Erratum: Sawtooth potassium and hemoglobin results (Clinical Chemistry (2019) 65 (1463–1464) DOI: 10.1373/clinchem.2019.304394)

CASE DESCRIPTION A 5-year-old boy was admitted with dyspnea, fever, night sweats, and unexplained bruising. Radiography revealed several pulmonary consolidations, and laboratory investigations showed marked hyperleukocytosis with 90% blasts. He was diagnosed with T-cell acute lymphoblastic leukemia. Hemoglobin (Hb)² and potassium results in the subsequent days, during therapy, showed a sawtooth pattern [Fig. 1: central lab, solid dots; point of care (POC), open dots]. The physician was confused and unsure what Hb and potassium results to act on and contacted the laboratory. (Figure Presented).