Introduction: Little is known about the relationship between serum levels of 25-hydroxyvitamin D [25(OH)D] and urinary excretion of proteins or renal function decline in patients with glomerulopathies.
Objectives: To evaluate the relationship between blood levels of 25(OH)D and proteinuria, demographics, clinical and laboratory renal and osteo-metabolic parameters, and chronic kidney disease (CKD) progression to advanced stages.
Patients and Methods: In this prospective observational cohort study including 175 adults with glomerulopathy, we evaluated clinical and laboratory renal and osteometabolic parameters, such as 25(OH)D, calcium, phosphorus, intact parathyroid hormone (iPTH), urinalysis, serum creatinine, and estimated glomerular filtration rate (eGFR).
Results: The mean age was 44.5±14.9 years, and 62.9% of participants were females; mean body mass index (BMI) was 28±5.1 kg/ m2; proteinuria, 1.48±2.18 g/24 h; eGFR, 75.9±32.9 mL/min; and follow-up, 1102±494 days. We identified that 32% and 54.3% of patients had 25(OH)D deficiency and insufficiency, respectively. Vitamin D and proteinuria levels were inversely related, regardless of the stage of CKD (P<0.001). Most patients were overweight or obese. BMI was significantly associated with reduced levels of 25(OH) D (P=0.024). Among patients with >1 year of follow-up, levels of 25(OH)D<15 ng/mL were associated with a higher rate of decline in eGFR (P=0.017).
Conclusion: Low levels of vitamin D were highly prevalent in chronic kidney disease patients with proteinuria, and vitamin D deficiency may have an impact on the progression of glomerulopathies.