Prevalence of hypothyroidism in patients with chronic kidney disease: a cross-sectional study from North India

BACKGROUND There is an increased prevalence of hypothyroidism in chronic kidney disease (CKD) patients as the glomerular filtration rate falls. However, there is a paucity of Indian data in this respect. METHODS A cross-sectional analysis was performed based on the database of the information system of a tertiary care hospital in northern India to retrieve results of nephrology CKD outpatients (> 18 years of age) from September 2013 to October 2015 to determine the prevalence of hypothyroidism in the non-dialysis-dependent CKD population. Overt hypothyroidism was defined by a thyroid-stimulating hormone (TSH) level > 5.5 mIU/L and free T4 level < 0.89 ng/dL with clinical symptoms. Subclinical hypothyroidism was defined by a TSH level > 5.5 mIU/L and a free T4 level ≥ 0.89 ng/dL. RESULTS Among 1,863 CKD patients, 358 patients underwent biochemical analysis for hypothyroidism. Among these, 143 had biochemical subclinical hypothyroidism and 59 had overt hypothyroidism. Patients in the overt hypothyroid group had significantly higher TSH levels and a lower free T4 level than those in the nonhypothyroid group. Patients with hypothyroidism (both clinical and subclinical) had significantly lower serum albumin and serum calcium levels than those in the nonhypothyroid group. Intact parathyroid hormone was also significantly higher in the hypothyroid groups. An increased prevalence of hypothyroidism was observed in patients with a reduction in the glomerular filtration rate. CONCLUSION There is growing evidence of increased prevalence of hypothyroidism in dialysis-independent CKD patients. A number of findings such as lower serum albumin, serum calcium, and hemoglobin levels and higher intact parathyroid hormone levels are seen in this group. Specific treatment can help improve these. Hence, there is a need to formulate guidelines to screen this population for hypothyroidism.