Total 25OHD Levels Research Articles

Association of Body Weight With Response to Vitamin D Supplementation and Metabolism

In the Vitamin D and Omega-3 Trial (VITAL), the effects of randomized vitamin D supplementation (cholecalciferol), 2000 IU/d, reduced the risk of several health outcomes among participants with normal, but not elevated, body weights. It was unclear whether weight had any association with the outcomes of the supplementation. To investigate whether baseline body mass index (BMI) modifies vitamin D metabolism and response to supplementation. VITAL is a completed randomized, double-blind, placebo-controlled trial for the primary prevention of cancer and cardiovascular disease. In the present cohort study, an analysis was conducted in a subset of VITAL participants who provided a blood sample at baseline and a subset with a repeated sample at 2 years' follow-up. VITAL was conducted from July 1, 2010, to November 10, 2018; data analysis for the present study was conducted from August 1, 2021, to November 9, 2021. Treatment outcomes of vitamin D, 2000 IU/d, supplementation vs placebo associated with clinical and novel vitamin D-related biomarkers by BMI category adjusted for other factors associated with vitamin D status. Multivariable-adjusted means (SE) or 95% CIs of vitamin D-related serum biomarkers at baseline and follow-up: total 25-hydroxyvitamin D (25-OHD), 25-OHD3, free vitamin D (FVD), bioavailable vitamin D (BioD), vitamin D-binding protein (VDBP), albumin, parathyroid hormone (PTH), and calcium, and log-transformed as needed. A total of 16 515 participants (mean [SD] age, 67.7 [7.0] years; 8371 women [50.7%]; 12420 non-Hispanic White [76.9%]) were analyzed at baseline, including 2742 with a follow-up blood sample. Before randomization, serum total 25-OHD levels were incrementally lower at higher BMI categories (adjusted mean [SE]: underweight, 32.3 [0.7] ng/mL; normal weight, 32.3 [0.1] ng/mL; overweight, 30.5 [0.1] ng/mL; obesity class I, 29.0 [0.2] ng/mL; and obesity class II, 28.0 [0.2] ng/mL; P < .001 for linear trend). Similarly, baseline 25-OHD3, FVD, BioD, VDBP, albumin, and calcium levels were lower with higher BMI, while PTH level was higher (all P < .001 for linear trend). Compared with placebo, randomization to vitamin D supplementation was associated with an increase in total 25-OHD, 25-OHD3, FVD, and BioD levels compared with placebo at 2 years' follow-up, but increases were significantly lower at higher BMI categories (all treatment effect interactions P < .001). Supplementation did not substantially change VDBP, albumin, PTH, or calcium levels. In this randomized cohort study, vitamin D supplementation increased serum vitamin D-related biomarkers, with a blunted response observed for participants with overweight or obesity at baseline. These longitudinal findings suggest that BMI may be associated with modified response to vitamin D supplementation and may in part explain the observed diminished outcomes of supplementation for various health outcomes among individuals with higher BMI.

Ultra-High Dose Vitamin D in Pediatric Hematopoietic Stem Cell Transplantation: A Nonrandomized Controlled Trial

