[Changes in thyroxine conversion (low T3 syndrome) in children at the time of their first manifestation of type I diabetes].

Measurements of T4, T3, rT3, and TSH were done in 27 children with newly diagnosed type I diabetes mellitus prior to institution of treatment. Serum T4 concentrations were low in 18%, serum T3 concentrations were low in 37%. Serum rT3 concentrations were elevated in 59%; the ratio rT3/T3 was elevated in 78%. The ratio rT3/T3 was significantly higher in the group of patients with the low pH, the low bicarbonate levels, the high blood glucose, and the high serum osmolality values than in the group of patients with the high pH, the high bicarbonate levels, the low blood glucose, and the low serum osmolality values.