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SERUM LEVELS OF THYROTROPIN, THYROXINE, 3,3‘,5‐TRIIODOTHYRONINE AND 3,3’,5‘‐TRIIODOTHYRONINE (REVERSE T 3 ) IN THE FIRST SIX DAYS OF LIFE
Author(s) -
CAVALLO L.,
MARGIOTTA W.,
KERNKAMP C.,
PUGLIESE G.
Publication year - 1980
Publication title -
acta pædiatrica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 115
eISSN - 1651-2227
pISSN - 0803-5253
DOI - 10.1111/j.1651-2227.1980.tb07027.x
Subject(s) - triiodothyronine , medicine , reverse triiodothyronine , endocrinology , hormone , thyroid function , gestational age , thyroid , pregnancy , biology , genetics
. Cavallo, L., Margiotta, W., Kernkamp, C. and Pugliese, G. (Istituto di Puericultura, Università di Bari and CNR, Italy). Serum levels of thyrotropin, thyroxine, 3,3′,5‐triiodothyronine, and 3,3′,5′‐triiodothyronine (reverse T 3 ) in the first six days of life. Acta Paediatr Scand, 69:43, 1980.—Serum concentrations of thyrotropin (TSH), thyroxine (T 4 ), 3,3′,5‐triiodothyronine (T 3 ), and 3,3′,5′‐triiodothyronine (rT 3 ) were determined in blood samples from 140 full‐term healthy newborns, 110 appropriate weight and 30 large‐forgestational age, aged 1 to 6 days, delivered vaginally and breast‐fed. Serum TSH levels decreased progressively from the 1st to the 4th day; serum T 4 levels increased, with a peak on the 2nd day, and then progressively decreased until the 6th day; serum T 3 levels increased to a maximum value on the 2nd day and then decreased to a minimum on the 5th day; serum rT 3 levels increased during the 1st day and the level remained constant from the 2nd to the 4th day and later decreased slightly. The decrease of T 3 was more pronounced than that of T 4 , while rT 3 remained at high levels until the 4th day. Dividing the data into narrower intervals of time, it was possible to show that the maximum value of TSH was followed first by a net increase in serum T 3 , then in T 4 , and lastly in rT 3 ant T 3 levels. These data indicate that the rapid increase after birth of serum T 3 levels is prevalently TSH‐dependent; the following increase in serum levels of T 3 and the increase in rT 3 are prevalently T 4 ‐dependent. This study provides data concerning physiological changes in TSH and thyroid hormones in serum from a large number of infants, during the first week of life. They should be useful for the understanding of thyroid function in early postnatal life