Vitamin D is essential for bone health and has immunomodulatory properties. Most pediatric patients are vitamin D insufficient (<30 ng/mL) before hematopoietic stem cell transplantation (HSCT). Standard supplementation strategies fail to achieve vitamin D sufficiency in the acute post-transplantation period, and there are scarce data to support optimal vitamin D supplementation in this patient population. This study aimed to evaluate whether a single, oral, weight-based ultra-high dose of vitamin D (Stoss dosing) was more effective than standard supplementation to achieve pre-HSCT vitamin D sufficiency and reduce the incidence of HSCT-related complications (acute graft-versus-host disease, veno-occlusive disease, and/or transplant-associated thrombotic microangiopathy) that are associated with immune-mediated endothelial damage. Secondary endpoints examined the immunomodulatory properties of vitamin D. We conducted a nonrandomized controlled clinical trial of Stoss-dosed vitamin D in pediatric patients receiving HSCT. The study prospectively enrolled 33 patients, 29 of whom successfully received Stoss-dosed vitamin D and were compared to 136 patients in a historical control. Patient characteristics were compared using Fisher's exact test or t-test. The one-sided Fisher's exact test was used for cohort comparison of the primary endpoints. Logistic regression was used to examine the association between patient-specific factors and total 25-hydroxy vitamin D (25-OHD) levels and the compiled HSCT complications. In the Stoss cohort, 97% (n=28/29) of patients achieved pre-HSCT vitamin D sufficiency compared to 67% (n=10/15) of patients in the historical control who were on standard supplementation at the time the total 25-OHD level was assessed (P=.013). The mean total 25-OHD level in the Stoss cohort was significantly higher than patients in the historical control who received standard supplementation (72.2 ng/mL versus 35.8 ng/mL, P < .001). Nine patients in the Stoss cohort maintained vitamin D sufficiency throughout the first 100 days after HSCT, and the remaining 19 patients maintained sufficiency for a median of 63 days (range 6-105 days) from the Stoss dose. Patients receiving Stoss-dosed vitamin D developed a lower combined incidence of HSCT-related complications than the historical control (25% [n=7/28] versus 42% [n=57/136], P=.055). After Stoss dosing, immunophenotyping studies found a significant decrease in subsets of CD8+ T cells and mononuclear cells (P=.040 and.013, respectively), and, in a subset of cells, larger decreases in phosphoprotein expression were seen with greater increases in total 25-OHD levels. Inflammatory cytokines did not change significantly after Stoss dosing. Stoss dosing is therefore a safe and effective approach to maintain vitamin D sufficiency in the immediate post-HSCT period and may be associated with decreased HSCT-related complications. Randomized studies are warranted to further investigate the efficacy of Stoss-dosed vitamin D to improve bone health and reduce complications in pediatric patients receiving HSCT.

Appropriate Cutoff for 25OHD Levels in the Diagnosis of Normocalcemic Primary Hyperparathyroidism (NPHPT): A Systematic Review

Introduction: The Fourth International Workshop in 2014 delineated guidelines for the diagnosis of NPHPT which include ruling out secondary causes of hyperparathyroidism, and recommended cutoffs for 25 vitamin D (25OHD) to be ≥20ng/mL. Keeping in mind that the exact levels to optimize 25OHD in hyperparathyroid states are unknown, we aim to review possible variation in the prevalence of NPHPT if 25OHD cutoffs were to be raised to rule out vitamin D deficiency with more specificity. Methods: A PubMed search was conducted with key words “normocalcemic primary hyperparathyroidism” to review studies about NPHPT and 25OHD status. 533 articles were found, and 127 articles were identified by title/abstract screening with year of publication between 2014 to 2020. Ten studies were identified for the systematic review based on full text review for relevance. Results: Studies have been conducted in various countries across all continents to characterize NPHPT further. 5/10 studies used 25OHD cutoff of ≥20ng/mL and 4 studies had a cutoff of ≥30ng/mL and 1 study looked into the difference in prevalence with both cutoffs. All 3 studies from Italy used the higher cutoff. Rosario et al from Brazil reported a decrease in prevalence of NPHPT from 6.8% (25OHD≥20ng/mL) to 0.74% by supplementing those subjects to 25OHD ≥30ng/mL without any increase in serum calcium or parathyroid hormone (PTH) levels.1 Wang et al found that when total 25OHD levels were kept between 30–40 ng/mL, free 25OHD levels were actually lower compared to normal subjects.2 Conclusion: The levels of 25OHD that would define deficiency in NPHPT remain undetermined and both >20 ng/mL and >30ng/mL have been studied as cutoffs. It is well known that vitamin D insufficiency (25D 20-30ng/mL) drives up PTH and supplementation to 30-40ng/mL is required to reduce such effects. Wang et al suggest that free 25OHD levels correlate better with PTH as compared to total 25OHD and maybe a more reliable marker of 25OHD status. We suggest that a diagnostic criterion of ≥30ng/mL would be more appropriate in ruling out 25OHD deficiency in this special population. The role of free 25OHD levels in PHPT needs further evaluation.

