**Core Concept**
Tumor lysis syndrome (TLS) is a life-threatening condition that occurs when large numbers of cancer cells die rapidly, releasing their contents into the bloodstream. This can lead to severe electrolyte imbalances, renal failure, and cardiac arrhythmias. The key underlying principle is the massive release of intracellular contents, including potassium, phosphate, and nucleic acids.

**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of TLS. When cancer cells die, they release their intracellular contents into the bloodstream, leading to hyperkalemia (elevated potassium levels), hyperphosphatemia (elevated phosphate levels), hypocalcemia (elevated calcium levels), and acute kidney injury (AKI). This is due to the massive breakdown of ATP, ADP, and nucleic acids, which are metabolized to uric acid, leading to hyperuricemia.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant to the pathophysiology of TLS. While hypernatremia can occur in various clinical conditions, it is not a characteristic feature of TLS.
* **Option B:** Hyperkalemia is a hallmark of TLS, and it occurs due to the release of intracellular potassium. This option is incorrect because it is a characteristic feature of TLS.
* **Option C:** Hyperphosphatemia is also a characteristic feature of TLS, occurring due to the release of intracellular phosphate. This option is incorrect because it is a feature of TLS.
* **Option D:** Hypocalcemia can occur in TLS due to the formation of calcium phosphate crystals in the tissues. This option is incorrect because it is a feature of TLS.

**Clinical Pearl / High-Yield Fact**
A classic exam trap is the association of TLS with certain types of cancer, such as acute lymphoblastic leukemia (ALL) and Burkitt lymphoma. When faced with a question about TLS, remember that it is more likely to occur in these types of cancers.

**Correct Answer: A.**