Using a precise and accurate ultrasonic scanning technique we have measured the volume of the thyroid gland in vivo in 271 healthy subjects (13-91 yr old). In these subjects the mean (+/- SD) thyroid volume was 18.6 +/- 4.5 ml. A significant difference between males (19.6 +/- 4.7 ml; n = 139) and females (17.5 +/- 4.2 ml; n = 132) was found (P less than 0.001). The thyroid volume was significantly correlated with both body weight and age, described by: Y = 1.97 + 0.21 . x1 + 0.06 . x2, where Y is the thyroid volume (milliters), x1 is the body weight (kilograms), and x2 is the age (years). The influence of body weight on the thyroid volume was about 3 times that of age. The difference in thyroid gland volume between males and females was explained solely by a difference in body weight.

Thyroid gland volume, ultrasonically determined, and thyroid function were investigated in 40 patients with chronic renal failure (33 of these on hemodialysis) and 40 sex-, age- and weight-matched healthy controls. None had thyroid autoantibodies or a clinically detectable goiter. The median thyroid gland volume was significantly elevated in the uremic patients: 24 ml (range 8–43 ml) compared with the healthy controls 17 ml (range 10–22 ml) (p < 0.005). The serum concentrations of thyroxine (T₄), triiodothyronine (T₃), free thyroxine index (FT₄I) and free triiodothyronine index (FT₃I) were significantly decreased in uremic subjects compared with the controls. The serum concentration of thyrotropin did not differ significantly between patients and controls. None of the thyroid function variables correlated with thyroid gland volume. In conclusion, thyroid gland volume was increased in patients with chronic renal failure. The alterations in thyroid hormone concentrations could, however, not explain this finding.

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