Neonatal level of thyroid-stimulating hormone and acute childhood leukemia

One of the move consistent findings in leukemia research is the association between birth weight and childhood leukemia. Because thyroid hormones are critically involved in growth and differentiation, we speculated that hormo ne levels could be of significance to the development of leukemia in early life. Specifically, we hypothesized that high levels of thyroid-stimulating hormone (TSH) would be associated with a low risk of leukemia. Accordingly , high TSH (low free thyroid hormone) early after birth most likely reflect s low function of the thyroid accompanied by low rate of cell turnover and so lower risk of faulty cell divisions leading to cancer. In a matched case -control study nested from all singleton children born in Denmark between 1 986 and 1998, we compared levels of TSH las measured in a neonatal screenin g program for congenital hypothyroidism) in 188 cases of acute lymphoblasti c leukemia (ALL) and 28 of acute myeloid leukemia (AML) with levels in 1,45 0 and 216 matched controls, respectively, Data were analyzed using conditio nal logistic regression and odds ratios (OR) were adjusted for birth weight , As hypothesized, we found a decreased risk of ALL and AML associated with high TSH (ORALL = 0.7 [0.5-1.0]; ORAML = 0.3 [0.1-1.0]), However, both con ditions were also associated with low levels of TSH (ORALL = 0.4 [0.2-0.7]; ORAML = 0.3 [0.1-1.4]). In conclusion, extreme TSH levels a few days after birth appears to be associated with a decreased risk of acute childhood le ukemia. Int. J. Cancer 88: 486-488, 2000. (C) 2000 Wiley-Liss. Inc.