Serum Bioavailable, Rather Than Total, 25-hydroxyvitamin D Levels Are Associated With Hepatocellular Carcinoma Survival.

Background and AimsFree and bioavailable 25‐hydroxyvitamin D (25OHD) are emerging measurements of vitamin D status. It remains unclear whether circulating free or bioavailable 25OHD are relevant to hepatocellular carcinoma (HCC) prognosis. Our aim was to test the hypothesis that bioavailable 25OHD may be a better serum biomarker of vitamin D status than total 25OHD on the association with HCC survival.Approach and ResultsWe included 1,031 newly diagnosed, previously untreated patients with HCC from the Guangdong Liver Cancer Cohort enrolled between September 2013 and April 2017. Serum total 25OHD levels were measured using an electrochemiluminescence immunoassay. Serum‐free 25OHD levels were measured using a two‐step enzyme‐linked immunosorbent assay. Bioavailable 25OHD levels were calculated from measured free 25OHD and albumin using a previously validated equation. Primary outcomes were liver cancer–specific (LCSS) and overall survival (OS). Cox proportional hazards models were performed to calculate the multivariable hazard ratios (HRs) and 95% confidence intervals (CIs). During a median follow‐up of 726 days, 430 patients had deceased, including 393 deaths from HCC. In multivariable analyses, higher bioavailable 25OHD levels were significantly associated with better survival, independent of nonclinical and clinical prognostic factors including serum C‐reactive protein, Barcelona Clinic Liver Cancer stage, and cancer treatment. The multivariable‐adjusted HRs in the highest versus lowest quartile of bioavailable 25OHD levels were 0.69 (95% CI: 0.51, 0.93; P for trend = 0.014) for LCSS and 0.71 (95% CI: 0.53, 0.94; P for trend = 0.013) for OS. In contrast, neither total nor free 25OHD levels were associated with LCSS or OS.ConclusionsHigher bioavailable, rather than total, 25OHD levels were independently associated with improved survival in a population‐based HCC cohort, suggesting a potential utility of bioavailable 25OHD in HCC prognosis.

Cord Blood Vitamin D Levels and Early Childhood Blood Pressure: The Healthy Start Study.

BackgroundVitamin D deficiency is associated with cardiovascular events among adults, but it is unclear whether early‐life vitamin D deficiency influences cardiovascular risk factors in children.Methods and ResultsWe measured total and bioavailable 25‐dihydroxyvitamin D (25OHD) in cord blood and in blood from 4‐ to 6‐year‐old children, and we assessed cardiovascular risk factors (blood pressure, arterial stiffness, body size, and adiposity) at 4 to 6 years. We tested for racial/ethnic differences in total and bioavailable 25OHD (n=715) and modeled the adjusted association between cord blood 25OHD and childhood cardiovascular risk factors (n=171). We observed racial/ethnic differences in total and bioavailable 25OHD levels in both cord and child blood samples (all P<0.05). Each 25‐nmol/L increase in cord blood total 25OHD was associated with a 2.5–mm Hg (SE 0.8) decrease in systolic blood pressure (P=0.002) and a 1.7–mm Hg (SE 0.6) decrease in diastolic blood pressure (P=0.01), independent of childhood 25OHD levels, race/ethnicity, and other covariates. There was no association between cord blood total 25OHD and any other cardiovascular risk factors. Cord blood levels of bioavailable and free 25OHD were not associated with any cardiovascular risk factor in childhood.ConclusionsIn this diverse prebirth cohort, we observed lower systolic and diastolic blood pressure among children with higher total 25OHD levels at birth. Our findings suggest that intrauterine exposure to vitamin D may contribute to early‐life programming of offspring blood pressure. Intervention studies are needed to determine whether increasing fetal vitamin D exposure can reduce the risk of elevated blood pressure in childhood.

A Randomized Placebo-Controlled Trial of Low- Versus Moderate-Dose Vitamin D3 Supplementation on Bone Mineral Density in Postmenopausal Women With HIV.

