Does climate change influence blood TSH concentrations in healthy newborns?

Emerging concern exists about possible health effects of climate change. Summer 2003 is known as the hottest in the last 400 years in Northern Europe. Although a possible effect of high air temperature on TSH levels has been previously reported in experimental models, to date no information exists on this phenomenon in human newborns. We tested the hypothesis that neonatal blood TSH concentrations on day 3 are inversely related with the air temperature, as assessed on a congenital hypothyroidism (CH) mass screening program. Our findings indicate relationship between high environmental temperature and early low neonatal TSH concentrations. The observation reveals a previously unrecognized, possible direct effect of climate change on human health, whose possible long-term consequences need to be investigated.