A Patient with Hypokalemia and Hypoxemia—What Is the Culprit?

Summary

https://doi.org/10.1093/clinchem/hvad158

A 72-year-old female presented to the hospital with a 2-month history of poor oral intake and lethargy.

Student discussion

Yin Ye Lai, Chee Hoe Lim, Muhamad Syahmi Nazli, Intan Nureslyna Samsudin, and Subashini Chellappah Thambiah

Case description

A 72-year-old female presented to the hospital with a 2-month history of poor oral intake and lethargy. There was no history of vomiting or diarrhea, and she was not on any medications. On admission, she had a body temperature of 37.2°C, blood pressure of 110/73 mmHg, pulse rate of 111/minute, respiratory rate of 19/minute and oxygen saturation (Carescape V100, GE Healthcare) under room air was 98%. An electrocardiogram showed no conduction abnormality. Cardiovascular and respiratory systems were unremarkable, and abdominal examination did not reveal hepatosplenomegaly. She had no muscle weakness.

Blood investigations revealed hyperleukocytosis with anemia, thrombocytopenia, and severe hypokalemia. Immunocytochemistry confirmed the diagnosis of acute myeloid leukemia with the presence of 93% blasts. Other abnormal blood results include hyperuricemia, raised lactate dehydrogenase, raised creatinine, hypoproteinemia, and hypoalbuminemia. She was started on intravenous potassium replacement (40 mmol over 24 hours, Injecsol K10; Ain Medicare Sdn. Bhd.) given in 1000 mL 0.9% NaCl and oral hydroxyurea (500 g stat and 1 g once daily, DHNP Hydroxyurea®; Dae Han New Pharm). The serum potassium concentration obtained 24 hours later following treatment had worsened. A repeated blood sample with a shorter time interval between blood collection and analysis [blood collected in a blood gas syringe, placed on ice, and immediately analyzed on a point-of-care (POC) blood gas analyzer (ABL90 Flex analyzer, Radiometer)], had a higher potassium level of 2.9 mmol/L.

During her ward admission, the patient developed a fever of 39.4°C. Blood culture with sensitivity, arterial blood gas measurements, and chest x-ray were ordered in response. The blood gas sample was placed on ice at the point of collection and for transport to the nearest POC analyzer. The arterial oxygen tension (PO2), and arterial oxygen saturation (SaO2) measured on the sample were discrepant from the chest radiograph findings and peripheral oxygen saturation as measured by pulse oximetry (Carescape V100, GE Healthcare). The patient also did not exhibit any respiratory distress or cyanosis.

Blood culture subsequently confirmed Streptococcus dysgalactiae bacteremia. Despite being started on intravenous piperacillin and tazobactam (4.5 g 6 hourly, Tazocin EF, Pfizer), supportive care with antipyretics—acetaminophen (1 g 6 hourly, Paracil, SM Pharmaceuticals Sdn. Bhd.) and oral potassium replacement (16 mmol 8 hourly, Potrelease TR, SM Pharmaceuticals Sdn. Bhd.)—the patient deteriorated and passed away on day 3 of admission.