Ketonuria in pregnancy--with special reference to calorie-restricted food intake in obese diabetics.

Early morning ketonuria, as judged by Ketostix testing, occurred in 19% of urine samples from insulin-independent diabetic pregnant women eating 1000 calorie diets, in 14% from diabetics on higher calorie diets, and in 7% of urines from nondiabetic pregnant women. Ketostix test was never found to be positive in blood, even when it was 2+ in urine samples, and acetoacetate levels were always below 1 mmol/L. Enzymatic estimations of acetoacetate (AA) and beta-hydroxybutyrate (BB) in urine and plasma samples revealed (1) no significant differences in range or mean between the groups receiving different restricted diets or full diets, the highest value observed for plasma AA being 0.34 mmol/L; (2) that Ketostix became positive at a concentration of AA above 1 mmol/L and that such a value in urine corresponded to plasma levels of between 0.06 and 0.1 mmol/L, i.e., double the normal; and (3) a 50-100-fold increase in urine AA when blood levels exceeded 0.08 mmol/L. Neonates born to diabetic mothers with ketonuria had no fetal distress or asphyxia neonatorum. The lowest Apgar score at 5 min was 8; 80% of neonates had a score of 10. Hence, positive Ketostix tests in urine samples do not indicate toxic levels in the blood, and a 1000 calorie diet for obese pregnant diabetics appears to be safe as regards neonatal outcome.