β₂-microglobulin and hypertensive complications in pregnant women at risk

Background and aim: β₂-microglobulin (β₂-m) is a polypeptide, which is freely filtered through the glomerular basement membrane and absorbed almost entirely by the proximal tubular cells. Preeclampsia, a common complication of pregnancy, is characterized by pathological renal changes, mainly glomerular lesions. The aim of the present study was to investigate whether serum β₂-m measured in the early stages of pregnancy could be used as a marker to predict hypertensive complications in women at increased risk. Patients and methods: Serum β₂-m concentrations were prospectively measured in 75 pregnant women with history of chronic hypertension, chronic renal disease, chronic vascular disease or preeclampsia and compared with those in 16 healthy pregnant women. Results: Of the 75 women in the study group, 10 (13%) developed preeclampsia and 20 (26%) had other complications, such as intrauterine growth restriction (n = 8), fetal or neonatal loss(n = 9) and delivery before 30 weeks of gestation (n = 8). Gestational age at delivery, birth weight and cesarean section rate were significantly worse in the patients with complications than in those without and in the healthy controls. No significant difference was detected in early serum β₂-m concentrations between the women who later developed preeclampsia or other complications and those who did not. There was a significant positive correlation of β₂-m concentrations with serum creatinine level (R² = 0.394, p < 0.001), but not with gestational week at blood collection. Conclusion: Serum β₂-m concentrations are not predictive of the development of preeclampsia or other complications in woman at risk.