Today in
morning report we discussed a case of newly diagnosed lymphoma and tumor lysis
syndrome. Here are a few key points based on our discussion this morning.
Tumor lysis syndrome is an emergency. There are a few oncologic
emergencies that every internist should be able to identify and manage. This is
one of them. The major concerns with tumor lysis syndrome (TLS) include the
complications associated with electrolyte abnormalities and renal failure. There
are two ways to describe tumor lysis syndrome: Laboratory TLS involves the
typical biochemical abnormalities in the right clinical context. Clinical TLS
is laboratory TLS plus one of (1) increased creatinine, (2) cardiac arrhythmia, or (3) seizure.
Think of the pathophysiology to remember the
biochemical abnormalities. Think about what is actually happening to the cells in tumor lysis
syndrome. The cells are rapidly being destroyed with the intracellular contents
being spilled into the systemic circulation. Since cells are full of potassium,
phosphate and nucleic acid; you get hyperkalemia, hyperphosphatemia and hyperuricemia.
Hypocalcemia also occurs because the calcium precipitates with phosphate. The
deposition of uric acid and calcium phosphate in the renal tubules causes AKI.
An ounce of prevention is worth a pound of cure. It is important to identify
patients at high risk of tumor lysis syndrome so that they can receive
appropriate prophylaxis in order to reduce the risk that they develop full
blown TLS. Patients at increased risk of
TLS include those with rapidly growing malignancy, hematologic malignancies and
those with high tumor burden. Tumor lysis syndrome can occur spontaneously
(like in our patient) but is commonly triggered by chemotherapy. Prophylaxis for TLS includes IV hydration and
uric acid lowering agents – allopurinol or rasburicase – depending on the risk.
Treatment of TLS involves close monitoring,
fluids and uric acid lowering agents. If your patient is diagnosed with TLS, the
first thing to do is place the patient on a cardiac monitor and check
electrolytes frequently. Acutely treat any dangerous electrolyte abnormalities
and start IV hydration to wash out the uric acid and calcium phosphate
crystals. Rasburicase is also used to reduce uric acid levels. Consider
dialysis if the symptoms/AKI are severe or if the electrolyte abnormalities are
persistent.
Check out this great review from the NEJM: The Tumor Lysis Syndrome. Scott C. Howard, M.D., Deborah P.
Jones, M.D., and Ching-Hon Pui, M.D.N Engl J Med 2011; 364:1844-1854. http://www.nejm.org/doi/full/10.1056/NEJMra0904569