Seasonal Variation of Neonatal Transient Hyperthyrotropinemia in Tehran Province, 1998–2005

Abstract

Seasonal aggregation and the monthly rate of neonatal transient hyperthyrotropinemia (THT) were assessed. From November 1998 to April 2005, neonates of gestational age ≥37 wks, birth weight 2500-4000 g, birth length 45-55 cm, and 1st min Apgar score >3, who had thyrotropin (TSH) ≥20 mU/L in their cord dried-blood specimen, but without congenital hypothyroidism, were enrolled in the study. The recall rate equals the rate of THT occurrence in this study. Of 47,945 neonates, 555 had THT (recall rate: 1.2%). The aggregated seasonal recall rate (recall for further assessment to rule out congenital hypothyroidism) was significantly higher in winter (January, February, and March) than the other seasons (p < .0001). Winter had higher recall rate in each year as compared to other seasons, but the overall rate of recalls decreased in 2001 and 2002. Excluding the first 6 months (due to erratic variations), the remaining 72 months revealed a relatively sinusoidal pattern in monthly recall rates; indeed, there was an initial 11-month high recall rates (1.7%), followed by a 33-month decrease (0.7%), a 19-month increase (1.9%), and a final 9-month decrease (0.8%). The recall rate of each of these time intervals was significantly different from that of the next time interval (p < .0001). The monthly recall rates were best fitted to cubic curve estimation and then autoregressive integrated moving average (ARIMA) (0, 1, 1) models. THT occurs significantly more in winter than in other seasons, and this suggests a possible role for time-varying factor(s) contributing to its seasonal preponderance.

Gender Differences in Risk Factors of Congenital Hypothyroidism: An Interaction Hypothesis Examination

“…Based on the univariate conditional logistic regression, our result are in agreement with Ordookhani et al (24) findings which showed that CH occurred significantly more in winter than other seasons. The incidence of CH was shown to vary seasonally in a number of studies in different parts of world including Iran (16, 17), Japan (25) and the West Midlands of England (26). Gu et al (25) found sex-specific seasonal patterns of CH incidence in Japan.…”

“…Many studies reported that CH was associated with individual and environmental factors, including gender (8), birth weight (9), race and ethnicity (10), mother’s age (8), gestational age (8, 11), consanguinity (12), parental education (13), type of labor (14), birth weight (15), twin (11), birth season (16, 17), and drug usage during pregnancy (1). All of these studies were limited to identify the CH risk factors to conduct new prevention strategies.…”

The incidence of congenital hypothyroidism and its determinants from 2012 to 2014 in Shadegan, Iran: a case-control study

“…According to research conducted in Isfahan, Tehran, and Shiraz, the average incidence of CH was determined to be one per 1,000 live births. The greatest incidence of CH has been reported to occur in the fall and winter [ 9 , 10 ]. In another study conducted in Isfahan, the maximum incidence of the disease was found to be in August [ 11 ].…”

The Medical Subject Headings® thesaurus remains inaccurate and incomplete for electronic indexing and retrieval of chronobiologic references

“…The MeSH descriptor ''seasons'' was associated with 17 (81%) Emens et al 2009;Lin HC et al 2009a;Riala et al 2009;Sasseville et al 2009;Staykov et al 2009;Takao et al 2009;Terrien et al 2009;Thorne et al 2009;Ahmad and Haldar 2010;Figueiro and Rea 2010;Huang et al 2010a;Mazzotta et al 2010;Melo et al 2010;Ordookhani et al 2010;Petrovski et al 2010) of the 21 articles actually dealing with seasonality, and it identified also the remaining four articles El Moussaouiti et al 2010;Huang et al 2010b;Parry et al 2010) when used as free text to search headings, abstracts and titles. Like in our previous study (Portaluppi 2007), however, the vast majority of articles retrieved in PubMed using ''seasons'' as a term to search the last 2 years of the entire MEDLINE database was found to be unrelated to chronobiology and dealing with entirely different concepts pertinent, for example, to environmental sciences, ecology, meteorology, hydrology and natural disasters.…”