Investigations
1st investigations to order
serum uric acid
Test
Biochemistry should be performed prior to initiation of cancer treatment, and for 2 to 3 days after initiation of treatment.
Elevated uric acid prior to initiation of cancer treatment correlates with large tumour burden and is considered an independent risk factor for TLS.[2][9][29]
If there is evidence of TLS, treatment should be initiated and biochemistry repeated at least twice daily until normalised.
Result
≥476 micromol/L (≥8 mg/dL) or 25% increase from baseline
serum phosphate
Test
Biochemistry should be performed prior to initiation of cancer treatment, and for 2 to 3 days after initiation of treatment.
Elevated phosphate prior to initiation of cancer treatment is an independent risk factor for TLS.[2][30]
If there is evidence of TLS, treatment should be initiated and biochemistry repeated at least twice daily until normalised.
Result
children: ≥2.1 mmol/L (≥6.5 mg/dL) or 25% increase from baseline; adults ≥1.45 mmol/L (≥4.5 mg/dL) or 25% increase from baseline
serum potassium
Test
Biochemistry should be performed prior to initiation of cancer treatment, and for 2 to 3 days after initiation of treatment.
Hyperkalaemia is a defining feature of laboratory TLS.[2]
If there is evidence of TLS, treatment should be initiated and biochemistry repeated at least twice daily until normalised.
Result
≥6.0 mmol/L (≥6.0 mEq/L) or 25% increase from baseline
serum calcium
Test
Biochemistry should be performed prior to initiation of cancer treatment, and for 2 to 3 days after initiation of treatment.
Hypocalcaemia is a defining feature of laboratory TLS.[2]
If there is evidence of TLS, treatment should be initiated and biochemistry repeated at least twice daily until normalised.
Result
≤1.75 mmol/L (≤7 mg/dL) or 25% decrease from baseline
FBC
Test
FBC should be performed prior to initiation of cancer treatment, and for 2 to 3 days after initiation of treatment.
Leukocytosis prior to initiation of cancer treatment correlates with large tumour burden and is considered an independent risk factor for TLS.[9][29]
Result
elevated WBC levels (>25 × 10⁹/L [>25,000/microlitre]) increase risk of TLS
serum lactate dehydrogenase (LDH)
Test
Biochemistry should be performed prior to initiation of cancer treatment, and for 2 to 3 days after initiation of treatment.
Elevated LDH prior to initiation of cancer treatment correlates with large tumour burden and is considered an independent risk factor for TLS.[9][29][30]
If there is evidence of TLS, treatment should be initiated and biochemistry repeated at least twice daily until normalised.
Result
elevated
serum creatinine
Test
Biochemistry should be performed prior to initiation of cancer treatment, and for 2 to 3 days after initiation of treatment.
Elevated creatinine prior to initiation of cancer treatment is an independent risk factor for TLS.[2][30]
Pre-existing renal impairment (elevated serum creatinine ≥1.5 times the upper limit of normal), dehydration (with elevated urea), and volume depletion are predisposing risk factors for TLS that may be modifiable and should be identified prior to initiation of cancer treatment.[1][28]
If there is evidence of TLS, treatment should be initiated and biochemistry repeated at least twice daily until normalised.
Result
≥1.5 times the upper limit of normal
serum urea
Test
Biochemistry should be performed prior to initiation of cancer treatment, and for 2 to 3 days after initiation of treatment.
Increased urea may be observed.[46]
Pre-existing renal impairment (elevated serum creatinine ≥1.5 times the upper limit of normal), dehydration (with elevated urea), and volume depletion are predisposing risk factors for TLS that may be modifiable and should be identified prior to initiation of cancer treatment.[1][28]
If there is evidence of TLS, treatment should be initiated and biochemistry repeated at least twice daily until normalised.
Result
elevated with renal impairment, acute kidney injury, or dehydration
urine pH
Test
Should be checked prior to initiation of cancer treatment and always in the presence of hyperuricaemia.
Uric acid is poorly soluble in water and becomes less soluble in an acidic environment (urine pH <5).[14] Uric acid crystals can precipitate in renal tubules and cause tubular obstruction and nephropathy.
Result
pH ≤5
Investigations to consider
ECG
Test
In the presence of hyperkalaemia, hyperphosphataemia, and hypocalcaemia, an ECG with or without continuous cardiac monitoring is required as life-threatening arrhythmias may develop.
Continuous cardiac monitoring is advised during any pharmacological treatment of an arrhythmia or when potassium is significantly high (>7 mmol/L [>7 mEq/L]).
Abnormalities with hyperkalaemia include peaked T waves, prolongation of PR and QRS intervals, and flattening of P waves. This might be followed by atrioventricular conduction blocks and ventricular fibrillation or asystole. In hypocalcaemia, QT prolongation may be seen, which predisposes to ventricular arrhythmias.
Result
arrhythmia
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