Neonatal hyperthyrotropinemia is associated with low birth weight: a twin study

Abstract

Objective: Contradictory reports ascribe neonatal hyperthyrotropinemia (HT) to prematurity or small weight for gestational age. We aimed to evaluate the association between neonatal HT and birth weight (BW), recovery rate of the disorder, and possible association with perinatal stress. Design: Based on a neonatal screening database, a retrospective twin study was designed where withinpair differences in thyroid function were evaluated while controlling for differences in gestational age and thyroid-affecting environmental confounders. Methods: Two thousand five hundred and ninety-five twin pairs that were screened both for TSH and thyroxine (T 4 ) over 3 years were included. TSH and T 4 levels were evaluated along with BW, birth order, gender, and 17-hydroxyprogesterone (17OHP) that was considered as a surrogate marker for stress. Results: Of all the twin pairs, 7.2% had neonatal HT. Among 156 pairs, HT was more prevalent in the smaller twins (64%; P!0.001), especially in the discordant pairs (76%; PZ0.001). Seventy-five percent of the twins demonstrated a recovery within the first few weeks of life. 17OHP levels were similarly distributed between twins with and without HT. In a cohort of 1534 twin pairs with normal thyroid function, mean TSH levels were significantly higher in the smaller than in the larger twin in the whole group (4.1G3.2 vs 3.8G2.9 mIU/l; P!0.001) and especially among discordant twins (4.7G3.4 vs 3.8G3.0 mIU/l; P!0.001). Conclusions: Elevated TSH levels are associated with low BW, both in infants with HT and in normal neonates. A rapid recovery rate is expected in most cases.

Guideline for the treatment of hypothyroidism in prematurity

“…Also, a normal level of free T4 is commonly reported within 1 to 2 weeks after birth. [ 19 20 ] On the other hand, premature neonates may face sick euthyroid syndrome after birth, which occurs under stress. In this setting, the body tries to decrease the basal-metabolic-rate and uses energy to combat the disease.…”

Incidence and Interrelated Factors in Patients With Congenital Hypothyroidism as Detected by Newborn Screening in Guangxi, China

“…In addition, an interaction between genes and the environment may also be related to the occurrence of TCH. 7 - 10 …”

“…In addition, an interaction between genes and the environment may also be related to the occurrence of TCH. [7][8][9][10] Up to now, there have been very few reports regarding the incidence and etiology of PCH and TCH in China. Guangxi Province, which is located in the southwest of China, is the largest minority nationality area for the Han and Zhuang nations.…”