Accuracy of Urine Microalbumin and Serum Uric Acid in the diagnosis of Preeclampsia

Preeclampsia (PE), a multisystemic disorder of pregnancy characterized by proteinuria and hypertension after 20 weeks of gestation, is one of the leading causes of maternal morbidity and mortality worldwide. Its aetiology is not fully understood though several studies attribute it to a widespread endothelial dysfunction originating from the placenta. The increasing prevalence of PE coupled with the need to identify and institutionalize more sensitive diagnostic tools has necessitated this study. This study sought to evaluate the diagnostic accuracy of urine microalbumin and serum uric acid as early markers of preeclampsia among Ghanaian women attending antenatal care at the Komfo Anokye Teaching Hospital (KATH). This case-control study was conducted among pregnant women at the Obstetrics and Gynaecology (O&G) department of the KATH, Kumasi-Ghana from October 2011 to May 2012. A total of 146 participants were recruited for this study. Written informed consent was obtained from the participants, and information on socio-demographic characteristics, medical history and previous obstetric history were obtained through medical records of the eligible participants. Blood pressure and anthropometrics were measured according to standard procedure; urine samples were collected for estimation of spot urine protein and microalbuminuria; and venous blood sample was taken for biochemical analysis and platelet count. The percentage of married participants with preeclampsia was significantly lower than the controls (p=0.004). More control participants had formal education compared to the participants with preelampsia (p=0.008), however, more preelamptics had informal education compared to the controls (p=0.004). The prevalence of abortion and blood pressure were higher in the preelamptics than the controls. Serum uric acid and hepatic enzymes (ALT and AST)] and urine microalbumin (p=0.005) were significantly elevated in the preeclamptic participants compared to the controls. The mean platelets count and serum albumin levels were however lower in the preelamptics than the controls (p>0.001). A significant positive linear correlation was observed between spot urine protein and urine microalbumin (r=0.324, p=0.006). A negative linear correlation was observed between uric acid and spot urine micro albumin (r=0.033, p=0.786). A urinary micro albumin value of 75.45 mg/g was identified as the best threshold to 2 detect a spot urine protein of > +2 with a sensitivity of 92.7% and a specificity of 80.0%, PPV of 81.03% and NPV of 33.3%. Area under the curve = 0.835; asymptomatic p-value of 0.0001 at 95% CI (0.678-0.991). In contrast, serum uric acid level of 263.5 mg/g was identified as the best cut-off point to detect a spot urine protein of > +2 with sensitivity and specificity of 89.1% and 33.3% respectively (PPV of 77.2% and NPV) of 20.8%. Area under the curve = 0.552; asymptotic p-value of 0.538 at 95% CI (0.364-0.740). Urine levels of microalbumin, as a measure of proteinuria are elevated in preeclamptics and can be used in place of spot macro protein estimation to diagnose preeclampsia especially in the early stages.

Source: KNUST