Influence of Renal Impairment on Serum Parathyroid Hormone and Vitamin D Status and their Association with Serum Creatinine in Patients Undergoing Haemodialysis: A Case-control Study

Introduction: A transition in the lifestyle of Saudi population over the past few decades has increased the burden of various metabolic disorders including, diabetes mellitus type 2, Chronic Kidney Disease (CKD), cardiovascular diseases, and vitamin D deficiency. Deficiency of vitamin D has been linked to the progression of kidney disease and many cardiovascular complications. Aim: The study focuses on the vitamin D status and associated changes in serum Parathyroid Hormone (PTH) in End Stage Renal Disease (ESRD) patients undergoing haemodialysis in the Northern Border Region (Arar city) of Saudi Arabia. The present study also investigated the relationship between serum creatinine, PTH and vitamin D levels in these patients. Materials and Methods: This case-control study was carried out for a period of five months (September 2019 to January 2020). It included 60 patients, suffering from ESRD on haemodialysis (cases) attending the Nephrology Centre of Prince Mohammed bin Saud Al Kabeer renal dialysis unit in Arar Central Hospital, Arar, Saudi Arabia. A control population (n=60) with normal kidney function, who visited the hospital for other reasons, was also identified. Their blood samples were collected for estimation of renal function parameters {Blood Urea Nitrogen (BUN) and creatinine}, serum calcium, phosphate, vitamin D and PTH. Statistical analysis was performed using the Statistical Package for the Social Sciences version 22.0. Results: The study included 60 patients (50% males and 50% females) undergoing haemodialysis and 60 healthy controls (50% males and 50% females) with a mean age of 46.83 +/- 14.19 (range 18-73 years) and 39.25 +/- 5.11 (range 30-54 years) years, respectively. The mean BMI of the patients was 27.3 +/- 3.4 kg/m(2) and that of controls was 23.7 +/- 2.2 kg/m(2). A significant elevation (p-value <0.001) of serum PTH showing hyperparathyroidism accompanied by significant (p-value <0.001) hypovitaminosis D and hypocalcaemia was observed in the patients as compared to controls. The results also demonstrated significantly elevated (p-value <0.001) levels of BUN and serum creatinine in ESRD patients. Results of correlation analysis exhibited a significant (p-value <0.05) positive correlation between serum creatinine and PTH whereas, there was a significant (p-value <0.05) negative correlation between serum creatinine and vitamin D; and serum PTH and vitamin D among the patients. Conclusion: This study highlights the importance of monitoring changes in PTH levels in patients with impaired renal function for the early detection and treatment of CKD. The study also showed a significant (p<0.05) positive association between serum creatinine and PTH followed by a significant (p<0.05) negative correlation between serum creatinine and vitamin D; and serum PTH and vitamin D.