Plasma oxytocin determinations in pregnancy with diabetes insipidus.

Diabetes insipidus is an extremely rare condition complicating pregnancy. The deficiency in antidiuretic hormone production has led to the assumption that oxytocin synthesis may also be affected. For this reason spontaneous onset of labor in a number of previously reported cases has been considered as evidence against implicating oxytocin as a relevant factor in the evolution and maintenance of labor. For the first time, plasma oxytocin levels were determined in a patient with known idiopathic diabetes insipidus during pregnancy, labor, and postpartum, using radioimmunoassay. Oxytocin was not detectable in plasma before labor. There was however a surge of plasma oxytocin detected during labor and puerperium, a pattern somewhat similar to that seen in normal pregnancy. Our findings suggest that at least some patients with diabetes insipidus do secrete oxytocin and that the role of oxytocin, threfore, cannot be discounted in the labor process.