[Excretion of water, sodium, and potassium during the compensatory renal hypertrophy in hypothyroid rats].

Renal compensatory hypertrophy is studied in age matched euthyroid and radiothyroidectomized female rats. 7 days after uninephrectomy, the hypertrophy of the remaining kidney is equally small in both groups. But 60 days after this operation, the hypothyroid animals show only a 12% increase in the wet weight of the remaining kidney whereas the euthyroid controls increase this weight by 21%. The excretion of water, Na and K are determined in the urine excreted in 5 h after a small water load. The results are related to 1 gram of kidney wet weight. These outputs increase in all animals after uninephrectomy. They are significantly higher in the hypothyroid rats than in the euthyroid controls as well before than 60 days after uninephrectomy. The reduction in tubular Na reabsorption found in the hypothyroid rat may account for the impairment of compensatory renal hypertrophy in hypothyroidism.