A 58-year-old man with a history of extensive alcohol use is admitted with the diagnosis of decompensated liver cirrhosis and ascites. The laboratory panel is shown below on the day of admission and 3 days later. Which of the following best explains the acid-base status change in this patient?

Question

A 58-year-old man with a history of extensive alcohol use is admitted with the diagnosis of decompensated liver cirrhosis and ascites.  The laboratory panel is shown below on the day of admission and 3 days later.  Which of the following best explains the acid-base status change in this patient?

Quizplus · Accepted Answer

On admission, this patient's acid-base status was borderline acidemic; now he is mildly alkalemic. The most likely intervention to have resulted in this change is administration of a loop diuretic. Volume overload and ascites are common complications in patients with decompensated liver cirrhosis, and loop diuretics such as furosemide are a common treatment, often in combination with spironolactone. Loop diuretics function by inhibiting the Na-K-2Cl carrier in the loop of Henle, which results in increased loss of sodium in the urine. The increased sodium delivery to the distal tubule subsequently results in elevated hydrogen and potassium ion secretion in the urine. Loop diuretics also result in volume contraction and increased aldosterone levels, further promoting the secretion of hydrogen ions in the urine. This patient's elevation in blood urea nitrogen and creatinine is likely secondary to reduction in circulating blood volume and subsequent mild acute kidney injury. This patient's mild hyponatremia on admission is due to volume overload (dilutional), which has improved with diuresis (excess water diuresis compared to sodium loss). (Choice A) This patient has likely developed mild acute kidney injury as evidenced by his mild increase in blood urea nitrogen and creatinine. However, acute kidney injury tends to cause an anion gap metabolic acidosis and hyperkalemia. (Choice B) Bowel ischemia results in an anion gap acidosis from increased circulating lactate; this patient has a metabolic alkalosis. (Choice D) Opioid medication may result in hypoventilation and subsequent respiratory acidosis. Although this can result in a compensatory increase in bicarbonate level, this patient's pH of 7.47 is more consistent with a primary metabolic alkalosis. (Choice E) Atelectasis is not a common cause of acid-base disturbances. Educational objective: Loop diuretics are frequently administered to cirrhotic patients with volume overload and ascites. Potential side effects include hypokalemia, metabolic alkalosis, and prerenal kidney injury. References: Metabolic alkalosis. (http://www.ncbi.nlm.nih.gov/pubmed/9294840)

A 58-Year-Old Man with a History of Extensive Alcohol Use