Lactate Dehydrogenase Variation in a Patient with History of Giant Cell Tumor.

Abstract

A 66-year-old female presented to the oncology clinic of an academic medical center for follow-up of a giant cell tumor that was resected from her sacrum 15 years prior. At her visit, the oncologist reviewed prior laboratory tests and noted increased lactate dehydrogenase (LDH) concentrations between January 2019 and February 2019 (Fig. 1, A). All of her previous LDH measurements were within normal limits (reference interval, 125–250 U/L) with the exception of one measurement in January 2018 (Fig. 1, A). The oncologist became concerned that the increased LDH concentrations were indicative of tumor recurrence and asked the patient to return to the oncology clinic for further investigations, which included a complete blood count, a comprehensive metabolic panel, plasma enzymes, LDH isoenzymes, positron emitted tomography (PET), and computed tomography (CT) scans. Her complete blood count, metabolic panel, plasma enzymes, and LDH isoenzymes were unremarkable. Based on...