Prevalence of thyroid autoimmunity and subclinical hypothyroidism in persons with chronic kidney disease not requiring chronic dialysis.

Background: The prevalence of thyroid autoimmunity and subclinical primary hypothyroidism in persons with chronic kidney disease (CKD) not requiring chronic dialysis is not well defined. Methods: We studied 1000 consecutive adult outpatients who were referred by their general practitioner for blood testing over the last 2 years. We excluded those with abnormal serum free thyroxine (FT4) levels (n=85). No participants required chronic renal replacement therapy. Thyroid autoimmunity was defined as increased concentrations of serum anti-thyroid antibodies. Subclinical primary hypothyroidism was defined as a serum thyrotropin (TSH) concentration >4 mIU/L. CKD was defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2. Results: Overall, 53 (5.8%) subjects had eGFR <60 mL/min/1.73 m2. Of these, 98 (10.7%) had subclinical hypothyroidism, and 213 (23.3%) subjects had increased anti-thyroid antibodies. Approximately 26% and 34% of those with eGFR <60 mL/min/1.73 m2 had laboratory evidence of subclinical hypothyroidism or thyroid autoimmunity, respectively. In subgroup analysis stratified by TSH and thyroid autoimmunity, decreasing eGFR values appeared to be more strongly related with the increase in TSH rather than antithyroid antibodies. Conclusions: Thyroid autoimmunity and subclinical primary hypothyroidism are highly prevalent in persons with CKD not requiring chronic dialysis.