Endocrine Abstracts

Background: Kisspeptin is an RF amide peptide hormone critical for reproductive function. Kisspeptin is also abundantly expressed in the placenta, where it has an important physiological role in regulating placental invasion. Accordingly, plasma kisspeptin levels rise dramatically during normal pregnancy. Lower plasma levels of kisspeptin are associated with poor pregnancy outcomes such as recurrent miscarriage, intrauterine growth restriction and pre-eclampsia. Urinary measurement of kisspeptin may provide a novel and practical tool for screening patients for major obstetric complications. However, it is not currently known whether kisspeptin can be detected and quantified in the urine of pregnant women.

Aim: To determine the clinical utility of urinary kisspeptin measurement in healthy pregnant women.

Methods: 49 healthy third trimester pregnant women (gestational age 34±0.6 weeks) from a single maternity unit and 50 healthy non-pregnant women were recruited. Urine and blood were simultaneously collected from all volunteers in plain containers and lithium heparin tubes respectively, each containing 5000 kallikrein inhibitor units of aprotinin. Kisspeptin levels were determined by in-house manual RIA and urine creatinine by kinetic alkaline picrate method.

Results: Mean levels of plasma kisspeptin were over 200-fold greater in third trimester pregnant women compared with non-pregnant women (13 783±864 pmol/l, pregnant; 65±13 pmol/l, non-pregnant; P<0.0001). Mean levels of urine kisspeptin were greater in pregnant women when compared with non-pregnant women (301±59 pmol/l, pregnant; 80±19 pmol/l, non-pregnant; P<0.001). Urine kisspeptin levels were significantly correlated with plasma kisspeptin levels in pregnant women (r=0.35, P<0.01). The urine kisspeptin:creatinine ratio was also significantly greater in pregnant women compared with non-pregnant (37±6 pmol/μmol, pregnant; 7±1 pmol/μmol, non-pregnant; P<0.0001).

Conclusion: We demonstrate for the first time that kisspeptin levels are elevated in urine during pregnancy. Urine collection may therefore offer a non-invasive and simple method of screening for pregnancy and obstetric complications, which is particularly suited to the busy clinical setting of the obstetric clinic.