Fine-tuning medical tests to better serve doctors in terms of diagnostic care was the subject of a study completed by researchers from the Department of Pediatrics at various hospitals and clinics associated with the University of Iowa. Researchers used the Iowa Neonatal Metabolic Screening Program to evaluate more than 220,000 newborns for six years.

The aim of the study was to find significant environmental factors that affected the outcome of metabolic screening. Among the environmental factors observed were gestational age, the season of birth, birth weight, the method of feeding and age when samples were collected.

Researchers found a connection between weight and gestational age at birth and differences in metabolic panel results, but these factors are well-known and clinically documented. One lesser-known factor was the season of birth. Infants born in winter months tended to test higher for thyroid-stimulating hormone (TSH) when the birth occurred during the winter months. About 0.9% of newborns born in winter months tested high for TSH compared to just 0.6% of newborns born during summer months.

Conclusion: Environmental factors should be taken into consideration when viewing results of newborn metabolic panels with special consideration on the season of birth. Additional research is needed into the correlation between season of birth and altered TSH levels.

Source: Ryckman KK, Berberich SL, Shchelochkov OA, Cook DE, Murray JC. Clinical and environmental influences on metabolic bio-markers collected for newborn screening. Clin Biochem. 2012 Sep 23. pii: S0009-9120(12)00543-7. doi: 10.1016/j.clinbiochem.2012.09.013.