Thyroid Dysfunction in Chronic Kidney Disease: A Study from North Kerala

Abstract

Introduction: Chronic kidney disease (CKD) is a leading cause of morbidity and mortality Worldwide. The understanding of metabolic and hormonal abnormalities in milder forms of renal dysfunction is expanding, but the knowledge of thyroid dysfunction in people with CKD is still limited. The growth, differentiation, and regulation of physiological mechanisms in all tissues, including the kidney, depend on thyroid hormones. They are essential for maintaining the balance of electrolytes and water. Prevalence of hypothyroidism in end stage renal disease (ESRD) has been estimated to be in the range of 0 to 9%. Patients with ESRD also have a higher prevalence of goitre. Although there are several indicators that can predict both overall mortality and the severity of renal impairment, thyroid dysfunction is one of the major ones. In order to improve the outcome, it is wise for the internist and treating physician to be aware of thyroid dysfunction. The importance of knowing the prevalence of thyroid dysfunction in CKD patients also lies in the fact that it adds to the already high cardiovascular mortality risk in this patient group.
 Objectives
 
 To find the proportion of thyroid dysfunction in patients with chronic kidney disease.
 To study the correlation between thyroid dysfunction and severity of renal diseases.
 
 Methodology
 A single center cross sectional study conducted in Departments of General Medicine and Nephrology in a tertiary care hospital in Calicut, Kerala. In the study period of 12 months, among patients admitted in Medical Ward after applying inclusion and exclusion criteria, 100 patients were included in the study. Patients who fulfilled the criteria for CKD and who are on conservative management and haemodialysis were taken up for the study. Thyroid profile was done in all patients who fulfilled the criteria. The prevalence of thyroid dysfunction in chronic kidney disease was described and analyzed in terms of percentages and averages. One way ANOVA test was used to analyze various parameters like T3, T4, Blood urea and Serum creatinine in relation to various grades of renal failure.
 Results
 Low T3 levels were seen in 65% and subclinical hypothyroidism was seen in 17% of the study subjects. Low T4 was seen in only 6% of the study subjects. There was no significant association observed between CKD stages and T3, T4, TSH values categorized as low, high and normal.
 Conclusion
 Low T3 syndrome was the commonest abnormality detected. This may be viewed as protective mechanism to conserve protein in chronic kidney disease patients. Subclinical hypothyroidism was the second most common abnormality detected and the number of patients with subclinical hypothyroidism progressively increased with the severity of chronic kidney disease. As subclinical hypothyroidism is associated with increased cardiovascular mortality in CKD patients, adult patients with CKD should be routinely screened for subclinical hypothyroidism and further studies are required concentrating on improving clinical and biochemical criteria to diagnose thyroid dysfunction in CKD.