Critically Elevated Potassium in a 55-Year-Old Female With Chronic Lymphocytic Leukemia

Jing Cao, PhD; Amy B. Karger, MD, PhD


Lab Med. 2018;49(3):280-283. 

In This Article

Clinical History

A 55-year-old Caucasian woman with a 6-year history of chronic lymphocytic leukemia (CLL) presented to an outside hospital (OSH) with enlarging neck lymph nodes; she reported having experienced fatigue and weakness for the past month. Three weeks before admission, the patient had been restarted on chemotherapy consisting of pentastatin, cyclophosphamide, and rituxan, due to her lymphadenopathy. On examination, her neck lymph nodes were 3 to 4 cm in diameter, a left axillary node was 5 cm in diameter, and smaller nodes were felt in her inguinal area.

After admission to the OSH, the patient had a peripheral blood smear performed; the results showed marked lymphocytosis and atypical prolymphocytoid cells (25% to 30% of cells). Flow cytometry results were consistent with CLL. Bone marrow biopsy results showed hypercellularity of approximately 90%. During her hospital stay, her white blood cell (WBC) count ranged between 200 and 300 × 109 per L (reference interval: 4.0 to 11.0 × 109/L) and her plasma uric acid level was elevated, at greater than 8 mg per dL (2.5 to 7.5 mg/dL). Also, the patient had fluctuating hyperkalemia, with whole blood (WB) potassium (K+) levels between 5 and 7 mmol per L (reference range, 3.4 to 5.3 mmol/L). Due to the hyperkalemia and hyperuricemia, tumor lysis syndrome (TLS) was suspected, and the patient was treated with rasburicase to lower her serum uric acid levels. She received sodium polystyrene sulfonate, and her WB K+ level decreased to 3.7 mmol per L on the day of transfer to a new institution (University of Minnesota Health).

The patient was transferred to University of Minnesota Health due to her high risk of complications from suspected TLS. On the day of her admission to the new facility, the patient had a WBC count of 277.6 × 109 per L; plasma K+ levels of 9.9 mmol per L, as measured on the VITROS 5600 immunoanalyzer (Ortho Clinical Diagnostics); a confirmatory K+ level of 9.3 mmol per L, as measured on the ABL90 FLEX blood gas analyzer (Radiometer America); lactate dehydrogenase (LDH) level of 2579 U per L (reference interval [RI], 325–750 U/L); phosphorus level of 1.1 mg per dL (RI, 2.5 to 4.5 mg/dL); magnesium level of 1.4 mg per dL (RI, 1.6 to 2.3 mg/dL); and uric acid levels in the normal range (4.4 mg/dL). Electrocardiogram (ECG) readings demonstrated normal PR intervals with no ST or T wave changes. The patient reported no major symptoms.

Because the markedly elevated potassium levels were concordant on the ABL90 FLEX blood gas analyzer and the VITROS 5600, and there was no evidence of hemolysis, the assessment from the medical team was that the patient had severe hyperkalemia, likely secondary to TLS, with concern for accelerated CLL transformation (particularly prolymphocyte leukemia). The patient was given calcium gluconate, insulin, dextrose, high-dose albuterol, intravenous fluids, and furosemide. The team planned to repeat K+ testing in 1 hour and requested a nephrology consultation to assess for the potential need for emergency dialysis.