Prevalence of osteoporosis and fracture is increased among older people with HIV. We compared the effects of low (1000 IU) vs moderate (3000 IU) vitamin D3 (VitD) supplementation on areal bone mineral density (aBMD) and volumetric bone mineral density (vBMD) in African American and Hispanic postmenopausal women with HIV on antiretroviral therapy. We performed a 12-month prospective, randomized, double-blind, placebo-controlled study with primary outcomes of change in aBMD by dual-energy X-ray absorptiometry (DXA) and secondary outcomes of change in vBMD by quantitative computed tomography and bone turnover markers. An intent-to-treat analysis was performed on 85 randomized subjects (43 low and 42 moderate) for primary DXA outcomes, and complete case analysis was performed for secondary outcomes. Mean age was 56 ± 5 years, median CD4 count was 722 cells/mm, and 74% had HIV RNA ≤ 50 copies/mL. Serum 25-OHD was higher in the moderate than low VitD group at 6 months (33.1 ± 10.3 vs 27.8 ± 8.1 ng/mL, P = 0.03) and 12 months, but parathyroid hormone levels remained similar. Percent change in aBMD, vBMD, and bone turnover markers did not differ between low and moderate VitD groups before or after adjustment for baseline aBMD. VitD supplementation at 3000 IU daily increased mean total 25-OHD levels in postmenopausal women with HIV, but we did not find evidence of an effect on BMD beyond those observed with 1000 IU daily. Future studies are necessary to determine whether VitD supplementation is beneficial in this patient population, and if so, what dose is optimal for skeletal health.

Genetic Variants of CYP2R1 Are Key Regulators of Serum Vitamin D Levels and Incidence of Myocardial Infarction in Middle-Aged Egyptians.

Myocardial Infarction (MI) is one of the leading causes of morbidity and mortality in Egypt and worldwide. Vitamin D deficiency has long been linked to incidence of cardiovascular diseases. Several factors were reported to contribute to serum vitamin D level including exposure to sunlight. However, genetic variations in the vitamin D metabolic pathways have also been considered as strong determinants of vitamin D levels. CYP2R1 is the major 25-hydroxylase enzyme that is responsible for the 1st activation step of vitamin D. to investigate the contribution of polymorphisms in CYP2R1 gene to vitamin D deficiency and incidence of MI in Egyptians. The study included 323 subjects; 185 MI patients and 138 healthy controls. Serum 25OHD3, 25OHD2 and total 25OHD levels were measured using LC-MS/MS. SNPs rs2060793 and rs1993116 were determined by polymerase chain reaction - restriction fragment length polymorphism (PCRRFLP) which is considered one of the most commonly used techniques in genotyping. SNP rs10766197 was detected using TaqMan allele discrimination assay. Serum 25OHD3, 25OHD2 and total 25OHD levels were found to be significantly lower in MI patients than controls. The three studied SNPs were associated with significantly different total 25OHD levels and their genotype distributions differed significantly between MI patients and controls where the high risk genotypes were AG/AA for rs2060793, AG/GG for rs1993116 and AG/AA for rs10766197. Additionally, the concurrent presence of high risk genotypes of the three studied SNPs rendered those individuals at extremely higher risk for MI than each individual SNP (OR 14.1, 95% CI (3.1-64.7), p-value = < 0.0001). Genetic variants of CYP2R1 are key determinants of serum 25OHD levels and are highly associated with MI risk.

