Spectrum of Vitamin D Deficiency across GFR Levels in a Senegalese Cohort

Abstract

The optimal serum concentration of vitamin D for bone and mineral homeostasis remains debated and few data are available in sub-Saharan Africa. We conducted a cross-sectional study between February 2022 and April 2025 at the Ouakam Military Hospital biochemistry laboratory to assess the prevalence of vitamin D deficiency and its relationship with renal function in adults referred for vitamin D testing at a tertiary hospital laboratory in Dakar, Senegal. All patients aged ≥ 18 years undergoing serum vitamin D testing were included. Vitamin D deficiency was defined as 25(OH)-vitamin D < 12 ng/mL, insufficiency as 12 - 19 ng/mL and sufficiency as ≥20 ng/ml. A total of 1192 patients were enrolled (median age 44.0 [31.0 - 62.0] years; M:F ratio 0.8). The prevalence of vitamin D deficiency and insufficiency was 15.44% and 22.99%, respectively. Deficient patients exhibited significantly lower serum calcium (p < 0.001). Both pathological fractures (p = 0.54) and kidney dysfunction (p = 0.07) were more frequent in deficient individuals. Serum 25(OH)-vitamin D correlated positively albeit weakly with eGFR (r = 0.10; p < 0.001). More than half (51.2%) of patients with stage 4 - 5 kidney dysfunction had vitamin D deficiency or insufficiency compared with 34.8% of those with preserved renal function. No significant seasonal variation was observed although higher mean levels coincided with sunnier months. Our findings highlight a substantial burden of hypovitaminosis D in Senegal and its association with impaired renal function.