Final answer:
Elevated serum creatinine levels should be reported to the provider by a nurse reviewing a preeclampsia patient's medical record, as it indicates possible renal impairment.
Step-by-step explanation:
A nurse reviewing the medical record of a postpartum client with preeclampsia should report elevated serum creatinine levels to the provider. Normally, plasma creatinine levels should be within the range of 0.6-1.2 mg/dl, depending on gender. Elevated levels can indicate impaired renal function, which is a concern in patients with preeclampsia. While a blood pressure of 140/90 mm Hg is high and indicates hypertension, it is a characteristic finding in preeclampsia and would have already been identified as part of the condition. Hemoglobin levels within the expected range and a platelet count of 150,000/mm³ are not typically of concern unless showing significant deviations from the expected values.