TUMOR LYSIS SYNDROME (TLS):
POTENTIALLY FATAL, tumor lysis syndrome (TLS) is a metabolic disturbance caused by breakdown of cancer cells with or sometimes without treatment and the release of their intracellular components into the bloodstream.
It's characterized by the rapid development of hyperkalemia, hyperphosphatemia, hypocalcemia, and hyperuricemia. Risk factors for TLS include a large tumor size, tumors with rapid cell division and growth, hematologic cancers such as acute leukemia or high-grade (aggressive) lymphoma, and tumors with a high sensitivity to chemotherapy.
Patients with high lactate dehydrogenase levels (greater than 1,000 U/L) and impaired renal function are also at risk, as are some patients with mediastinal tumors. Several chemotherapy agents, including cytarabine, cisplatin, etoposide, and paclitaxel, are associated with TLS.
Risk categories of having TLC:
• High-risk patients are those with Burkitt lymphoma, lymphoblastic lymphoma, or B-cell acute lymphoblastic leukemia.
• Patients at intermediate risk have diffuse large-cell lymphoma or another type of rapidly growing cancer.
• Low-risk patients have indolent (slow-growing) lymphoma or another slowly proliferating cancer.
Preventing and treating TLS:
To help prevent TLS, assess patients undergoing chemotherapy for risk factors at baseline and monitor them during and after the initiation of treatment as ordered. Mainstays of preventive care are hydration and the medications allopurinol and recombinant urate oxidase (rasburicase). Alkalinization of the urine, once a common treatment for TLS, is no longer routinely recommended.
I.V. hydration should begin as soon as possible, ideally 2 days before initiating chemotherapy, and continue during chemotherapy and for 2 to 3 days afterward. The optimal fluid volume administered parenterally is 3,000 mL/m2 each day. Electrolytes, such as potassium, aren't added to I.V. fluids to avoid the risk of worsening electrolyte abnormalities.
Allopurinol inhibits the conversion of hypoxanthine to xanthine and of xanthine to uric acid by inhibiting xanthine oxidase. Optimally, it's initiated 1 to 2 days before starting chemotherapy. Monitor patients for a skin rash or fever, which may indicate a hypersensitivity reaction.
Unlike allopurinol, rasburicase is a drug that treats hyperuricemia. Administered I.V., rasburicase converts uric acid to allantoin, which is much more soluble in urine than uric acid. The drug works quickly (in 4 hours) to reduce uric acid levels and also helps control serum potassium, phosphate, calcium, and creatinine levels. Most patients receive 2 days of therapy, but just one treatment is effective for some.
• Educate patients and their families about the prevention and management of TLS, including the signs and symptoms of hyperuricemia and serious adverse reactions or signs and symptoms they should notify the healthcare provider about at once.
• Complete a nursing admission assessment, including a risk factor assessment for TLS. Notify the healthcare provider of any abnormal lab results that may indicate TLS.
• Administer I.V. hydration as prescribed and monitor fluid balance by weighing the patient daily and documenting intake and output accurately. Urine output should be in balance with the intake.
• Assess urine output, including pH, color, odor, volume, and clarity, and test for the presence of red blood cells and hemoglobin.
• Insert an indwelling urinary catheter if prescribed, but avoid catheters in patients with low neutrophil or platelet counts due to the risk of infection and bleeding, and remove urinary catheters as soon as they're no longer needed to prevent catheter-associated urinary tract infections.
• Assess breath sounds (pulmonary crackles) and heart sounds (S3) for signs of fluid overload.
• Weigh the patient daily.
• Monitor BUN, serum uric acid and creatinine levels.
• Perform medication reconciliation and collaborate with the prescriber and pharmacist to stop or hold any medications that may adversely affect renal function or serum electrolyte and uric acid levels.
• Closely monitor electrolyte, phosphorus, and calcium levels, and monitor ECG results.