Thyroid function in Legg-Calvé-Perthes disease: cross-sectional and longitudinal study.

Thyroid function was studied in 59 consecutive children with Legg-Calvé-Perthes disease (LCPD) and 239 controls. The subjects of both groups were generally euthyroid. In the Perthes group, however, plasma concentrations of free thyroxin (FT4) were increased by 16% (p < 10(-8)) and those of free triiodothyronine (FT3) were increased by 10% (p < 0.001) as compared with controls. There was a tendency toward higher FT4 levels in children with necrosis of more than one half of the femoral head (p < 0.015), as compared with those with lesser involvement. The observed moderate hormonal changes were already evident at the time of diagnosis of LCPD and were not appreciably influenced by stage of disease or mode of treatment, as determined by longitudinal evaluation of 38 children. Our data may support the assumption of other investigators that systemic abnormalities exist in children with LCPD, but the relation between these findings and the femoral head necrosis is not known.