Serum water analysis in normal pregnancy and preeclampsia

Hemodilution and hemoconcentration affect hematology measurements and serum analyte concentrations but whether a given blood sample is hemodiluted or hemoconcentrated is frequently not known. Preeclampsia (PE) is a serious pregnancy complication and samples obtained from PE patients may be relatively hemoconcentrated when compared to those of normal pregnancy, where hemodilution is the norm. Laboratory test results may appear similar when values would differ if adjusted for hemodilution and hemoconcentration. We sought to determine if serum water (SW) content analysis can facilitate differentiation of the hemodilution of normal pregnancy from the hemoconcentration of PE, within the broader search of a clinical laboratory method to potentially correct for pregnancy-related, sample concentration variations. Serum samples from 59 non-pregnant, 64 normal pregnant, 23 mild PE, and 8 severe PE patients were tested for SW content. The mean results in g/100g were as follows: 91.15, 91.86, 92.00, and 92.46 respectively. SW data were also compared with corresponding total protein (TP), serum albumin (SA), and hematocrit (HCT) results. The t-test was significant (p= <0.001) for TP, SA, HCT, and SW in group-by-group comparisons. SA and SW were significantly, inversely correlated in the normal pregnant and severe PE groups, while TP and SW were significantly, inversely correlated in all groups. Correlation coefficients were stronger in the pregnancy groups than the non-pregnant group. This study demonstrates differences in the SW content between: non-pregnant, normal pregnant, mild PE, and severe PE patient sera.