Kidney function among adult sickle cell disease patients at Ahmadu Bello University Teaching Hospital, Zaria, Nigeria.

backgroundSickle cell disease (SCD) patients are certainly experiencing improved longevity with improved care and it is not unexpected that long-term complications including kidney diseases are being seen more often than before. Unfortunately, late diagnosis is not unusual. This can in part be explained by some aspects of pathogenesis of kidney disease in SCD including body compensatory mechanisms such as hyperfiltration with its associated lower creatinine levels and exaggerated estimated glomerular filtration rate (eGFR). Worse still, no single eGFR formula has been validated across board in this patient population. Based on the forgoing, it is not surprising that there is paucity of data regarding kidney disease among SCD patients even in Nigeria with 2–3% of her population affected, with about 150,000 new-borns affected yearly and 50 million people carrying the sickle cell trait representing the highest burden of SCD globally. Hence, this study is relevant to the field of nephrology as it is expected to draw attention to this emerging cause of kidney disease as it were and also serve as a reminder to non-nephrologists to look beyond serum creatinine levels and eGFR to assess urine of SCD patients for early evidence of kidney disease including loss of urine concentration and pH regulation ability as well as microalbuminuria.

aims(1) This study was conducted to evaluate kidney function among patients with SCD in ABUTH, Zaria. (2) To assess the relationship of BMI, sex, age, Blood pressure, and disease duration, on kidney dysfunction among patients with SCD in ABUTH, Zaria.

methodThis was cross sectional descriptive study involving 210 SCD patients (188 HbSS and 22 HbSC) attending Haematology Clinic in ABUTH Zaria and 210 apparently healthy controls. The subject and control groups were selected using convenience sampling technique. Clinical examinations such as body mass index, blood pressure, were done for both patients and controls. Glomerular Filtration Rates were estimated using (CKD-EPI equation). Albuminuria was quantified using albumin creatinine ratio. Tubular function was assessed for pH and specific gravity (SG) using dip sticks and hygrometer respectively. All data were checked for errors before entering into computer programme version 17.0 SPSS for windows. Categorical data were represented as diagram (charts and tables) while continuous variable data were represented as mean and standard deviation. Student t- test and Pearson’s Chi square were used to test for relationship.

resultsThe study found the prevalence of albuminuria to be 47.2% among patients with SCD in ABUTH Zaria. The prevalence of CKD from stages 3–5 using eGFR was found to be 8.6%. It was observed that 35.2% of the patients with SCD in this study were unable to acidify their urine and 33.3% of them have impaired ability to concentrate their urine. A significant relationship was observed between blood pressure, and ACR with p < 0.001. An inverse relationship between blood pressure and eGFR was observed with p < 0.001. The study shows a significant inverse relationship between age and eGFR with p < 0.001. A positive significant relationship was observed between age and ACR p < 0.001. No significant relationship was observed between BMI and kidney function. Limitations of this study: (1) Lack of determination of HbF to determine its impacts on kidney function. (2) History of use of Hydroxyurea and its impacts on kidney function couldn’t be obtained.

conclusionThis study has shown high prevalence of albuminuria, impaired urine acidification and urine concentrating ability among patients with SCD. A significant relationship was observed between increasing age, BP and kidney dysfunction (albuminuria, eGFR,) among patients with SCD in ABUTH Zaria. This study therefore, highlights the importance of early screening and detection of markers of chronic kidney among patients with SCD, so that early intervention can be deployed to retard its progression.