CHANGES IN URINARY TISSUE KALLIKREIN EXCRETION IN BLACK-AFRICAN WOMENWITH HYPERTENSIVE DISORDERS OF PREGNANCY

The aim of this study was firstly to establish whether tissue kallikre in (TK) was involved in the aetiology of hypertensive disorders of pre gnancy. Secondly, to assess whether tissue kallikrein:creatinine ratio s may differentiate normotensive pregnant women from those with hypert ensive disorders of pregnancy and have a predictive value. Random unti med urine samples were collected from all women (n = 264) recruited to this study. Urine specimens were analyzed for urinary tissue kallikre in using a selective, synthetic chromogenic tripeptide substrate (H-D- Val-Leu-Arg-pNA). Urinary creatinine levels were measured using standa rd methods. There was a significant difference in the excretion of uri nary tissue kallikrein between normotensive pregnant women (2.91 ng TK /mu g protein) and women with mild (2.52 ng TK/mu g protein; p < 0.000 1) and severe (1.53 ng TK/mu g protein; p < 0.0001) hypertension in pr egnancy. No statistical difference was observed with regard to urinary tissue kallikrein excretion between normotensive pregnant and normote nsive non-pregnant women (2.87 ng TK/mu g protein; p = 0.16). A positi ve correlation was observed between the diastolic blood pressure and u rinary tissue kallikrein excretion in women with hypertensive disorder s of pregnancy. When compared to the normotensive pregnant group, the urinary kallikrein: creatinine ratios were significantly lower in the mild (0.6 versus 0.3; p < 0.0001) and severe (0.6 versus 0.12; p < 0.0 001) hypertensive groups. The urinary creatinine excretion was signifi cantly higher in the mild (9.55 +/- 2.6 mmol/l; p < 0.0001) and in sev ere (15.62 +/- 5.48 mmol/l; p < 0.0001) hypertensives when compared to normotensive pregnant values (5.65 +/- 2.6 mmol/l). The reduced urina ry tissue kallikrein excretion in hypertensive disorders of pregnancy may be a significant factor in the development of the hypertension in pregnancy. Measurement of urinary tissue kallikrein: creatinine ratios may represent a simple and practical predictive test to differentiate women with hypertensive disorders of pregnancy from normotensive preg nant women.