What are the key lab findings for tumor lysis syndrome (TLS)?

From the Guidelines

The key laboratory findings for tumor lysis syndrome (TLS) include hyperuricemia (elevated uric acid), hyperkalemia (elevated potassium), hyperphosphatemia (elevated phosphate), and hypocalcemia (decreased calcium). These abnormalities typically develop within 12-72 hours after initiation of cytotoxic therapy for malignancies with high cell turnover. Specifically, uric acid levels often exceed 8 mg/dL, potassium levels rise above 6 mEq/L, phosphate levels increase above 4.5 mg/dL, and calcium levels drop below 7 mg/dL. Additional findings may include elevated blood urea nitrogen (BUN) and creatinine, indicating acute kidney injury, and elevated lactate dehydrogenase (LDH), reflecting extensive cell death 1.

These laboratory abnormalities occur because rapid destruction of tumor cells releases intracellular contents into the bloodstream, overwhelming the body's excretory mechanisms. Phosphate released from dying cells binds to calcium, causing hypocalcemia and calcium phosphate precipitation in the kidneys. Potassium and nucleic acids (which metabolize to uric acid) are also released in large amounts, leading to their respective elevations. Monitoring these parameters is essential in high-risk patients, particularly those with hematologic malignancies or large tumor burdens undergoing cytotoxic therapy 1.

Some key points to consider in the management of TLS include:

• Identification of high-risk patients, including those with hematologic malignancies or large tumor burdens 1
• Implementation of prophylactic measures, such as hydration and uric acid-lowering therapy 1
• Vigilant monitoring of electrolyte levels and renal function in patients undergoing chemotherapy 1
• Initiation of more active treatment measures when necessary, such as rasburicase or hemodialysis 1.

Overall, prompt recognition and management of TLS are critical to preventing morbidity and mortality in patients with malignancies undergoing cytotoxic therapy.

From the Research

Key Lab Findings for Tumor Lysis Syndrome (TLS)

The key lab findings for TLS include:

• Hyperuricemia: elevated levels of uric acid in the blood 2, 3, 4, 5, 6
• Hyperkalemia: elevated levels of potassium in the blood 2, 3, 4, 5, 6
• Hyperphosphatemia: elevated levels of phosphate in the blood 2, 3, 4, 5, 6
• Hypocalcemia: low levels of calcium in the blood 2, 3, 4, 5, 6

Laboratory Abnormalities

These laboratory abnormalities can lead to clinical complications such as:

• Cardiac arrhythmias 4, 5, 6
• Acute renal failure 3, 4, 5
• Seizures 4, 5
• Death 4, 5

Diagnosis and Management

Diagnosis of TLS is based on the presence of two or more of the following laboratory abnormalities: hyperuricemia, hyperkalemia, hypocalcemia, and hyperphosphatemia, with resultant end-organ damage 4. Management includes aggressive hydration, antihyperuricemic therapy, and in severe cases, renal replacement therapy 2, 3, 4, 5. Rasburicase, a recombinant urate oxidase, is a effective treatment option for hyperuricemia in patients with TLS 2, 3, 4.