β2-microglobulin in hypertensive pregnancies

beta(2)-Microglobulin (beta(2)-m) is a polypeptide that is freely filtered and then mostly reabsorbed and degraded in the proximal renal tubule, beta(2)-m is a marker of glomerular filtration (GFR) in renal failure, whereas urinary beta(2)-m is a marker of proximal renal tubular dysfunction. Preeclampsia (PE) tie, de novo hypertension in pregnancy with accompanying renal, cerebral, or liver disease or thrombocytopenia) often has renal involvement characterized by proteinuria, decreasing glomerular filtration, or renal tubular dysfunction. The aim of this study was to determine whether serum beta(2)-m concentration or urinary beta(2)-m excretion were greater in women with PE than in women with gestational hypertension (GH) tie, isolated de novo hypertension in the second half of pregnancy) and normal pregnant women, Seventy-five pregnant women (35 with RE, 22 with GH, and 18 normotensives) were studied prospectively. Serum creatinine and Pn-m concentrations, 24 hour proteinuria, and fractional excretion (FE) of beta(2)-m were measured, Preeclamptics had similar serum creatinine but higher serum beta(2)-m (3.26 +/- 0.99 mg/L) than gestational hypertensives (2.44 +/- 0.77 mg/L; P = 0.016), and both groups had higher serum beta(2)-m than controls (1.62 +/- 0.54 mg/L; P = 0.001). FE of beta(2)-m was similar amongst groups (PE: 0.27%; interquartile range [IQR]: 0.20-0.86; GH: 0.21%; IQR: 0.11-0.40; controls: 0.26%, IQR: 0.12-0.69), PE is characterized by higher serum beta(2)-m but similar serum creatinine to GH. Because FE beta(2)-m is similar in these groups, this implies reduced filtering of Pn-m in PE rather than altered tubular handling of beta(2)-m Further studies are now necessary to assess whether measurement of serum Pn-m is helpful in the clinical management of the hypertensive disorders of pregnancy, (C) 1998 by the National Kidney Foundation, Inc.