A 28-year-old woman, gravida 1 para 0, at 12 weeks gestation comes to the office for follow-up. During the first trimester, the patient had mild nausea, which has now resolved, and the patient feels well. She has a history of epilepsy for which she is taking lamotrigine; her only other medication is a prenatal vitamin with folic acid. Vital signs and physical examination show no abnormalities. Fetal heart tones are normal. In addition to routine prenatal care, the patient's serum lamotrigine level is being closely monitored because the drug is eliminated primarily by the kidneys. Which of the following renal changes are expected in this patient during her pregnancy?

Question

Quizplus · Accepted Answer

11ec160b_3cf5_8f95_9249_051fe4558e95_MD0001_00 Pregnancy results in multiple maternal hemodynamic changes that affect renal physiology. Marked volume expansion occurs due to renin release from extrarenal sources (eg, ovaries, decidua) with upregulation of the renin-angiotensin-aldosterone system (RAAS). Despite the increased sodium and water retention and RAAS activity, pregnancy is marked by widespread vasodilation and increased arterial compliance, likely due to the release of relaxin and reduced sensitivity to angiotensin II and norepinephrine. Increased blood volume and cardiac output result in the following alterations in renal hemodynamics: These alterations result in increased creatinine clearance, leading to decreased serum creatinine levels, typically by an average reduction of approximately 0.4 mg/dL. Therefore, serum creatinine levels considered normal in nonpregnant patients (eg, 1.0 mg/dL) represent significant renal dysfunction in this population. Furthermore, a small rise in creatinine in a pregnant woman reflects a marked reduction in renal function. (Choices A, B, C, and E) These hemodynamic alterations would not occur in normal pregnancy and represent renal dysfunction in a pregnant patient. Educational objective: Pregnancy results in significant plasma expansion and widespread vasodilation, leading to increased renal plasma flow and glomerular filtration rates. Serum creatinine is reduced by approximately 0.4 mg/dL in this population; therefore, a rise in serum creatinine, even to levels that are normal in nonpregnant patients, represents significant renal dysfunction.

A 28-Year-Old Woman, Gravida 1 Para 0, at 12 Weeks