Thyroid function in children with nephrotic syndrome.

The thyroid function of seven children with untreated nephrotic syndrome who had a normal serum creatinine concentration was compared with that of the same patients in remission and age-matched controls. There was a significant decrease in serum thyroxine (T4), tri-iodothyronine (T3) and thyroid-binding globulin (TBG) concentrations in untreated nephrotic children compared with the same patients in remission and age-matched controls. Most values for serum free T4, free T3 and thyroid-stimulating hormone (TSH) in the patients with nephrosis were within the normal range. However, the mean serum free T4 and free T3 concentrations were significantly (P < 0.05) lower in the untreated patients than in the same patients in remission, and the mean serum TSH concentrations were significantly (P < 0.05) higher in the untreated patients than in the same patients in remission. There were massive urinary losses of T4, T3, TBG, free T4 and free T3 in the untreated nephrotic children compared with the same patients in remission and age-matched controls. The daily urinary protein excretion showed a positive correlation with the urinary T4, T3, free T4, free T3 and TBG excretion. Furthermore, the urinary protein excretion showed a negative correlation with the serum T4, T3, free T4, free T3 and TBG levels. There was a negative correlation between serum albumin and serum TSH. These findings provide evidence of mild hypothyroidism in children with untreated nephrotic syndrome, partly because of losses of T4, T3, free T4, free T3 and TBG into the urine.