Renal growth in maternal-fetal axis: clinical and laboratory studies.

A hormone (renotropin) is said to play an important role in compensatory renal growth. The role of renotropin in obligatory growth (normal developmental growth) is unknown. It was observed that contralateral renal size in children with unilateral multicystic kidney was found to be normal at birth but became hypertrophied later. The kidneys of twenty-one-day-old fetal rats were significantly smaller than sham controls in animals whose mothers had uninephrectomies at day 8 (26.5 +/- 1.1 mg. versus 18.5 +/- 1.1 mg.). The mothers' kidneys hypertrophied compared with sham controls (1,065 +/- 23 mg. versus 1,347 +/- 78 mg.). It was concluded that renotropin passes the placenta and modifies so-called obligatory renal growth.