Tumour lysis syndrome is caused by the release of uric acid from cells that are being destroyed by chemotherapy. The uric acid can form crystals in the interstitial tissue and tubules of the kidneys and causes acute kidney injury.

Allopurinol or rasburicase are used to reduce the high uric acid levels. Other chemicals such as potassium and phosphate are also released so these need to be monitored and treated appropriately. High phosphate can lead to low calcium, which can have an adverse effect, so calcium is also monitored.

PC

A common presentation would be e.g. 2 days after receiving high dose chemotherapy for acute leukaemia or lymphoma. Patients may present with dysuria/oliguria, abdominal pain, or weakness.

Investigations

• ECG (metabolic abnormalities e.g. hyperkalaemia may precipitate life-threatening arrhythmias).
• U&E (potassium and phosphate are typically raised)
• uric acid (raised),
• calcium (low)

To diagnose tumour lysis syndrome you require both a positive laboratory TLS and positive clinical TLS.

Positive laboratory TLS requires 2 or more of the below within 7 days of chemotherapy or 3 days before:

• uric acid > 475umol/l or 25% increase
• potassium > 6 mmol/l or 25% increase
• phosphate > 1.125mmol/l or 25% increase
• calcium < 1.75mmol/l or 25% decrease

Positive clinical TLS requires any one of:

• increased serum creatinine (1.5 times upper limit of normal)