Transient increase in lactate dehydrogenase after granulocyte colony‐stimulating factor administration during chemotherapy in a patient with advanced seminoma

INTRODUCTION: Granulocyte colony‐stimulating factor is often reported to induce increases in lactate dehydrogenase, complicating the evaluation of treatment effects on germ cell tumors. CASE PRESENTATION: A 30‐year‐old patient was diagnosed with left testicular seminoma showing enlarged para‐aortic lymph nodes and a retroperitoneal tumor. Serum levels of lactate dehydrogenase were elevated. Three cycles of bleomycin, etoposide, and cisplatin were administered. After chemotherapy, computed tomography showed marked reduction in the metastatic sites. However, serum lactate dehydrogenase levels increased transiently at the end of each course of chemotherapy. In consideration of the residual tumors, one cycle of another chemotherapy was added. Five months after final chemotherapy, lactate dehydrogenase remained within normal limits with no evidence of tumor recurrence. CONCLUSION: In our case, transient elevation of lactate dehydrogenase was considered relevant to granulocyte colony‐stimulating factor use. Examination of lactate dehydrogenase isoenzymes may be helpful to estimate the cause of serum lactate dehydrogenase elevation.