A patient with chronic kidney disease presents with bradycardia, flaccid paralysis, ileus, and a peaked T wave on ECG. Which lab abnormality is most likely?

A patient with chronic kidney disease presents with bradycardia, flaccid paralysis, ileus, and a peaked T wave on ECG. Which lab abnormality is most likely?

• A. Hypomagnesemia
• B. Hypercalcemia
• C. Hypokalemia
• D. Hyperkalemia

Answer: (D)

Hyperkalemia is the most likely lab abnormality. In chronic kidney disease, the kidneys’ ability to excrete potassium is diminished, so potassium accumulates in the blood. Elevated extracellular potassium disrupts cardiac conduction, first causing tall, peaked T waves on ECG and, as it worsens, slowing of conduction that can lead to bradycardia. It also impairs skeletal and smooth muscle function, producing weakness such as flaccid paralysis and ileus. Metabolic acidosis common in kidney failure further drives potassium out of cells, worsening hyperkalemia. The other options don’t fit the presentation as well. Hypokalemia typically causes flattened or inverted T waves with U waves and can lead to muscle cramps, not flaccid paralysis or peaked T waves. Hypercalcemia tends to shorten the QT interval and cause different neurologic/musculoskeletal symptoms. Hypomagnesemia can cause arrhythmias like torsades de pointes but doesn’t produce the classic peaked T waves and the constellation of findings seen here.

Hyperkalemia is the most likely lab abnormality. In chronic kidney disease, the kidneys’ ability to excrete potassium is diminished, so potassium accumulates in the blood. Elevated extracellular potassium disrupts cardiac conduction, first causing tall, peaked T waves on ECG and, as it worsens, slowing of conduction that can lead to bradycardia. It also impairs skeletal and smooth muscle function, producing weakness such as flaccid paralysis and ileus. Metabolic acidosis common in kidney failure further drives potassium out of cells, worsening hyperkalemia.

The other options don’t fit the presentation as well. Hypokalemia typically causes flattened or inverted T waves with U waves and can lead to muscle cramps, not flaccid paralysis or peaked T waves. Hypercalcemia tends to shorten the QT interval and cause different neurologic/musculoskeletal symptoms. Hypomagnesemia can cause arrhythmias like torsades de pointes but doesn’t produce the classic peaked T waves and the constellation of findings seen here.