Tumour lysis
syndrome
When cancer cells break down and die, they release substances into
the blood. If cancer cells break down so quickly that the kidneys can’t remove
these substances from the blood, it can lead to tumour lysis syndrome (TLS).
TLS is a group of problems with blood levels, including high levels of uric
acid (hyperuricemia), potassium (hyperkalemia) and phosphate
(hyperphosphatemia), and low levels of calcium (hypocalcemia).
TLS is a potentially life-threatening problem and needs to be
treated right away. If it is not controlled, abnormal blood levels can cause a
variety of problems. Uric acid can be deposited in the joints, causing a painful
gout-like condition. A buildup of uric acid in the kidneys can cause damage and
stones to form. High phosphate levels can also damage the kidneys and lead to
kidney failure. Abnormal levels of potassium and calcium can affect heart
rhythm and lead to neurological changes such as weakness, irritability and
confusion.
Causes
TLS is more likely to develop when certain cancers or blood
disorders are treated with chemotherapy. These cancers cause a high white blood
cell count, have a high tumour
burden or have rapidly dividing cells that respond well to
treatment. These include:
- acute leukemia
- aggressive non-Hodgkin lymphoma
- myeloproliferative disorders
- solid tumours such as hepatoblastoma and stage IV neuroblastoma
- cancers that cause poor kidney function before treatment starts
Tumour lysis syndrome usually occurs at the start of chemotherapy
when a large number of tumour cells are destroyed. It can occur within a few
hours of treatment, but it is most often seen 48–72 hours (2–3 days) after
treatment starts.
TLS is not limited to systemic chemotherapy, which travels
throughout the body to destroy cancer cells. It can also occur with intrathecal
chemotherapy, which is given directly into the fluid-filled space around the
brain and spinal cord. TLS can develop after chemoembolization, which is a
procedure that stops blood flow to a tumour and delivers chemotherapy directly
to the tumour.
TLS has been linked with other treatments, including radiation
therapy, corticosteroids, hormonal therapy and biological therapy.
Symptoms
Symptoms of tumour lysis syndrome may be mild at first. They get
worse as the levels of abnormal substances in the blood increase. Symptoms of
TLS include:
- nausea
- vomiting
- diarrhea
- muscle cramps or twitches
- weakness
- numbness or tingling
- fatigue
- decreased urination
- irregular heart rate
- confusion
- restlessness
- irritability
- delirium
- hallucinations
- seizures
Report symptoms to your doctor or healthcare team as soon as
possible.
Diagnosis
Tumour lysis syndrome is usually diagnosed by:
- complete blood count (CBC)
- blood chemistry and uric acid levels in the blood
- urinalysis
Find out more about these tests and
procedures.
Treating TLS
Before treatment begins, your healthcare team will determine if
you have a risk of developing tumour lysis syndrome. The risk is based on:
- the type of cancer
- how far the cancer has progressed
- pre-existing conditions, such as poor kidney function, heart disease or high blood pressure
- lab tests
If you have a risk of developing TLS, your healthcare team can
suggest ways to prevent it before you start cancer treatment. This usually
includes making sure your body gets enough fluids. You may be given fluids
through a needle in a vein, or intravenously. Fluids are usually given 24–48
hours before treatment starts and for several days after treatment is finished.
While you are given fluids, the healthcare team will monitor how much urine you
produce (urine output). It is important that you output 150–200 ml of urine
every hour. They may prescribe a diuretic to maintain urine flow. Diuretics are
drugs that help the body make urine.
Your healthcare team will do blood tests and watch for symptoms of
TLS throughout treatment. If TLS develops, they may suggest the following
measures to treat it.
Medicines
You may be given a medicine to lower the level of uric acid in
your body. Allopurinol (Zyloprim) is a drug that stops the body from making
uric acid. Rasburicase (Fasturtec) is a drug that breaks down uric acid so that
the body can get rid of it.
You may also be given drugs to stop uric acid from forming
crystals. This makes it easier for the kidneys to remove uric acid from the
body. You may be given sodium bicarbonate or acetazolamide (Diamox) with the
intravenous fluids. You don’t need to take this drug if you receive
rasburicase.
Dialysis
You may need to have dialysis if TLS can’t be corrected or if
kidney failure worsens. Dialysis removes wastes from the blood when the kidneys
don’t work properly.
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