Eight men were studied during graded (47, 77 and 100% of maximal oxygen uptake) and prolonged (76%) exhaustive treadmill running. Plasma catecholamine levels increased progressively with intensity and duration of exercise. Serum concentrations of thyroid-stimulating hormone (TSH) increased with increasing work loads and were 107 (58--243)% (P less than 0.001) above resting values after maximal work. Thyroxine, triiodothyronine and luteinizing hormone in serum never changed significantly. While a small increase in testosterone concentrations (13 [1--24]%) after maximal exercise probably could be explained by changes in plasma volume, a definite increase (31 [14--56]%) occurred after 40 min of prolonged exercise. During continued exercise testosterone concentrations then gradually declined. Testicular stimulation by the increased catecholamine concentrations possible contributed to the rise in testosterone concentrations, but no evidence was found for a direct catecholamine induced increase in the activity of the thyroid gland. The exercise induced increase in TSH levels possibly explians the increased thyroid hormone secretion rate, which previously has been found in individuals participating in physical training programs.

Jacobsen, B. B., Andersen, H. J., Peitersen, B., Dige-Petersen, H. and Hummer, L. (The University Clinic of Paediatrics, Children's Hospital Fuglebakken and the Department of Nuclear Medicine, Rigshospitalet, Copenhagen, Denmark). Serum levels of thyrotropin, thyroxine and triiodothyronine in fullterm, small-for-gestational age and preterm newborn babies. Acta Paediatr Scand, 66: 681, 1977.Simultaneous serum concentrations of TSH, total thyroxine (TJ and triiodothyronine (T,) were determined in 93 fullterm (FT), 37 small-for-gestational age (SGA) and 38 preterm (PT) babies with a postnatal age from 2 to 144 hours. In addition, TSH, T, and T, concentrations were measured in cord sera from 27 FT, 4 SGA and 5 PT babies and in venous blood from 20 mothers at delivery. Cord blood concentrations of TSH were higher and T, and T3 concentrations were lower than seen in the mothers. Serum concentrations of TSH were high during the first day of life followed by a decline. There was no statistically significant difference between serum TSH concentrations of the three groups of newborns. On the 5th day of life no elevated serum TSH values were found in any of the groups (TSH<5mU/l). Serum concentrations of thyroid hormones increased after birth and reached maximum levels within 24 hours in all groups. The relative increases above cord level were of the same magnitude in the newborns: Two times for serum T, and six times for serum T,. The thyroid hormone concentrations in blood samples from FT babies decreased from the second day of life, whereas in low birth weight newborns the decreases were more variable. The serum levels of T, and T, were significantly different in the three groups of newborns, the highest values were seen in FT and the lowest values in PT babies. In contrast, the ratios between molar serum concentrations of T, and T, were found to be highest in PT, lower in SGA and lowest in FT babies, approaching maternal values during the first week of life. The data are discussed with regard to hormone secretion, thyroxine-binding capacity and peripheral T, to T, conversion in the three groups of newborns. It is concluded that from day 5 after birth serum TSH determinations, alone or in combination with serum T,, seem to be the method of choice in screening for congenital hypothyroidism.

Simultaneous serum concentrations of thyroxine-binding globulin (TBG), prealbumin (TBPA) and albumin (Alb) were measured in 130 fullterm, 32 small-for-gestational age and 25 preterm infants during their first six days of life. In all infants serum concentrations of TBG were higher and serum TBPA and Alb were lower than in male adults. Even higher serum TBG levels were found in the mothers. There was no correlation between serum concentrations in paired maternal and cord sera. In infants with birth weights appropriate for gestation serum TBG, TBPA, and Alb concentrations increased progressively with gestational age. In small-for-gestational age infants born at term serum concentrations of TBG and Alb were lower than those in fullterm, but higher than those in premature newborns. Serum TBPA in small-for-gestational age babies was even lower than seen in prematures. A positive correlation was found between thyroid hormones and TBG concentrations, not between serum TBPA and thyroid hormones. The ratios between serum concentration of thyroid hormones and proteins might indicate that more thyroid hormonebinding sites are occupied in fullterm than in low birth-weight newborns. However, the main reason for the different serum levels of thyroid hormones in fullterm, small-for-gestational age and preterm babies is probably the various serum TBG concentrations demonstrated in these infants.

To examine the effect of endogenous oestrogens on calcium metabolism during the menstrual cycle, fasting blood and urinary samples were obtained every day throughout the menstrual cycle in 5 young women.Bone turnover was estimated by serum alkaline phosphatase and fasting urinary excretions of hydroxyproline and calcium. Serum levels of oestradiol (E2), oestrone (E1), and androstenedione (A) showed the well known cyclic fluctuations, the serum 1,25-dihydroxyvitamin D (1,25(OH)2D) nearly doubled from the early follicular phase to the time of ovulation, although 25-hydroxyvitamin D (25OHD) and 24,25-dihydroxyvitamin D (24,25(OH)2D) were almost unchanged. No correlation between the rise in the serum 1,25(OH)2D level and the measured parameters of calcium metabolism was observed.