ArticleThe Journal of clinical endocrinology and metabolism2018
Determination of Free 25(OH)D Concentrations and Their Relationships to Total 25(OH)D in Multiple Clinical Populations.
Article in The Journal of clinical endocrinology and metabolism, 2018. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 58 papers, 1 of them a synthesis that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
58 citing papers in PubMed, 1 synthesis or guideline pooled it.
- Vitamin D deficiency in nursing home residents: a systematic review.Nutrition reviews · 2023Pooled it
- Exploring associations between maternal vitamin D-binding protein, vitamin D, and offspring asthma/recurrent wheeze.The American journal of clinical nutrition · 2026Trial
- Effects of High Dose Bolus Cholecalciferol on Free Vitamin D Metabolites, Bone Turnover Markers and Physical Function.Nutrients · 2024Trial
- 25-Hydroxyvitamin D status does not affect energy metabolism among young, healthy, non-obese adults: a metabolic chamber study.Frontiers in endocrinology · 2024Trial
- Serum Vitamin D: Correlates of Baseline Concentration and Response to Supplementation in VITAL-DKD.The Journal of clinical endocrinology and metabolism · 2022Trial
- Principal results of the VITamin D and OmegA-3 TriaL (VITAL) and updated meta-analyses of relevant vitamin D trials.The Journal of steroid biochemistry and molecular biology · 2020Trial
- Vitamin D, Marine n-3 Fatty Acids, and Primary Prevention of Cardiovascular Disease Current Evidence.Circulation research · 2020Trial
- Vitamin D binding protein is not affected by high-dose vitamin D supplementation: a post hoc analysis of a randomised, placebo-controlled study.BMC research notes · 2018Trial
- Vitamin D: Physiology, Pharmacology and Clinical Evidence for Supplementation-A Narrative Review.Basic & clinical pharmacology & toxicology · 2026Review
- From the Vitamin D Paradox to Precision Nutrition: Targeted Supplementation, Assay Pitfalls, and Clinical Decision-Making.Current nutrition reports · 2026Review
- Disrupted Vitamin D Metabolism in Hepatocellular Carcinoma: Free and Bioavailable 25(OH)D as Novel Biomarkers of Hepatic Reserve and Clinical Risk.Molecules (Basel, Switzerland) · 2026Article
- Article
- Decrease in Vitamin D Binding Protein in Acute Fractures Does Not Affect Vitamin D Levels.Clinics in orthopedic surgery · 2025Article
- Polymorphisms of the Vitamin D Binding Protein (VDBP) and Free Vitamin D in Patients with Cystic Fibrosis.Nutrients · 2024Article
- Consensus Statement on Vitamin D Status Assessment and Supplementation: Whys, Whens, and Hows.Endocrine reviews · 2024Article
- Circulating total 25(OH)D and calculated free 25(OH)D in professional academy footballers at a northerly latitude in the UK.Biology of sport · 2024Article
- Vitamin D binding protein correlate with estrogen increase after administration of human chorionic gonadotropin but do not affect ovulation, embryo, or pregnancy outcomes.Frontiers in endocrinology · 2024Observational
- No causal relationship between serum vitamin D levels and alcoholic liver disease: a two-sample bidirectional Mendelian randomization study.Frontiers in nutrition · 2024Article
- Total and free 25-hydroxyvitamin D concentrations and risk of urinary incontinence in women participating in Nurses Health Studies I & II.The American journal of the medical sciences · 2023Article
- The Effect of Narrow-Band Ultraviolet B Phototherapy on Free and Total Vitamin D Serum Levels in Mild to Severe Plaque Psoriasis.Biomolecules · 2023Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
20 authors.
Funding
Abstract
Context: The optimal measure of vitamin D status is unknown. Objective: To directly measure circulating free 25-hydroxyvitamin D [25(OH)D] concentrations and relationships to total 25(OH)D in a clinically diverse sample of humans. Design: Cross-sectional analysis. Setting: Seven academic sites. Patients: A total of 1661 adults: healthy (n = 279), prediabetic (n = 479), outpatients (n = 714), cirrhotic (n = 90), pregnant (n = 20), nursing home resident (n = 79). Interventions: Merge research data on circulating free 25(OH)D (directly-measured immunoassay), total 25(OH)D (liquid chromatography/tandem mass spectrometry), D-binding protein [DBP; by radial (polyclonal) immunodiffusion assay], albumin, creatinine, intact parathyroid hormone, and DBP haplotype. Main outcome measures: Distribution of free 25(OH)D (ANOVA with Bonferroni correction for post hoc comparisons) and relationships between free and total 25(OH)D (mixed-effects modeling incorporating clinical condition, DBP haplotype with sex, race, estimated glomerular filtration rate (eGFR), body mass index (BMI), and other covariates). Results: Free 25(OH)D was 4.7 ± 1.8 pg/mL (mean ± SD) in healthy persons and 4.3 ± 1.9 pg/mL in outpatients, with levels of 0.5 to 8.1 pg/mL and 0.9 to 8.1 pg/mL encompassing 95% of healthy persons and outpatients, respectively. Free 25(OH)D was higher in patients with cirrhosis (7.1 ± 3.0 pg/mL; P < 0.0033) and nursing home residents (7.9 ± 2.1 pg/mL; P < 0.0033) than in other groups and differed between whites and blacks (P < 0.0033) and between DBP haplotypes (P < 0.0001). Mixed-effects modeling of relationships between free and total 25(OH)D identified clinical conditions (patients with cirrhosis > nursing home residents > patients with prediabetes > outpatients > pregnant women) and BMI (lesser effect) as covariates affecting relationships but not eGFR, sex, race, or DBP haplotype. Conclusions: Total 25(OH)D, health condition, race, and DBP haplotype affected free 25(OH)D, but only health conditions and BMI affected relationships between total and free 25(OH)D. Clinical importance of free 25(OH)D needs to be established in studies assessing outcomes.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.