QuestionSBA
QuestionChoice
This would likely be raised in the setting of AKI.
10017210
e
Normal serum creatinine
QuestionChoice
Phosphate would be raised in tumour lysis syndrome, due to increased cell breakdown.
10017208
c
Decreased serum phosphate
QuestionChoice
Potassium would be raised in tumour lysis syndrome, due to the increased cell breakdown.
10017207
b
Decreased serum potassium
QuestionChoice
Calcium is normally low in tumour lysis syndrome as phosphate binds to calcium. Hypocalcaemia may be contributing to this patient's paraesthesia.
10017209
d
Increased serum calcium
QuestionChoice
The diagnosis is tumour lysis syndrome, which classically occurs 2-3 days after chemotherapy for high grade haematological malignancies. The increased uric acid is due to increased due to increased cancer cell breakdown, which would also increase potassium and phosphate. The oliguria described is due to AKI.
10017206
a
Raised serum uric acid
Concept
Chapter
# Summary


Tumour lysis syndrome is a potentially lethal condition caused by the rapid death of tumour cells often following chemotherapy or rapid progression of haematological malignancies, resulting in the massive release of intracellular contents. It is an oncological emergency. Patients commonly present with acute-onset dysuria/oliguria, abdominal pain, or weakness. Key investigations include measurements of U&E (showing raised potassium and phosphate), calcium (typically low), uric acid (raised), and ECG to detect metabolic abnormalities and life-threatening arrhythmias. Initial management involves the correction of electrolyte abnormalities and intravenous fluid administration.


# Definition


Tumour lysis syndrome is a serious metabolic disorder caused by the rapid death of tumour cells in response to chemotherapy. This results in a massive release of intracellular contents into the bloodstream, leading to significant electrolyte imbalances.


Tumour lysis syndrome is most commonly associated with aggressive, rapidly proliferating tumours such as acute leukaemia and high-grade lymphomas, particularly after the initiation of cytotoxic therapy. 


# Aetiology


The syndrome occurs due to the rapid release of intracellular contents from dying tumour cells, often following chemotherapy. It can however also be caused by high-grade lymphomas and acute leukaemias. This leads to hyperuricaemia, hyperphosphatemia, hyperkalaemia, and hypocalcaemia. These metabolic abnormalities lead to the clinical manifestations including acute kidney injury and arrhythmias.


# Signs and symptoms


Patients may present with symptoms related to electrolyte abnormalities and hyperuricaemia, which include:


* Dysuria or oliguria
* Abdominal pain
* Weakness
* Nausea or vomiting
* Muscle cramps
* Seizures
* Cardiac arrhythmias
* Gout/joint swelling


# Differential diagnosis


Differential diagnosis should consider other causes of similar symptoms and laboratory abnormalities, such as:


* **Acute kidney injury**: while tumour lysis syndrome can cause AKI, other causes should be considered. For example, patients may have significant dehydration or have received nephrotoxic drugs contributing to AKI. Careful history-taking and the absence of other features of tumour lysis syndrome should raise suspicion of AKI due to other causes. It is important to note though, that AKI can cause significant electrolyte abnormalities, so careful monitoring is required.
* **Isolated hyperkalaemia**: presents with muscle weakness, fatigue, palpitations, and potentially life-threatening cardiac arrhythmias. Patients may have a history of renal failure or taking potassium-sparing medications. Uric acid, phosphate and calcium levels would be normal.
* **Isolated hyperphosphateamia**: presents with muscle cramps, itching, and perioral tingling or numbness. Uric acid and potassium would be normal.
* **Isolated hypocalcaemia**: presents with numbness and tingling in the hands, feet, and around the mouth, muscle cramps, and seizures. Uric acid, potassium and phosphate would be normal


# Investigations


Key investigations for tumour lysis syndrome include:

* Basic observations
* U&E: Potassium and phosphate are usually raised, raised Cr suggestive of AKI/renal failure.
* Calcium: Typically low in tumour lysis syndrome.
* Uric acid: Usually elevated.
* ECG: To assess risk of arrhythmias caused by electrolyte abnormalities.
* Hyperkalaemia may cause tented T waves, broad QRS, flattened P-wave and a prolonged PR interval. 
* Hypocalcaemia may cause a prolonged QT interval.


# Management


Management of tumour lysis syndrome primarily focuses on:


* Correction of electrolyte imbalances & mitigation of arrhythmia risk.
* For example in severe hyperkalaemia, calcium gluconate is given followed by an insulin-dextrose infusion or nebulised salbutamol. Further management may include calcium resonium to prevent further potassium absorption from the gut.
* Severe hypocalcaemia may require parenteral replacement.
* Dialysis may be required in severe cases.
* Administration of intravenous fluids to help flush out the intracellular contents released by the dying tumour cells.
* Medications: rasburicase (a recombinant form of the urate oxidase enzyme) transforms uric acid into allantoin. Allantoin is more soluble in urine than uric acid, and more easily eliminated by the kidney.


### Prevention 


* Low/intermediate risk patients can be managed with a combination of adequate hydration and allopurinol. 
* Rasburicase (a recombinant form of the urate oxidase enzyme) can be used as a prophylactic agent in adults with hyperuricaemia that is inadequately managed by allopurinol or febuxostat.


# References

[British Society for Haemotology: Management of Tumour Lysis Syndrome in Adults and Children with Haematological Malignancies](https://b-s-h.org.uk/guidelines/guidelines/management-of-tumour-lysis-syndrome-in-adults-and-children-with-haematological-malignancies)

[Patient.info: Oncological emergencies](https://patient.info/doctor/oncological-emergencies#tumour-lysis-syndrome)
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Quesmed Tutorial: Lymphoma
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Tumour lysis syndrome can occur after chemotherapy, leading to elevated serum uric acid, potassium, and phosphate levels, alongside acute kidney injury.
A 47-year-old woman with high grade non-Hodgkin’s lymphoma is treated with R-CHOP chemotherapy. 3 days after her first course of treatment, she has diarrhoea, paraesthesia, and decreased urine output.

Given the likely diagnosis, which of the following investigation results would you expect to see?
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