PANCE (Physician Assistant National Certifying Exam) — All Questions

A 78-year-old woman has vomiting and poor intake for 3 days. Creatinine has risen from 0.9 to 1.8 mg/dL. BUN-to-creatinine ratio is 30 and fractional excretion of sodium is 0.4%. Which category of acute kidney injury is most likely?

• a.Prerenal✓
• b.Acute interstitial nephritis
• c.Intrinsic, from acute tubular necrosis
• d.Postrenal obstruction

A BUN-to-creatinine ratio above 20 and a fractional excretion of sodium below 1% show avid sodium retention by intact tubules, the pattern of prerenal azotemia from volume depletion. Acute tubular necrosis typically gives a FENa above 1% and a ratio below about 10 to 15. Obstruction is suggested by hydronephrosis or a large post-void residual, and interstitial nephritis often shows pyuria and white cell casts after a drug exposure.

A 44-year-old with chronic hyponatremia (sodium 112 mEq/L) receives aggressive IV saline, and her sodium rises to 128 mEq/L within 24 hours. Several days later she develops dysarthria, dysphagia and quadriparesis. Which complication is most likely?

• a.Osmotic demyelination syndrome✓
• b.Acute ischemic stroke
• c.Cerebral edema from overcorrection
• d.Hyperkalemic periodic paralysis

Overly rapid correction of chronic hyponatremia can cause osmotic demyelination syndrome, typically days later, with dysarthria, dysphagia and quadriparesis from pontine injury. Cerebral edema is the danger of acute hyponatremia or of lowering sodium too fast, not raising it. Hyperkalemic periodic paralysis and a stroke do not follow sodium correction in this pattern.

A confused man has the following labs: sodium 140 mEq/L, chloride 102 mEq/L, bicarbonate 10 mEq/L, pH 7.18. What is the anion gap, and which cause fits the result?

• a.28; methanol or ethylene glycol✓
• b.28; profuse watery diarrhea
• c.12; methanol or ethylene glycol
• d.12; profuse watery diarrhea

Anion gap = sodium - (chloride + bicarbonate) = 140 - (102 + 10) = 28 mEq/L, well above a normal gap of about 12. A high anion gap metabolic acidosis fits added unmeasured acids such as the toxic metabolites of methanol (formate) or ethylene glycol. Diarrhea causes a normal anion gap (hyperchloremic) acidosis through bicarbonate loss, and 12 is the wrong arithmetic.

A 6-year-old has periorbital and leg edema. Urinalysis shows 4+ protein without red cell casts; serum albumin is 1.9 g/dL and cholesterol is elevated. Which diagnosis best describes this picture?

• a.Nephritic syndrome
• b.Acute tubular necrosis
• c.Renal artery stenosis
• d.Nephrotic syndrome✓

Heavy proteinuria, hypoalbuminemia, edema and hyperlipidemia define nephrotic syndrome, which is common in children, most often from minimal change disease. Nephritic syndrome features hematuria with red cell casts, hypertension and a lower degree of proteinuria. Tubular necrosis causes AKI with muddy brown casts, and renal artery stenosis causes hypertension without nephrotic-range protein loss.

A 38-year-old man has hypertension, intermittent flank pain and hematuria. His father needed dialysis in his 50s. Ultrasound shows bilaterally enlarged kidneys with multiple cysts. Which extrarenal condition should be considered in his evaluation?

• a.Pheochromocytoma
• b.Intracranial (berry) aneurysm✓
• c.Medullary thyroid carcinoma
• d.Pulmonary fibrosis

Autosomal dominant polycystic kidney disease causes flank pain, hematuria, hypertension and enlarged cystic kidneys, and it is associated with intracranial aneurysms, particularly with a family history of aneurysm or hemorrhage. Pheochromocytoma and medullary thyroid carcinoma are features of multiple endocrine neoplasia type 2, and pulmonary fibrosis is not an ADPKD feature.

After a marathon in hot weather, a 25-year-old has severe muscle pain and dark brown urine. Urine dipstick is strongly positive for blood, but microscopy shows no red blood cells. Creatine kinase is 48,000 U/L. What is the mainstay of treatment?

• a.IV furosemide diuresis
• b.Early emergent hemodialysis
• c.Oral NSAIDs for pain
• d.Aggressive IV isotonic fluids✓

A dipstick positive for heme without red cells on microscopy and a markedly elevated creatine kinase indicate rhabdomyolysis with myoglobinuria, treated with aggressive IV fluids to prevent pigment-induced kidney injury while monitoring potassium. Loop diuretics can worsen volume depletion, NSAIDs add nephrotoxicity, and dialysis is reserved for refractory complications such as severe hyperkalemia or renal failure.