Background: Human immunodeficiency virus (HIV) infection impairs renal function,
thereby affecting renal phosphate metabolism.
Objectives: We prospectively estimated the prevalence of phosphate abnormalities (mild, moderate
to life-threatening hypophosphataemia, and hyperphosphataemia) before initiating antiretroviral
Methods: A cross-sectional analysis was performed on 170 consecutive newly diagnosed ARTnaive,
HIV-infected patients attending our HIV/AIDS clinics over a period of one year. Fifty (50)
screened HIV-negative blood donors were used for comparison (controls). Blood and urine were
collected simultaneously for phosphate and creatinine assay to estimate fractional phosphate excretion
(FEPi %) and glomerular filtration rate (eGFR).
Results: eGFR showed significant difference between patients’ and controls’ medians (47.89ml/
min/1.73m2 versus 60ml/min/1.73m2, p <0.001); which denotes a moderate chronic kidney disease
in the patients. Of the 170 patients, 78 (45.9%) had normal plasma phosphate (0.6-1.4
mmol/L); 85 (50%) had hyperphosphataemia. Grades 1, 2 and 3 hypophosphataemia was observed
in 3 (1.8%), 3 (1.8%), and 1(0.5%) patient(s) respectively. None had grade 4 hypophosphataemia.
Overall, the patients had significantly higher median of plasma phosphate than the controls, 1.4
mmol/L (IQR: 1.0 – 2.2) versus 1.1 mmol/L (IQR: 0.3 – 1.6), p <0.001, implying hyperphosphataemia
in the patients; significantly lower median urine phosphate than the controls, 1.5 mmol/L
(IQR: 0.7 -2.1) versus 8.4 mmol/L (IQR: 3.4 – 16), p <0.001), justifying the hyperphosphataemia
is from phosphate retention; but a non-significantly lower median FEPi% than the controls, 0.96%
(IQR: 0.3 -2.2) versus 1.4% (IQR: 1.2 -1.6), p > 0.05. Predictors of FEPi% were age (Odds ratio,
OR 0.9, p = 0.009); weight (OR 2.0, p < 0.001); CD4+ cells count predicted urine phosphate
among males (p = 0.029).
Conclusion: HIV infection likely induces renal insufficiency with reduced renal phosphate clearance.
Thus, hyperphosphataemia is highly prevalent, and there is mild to moderate hypophosphataemia
but its life-threatening form (grade 4) is rare among ART-naive HIV patients.