What primarily causes the electrolyte imbalances in tumor lysis syndrome?

The primary cause of electrolyte imbalances in tumor lysis syndrome is the rapid breakdown of tumor cells that release their intracellular contents into the bloodstream. This phenomenon typically occurs after the initiation of cancer treatment, such as chemotherapy, which can lead to the rapid destruction of a large number of cancer cells.

When tumor cells break down, they release potassium, phosphate, and nucleic acids. The influx of these substances into the bloodstream can lead to hyperkalemia (excess potassium), hyperphosphatemia (excess phosphate), and ultimately result in secondary hypocalcemia (low calcium levels) due to the binding of calcium with elevated phosphate levels. This cascade of events significantly disrupts normal electrolyte balance and can lead to serious complications such as arrhythmias or renal failure.

Dehydration, overhydration, and medication side effects may contribute to electrolyte imbalances in different contexts but are not the primary drivers of the specific imbalances observed in tumor lysis syndrome. Instead, it is the cellular breakdown and the subsequent release of electrolytes and metabolites that are the critical factors leading to this syndrome.