Differential diagnosis
Pre-eclampsia can mimic and be confused with many other diseases, including chronic hypertension, chronic renal disease, primary seizure disorders, gallbladder and pancreatic disease, immune or thrombotic thrombocytopenic purpura, antiphospholipid syndrome and hemolytic-uremic syndrome. It must be considered a possibility in any pregnant woman beyond 20 weeks of gestation. It is particularly difficult to diagnose when pre-existing conditions such as hypertension are present. Women with acute fatty liver of pregnancy may also present with elevated blood pressure and protein in the urine, but differ by the extent of liver damage. Other disorders that can cause high blood pressure include thyrotoxicosis, pheochromocytoma, and drug misuse. Prevention
Preventive measures against pre-eclampsia have been heavily studied. Because the pathogenesis of pre-eclampsia is not completely understood, prevention remains a complex issue. Some currently accepted recommendations are:

Diet
Supplementation with a balanced protein and energy diet does not appear to reduce the risk of pre-eclampsia. Further, there is no evidence that changing salt intake has an effect.Supplementation with antioxidants such as vitamin C, D and E has no effect on pre-eclampsia incidence; therefore, supplementation with vitamins C, E, and D is not recommended for reducing the risk of pre-eclampsia.Calcium supplementation of at least 1 gram per day is recommended during pregnancy as it prevents pre-eclampsia where dietary calcium intake is low, especially for those at high risk. Higher selenium level is associated with lower incidence of pre-eclampsia. Higher cadmium level is associated with higher incidence of pre-eclampsia.
Elevations in serum uric acid (hyperuricemia) is used by some to "define" pre-eclampsia, though it has been found to be a poor predictor of the disorder. Elevated levels in the blood (hyperuricemia) are likely due to reduced uric acid clearance secondary to impaired kidney function. Angiogenic proteins such as vascular endothelial growth factor (VEGF) and placental growth factor (PIGF) and anti-angiogenic proteins such as soluble fms-like tyrosine kinase-1 (sFlt-1) have shown promise for potential clinical use in diagnosing pre-eclampsia, though evidence is insufficient to recommend a clinical use for these markers.A recent study, ASPRE, known to be the largest multi-country prospective trial, has reported a significant performance in identifying pregnant women at high risk of pre-eclampsia yet during the first trimester of pregnancy. Utilizing a combination of maternal history, mean arterial blood pressure, intrauterine Doppler and PlGF measurement, the study has shown a capacity to identify more than 75% of the women that will develop pre-eclampsia, allowing early intervention to prevent development of later symptoms. This approach is now officially recommended by the International Federation of Gynecologists & Obstetricians (FIGO) 
Recent studies have shown that looking for podocytes (specialized cells of the kidney) in the urine has the potential to aid in the prediction of pre-eclampsia. Studies have demonstrated that finding podocytes in the urine may serve as an early marker of and diagnostic test for pre-eclampsia.