What electrolyte disturbances characterize tumor lysis syndrome?

• A. Hyperkalemia, hyperphosphatemia, hyperuricemia, and hypocalcemia.
• B. Hypokalemia, hypophosphatemia, hypouricemia, and hypercalcemia.
• C. Hyperkalemia, hypophosphatemia, hyperuricemia, and hypocalcemia.
• D. Hyperkalemia, hyperphosphatemia, hypouricemia, and hypocalcemia.

Answer: (A)

Tumor lysis syndrome happens when a large amount of tumor cells are destroyed quickly, releasing their intracellular contents into the blood. This leads to high potassium (hyperkalemia), high phosphate (hyperphosphatemia), and high uric acid (hyperuricemia) from the breakdown of nucleic acids. The excess phosphate binds calcium, causing low calcium levels (hypocalcemia). This combination—even before any kidney damage—drives the serious problems seen in TLS, like kidney injury and potential cardiac or neurological complications. Patterns with low potassium, low phosphate, low uric acid, or high calcium don’t match what TLS causes, so they aren’t the characteristic disturbances.