol/L), grip strength was higher in those with inadequate (30 to <50 nmol/L) and adequate (≥50 to ≤125 nmol/L) levels (ß inadequate = 1.222, 95% CI: 0.377; 2.067, P = 0.005; ß adequate = 1.228, 95% CI: 0.437; 2.019, P = 0.002). Modelling on a continuous scale revealed grip strength to increase with higher 25-OHD levels up to ~100 nmol/L, after which the direction reversed (ß linear = 0.505, 95% CI: 0.179; 0.830, P = 0.002; ß quadratic = –0.153, 95% CI: –0.269; -0.038, P = 0.009). Older adults showed weaker effects of 25-OHD levels on grip strength than younger adults (ß 25OHDxAge = –0.309, 95% CI: –0.594; –0.024, P = 0.033).

Conclusions

Our findings highlight the importance of sufficient 25-OHD levels for optimal muscle function across the adult life span. However, vitamin D supplementation should be closely monitored to avoid detrimental effects.

DOI:
https://doi.org/10.1530/EC-22-0501
Volume 12: Issue 4
Open access

The association between circulating IGF1, IGFBP3, and calcium: results from NHANES III

Mieke Van Hemelrijck, Thurkaa Shanmugalingam, Cecilia Bosco, Wahyu Wulaningsih, and Sabine Rohrmann

Background

Despite mounting evidence linking both calcium and IGF1, there is a lack of studies investigating any association between circulating levels of IGF1 and serum calcium.

Methods

Serum calcium, IGF1, and IGF-binding protein 3 (IGFBP3) were measured for 5368 participants in NHANES III. We calculated multivariable-adjusted geometric means of serum concentrations of IGF1, IGFBP3, and IGF1/IGFBP3 by categories of calcium (lowest 5% (<1.16 mmol/l), mid 90%, and top 5% (≥1.31 mmol/l)). We also performed stratified analyses by sex, age, ethnicity, BMI, serum levels of vitamin D, and bone mineral density (BMD).

Results

Overall, we found that circulating calcium was positively associated with circulating levels of IGF1 and IGFBP3, but not their molar ratio (i.e., geometric mean of IGF1 by increasing calcium categories: 237.63, 246.51, and 264.22 ng/nl; P trend: 0.43; P first vs third category: 0.01). In particular, these associations were observed in women, people aged <60, non-Hispanic whites, those with vitamin D levels above the mean, and those with low BMD. In contrast, there was an inverse association with the molar ratio for those with BMI ≥30 kg/m2.

Conclusion

We found an overall positive association between circulating levels of IGF1 and IGFBP3 and serum calcium. However, stratification by potential effect-modifiers did not support all suggested hypotheses. Our findings provide more insight into the interplay between calcium and IGF1, which in the future can be investigated in larger observational studies allowing for additional stratifications based on a combination of the different effect-modifiers investigated here.

DOI:
https://doi.org/10.1530/EC-15-0039
Volume 4: Issue 3,
Pages:
187–195 (9 total)
Open access

Diagnostic performance of the calcium/phosphate ratio for primary hyperparathyroidism in southwest China

Mengting Yin, Qianhui Liu, Qingzhong Wang, Yong He, Haolan Song, Xin Nie, and Guixing Li

Background

The diagnosis of primary hyperparathyroidism (PHPT) remains a challenge because of increased asymptomatic PHPT or patients with normocalcaemic PHPT (NPHPT). In addition, some primary hospitals in China have no equipment to measure parathyroid hormone (PTH) levels. Therefore, an additional, simple, and inexpensive laboratory biochemical marker is urgently needed. The calcium/phosphate (Ca/P) ratio and chloride/phosphate (Cl/P) ratio have been proposed as suitable tools to diagnose PHPT in Europe; however, the Ca/P ratio has never been tested in China. We aimed to conduct a confirmatory study to explore the diagnostic performance of the Ca/P ratio for PHPT in China.

Methods

From January 2015 to December 2020, a total of 155 patients who underwent parathyroidectomy (143 PHPT patients and 12 NPHPT patients) and 153 controls were enrolled in this single-center , retrospective study. Serum calcium, phosphate, parathyroid hormone, 25-hydroxyvitamin vitamin D (25(OH) vitamin D), chloride, alanine transaminase (ALT), aspartate aminotransaminase (AST), estimated glomerular filtration rate (eGFR), and creatinine levels were recorded for all the study participants. Pairwise comparisons were made between groups, and the diagnostic performance of the Ca/P ratio was determined using receiver-operating characteristic (ROC) analysis.

Results

Patients with PHPT had a higher Ca/P ratio than controls (P < 0.001). A Ca/P ratio above 2.94 with a sensitivity of 95.5% and specificity of 98.7% can distinguish PHPT patients from healthy individuals. This index was positively correlated with the PTH level (r = 0.875, P < 0.001).

Conclusion

The Ca/P ratio is an ideal and inexpensive indicator for diagnosing PHPT in China when using a cut-off value of 2.94.

DOI:
https://doi.org/10.1530/EC-21-0267
Volume 10: Issue 11,
Pages:
1387–1392 (6 total)
Open access

A preliminary transcriptome analysis suggests a transitory effect of vitamin D on mitochondrial function in obese young Finnish subjects

Elisabet Einarsdottir, Minna Pekkinen, Kaarel Krjutškov, Shintaro Katayama, Juha Kere, Outi Mäkitie, and Heli Viljakainen

Objective

The effect of vitamin D at the transcriptome level is poorly understood, and furthermore, it is unclear if it differs between obese and normal-weight subjects. The objective of the study was to explore the transcriptome effects of vitamin D supplementation.

Design and methods

We analysed peripheral blood gene expression using GlobinLock oligonucleotides followed by RNA sequencing in individuals participating in a 12-week randomised double-blinded placebo-controlled vitamin D intervention study. The study involved 18 obese and 18 normal-weight subjects (of which 20 males) with mean (±s.d.) age 20.4 (±2.5) years and BMIs 36 (±10) and 23 (±4) kg/m2, respectively. The supplemental daily vitamin D dose was 50 µg (2000 IU). Data were available at baseline, 6- and 12-week time points and comparisons were performed between the vitamin D and placebo groups separately in obese and normal-weight subjects.

Results

Significant transcriptomic changes were observed at 6 weeks, and only in the obese subjects: 1724 genes were significantly upregulated and 186 genes were downregulated in the vitamin D group compared with placebo. Further analyses showed several enriched gene categories connected to mitochondrial function and metabolism, and the most significantly enriched pathway was related to oxidative phosphorylation (adjusted P value 3.08 × 10−14). Taken together, our data suggest an effect of vitamin D supplementation on mitochondrial function in obese subjects.

Conclusions

Vitamin D supplementation affects gene expression in obese, but not in normal-weight subjects. The altered genes are enriched in pathways related to mitochondrial function. The present study increases the understanding of the effects of vitamin D at the transcriptome level.

DOI:
https://doi.org/10.1530/EC-18-0537
Volume 8: Issue 5,
Pages:
559–570 (12 total)