USMLE Step 1 Nephritic vs Nephrotic Syndrome Practice Questions
Nephritic and nephrotic syndromes represent two distinct patterns of glomerular disease, each characterized by a unique constellation of clinical features, underlying pathophysiology, and typical etiologies. Understanding their differentiating characteristics is crucial for USMLE Step 1, as questions frequently test the ability to distinguish between them based on presenting symptoms, lab findings, and basic science mechanisms.
Patient Information Age: 7 years | Gender: M, self-identified | Site of Care: emergency department History Reason for Visit/Chief Concern: "My son's face is swollen, and his urine looks dark." History of Present Illness: • 1 week ago, patient had a sore throat, which resolved spontaneously. • Today, he developed periorbital edema and dark-colored urine. His mother also notes decreased urine output. Physical Examination Temp: 37.2°C | Pulse: 88/min | Resp: 18/min | BP: 140/90 mm Hg General: Mild facial puffiness. Cardiovascular: S1, S2, no murmurs. Lungs: Clear to auscultation bilaterally. Extremities: No peripheral edema. Diagnostic Studies Urinalysis: Protein 2+, Blood 3+, Red blood cell casts present. Serum Creatinine: 1.5 mg/dL (ref range: 0.2-0.7 mg/dL) C3 complement: Decreased Which of the following is the most likely underlying mechanism for this patient's condition?
A 3-year-old boy is brought to the pediatrician by his parents due to generalized swelling. His parents report that he has been unusually tired and has gained weight over the past few weeks. They also note that his urine appears frothy. He has no history of recent infections or significant past medical problems. Physical Examination Temp: 36.8°C | Pulse: 92/min | Resp: 20/min | BP: 90/60 mm Hg General: Pitting edema of the lower extremities, periorbital edema. Abdomen: Distended with shifting dullness. Diagnostic Studies Urinalysis: Protein 4+, no blood, no casts. Serum Albumin: 1.8 g/dL (ref range: 3.5-5.5 g/dL) Serum Cholesterol: 320 mg/dL (ref range: <200 mg/dL) Which of the following is the most likely primary defect leading to this patient's clinical presentation?
A 58-year-old man with a long-standing history of type 2 diabetes mellitus and hypertension presents with gradual onset of lower extremity edema, fatigue, and decreased appetite over several months. He reports no recent infections or changes in his medications. Physical Examination Temp: 37.0°C | Pulse: 70/min | Resp: 16/min | BP: 145/85 mm Hg General: Bilateral pitting edema of the ankles and shins. Diagnostic Studies Urinalysis: Protein 3+, Trace blood, no casts. 24-hour urine protein: 4.5 g (ref range: <150 mg/24h) Serum Albumin: 2.9 g/dL (ref range: 3.5-5.5 g/dL) Serum Creatinine: 1.8 mg/dL (ref range: 0.6-1.2 mg/dL) HbA1c: 8.2% (ref range: <5.7%) Given this patient's presentation, which of the following is the most likely finding on renal biopsy?
A 22-year-old woman presents to the clinic with recurrent episodes of gross hematuria, typically occurring 1-2 days after an upper respiratory tract infection. She reports no edema or other systemic symptoms. Her blood pressure is consistently within normal limits. Diagnostic Studies (during a hematuria episode) Urinalysis: Blood 3+, Protein 1+, no casts. Serum Creatinine: 0.8 mg/dL (ref range: 0.6-1.2 mg/dL) C3 complement: Normal Which of the following is the most likely diagnosis?
A 65-year-old man with a history of recurrent deep vein thromboses is found to have significant proteinuria during a routine check-up. He denies any edema, hematuria, or recent infections. Further workup reveals a 24-hour urine protein excretion of 6 g. Renal biopsy shows diffuse thickening of the glomerular capillary walls without significant cellular proliferation, and granular subepithelial deposits on electron microscopy. Which of the following is the most likely explanation for his increased risk of deep vein thromboses?
Nephritic vs Nephrotic Syndrome — frequently asked
What are the key differentiating features between nephritic and nephrotic syndromes for USMLE Step 1?
Nephritic syndrome is characterized by inflammation, leading to hematuria (especially red blood cell casts), hypertension, mild-to-moderate proteinuria, and often azotemia/oliguria. Nephrotic syndrome is characterized by massive proteinuria (>3.5 g/day), hypoalbuminemia, severe edema, hyperlipidemia, and lipiduria, typically without significant hematuria or inflammation.
How do complement levels help differentiate causes of glomerular disease?
Complement levels, particularly C3, are often decreased in immune-complex mediated nephritic syndromes like acute post-streptococcal glomerulonephritis (APSGN) and lupus nephritis, indicating complement consumption. In contrast, complement levels are typically normal in most nephrotic syndromes (e.g., minimal change disease, membranous nephropathy) and in IgA nephropathy.
What are the most common causes of nephrotic syndrome in children vs. adults?
In children, minimal change disease (MCD) is the most common cause of nephrotic syndrome. In adults, the most common causes are focal segmental glomerulosclerosis (FSGS), membranous nephropathy, and diabetic nephropathy.
Why are patients with nephrotic syndrome at increased risk for thrombosis?
Patients with nephrotic syndrome are hypercoagulable due to the urinary loss of anticoagulant proteins, especially Antithrombin III, through the damaged glomeruli. They also tend to have increased hepatic synthesis of procoagulant factors and increased platelet aggregation.
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