Endogenous Thyroid-Stimulating Hormone and Radioactive Iodine Uptake in Normal Subjects

Abstract

In 105 normal volunteers, 52 male and 53 female, mean age 45 (range, 20-68), serum thyroid-stimulating hormone (TSH) (1.46 ± 0.7; range, 0.43-3.87 microUI/mL) and 24-hour thyroid radioactive iodine uptake (RAIU) (16.15% ± 4.78% range, 6.45%-30.08%) were measured. Additionally, TSH was 1.18 ± 0.5 microUI/mL for 20 to 29 year-olds and 1.59 ± 0.9 microUI/mL for 60 to 68 year old (P = 0.037). RAIU was 18.30 ± 4.5 for 20 to 29-year-olds and 14.92 ± 3.1 for 60 to 68 year-olds (P = 0.009). TSH trends positively and RAIU at 24 hours correlates negatively with aging of the pituitary axis.