Evaluation of the Analytical and Clinical Concordance of 25-Hydroxyvitamin D Levels in Dried Blood Spots, Dried Serum Spots, and Serum as Potential Biorepository Specimens

The promising perspective of storing dried blood spot (DBS) for evaluating 25-hydroxyvitamin D (25OHD) levels is increasingly being realized. While strong correlations have been demonstrated between 25OHD levels measured in DBS and in systemic serum samples in earlier works, the clinical concordance of the assay results has not been evaluated. Moreover, the utility of dried serum spot (DSS), a highly suitable matrix for sample archiving, has not been investigated in this respect. 25-hydroxycholecalciferol and 25-hydroxyergocalciferol levels were established selectively in DBS (n = 73) and DSS (n = 67) specimens obtained from deidentified whole blood and serum using a previously validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. In addition, total 25OHD levels were determined in the serum samples using the LIAISON 25OH Total Vitamin D Assay (LIA, n = 73). The analytical and clinical performance of the three approaches was compared pairwise. Deming regression, Bland-Altman analysis, and concordance correlation coefficients consistently demonstrated the lack of analytical equivalence among the three result sets. The overall percentage agreement of the clinical classifications (hypovitaminosis or euvitaminosis) was moderate (67.1%-83.6%). The delivery of positive cases was decreasing significantly in the order LIA>DSS>DBS (p < 0.05). The approaches tested did not deliver equivalent outputs either in an analytical or a clinical context. Therefore, specific reference ranges must be established for each matrix to avoid false clinical evaluation. 25OHD can be quantified when assay results are scaled by a factor of 1.60-1.67. Considering the convenience and efficiency of the storage and processing of DSS, along with the difficulties of quantifying 25OHD in real-life DBS samples accurately, DSS is proposed as an alternative for the long-term archiving of specimens.

Vitamin D2 from UVB light exposed mushrooms modulates immune response to LPS in rats

Poor vitamin D (vitD) status is linked to increased risk of infectious diseases, thus there is need for vitD-rich foods. UVB-exposed mushrooms synthesize vitD₂ but knowledge of bioavailability and function in immune response is lacking. One hundred rats were fed one of five diets--control, 20 IU vitD₃/day; no vitD₃/day; 5% unexposed mushroom, 2.4 IU vitD₂/day; 2.5% UVB mushroom, 300 IU vitD₂/day; and 5% UVB mushroom, 600 IU vitD₂/day--for 10 wk and challenged with either saline or the endotoxin LPS. Blood and tissues were collected at 3 h postchallenge. Plasma 25-hydroxyvitamin D (25OHD) levels from UVB-exposed mushroom fed rats were significantly elevated and associated with higher natural killer cell activity and reduced plasma inflammatory response to LPS compared to control diet fed rats. Microarray evaluation of rat spleens for changes in inflammatory gene expression showed significant upregulation of proinflammatory genes after LPS compared to saline controls in all groups. However, compared to control rats, upregulation of the proinflammatory genes was markedly reduced in the groups fed vitD₂-enriched mushrooms. Rats fed UVB-exposed mushrooms had significantly higher plasma total 25OHD levels that were associated with increased innate immune response and anti-inflammatory effects.

Age‐, gender‐, and weight‐related effects on levels of 25‐hydroxyvitamin D are not mediated by vitamin D binding protein

25-hydroxyvitamin D (25OHD) levels are inversely related to body weight, and have been reported to decline with age and be lower in women than men. We hypothesized that these findings might be explained by effects of these variables on vitamin D binding protein (DBP) levels. We set out to determine the relationships between DBP and gender, 25OHD, body weight and body composition. Cross-sectional analysis. One hundred healthy, middle-aged and older, community-dwelling men and women. All participants were measured for 25OHD, DBP, body weight, bone mineral density and body composition. Women had higher mean DBP levels than men but lower total 25OHD levels [DBP: women, mean (SD) 339 (36) mg/l, men 307 (71) mg/l, P = 0.005; 25OHD: women 67 (23) nmol/l, men 91 (39) nmol/l, P < 0.001]. In women, there were significant positive relationships between DBP and albumin (r = 0.33) and 25OHD (r = 0.34) whereas in men there were no significant relationships between DBP and any measured variables. There was no significant relationship between DBP and age, body weight, body mass index, fat mass or percentage fat in men or women. We found no evidence to support the hypothesis that DBP levels are related to age, or adiposity. The changes in 25OHD levels with age, gender, or fat mass are not due to underlying relationships between DBP and these variables. This suggests that the relationships consistently observed between 25OHD and body composition and gender are of biological origin and not due to adaptation to changes in transport proteins.

