A 3 year old boy is recently diagnosed with Acute lymphoblastic leukemia/lymphoma. His peripheral blood film is shown below. A bone marrow biopsy is performed and reveals > 50 % lymphoblasts. Immunostaining reveals cells positive TdT. He is staed on chemotherapy. Few days later his condition deteriorated. The doctor on duty is suspecting that child may have developed tumor lysis syndrome. Which of the following electrolyte abnormality is not seen in the above condition?

**Core Concept**
Tumor lysis syndrome (TLS) is a life-threatening complication that occurs when a large number of cancer cells die rapidly, releasing their contents into the bloodstream. This can lead to a series of electrolyte and metabolic disturbances, including hyperkalemia, hyperphosphatemia, hypocalcemia, and hyperuricemia.

**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, including potassium, phosphate, and nucleic acids, into the bloodstream. This leads to hyperkalemia (elevated potassium levels), hyperphosphatemia (elevated phosphate levels), and hyperuricemia (elevated uric acid levels). Hypocalcemia (low calcium levels) is also a common finding due to the formation of calcium phosphate complexes in the kidneys.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because hyperkalemia is a characteristic feature of TLS, as cancer cells release potassium into the bloodstream when they die.

**Option B:** This option is incorrect because hyperphosphatemia is also a common finding in TLS, as cancer cells release phosphate into the bloodstream.

**Option C:** This option is incorrect because hyperuricemia is a common feature of TLS, as cancer cells release nucleic acids into the bloodstream, which are then broken down to uric acid.

**Option D:** This option is correct because hypokalemia (low potassium levels) is not typically seen in TLS. Instead, hyperkalemia is the expected finding due to the release of potassium from dying cancer cells.

**Clinical Pearl / High-Yield Fact**
In patients with TLS, it's essential to monitor electrolyte levels closely and provide supportive care, including hydration, electrolyte replacement, and allopurinol to prevent uric acid nephropathy.

**Correct Answer:** D.

✓ Correct Answer: C. Hypokalemia