ACDIS insight: Clinical validation of tumor lysis syndrome

by Lynette Byerly, BSN, RN, CCDS, CCS

Many conditions can be confusing both to diagnose and assign the proper coding. One such condition is tumor lysis syndrome (TLS), which occurs when treating cancers like lymphomas, leukemias, and certain fast‑growing solid tumors, especially when the tumor is large or responds very quickly to treatment. TLS is considered an emergency for an oncology patient and is often referred to as a massive tumor cell lysis.

TLS is more common and tends to be quite severe with the increased use of stronger, targeted drug treatments that focus directly on cancer cells. When there is a rapid breakdown of tumor cells, these cells leak the intracellular contents into the blood. Patients are at a higher risk for developing TLS if they have a diagnosis of leukemia and poorly differentiated lymphoma, are receiving combined chemotherapy treatments, or are on steroid treatments for cancer therapies.

When trying to identify or clinically validate TLS, evaluate the laboratory findings. Specifically, look at the serum phosphorus (phosphate), uric acid, potassium, and calcium. Hyperphosphatemia or hypocalcemia with hyperuricemia are hallmark laboratory abnormalities commonly associated with TLS. Serum creatinine and the occurrence of heart arrhythmias may also be present, but are not direct symptoms of this syndrome. Providers will treat these patients most often with IV fluids. Depending on the patient’s malignancy and other course of treatments, hypouricemic agents are a possibility. Sodium bicarbonate, allopurinol, and rasburicase may also aid in the excretion of turic acid.

The questions we ask quite often are: Do providers need to document each individual metabolic disturbance as a diagnosis? Do CDI specialists need to query for each individual metabolic disturbance? Can we capture all the associated codes of TLS?

The answer is yes and no. Per the fiscal year 2026 ICD-10-CM Official Guidelines for Coding and Reporting, we are unable to capture individual metabolic disturbances. The Guidelines state:

B. General Coding Guidelines

5. Conditions that are an integral part of a disease process

Signs and symptoms that are associated routinely with a disease process should not be assigned as additional codes, unless otherwise instructed by the classification.

6. Conditions that are not an integral part of a disease process

Additional signs and symptoms that may not be associated routinely with a disease process should be coded when present.

The Guidelines also state:

15. Syndromes

Follow the Alphabetic Index guidance when coding syndromes. In the absence of Alphabetic Index guidance, assign codes for the documented manifestations of the syndrome. Additional codes for manifestations that are not an integral part of the disease process may also be assigned when the condition does not have a unique code.

In this case, the diagnoses of hyperphosphatemia, hyperuricemia, hypocalcemia, and hyperkalemia are considered symptoms that can establish the diagnosis of TLS.

We would also want to capture any additional diagnosis such as acute kidney injury (AKI). AKI is a diagnosis that is not present in every case of TLS as it is not inherently integral to all TLS cases in the way the metabolic disturbances are. Because of this, AKI should be documented and coded separately when present, as it represents a distinct complication with its own clinical significance. Clear identification of AKI ensures accurate reflection of patient severity of illness and resource utilization.

Editor’s note: Byerly is a CDI education specialist for ACDIS. Contact her at lynette.byerly@hcpro.com. For more information on TLS, click here.