Previous studies of patients with end-stage renal disease (ESRD) indicate that the prevalence of goiter varies from 0 to 58% while that of hypothyroidism ranges from 0 to 9.5%. In addition, altered serum thyroid hormone levels are present in euthyroid patients with ESRD and may be related to nonthyroidal disorders including malnutrition. To examine these issues further, 306 patients with ESRD were compared to 139 hospitalized patients without renal disease (control population). Goiter was present in 43% with ESRD compared to 6.7% of controls (P less than 0.001). Goiter frequency was greater (49.6%, P = 0.047) and serum parathyroid hormone levels higher (mean: 238.6 microlitersEq/ml, P less than 0.001; normal: less than 15 microlitersEq/ml) in 115 patients dialyzed for longer than 1 year than in 191 dialyzed for less than 1 year or not at all (38.7%, and 61.5 microlitersEq/ml, respectively). In addition, goiter was more common in females (50.0%) than in males (35.1%, P = 0.008) with ESRD. No significant relationships were observed between goiter frequency and age, race, diabetes mellitus, or elevated antimicrosomal antibody titers. The prevalence of primary hypothyroidism was higher in ESRD (2.6%) than in 2122 in- and out-patients (1.1%) (P = 0.024). Compared to the total group of ESRD patients, the hypothyroid patients were predominantly female (88% vs. 50%) and had a higher frequency of positive antimicrosomal antibody titers (50% vs. 6.7%, P = 0.029). The frequency of hyperthyroidism was not significantly different, being 1.0% in ESRD compared to 0.3% in the general population (P = 0.057). There was a higher frequency of reduced free T4 index values in the 287 euthyroid patients with ESRD (12.9%) than in controls (3.6%) (P = 0.002). Similarly, free T3 index values were reduced below 100 in 65.5% with ESRD compared to 33.8% of controls (P less than 0.001). In addition, serum albumin levels were lower in euthyroid patients with ESRD (3.5 g/dl, P less than 0.001) than in controls (3.8 g/dl). Serum T3 levels correlated directly with both serum albumin (r = 0.57, P less than 0.001) and transferrin (r = 0.54, P less than 0.001) levels in ESRD as well as in controls (r = 0.74, P less than 0.001, and r = 0.69, P less than 0.001, respectively).(ABSTRACT TRUNCATED AT 400 WORDS)