Serum 25-hydroxyvitamin D concentration is not associated with glomerular filtration rate in a predominantly obese otherwise healthy population

- Estimated GFR was not associated with 25(OH)D concentration in a predominantly obese but otherwise healthy adult population.
- EGFR remained not related to 25(OH)D when examined across BMI categories.
- There was no significant difference in eGFR between severely deficient, deficient, and non-deficient vitamin D subgroups.

Evidence from observational studies indicates a role for vitamin D in kidney function and progression to chronic kidney disease. Findings from animal studies have proposed underlying mechanisms including increased activation of the renin-angiotensin system, increased blood pressure, insulin resistance and chronic low-grade inflammation. However, human studies are limited by confounders arising from heterogeneous samples of participants. We examined the relationship between 25(OH)D and estimated glomerular filtration rate (eGFR) in a predominantly obese otherwise healthy and drug-naive population with no history of chronic kidney disease (CKD).One hundred and twenty one non-diabetic (75 g oral glucose tolerance test; OGTT) volunteers (70 males and 51 females), aged 18-57 years participated in the study. Median 25(OH)D level was 37 nmol/L with no difference by sex. Twenty six participants (21.5%) had 25(OH)D <25 nmol/L, 75 participants (62%) had 25(OH)D of 25-49.99 nmol/L, and 20 participants (16.5%) had 25(OH)D ≥50 nmol/L. In univariate analysis, 25(OH)D was related negatively to percent body fat and 2-h glucose level post OGTT. Mean (SD) eGFR was 113.1 (14.9) mL/min/1.73 m2, and in the multivariable analysis, it was related to age, sex, percent body fat and 2-h glucose level post OGTT, but not to 25(OH)D. Furthermore, there was no relationship between eGFR and 25(OH)D across BMI categories.Our data suggest that measuring 25(OH)D in predominantly obese otherwise healthy individuals with no history of CKD may not be beneficial in early recognition of kidney disease.