Pavelka S, Kopecký P, Bendlová B, Stolba P, Vítková I, Vobruba V, Plavka R, Houstek J, Kopecký J
Institute of Physiology, Academy of Sciences of the Czech Republic, Prague.
Pediatr Res. 1997 Dec;42(6):812-8. doi: 10.1203/00006450-199712000-00016.
Thyroid status was characterized in very preterm infants (gestational age < or =32 wk; n = 61) from birth through d 14, and in infants who died within 16 d after delivery (n = 10), where it was also correlated with metabolism of iodothyronines in peripheral tissues (brain, liver, kidney, skeletal muscle, and adipose tissue). At 3 d of life, mean plasma levels of thyroxine, triiodothyronine, and TSH started to decrease, being lower in the critically ill compared with healthy premature neonates. Activities of the three iodothyronine deiodinases enzymes (type I, II, and III, respectively) were detected in all postmortem tissue samples, except for absence of the type II activity in kidney. All activities were the highest in liver and differed in other tissues. Lack of correlation between the type I activity in liver (and kidney), and plasma levels of thyroid hormones suggested that the thyroid was the primary source of circulating triiodothyronine. On the other hand, namely in brain, correlations between activity of the deiodinases and plasma hormone levels were found which suggested a complex control by thyroid hormones of their own metabolism. High activity of type III in liver, adipose tissue, and skeletal muscle demonstrated a role of these tissues in thyroid hormones degradation. Results support the view that peripheral tissues of very preterm infants are engaged in local generation of triiodothyronine, and inactivation of thyroid hormones, but do not represent a major source of circulating triiodothyronine.
对极早产儿（胎龄≤32周；n = 61）从出生至出生后第14天的甲状腺状态进行了评估，并对出生后16天内死亡的婴儿（n = 10）进行了评估，在这些死亡婴儿中还研究了甲状腺状态与外周组织（脑、肝、肾、骨骼肌和脂肪组织）中甲状腺素代谢的相关性。出生后第3天，甲状腺素、三碘甲状腺原氨酸和促甲状腺激素的平均血浆水平开始下降，危重症婴儿的这些水平低于健康早产儿。在所有尸检组织样本中均检测到三种碘甲状腺原氨酸脱碘酶（分别为I型、II型和III型）的活性，但肾脏中未检测到II型活性。所有活性在肝脏中最高，在其他组织中有所不同。肝脏（和肾脏）中I型活性与甲状腺激素血浆水平之间缺乏相关性，这表明甲状腺是循环三碘甲状腺原氨酸的主要来源。另一方面，即在脑中，发现脱碘酶活性与血浆激素水平之间存在相关性，这表明甲状腺激素对其自身代谢具有复杂的调控作用。肝脏、脂肪组织和骨骼肌中III型活性较高，表明这些组织在甲状腺激素降解中发挥作用。研究结果支持以下观点：极早产儿的外周组织参与三碘甲状腺原氨酸的局部生成和甲状腺激素的失活，但并非循环三碘甲状腺原氨酸的主要来源。
