Magnitude and determinants of biochemical mineral bone disease abnormalities among predialysis chronic kidney disease patients in Tikur Anbessa Specialized Hospital

Introduction: Mineral bone disease (MBD) abnormalities are common complications in patients with chronic kidney disease (CKD). The MBD abnormalities are known to be associated with increased morbidity and mortality. In spite of their importance, there are limited data on CKD-MBD abnormalities in Ethiopia. This study looked in to the magnitude and determinants of biochemical CKD-MBD abnormalities among predialysis CKD patients. Methods: A cross-sectional study was conducted from July 1 to September 30, 2020 in Tikur Anbessa specialized hospital. One hundred patients who had had follow-up for at least 6 months with an estimated glomerular filtration rate (eGFR)<60ml/min/1.73m2 using CKD-EPI equation without race factor were included. Serum calcium, albumin, phosphorus and PTH levels were determined. Demographic and clinical data were collected using a structured questionnaire. IBM SPSS software version 26 was used for analysis. Descriptive statistics was used to describe the demographic and clinical data. Chi-square was used to identify correlations between the grouped variables. The analysis for comparison among three or more categories was done using one-way ANOVA and Tukey post hoc test. Linear correlation and multiple regression analysis were used to identify associations between clinical and biochemical findings. Results: Among the 100 patients included in this study; the median age was 58 years with IQR of 73. The male to female ratio was 2.7:1. Patients in stages 3a, 3b, 4 and 5 CKD accounted for 23%, 29%, 26% and 22%, respectively. The main causes of CKD were diabetes and hypertension. Among these patients, 31% had hyperphosphatemia, 36% had hypocalcemia, and 89% had hyperparathyroidism. The mean values of calcium in CKD stage 3a,3b,4 and 5 were 8.91, 8.81, 8.7 and 7.14mg/dl, respectively; where as those of serum phosphorus were 3.58, 3.83, 3.83 and 5.53mg/dl, respectively. The median values of PTH were 140.6, 137.2, 274.05 and 440.85Pg/ml, respectively. Estimated GFR correlated negatively with serum parathyroid hormone (PTH) level but correlated positively with serum calcium level. In addition, serum calcium level is inversely associated with diabetes and diastolic blood pressure whereas serum PTH is directly associated with diastolic blood pressure and female sex. Conclusion: Hypocalcemia, hyperparathyroidism, and hyperphosphatemia are common biochemical CKD-MBD abnormalities among predialysis CKD patients in the renal clinic of Tikur Anbessa specialized hospital. Monitoring for CKD-MBD should begin earlier and treatment should be initiated accordingly to improve patient outcome.