Tumor lysis syndrome

Tumor lysis syndrome is a clinical condition that can occur spontaneously or after the initiation of chemotherapy associated with the following metabolic disorders: hyperkalemia, hyperphosphatemia, hypocalcemia, and hyperuricemia leading to end-organ damage. It is most common in patients with solid tumors. Tumor lysis syndrome usually develops after the initiation of chemotherapy treatment. However, there are more cases of spontaneous development of tumor lysis syndrome with high-grade hematology-oncology malignancies.

Hallmarks of this condition

• Potassium >6.0 meq/L or a 25% increase from baseline
• Phosphorous >4.5 mg/dL or a 25% increase from baseline
• Calcium <7 mg/dL or a 25% decrease from baseline
• Uric acid >8 mg/dL or a 25% increase from baseline

Clinical tumor lysis syndrome:

• Creatinine greater than 1.5 times normal
• Cardiac arrhythmia/sudden death
• Seizure

Most of the symptoms seen in patients with tumor lysis syndrome are related to the release of intracellular chemical substances that cause impairment in the functions of target organs. This can lead to acute kidney injury (AKI), fatal arrhythmia, and even death.

In patients at low risk for developing TLS, management includes hydration and close monitoring of volume status and renal function. The use of urine alkalinization to promote elimination of urate is not recommended because it can induce calcium phosphate deposition and therefore aggravate TLS.
In patients at intermediate risk with uric acid levels lower than 8 mg/dl, a xanthine oxidase inhibitor such as allopurinol also should be started 2 days before chemotherapy, whereas rasburicase should be used in patients with uric acid levels higher than 8 mg/dl. 

Rasburicase should not be used in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency. For high-risk patients, a single dose of rasburicase (up to 0.2 mg/kg, although a lower dose is usually prescribed) is recommended, followed by close monitoring of uric acid levels. If uric acid normalizes, allopurinol treatment can be started. If urine output decreases despite adequate fluid administration, a loop diuretic should be added, and RRT will be required if oliguria persists.