A 68-year-old man has had worsening dyspnea and orthopnea for the past 3 years with increased production of frothy sputum. On examination, crackles are auscultated at lung bases. A chest radiograph shows bilateral interstitial infiltrates, distinct Kerley B lines, and a prominent left heart border. Laboratory studies show Na+, 135 mmol/L; K+, 3.8 mmol/L; Cl-, 99 mmol/L; CO2, 25 mmol/L; glucose, 76 mg/ dL; creatinine, 1.5 mg/dL; and urea nitrogen, 30 mg/dL. Fractional excretion of sodium is less than 1%. Plasma renin, aldosterone, and antidiuretic hormone levels all are increased. B-type natriuretic peptide (BNP) is 200 pg/mL (normal <100 pg/mL). Which of the following pathologic findings is this man most likely to have?
Correct Answer: Ischemic heart disease
Description: He has left-sided heart failure with pulmonary edema and congestion. His reduced cardiac output leads to diminished renal blood flow that stimulates the renin-angiotensin mechanism to retain salt and water to increase plasma volume. He has prerenal azotemia with a high BUN-to-creatinine ratio and low fractional excretion of sodium. The other options do not explain his pulmonary edema. An aldosterone- secreting adrenal adenoma (Conn syndrome) would increase aldosterone, but decrease the plasma renin. In chronic adrenal failure (Addison disease), there should be hyperkalemia and hypoglycemia accompanying hyponatremia. Chronic glomerulonephritis with chronic renal failure would be associated with a BUN-to-creatinine ratio around 10:1. Pulmonary fibrosis would lead to cor pulmonale and a prominent right heart border with features of right-sided congestive heart failure. The syndrome of inappropriate antidiuretic hormone (ADH) is a paraneoplastic syndrome that can occur with pulmonary small cell carcinomas, and secretion of antidiuretic hormone (SIADH) would increase ADH and cause more severe hyponatremia, but would not have a major effect on the renin-angiotensin mechanism, and sodium excretion would be higher.
Category:
Pathology
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