MINERAL AND BONE DISEASE IN ADULT PATIENTS WITH CHRONIC KIDNEY DISEASE IN THE UNIVERSITY OF PORT HARCOURT TEACHING HOSPITAL
BACKGROUND: Mineral bone disease (MBD) is a common complication in patients with chronic kidney disease (CKD). Various studies reported a global prevalence between 33% and 67%. However, there is paucity of study of CKDMBD in Africa and in particular Nigeria.
OBJECTIVE: The objective of this study is to determine the prevalence and characteristics of CKD-MBD among adult patients with CKD in the University of Port Harcourt Teaching Hospital.
METHOD: This is a cross-sectional study. One hundred and fifty consecutive consenting chronic kidney disease patients who fulfilled the inclusion criteria for this study were recruited. Patients had a detailed clinical assessment, biochemical and radiological evaluations for CKD-MBD. Biochemical investigations included serum calcium, phosphate, parathyroid hormone (PTH) and alkaline phosphatase while the radiological investigations included X-ray of the skull, spine, wrist and phalanges.
RESULTS: The age range of the patients was 22-80 years, with a mean of 45.1(±11.9) years. There were 90 males and 60 females with male to female ratio of 1.5 : 1.
The prevalence of CKD-MBD in the study population was 55.3%. Of this, sixty one (73.5%) patients had low turnover bone disease while 22 (26.5%) patients had high turnover bone disease.
Symptoms suggestive of CKD-MBD in the study population were bone pain and pruritus occuring in 36.7% and 13.3% of the study population respectively but present in 34.9% and 12.0% of the CKD-MBD patients respectively. Other symptoms presented by the patients included leg swelling in 126(84%), frothiness
of urine in 123(82%), vomiting in 109(72.7%), facial puffiness in 102(68%), haematuria in 18(12%) and chest pain in 73(48.7%) of the patients.
The mean values for serum PTH, serum calcium, serum phosphate, alkaline phosphatase and caxpo4 product among the CKD-MBD patients were 205.06±112.6 pg/ml, 2.56±0.73mmol/l, 1.63±0.63mmol/l, 109.26±65.57IU/L and 4.07±1.28mmol2/l2 respectively but the values among non CKD-MBD patients were 123.08±120.99pg/ml, 2.32±0.46mmol/l, 1.54±0.57mmol/l, 108.13±51.84I U/L and 3.52±1.32mmol2/l2 respectively.
There was hypercalcaemia in 44.6%, hypocalcaemia in 26.0%, hypophosphataemia in 12.0% and hyperphosphataemia in 29.3% of the patients. High alkaline phosphatase was observed in 36.0% while 8.7% had low alkaline phosphatase. There was high calcium x phosphate product in 34.0% of the patients.
Hypercalcaemia was the most common biochemical abnormality in this study occuring in 44.6% of the patients.
Radiological features in keeping with CKD-MBD was present in only 6% of those with CKD-MBD.
Among the biochemical markers of CKD-MBD, estimated glomerular filteration rate (eGFR) showed a significant negative correlation with serum phosphate (r = -0.34, p = <0.001), serum PTH (r = -0.25, p= 0.02), and Caxpo4 product (r = -0.173, p = 0.03).
CONCLUSION: The prevalence of CKD-MBD in our environment is high and low turnover bone disease is the commonest type. Bone pain was the commonest clinical presentation of CKD-MBD while hypercalcaemia was most common mineral abnormality among the study population. Only 6% of those with CKD-MBD had radiological features.