Urinary kallikrein excretion in the human menstrual cycle, normal pregnancy and lactation

Objectives To evaluate the temporal pattern of active and total urinary kal likrein excretion during the menstrual cycle, pregnancy and lactation, and to associate changes in kallikrein excretion with those of ovarian and plac ental hormones. Study design Nine volunteer women with ovulatory menstrual cycles and ten w omen who underwent physiological gestations were followed prospectively. Ur ine was collected on days 10, 16, 21 and 26 of the cycle and every 14 days from 4 to 13 weeks, and in weeks 15-17, 21-25 and 33-36 of gestation. Urina ry active and total kallikrein were determined using DL-VAL-LEU-ARC pNA, es trogens and pregnanediol glucuronides by enzyme immunoassay, and total huma n chorionic gonadotropin (hCG) by an immunoradiometric assay. Results Urinary active and total kallikrein levels remained stable during t he ovulatory menstrual cycle; both forms increased in the first 15 weeks of pregnancy, and decreased in lactation below the values observed during the menstrual cycle. Conclusions The rise of urinary kallikrein in early gestation suggests that the kallikrein-kinin system may participate in the vasodilatatory changes necessary for the uterine and systemic adaptations of physiological gestati on. In early pregnancy, renal kallikrein production is possibly stimulated by a trophoblastic signal.