Factors associated with moderate neonatal hyperthyrotropinemia

Abstract

Background Maternal iodine deficiency is related to high neonatal thyroid-stimulating hormone (TSH) values, with the threshold of 5 mIU/L recommended as an indicator of iodine nutrition status. The objective of this study was to analyse possible risk factors for increased TSH that could distort its validity as a marker of iodine status. The clinical relevance of this research question is that if the factors associated with iodine deficiency are known, iodine supplementation can be introduced in risk groups, both during pregnancy and in newborns. Methods A case-control study was carried out in a sample of 46,622 newborns in 2002–2015 in Spain. Of these, 45,326 had a neonatal TSH value ≥5 mIU/L. The main variable was having TSH ≥5 mIU/L and the secondary variables were: sex, gestational age, day of sample extraction and maternal origin. Associated factors were analysed through a logistic regression model, calculating the odds ratio (OR). Results The factors associated with this outcome were: male sex (OR = 1.34, 95% CI: 1.20–1.50, p<0.001), originating from an Asian/Oceanic country (OR = 0.80, 95% CI: 0.54–1.20, p = 0.536) or Europe (OR = 0.80, 95% CI: 0.66–0.96, p = 0.285) (including Spain, OR = 1) [p<0.001 for America (OR = 0.54, 95% CI: 0.44–0.68) and p = 0.025 for Africa (OR = 0.78, 95% CI: 0.62–0.97)] and fewer days from birth to sampling (OR = 0.80, 95% CI: 0.77–0.82, p<0.001). Conclusions The risk of high neonatal TSH without congenital hypothyroidism is higher in males, decreases with a greater number of days from birth to extraction, and is dependent on maternal ethnicity but not on gestational age.

Update on Neonatal Isolated Hyperthyrotropinemia: A Systematic Review

“…Gender is a known factor influencing neonatal TSH level. The percentage of neonatal HTT is higher among male newborns, in contrast with the higher number of female newborns with CH in general (6,16,39,40).…”

“…The disparity in the reported prevalence may also be in part to population genetics and ethnicity. The risk of high neonatal isolated TSH has been previously shown to be dependent on maternal ethnicity (6). A cohort study conducted in Skopje, the capital of Macedonia, also reported ethnic differences in the incidence of high serum TSH levels in neonates (46).…”

“…Probably, an underestimation of the prevalence of HTT may occur in countries where the thyroid NBS is practiced by measuring the total T4 level, which is expected to be within the normal range in HTT (8). Finally, there is some discussion about adapting the threshold according to the time of year (6). Seasonal aggregation has been described for recall rates in Iran, with recall occurring significantly more in winter than in other seasons (47,48).…”

“…During the first few hours of life, newborns experience a physiological increase in TSH levels in response to the environment, followed by a progressive decrease in its levels. The occurrence of high neonatal TSH (TSH ≥ 5 mU/L) decreases with the number of days from birth to sampling (6). It has been also demonstrated that the concentration of neonatal TSH decreases with age until it stabilizes at between 11 and 15 days of life (7).…”

Cord Blood TSH and Free T4 Correlation with Maternal and Neonatal Factors and Heel-Stick TSH For the Early Detection of Congenital Hypothyroidism: A Cross-sectional Study in Iran

“…Consistent with our result, Gupta et al (30) demonstrated that male neonates had slightly higher amount of CBTSH than their female counterparts. Cortés-Castell et al (31) have reported the risk of high neonatal TSH without congenital hypothyroidism is higher in males. Although paralleled results have been extracted by other studies (13,32), several reports emphasized on no signi cant association of mean cord blood TSH and sex (1,24,25,33).…”