A longitudinal study of total and free thyroid hormones and thyroxinebinding globulin during normal puberty

Abstract

Thyroid hormones are essential for normal pubertal growth, yet the changes in total and, especially, free thyroid hormones and thyroxine-binding globulin during puberty have not been adequately defined. Serum from 39 normal children (20 girls, 19 boys) between the ages of 10 and 15 years were assayed for total T4, free T4, free T3 and thyroxine-binding globulin at 6-monthly intervals; the free hormone assays were valid, non-analogue methodologies. In the girls, free T4 levels fell from 15.7\m=+-\0.6 pmol/l at 10 years to 13.0\m=+-\0.6(p<0.001) at 12.5 years before rising to 15.9\m=+-\0.7at 15 years; this nadir occurred at puberty stages 3-4. Changes in total T4 followed a similar pattern with a slight delay in the nadir (13 years, puberty stage 4). In the boys, free T4 fell from 16.3\m=+-\0.6pmol/l at 10 years to 14.3\m=+-\0.3at 13.5 years, then rising to 15.4\m=+-\0.5at 15 years; the nadir again occurred at puberty stages 3-4. The corresponding nadir in total T4 which occurred at puberty stages 4-5 was not apparent by age analysis. Thyroxine-binding globulin concentrations remained unchanged in the girls, but fell slightly in the boys during later puberty. Free T3 concentrations in the girls showed a progressive fall after 12.5 years which was significant by the age of 14 when most had been in puberty stage 5 for more than 1 year. The boys showed no change of free T3 concentration throughout the study. These data demonstrate important differences in the levels of free thyroid hormones in males and females during puberty. Normal ranges for girls and boys between the ages of 9.5 and 15.5 years are presented.

Thyroid hormone concentrations in relation to age, sex, pregnancy, and perinatal loss in bottlenose dolphins (Tursiops truncatus)

“…In a more recent study with wild dolphins (Fair et al, 2011), thyroid hormone concentrations (i.e., total and free T 4 and total T 3 ) were not different between female and male dolphins after adjustment for age (juvenile and adult). Correspondingly, circulating concentrations of T 4 were not different between peripubertal girls and boys with matched ages at 10 and 15 y (Dunger et al, 1990). In the present study, thyroid hormone concentrations were not adjusted for age since actual ages were only known for juvenile females (mean, 2.9 y) and males (mean, 4.8 y) born under human care and not adults born in the wild.…”

Reduced gains in fat and fat-free mass, and elevated leptin levels in children and adolescents with cystic fibrosis

“…Somerset (12) served as the control group. They were seen twice a year for measurements of height, weight and skinfolds.…”

Leptin and thyroxine during sexual development in male monkeys: effect of neonatal gonadotropin-releasing hormone antagonist treatment and delayed puberty on the developmental pattern of leptin and thyroxine secretion

“…In a small longitudinal study (39 children, ranging in age from 10 to 15 years), there were significant fluctuations in both total and free T3 and T4 in association with pubertal stages of development (29). It has been suggested that these changes in thyroid hormone may play a role in the onset or evolution of puberty in children, and may serve as an effective adaptive mechanism for a period of rapid growth and increased energy requirements (28,29). One of the objectives of the current longitudinal study was to examine in greater detail the relationship between thyroid status and critical peripubertal events in a non-human primate model (male rhesus monkey).…”

“…In another crosssectional study in children in which data from boys and girls were combined, there was a transient increase in thyrotropin secretion and a resultant rise in T4 and tri-iodothyronine (T3) that preceded clinical pubertal changes (28). In a small longitudinal study (39 children, ranging in age from 10 to 15 years), there were significant fluctuations in both total and free T3 and T4 in association with pubertal stages of development (29). It has been suggested that these changes in thyroid hormone may play a role in the onset or evolution of puberty in children, and may serve as an effective adaptive mechanism for a period of rapid growth and increased energy requirements (28,29).…”