What laboratory finding would confirm preeclampsia in a postpartum patient?

In the context of diagnosing preeclampsia, particularly in a postpartum patient, the presence of proteinuria is a crucial laboratory finding. Preeclampsia is characterized by hypertension and significant protein excretion in the urine, typically defined as 300 mg or more of protein in a 24-hour urine collection or a protein/creatinine ratio of 0.3 or higher.

Proteinuria indicates that the kidneys are not functioning normally, which is a common complication associated with preeclampsia. This renal impairment arises due to the effects of high blood pressure and the underlying pathophysiological changes induced by the condition, such as endothelial dysfunction.

While other symptoms like severe headache may suggest the presence of hypertension-related complications, they do not provide the same definitive evidence as proteinuria. Additionally, elevated serum glucose could indicate other metabolic conditions but is not a specific marker for preeclampsia. Low blood pressure is antithetical to the hypertensive nature of preeclampsia and therefore does not align with confirming the condition.

Thus, the confirmation of preeclampsia relies heavily on the identification of proteinuria in conjunction with elevated blood pressure readings.