BETA(2)-MICROGLOBULIN IN HYPERTENSIVE PREGNANCIES

beta(2)-Microglobulin (beta(2)-m) is a polypeptide that is freely filt ered and then mostly reabsorbed and degraded in the proximal renal tub ule, beta(2)-m is a marker of glomerular filtration (GFR) in renal fai lure, 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 thrombocytopeni a) often has renal involvement characterized by proteinuria, decreasin g glomerular filtration, or renal tubular dysfunction. The aim of this study was to determine whether serum beta(2)-m concentration or urina ry beta(2)-m excretion were greater in women with PE than in women wit h 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 stu died 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 contro ls (1.62 +/- 0.54 mg/L; P = 0.001). FE of beta(2)-m was similar amongs t 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 filterin g of Pn-m in PE rather than altered tubular handling of beta(2)-m Furt her studies are now necessary to assess whether measurement of serum P n-m is helpful in the clinical management of the hypertensive disorder s of pregnancy, (C) 1998 by the National Kidney Foundation, Inc.