Tumour Lysis Syndrome

Question 1

What is Tumour Lysis Syndrome?

Answer 1

• Tumor lysis syndrome (TLS) is the result of a series of events leading to the rapid death of a high number of malignant cells.
• Lysis of these cells leads to the release of intracellular ions and metabolic byproducts into the bloodstream, resulting in hyperuricemia, hyperkalemia, hyperphosphatemia, and hypocalcemia.
• All these disturbances may cause serious complications such as AKI, cardiac arrhythmias, seizures, and even death.

Question 2

Which patients are at risk for TLS?

Answer 2

• High-grade hematological malignancies, such as acute leukemia and Burkitt’s lymphoma
• Large and rapidly growing solid organ tumors, especially after starting chemotherapy
• It may occur either spontaneously, or after antineoplastic therapy such as conventional chemotherapy, corticosteroids, molecular-targeted therapy, immunotherapy, and even after radiotherapy and chemoembolization

Question 3

Why does TLS cause AKI?

Answer 3

• Hyperuricemia - Lysis leads to release of nucleic acids, whichis broken down to uric acid. Due to abnormal high levels, uric acid may precipitate into the renal tubules, especially in association with an acidic urine, contributing to renal dysfunction. It can also led to vasoconstriction and release of inflammatory mediators
• Hyperphosphatemia - Malignant cells have a four times higher level of phosphate than normal cells. High levels of serum phosphate can lead to precipitation of calcium phosphate in the renal tissue (nephrocalcinosis), especially in patients with an alkaline urine. Calcium phosphate can also precipitate in the conduction system of the heart, leading to conduction abnormalities and sometimes fatal arrhythmias

Question 4

How would you manage a patient with TLS?

Answer 4

• Prophylaxis with electrolyte monitoring
• Volume expansion
• Treat hyperkalaemia
• Treat hyperphosphataemia - volume expansion, CVVH
• Allopurinol - decreases the production of uric acid from xanthine, but it has no effect on the uric acid that has been already synthetized
• Rasburicase converts uric acid in allantoin, carbon dioxide and hydrogen peroxide
• Consider Dialysis