Vitamin D Level and Its Correlation to Certain Biochemical Markers in Patients with Chronic Kidney Disease in Erbil City
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Background: Chronic kidney disease (CKD) is a growing public health challenge associated with disturbances in mineral metabolism and progressive loss of renal function. Vitamin D deficiency is particularly prevalent in CKD due to impaired renal activation of 25-hydroxyvitamin D [25(OH)D], potentially exacerbating mineral imbalances and secondary hyperparathyroidism. Despite its clinical importance, data on the biochemical correlations of vitamin D in CKD patients remain limited in the Kurdistan region.
Objective: This study aimed to assess serum vitamin D levels and explore their relationship with key biochemical markers—including PTH, FGF-23, ALP, creatinine, and eGFR—among CKD patients in Erbil City, Iraq.
Methods: In a cross-sectional design, 146 participants were enrolled, including 86 CKD patients (stages 1–4) and 60 healthy controls. Serum levels of 25(OH)D, PTH, FGF-23, ALP, and creatinine were measured, and eGFR was calculated using the CKD-EPI formula. Correlations between vitamin D and other biochemical parameters were statistically analyzed using Pearson’s correlation.
Results: CKD patients showed significantly higher levels of creatinine, PTH, FGF-23, and ALP, and lower eGFR compared to controls (p < 0.001), while vitamin D levels did not differ significantly (p = 0.15). However, stratification by eGFR revealed a progressive increase in vitamin D levels with higher kidney function stages. Vitamin D showed a moderate positive correlation with eGFR (r = 0.55, p < 0.001) and moderate to weak negative correlations with creatinine (r = -0.45), PTH (r = -0.50), FGF-23 (r = -0.40), and ALP (r = -0.35).
Conclusion: Although serum vitamin D levels were not significantly different between CKD patients and controls, they showed strong associations with key renal and bone metabolism markers. These findings suggest that vitamin D status may reflect disease severity in CKD and support its potential role in early intervention strategies. Integrating routine vitamin D monitoring alongside biochemical markers could enhance clinical management and slow CKD progression. Further longitudinal and interventional studies are warranted to validate these relationships and optimize therapeutic approaches.
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