A 32-year-old woman at 14 weeks gestation comes to the office for an initial prenatal care visit. She has had no headaches, chest pain, abdominal pain, or lower extremity swelling. Medical history is significant for type 1 diabetes mellitus managed with multiple daily insulin injections. Blood pressure is 154/94 mm Hg and pulse is 86/min. Fetal heart tones are 152/min on Doppler ultrasonography. Laboratory results are as follows: Urinalysis reveals 2+ protein but no red or white blood cells. Which of the following is the most likely direct cause of this patient's proteinuria?

Question

A 32-year-old woman at 14 weeks gestation comes to the office for an initial prenatal care visit.  She has had no headaches, chest pain, abdominal pain, or lower extremity swelling.  Medical history is significant for type 1 diabetes mellitus managed with multiple daily insulin injections.  Blood pressure is 154/94 mm Hg and pulse is 86/min.  Fetal heart tones are 152/min on Doppler ultrasonography.  Laboratory results are as follows:  Urinalysis reveals 2+ protein but no red or white blood cells.  Which of the following is the most likely direct cause of this patient's proteinuria?

Quizplus · Accepted Answer

This patient with type 1 diabetes mellitus has proteinuria and an elevated creatinine level at 14 weeks gestation; this presentation suggests diabetic nephropathy. The development of significant proteinuria (>300 mg/day; 1+ protein) prior to 20 weeks gestation suggests underlying renal disease that was likely present preconception. In diabetic nephropathy, chronic hyperglycemia causes dilation of renal afferent arterioles and constriction of efferent arterioles, resulting in glomerular hyperfiltration. Structural and functional changes in the glomerular basement membrane (GBM) and podocytes lead to loss of albumin in the urine (microalbuminuria). During normal pregnancy, renal perfusion and glomerular filtration rates increase by as much as 50%, and the GBM becomes more permeable to proteins. Therefore, patients with diabetic nephropathy are at risk for acceleration of their renal disease during pregnancy (worsening albuminuria, elevated creatinine) due to the combined effects on the kidney. This risk is particularly high in those with an elevated creatinine at baseline. Hypertension is a common complication of diabetic nephropathy due to excess sodium retention and activation of the renin-angiotensin-aldosterone system. (Choice B) Gestational hypertension causes new-onset hypertension but does not cause proteinuria and occurs exclusively at ≥20 weeks gestation. (Choice C) Normal pregnancy can cause trace proteinuria, but creatinine is expected to decline, not increase. In addition, blood pressure typically declines in early pregnancy; the presence of hypertension indicates underlying pathology. (Choice D) Preeclampsia causes new-onset hypertension and proteinuria but also occurs exclusively at ≥20 weeks gestation. It may also be accompanied by evidence of end-organ dysfunction (eg, elevated transaminases, thrombocytopenia). (Choice E) Renal artery stenosis due to fibromuscular dysplasia is a rare cause of hypertension in women of childbearing age but typically does not result in acute kidney injury unless ACE inhibitors or diuretics are administered; marked proteinuria is uncommon. Educational objective: Pregnancy can cause worsening of diabetic nephropathy, leading to hypertension, elevated creatinine, and frank proteinuria. Preeclampsia also causes hypertension and proteinuria but occurs later in pregnancy; findings prior to 20 weeks gestation are usually due to preexisting nephropathy.

A 32-Year-Old Woman at 14 Weeks Gestation Comes to the Office