Tumor Lysis Syndrome: Patient Action Guide

• You pass very little urine, or none at all.
• Muscle cramps or twitching start in the first days of treatment. The same goes for tingling around the mouth or in the fingers.
• Your heart skips, races, or pounds at rest.
• You have a seizure, faint, or become confused.
• Nausea and vomiting stop you keeping fluids down after a new treatment started.

Say the words "possible tumor lysis" at the desk. Then say which treatment you started and when.

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Tumor lysis syndrome happens when a large number of cancer cells break open at once. Their contents spill into the blood.

Cells hold potassium and phosphate at levels far higher than the blood normally carries. They also hold DNA. When many cells rupture together, potassium and phosphate flood out. The DNA is broken down through xanthine into uric acid.

Most mammals have an enzyme called urate oxidase. It turns uric acid into allantoin, which dissolves easily and washes out in urine. Humans do not have that enzyme. So uric acid builds up. It forms crystals inside the kidney tubules and blocks them. Uric acid also mops up nitric oxide, a natural blood vessel widener. That narrows the vessels and starves the kidney of blood.

Meanwhile, the flood of phosphate binds calcium in the blood. Calcium levels fall. Calcium-phosphate crystals settle in tissue and kidney. That is the whole syndrome: high potassium, high phosphate, high uric acid, low calcium, and failing kidneys.

Expert panels sort tumors into three bands. High risk means more than 5% of patients develop the syndrome. Intermediate means 1% to 5%. Low means under 1%.

Several cancers sit in the high-risk band. One is advanced Burkitt lymphoma. Another is acute lymphoblastic leukemia with a white cell count above 100,000 per microliter, or an LDH more than twice the upper limit of normal. A third is diffuse large B-cell lymphoma with bulky disease over 10 cm and LDH more than twice normal. The fourth is acute myeloid leukemia with a white cell count of 100,000 per microliter or more. Diffuse large B-cell lymphoma covers what bulky means there.

Intermediate risk includes acute myeloid leukemia with a white cell count of 25,000 to 100,000. It also includes diffuse large B-cell lymphoma with high LDH but no bulky mass.

Low risk covers solid cancers, myeloma, indolent lymphomas, chronic lymphocytic leukemia, and chronic myeloid leukemia.

So two numbers from your own chart matter most. They are your white cell count and your LDH. Ask for both before treatment starts.

Certain drugs carry the risk whatever the tumor type. The list includes venetoclax, rituximab, obinutuzumab, bortezomib, fludarabine and etoposide. It also includes hydroxyurea, paclitaxel, thalidomide, and CAR T-cell therapy. Venetoclax is started on a five-week ramp-up rather than at full strength. The FDA label says that schedule "is designed to gradually reduce tumor burden (debulk) and decrease the risk of TLS."

Patient factors add up too. They include high uric acid before treatment, existing kidney disease, low urine output, and dehydration.

Numbers vary by setting. One United States center looked at 951 newly diagnosed cancer patients. Laboratory tumor lysis occurred in 9.3% of them. Clinical tumor lysis occurred in 6.7%. In blood cancers those figures rose to 21.1% and 15.1%.

A European study looked at 788 adults and children with acute leukemia or non-Hodgkin lymphoma. It found 18.9% had laboratory tumor lysis and 5% had the clinical form.

In-hospital mortality once it develops is about 21%. That is the reason for the fluids and blood draws that can feel excessive.

The Cairo-Bishop criteria separate the two. Knowing which one your team means will save confusion.

Laboratory tumor lysis needs two or more lab changes within the same 24 hours. The window runs from 3 days before treatment to 7 days after it starts. Uric acid rising 25% from baseline, or reaching 8.0 mg/dL or more, counts as one. So does potassium rising 25% or reaching 6.0 mEq/L. So does phosphorus rising 25% or reaching 4.5 mg/dL, or 6.5 mg/dL in children. And so does calcium falling 25% or dropping to 7.0 mg/dL or below.

Clinical tumor lysis means laboratory tumor lysis plus at least one other problem. That can be creatinine above 1.5 times the age-adjusted upper limit of normal. It can also be a seizure, a cardiac arrhythmia, or sudden death.

So being told you have "lab tumor lysis" while feeling fine is real and treatable. It is not a false alarm. It is the stage where treatment still prevents the clinical version.

Fluids come first. Intravenous fluid usually starts about 48 hours before treatment and continues about 48 hours after. The volumes are large, which is why the drip may run day and night. Your team works out the amount from your body size and watches how much urine you pass.

Those fluids are deliberately free of potassium and calcium at the start. If you notice your bag has no added potassium, that is intentional.

Blood tests are timed by risk band. These are the intervals StatPearls describes, and your unit may use its own. High-risk patients are tested every 4 to 6 hours after treatment begins. Intermediate risk means every 8 to 12 hours. Low risk means daily.

Two drugs lower uric acid, and they work by different routes. Allopurinol blocks the enzyme that makes uric acid, so less is made. It does not clear uric acid that is already there. It is started a day or two before chemotherapy, and the dose is lowered if your kidneys are struggling. Ask which medicine you will get to protect your kidneys, and when it starts.

Rasburicase does the opposite job. It is a manufactured version of the urate oxidase enzyme humans lack. It destroys uric acid already in the blood. StatPearls says it is favoured over allopurinol for high-risk patients, especially those with kidney or heart problems.

Rasburicase has one hard contraindication worth knowing by name. It is G6PD deficiency, a common inherited enzyme problem. The reaction produces hydrogen peroxide. In people lacking that enzyme, hydrogen peroxide can cause severe hemolytic anemia or methemoglobinemia. G6PD deficiency is more common in people of African, Mediterranean, and Southeast Asian ancestry. Ask whether you have been tested.

Allopurinol has its own genetic caution. Screening for the HLA-B*58:01 allele is recommended in specific high-risk groups. That mainly means people of Asian ancestry. The reason is severe skin reactions.

Febuxostat is an alternative when rasburicase is unavailable or unsafe. It needs no dose change for mild to moderate kidney impairment.

Nonsteroidal anti-inflammatory drugs such as ibuprofen and naproxen narrow the kidney's blood vessels, so teams generally keep them away from this window, along with iodinated contrast dye where the scan can wait. Do not start one over the counter without asking. If you already take an anti-inflammatory that was prescribed to you, raise it with the team rather than stopping it yourself: which of your regular medicines pause and which continue is their call, and stopping some abruptly causes its own problems.

Routine urine alkalinization with sodium bicarbonate has fallen out of favor. It does make uric acid about 10 times more soluble. But it lowers ionized calcium. It also encourages calcium-phosphate crystals to settle in the kidney. It is now reserved for patients with metabolic acidosis when rasburicase is unavailable. Kidney problems during cancer treatment covers how the damage is tracked.

• What is my white cell count and my LDH today?
• Which risk band does that put me in: high, intermediate, or low?
• Will I get allopurinol or rasburicase, and why that one?
• Have I been tested for G6PD deficiency if rasburicase is planned?
• How often will bloods be drawn in the first 48 hours? And who calls me with the results?

• NIH StatPearls (NCBI Bookshelf) — Tumor Lysis Syndrome
• FDA — VENCLEXTA (venetoclax) prescribing information