Effect of prednisone on serum and urinary thyroid hormone levels in children during the nephrotic syndrome.

Thyroxine (T4), triiodothyronine (T3), free T4, and thyroxine binding globulin (TBG) were measured in serum and urine, thyrotropin (TSH) only in serum, in children with nephrotic syndrome (NS) of less than one month's duration, in children with the disease for more than one month and with steroid treatment, and in children in total or partial remission. There was a significant decrease in serum T4, T3 and TBG in nephrotic children compared to normal children. There was no change in free T4 but a slight increase of TSH levels. In urine, there was an excretion of TBG and a dramatic loss of T4. When prednisone was without effect on the NS, these parameters were very similar in serum and urine, indicating that prednisone did not modify thyroid function. During total or partial remission, thyroid hormone serum concentrations were lower than normal concentrations, but higher than during NS. During partial remission, TBG and T4 losses in the urine were lower than during DS. During total remission, the excretion was similar to normal excretion. The maximal capacity of TBG in serum was similar to controls; no alteration of this protein can explain the decrease of T4 in the serum.