Effect of Vitamin D supplement use on serum concentrations of total 25OHD levels in elderly women

Vitamin D 2 and D 3 are generally considered equipotent in humans. As Vitamin D 2 supplements are commonly used by elderly in United States, we determined the contribution of 25OHD 2 to the total serum 25OHD levels by HPLC in elderly women who reported taking Vitamin D 2 supplements ( n=56) and also in a group of randomly selected unsupplemented women ( n=60). In addition, we compared the total serum 25OHD measured by HPLC with competitive protein-binding assay (CPBA), a method routinely employed to measure Vitamin D status. A correlation of 0.91 ( P<0.001) was observed between the two methods for the serum total 25OHD measurement. The mean serum 25OHD level in Vitamin D 2 supplemented group was significantly higher than in unsupplemented group measured by HPLC (32 versus 28 ng/ml) and marginally higher measured by CPBA (33 vs. 31 ng/ml). Seventy eight percent of women taking Vitamin D 2 supplements had appreciable amounts of circulating 25OHD 2, which constituted about 25 percent of their total serum 25OHD. It is also interesting to note that Vitamin D deficiency was less prevalent in elderly women taking Vitamin D 2 supplements (1.8%) compared to women not taking any supplements (12%).

Effect of vitamins D2 and D3 supplement use on serum 25OHD concentration in elderly women in summer and winter.

Vitamin D2 and D3 are generally considered equipotent in humans. A few studies have reported that serum 25OHD levels are higher in vitamin D3- compared with vitamin D2-supplemented subjects. As both vitamin D2 and D3 supplements are commonly used by elderly in United States, in the present study we determined the effect of self-reported vitamin D2 and vitamin D3 supplement use on serum total 25OHD levels according to season in elderly women aged 65-77 years. Serum total 25OHD levels were determined in winter and summer in unsupplemented women ( N = 307) and in women who reported taking vitamin D2 ( N = 56) and vitamin D3 ( N = 55) supplements by competitive protein binding assay. In vitamin D2-supplemented women, the contribution of vitamin D2 and D3 to the mean serum total 25OHD level was assessed by HPLC. In summer, there were no significant differences in the mean total serum 25OHD levels (ng/ml) among the vitamin D2 (32 +/- 2.1), vitamin D3 (36.7 +/- 1.95), and unsupplemented (32.2 +/- 0.95) groups. In winter, the mean serum total 25OHD levels were higher in women on vitamin D2 (33.6 +/- 2.34, P < 0.05) and vitamin D3 (29.7 +/- 1.76, NS) supplements compared with unsupplemented women (27.3 +/- 0.72). In vitamin D2-supplemented women, about 25% of the mean serum total 25OHD was 25OHD2, in both summer and winter. Twelve percent of unsupplemented women and 3.6% of vitamin D-supplemented women had a mean serum total 25OHD level below 15 ng/ml in winter. In elderly subjects, both vitamin D2 and Vitamin D3 supplements may contribute equally to circulating 25OHD levels, with the role of vitamin D supplement use being more predominant during winter.

Free 25-hydroxyvitamin D levels are normal in subjects with liver disease and reduced total 25-hydroxyvitamin D levels.

We determined the free fraction of 25-dihydroxyvitamin D (25OHD) in the serum of subjects with clinical evidence of liver disease and correlated these measurements to the levels of vitamin D binding protein and albumin. These subjects when compared to normal individuals had lower total 25OHD levels, higher percent free 25OHD levels, but equivalent free 25OHD levels. These subjects also had reduced vitamin D binding protein and albumin concentrations. The total concentration of 25OHD correlated positively with both vitamin D binding protein and albumin, whereas the percent free 25OHD correlated negatively with vitamin D binding protein and albumin. The free 25OHD levels did not correlate with either vitamin D binding protein or albumin. We conclude that total vitamin D metabolite measurements may be misleading in the evaluation of the vitamin D status of patients with liver disease, and recommend that free 25OHD levels also be determined before making a diagnosis of vitamin D deficiency.