Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Tokyo 113-8655, Japan.
Osteoporosis Center, The University of Tokyo Hospital, Tokyo 113-8655, Japan.
Endocr J. 2023 Oct 30;70(10):1005-1013. doi: 10.1507/endocrj.EJ23-0086. Epub 2023 Jul 20.
Although there are a few case reports of patients with small cell lung cancer developing hypophosphatemia, detailed information on this condition is scarce. A 52-year-old patient with advanced stage small cell lung cancer developed hypophosphatemia (1.1 mg/dL) during chemotherapy. A reduced level of the tubular reabsorption of phosphate concomitant with an inappropriately elevated level of fibroblast growth factor (FGF) 23 (48.4 pg/mL) was noted, leading to the diagnosis of FGF23-related hypophosphatemia. Laboratory data also showed hypercortisolemia with an elevated ACTH level and hyponatremia with an inappropriately unsuppressed level of antidiuretic hormone (ADH). These data suggested the overproduction of FGF23 in addition to ACTH and ADH. Because the octreotide loading test did not present a suppressive effect on ACTH or FGF23 levels, the patient was treated with phosphate supplementation, active vitamin D and metyrapone, which partially improved the serum phosphate and cortisol levels. Even after two subsequent courses of chemotherapy, the small cell lung cancer progressed, and the FGF23 level was further elevated (83.7 pg/mL). Although it is very rare, FGF23-related hypophosphatemia is one of the hormonal disturbances that could be observed in patients with small cell lung cancer. This article reviews similar clinical conditions and revealed that advanced states of malignancy seemed to be associated with the development of renal wasting hypophosphatemia, especially in lung cancer and prostate cancer. Therefore, the parameters related to hypophosphatemia should be monitored in patients with advanced small cell lung cancer to prevent the development of hypophosphatemic osteomalacia.
虽然有少数小细胞肺癌患者发生低磷血症的病例报告，但对此病症的详细信息却很少。一名 52 岁的晚期小细胞肺癌患者在化疗过程中出现低磷血症（1.1mg/dL）。检测到肾小管磷重吸收减少，同时成纤维细胞生长因子 23（FGF23）水平异常升高（48.4pg/mL），从而确诊为 FGF23 相关性低磷血症。实验室数据还显示皮质醇水平升高，促肾上腺皮质激素（ACTH）水平升高，以及抗利尿激素（ADH）水平不适当的未被抑制，导致低钠血症。这些数据表明 FGF23 的产生除了受到 ACTH 和 ADH 的影响外，还受到其他因素的影响。由于奥曲肽负荷试验对 ACTH 或 FGF23 水平没有抑制作用，该患者接受了磷酸盐补充、活性维生素 D 和米托坦治疗，这部分改善了血清磷和皮质醇水平。即使在随后进行了两次化疗后，小细胞肺癌仍进展，FGF23 水平进一步升高（83.7pg/mL）。虽然这种情况非常罕见，但 FGF23 相关性低磷血症是小细胞肺癌患者可能出现的激素紊乱之一。本文回顾了类似的临床情况，并揭示恶性肿瘤的晚期状态似乎与肾脏消耗性低磷血症的发生有关，尤其是在肺癌和前列腺癌中。因此，应在晚期小细胞肺癌患者中监测与低磷血症相关的参数，以预防低磷性骨软化症的发生。
