Protein turnover and 3-methylhistidine excretion in non-pregnant, pregnant and gestational diabetic women.

: Protein turnover was studied in nine non-pregnant (NP) and eight pregnant (P) women. The data from two gestational diabetic (GDM) women are included for comparison. Pregnant women were studied at 30-36 weeks gestation. Whole-body protein turnover, synthesis and catabolism rates were measured using a single dose of 15N-glycine followed by measurement of enrichment of urinary ammonia during the next 10 h. P and NP women had similar rates of protein turnover (4.8 g protein/kg/d) and synthesis (3.8 g protein/kg/d). GDM women appeared to have considerably higher rates for both turnover (5.6 g protein/kg/d) and synthesis (4.7 g protein/kg/d). Normal pregnant women excreted significantly more urinary 3-methylhistidine (3MH) than did non-pregnant women (190 vs 149 mumole/d). Correlation between 3MH excretion and protein catabolism rate approached significance (P = 0.087) in the NP women, but was poorly correlated (P = 0.355) in the P women.