Urinary Protein Excretion in Normal Mice

Levels of protein excretion were assessed in female and male mice for 12 consecutive months. In females, protein excretion was low and relatively uniform throughout the study. By contrast, in males, there was considerable variation in protein excretion and more protein was excreted at all times; proteinuria more than doubled by 3 and peaked by 5 months, returning to lower levels by 13 months. These studies (a) provide detailed data on levels and variations of protein excretion in mice considering sex and age, (b) establish values of protein excretion above which pathologic proteinuria would be expected to occur, and (c) are consonant with the notion that, in mice, physiologic proteinuria is, at least in part, gonadal hormone-related.