Endocrine Abstracts

Small cell lung cancer (SCLC) is accepted as a neuroendocrine tumor and usually accompanied with paraneoplastic syndromes. Our case has been diagnosed as SCLC and the only finding of disease was hyponatremia.

Case: Forty-four-year of female patient has admitted because of nausea, vomitting and fatigue. Serum Na level was 116 mEq/l. The patient hospitalized for further investigation. In physical examination BP was 140/80 mmHg, HR was 72 beats/min. Patient didn’t have complaints such as coughing, sputum, weight loss, dispnea or chest pain. Serum glucose level 101 mg/dl, urea 9 mg/dl, Cr: 0.6 mg/dl and K: 4.1 mEq/l were. Plasma osmolality was measured as 226 mosm/l, urine osmolality was 306 mosm/l, urine dansity was 1013 and Na in 24 h collection of urine was 147 mmol/l. In imaging of brain with MRI, there were hyperintense lesions located in white matter which were interpreted as finding of encephalomyelitis or demyelinating disease. It could be related to hyponatremia. In abdominal MRI images adrenal glands were normal. Plasma cortisol and 17-OH progesterone responses to short ACTH stimulating test, pitiutary hormones, cortisol and GH response to insulin tolerance test were normal. We thought all these results could be due to SIADH. In thorax CT, we have detected multiple nodules biggest 6 mm in dimension and multiple enlarged hilar and mediastinal lymph nodes biggest in 23 mm in size. Endobronchial biopsy was taken from the enlarged lymph nodes. Histopathology results were compatible with SCLC metastasis and patient was referred to an oncology clinics.

SIADH syndrome occurs in oncology patients due to ectopic production of hormone by cancer itself, complications or treatments. Early recognition of it is important in order to reduce morbidity and mortality. It should be kept in mind that hyponatremia might be first sign of cancer as it is in our case.