[The low serum triiodothyronine syndrome in nonthyroid diseases. Distribution of plasma TSH concentrations]

T3 serum concentrations (RIA) was low in 25 cases and normal low in 10 among 57 patients with serious systemic illnesses. These 35 patients were in clinical euthyroid state and had a normal T4 serum concentration and F.T.I. T.S.H. serum concentration was normal in 28 cases of 31 low T3 syndrome observed.