Prevalence of subclinical hypothyroidism in patients with chronic kidney disease.

BACKGROUND AND OBJECTIVES Subclinical primary hypothyroidism is highly prevalent in the general population, especially in the elderly. However, the prevalence of subclinical primary hypothyroidism in persons with chronic kidney disease (CKD) not requiring chronic dialysis is not well defined. DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS Cross-sectional data from 3089 adult outpatients, who were consecutively referred by general practitioners for routine blood testing over the last two years, were analyzed. Glomerular filtration rate (GFR) was estimated by the abbreviated Modification of Diet in Renal Disease equation. Multivariable logistic regression was used to evaluate the independent association between prevalent subclinical primary hypothyroidism and estimated GFR. RESULTS Among 3089 adult participants, 293 (9.5%) had subclinical primary hypothyroidism and 277 (9%) had an estimated GFR <60 ml/min per 1.73 m(2). The prevalence of subclinical primary hypothyroidism increased from 7% at an estimated GFR >or=90 ml/min per 1.73 m(2) to 17.9% at an estimated GFR <60 ml/min per 1.73 m(2) (P < 0.0001 for trend). Compared with participants with an estimated GFR >or=60 ml/min per 1.73 m(2), those with estimated GFR <60 ml/min per 1.73 m(2) had an increased odds of subclinical primary hypothyroidism after adjusting for age, gender, fasting plasma glucose, total cholesterol, and triglyceride concentrations. CONCLUSIONS These findings suggest that subclinical primary hypothyroidism is a relatively common condition ( approximately 18%) among persons with CKD not requiring chronic dialysis, and it is independently associated with progressively lower estimated GFR in a large cohort of unselected outpatient adults.