Impact of Haemoglobin S on the Renal Function of Individuals with Sickle Cell Trait (HB AS) in Nigeria

Abstract

Background: Individuals with the heterozygous state of sickle haemoglobin β-globin gene, the sickle cell trait (HB AS), are generally believed to be healthy and the carrier status does not affect their renal functions. Study Design: It is a cross-sectional study consisting of 80 consecutive Hb AS individuals and 80 age and sex-matched controls with Hb AA, all of whom were apparently healthy. All subjects who were apparently healthy individuals between the ages of 18 and 65 years with Hb AS or Hb AA (controls) matched for age and sex were included into the study, while Individuals with positive serological reaction to viral screening tests such as HIV, Hepatitis B and C or have any other systemic conditions like diabetes mellitus or hypertension were excluded from the study. Place and Duration of Study: Department of Haematology and Blood Transfusion, Chemical Pathology, Haematology and Immunology, of Obafemi Awolowo University Teaching Hospitals Complex, and Obafemi Awolowo University, Ile-Ife, Osun State respectively, between the periods of 10th July, 2017 to 31 July, 2018. Materials and Methods: This is a cross-sectional study consisting of 80 consecutive Hb AS individuals and 80 age and sex-matched controls with HB AA, all of whom were apparently healthy. A structured questionnaire was used to obtain demo-sociographic data after informed consent was obtained. Venous blood (10mls) was obtained for haematological and biochemical parameters that include percentage HB S, plasma creatinine, total protein, albumin, uric acid, urea. On the spot mid-stream urine was obtained and tested for microalbuminuria. Data was analysed on SPSS version 24 software. Results: The mean ages of HB AS and HB AA across the groups were 35.30 ± 11.40 years and 36.1 ± 11.39 years respectively. The body mass indexes (BMI) for the two groups were 20.67 ± 1.45 kg/m2 and 21.10 ± 2.11 kg/m2 for the HB AS and HB AA groups respectively. The combined prevalence of stages 2 and 3 renal dysfunction as estimated by the eGFR in Hb AS is 35.5%, the majority being stage 2 with 28.8% while that of HB AA is 2.5%, only in stage 2 category. The prevalence of microalbuminuria in the HB AS participants is 18.8% as compared to 0% in the Hb AA participants. Percentage haemoglobin S is the only independent predictor of estimated glomerular filtration rate from multivariate regression on predictors of estimated glomerular filtration rate. This study concluded that percentage haemoglobin S is the only independent predictor of renal complication seen in apparently healthy individuals with Sickle cell trait.