[Reciprocal changes in T3 nd rT3 serum concentrations in digestive diseases resulting in childhood protein-calorie malnutrition (author's transl)].

In 14 children affected by digestive diseases producing protein-calorie malnutrition T3 and rT3, T4, TSH serum levels and TBG and TBPA maximum binding capacity were measured at the moment of the hospitalisation and up to their clinical and biochemical amelioration. No changes in serum T4 and TSH levels and in TBGcap values were detected. TBPAcap was found to be persistently low. At the moment of the hospitalisation serum T3 and rT3 average values were found to be 65 +/- 25 ng/dl and 58 +/- 25 ng/dl respectively. Opposite changes in serum concentrations of the triiodothyronines were observed at the moment of the interruption of the study; T3 values were 200 +/- 64 ng/dl and rT3 value 25 +/- 16 ng/dl. T4 deiodination may be a homeostatic process and its preferential conversion to either activating (T3) or inactivating (rT3) pathways is related to the state of the organism.