Which metabolite increases due to nucleic acid breakdown in TLS?

• A. Creatinine
• B. Uric acid
• C. Lactic acid
• D. Bilirubin

Answer: (B)

Rapid tumor cell lysis releases large amounts of nucleic acids, which are broken down into purines and then metabolized to uric acid. The surge in purine turnover produces more uric acid than the kidneys can handle, leading to hyperuricemia. Uric acid is not very soluble in urine and can crystallize in renal tubules, contributing to uric acid nephropathy, a hallmark concern in tumor lysis syndrome. The other metabolites listed aren’t direct products of nucleic acid breakdown in TLS—creatinine reflects kidney function (often affected secondarily), lactic acid comes from cellular anaerobic metabolism, and bilirubin results from heme breakdown.