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Endocrine Abstracts (2017) 49 EP900 | DOI: 10.1530/endoabs.49.EP900

1Hospital Clínico San Carlos, Madrid, Spain; 2Hospital Clínico de Valladolid, Valladolid, Spain.


Introduction: Euvolemic hyponatremia (HN) caused by the Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) can predate a diagnosis of malignancy. It is thus essential to accurately diagnose the etiology of HN/SIADH when detected.

Methods: Retrospective, descriptive study of all 52 oncological/hematological malignancy patients diagnosed with SIADH in our Department between January 2011 and December 2016. HN was detected via computerized Primary-care/hospital case histories, and the computerized laboratory data base. Hyponatremia was considered to predate detection of malignancy/initiation of diagnostic study when a serum sodium (SNa) <135 mmol/l was detected 6 months before definitive oncological/hematological diagnosis (PTD). A patient was considered probably euvolemic (PE) when SNa descent was accompanied by a predominant pattern of lowering serum urea, creatinine and Uric acid levels, probably hypovolemic (PH) if urea, creatinine and Uric acid levels rose while not hypervolemic. SNa in mmol/l.

Results: Males: 32/52(61.5%), mean age:63.4 (S.D.:11)years. Etiology of SIADH: lung cancer: 18/52(34.6%), gastrointestinal: 6/52 (23.1%), genitourinary: 11/52 (21%), hematological: 5/52 (9.6%). 11/52 (21%) patients presented HN> 6 months PTD: median 40 (24–60), median age: 67 (63–76) years, initial SNa: 133 (130–134). Three patients were PH. Eight were PE, one receiving enalapril, another carbamazepine, another thiazide. In 5/8 (62%) PE patients, case histories revealed no initial cause for HN. HN was present a median of 25 (19–40.5) months PTD, range: 14–41. Initial SNa: 133 (129.5–133). None presented a low Urine Density. Hyponatremia was persistent, present in 42/50 (84%) tests, with a continuum up to ectopic-SIADH diagnosis, suggesting that SIADH induced their sustained hyponatremia. Etiology: lung (epidermoid), endometrial, breast, gastric, prostate. In only 1/11 (9%) patients was hyponatremia studied PTD, with SIADH workup responsible for prostate tumor diagnosis.

Conclusion: Mild hyponatremia can predate the diagnosis of a malignancy. However, in our series of 11/52 patients, in only one was hyponatremia studied. The lack of importance given to the finding of frank hyponatremia, albeit mild, could delay tumor diagnosis.

Volume 49

19th European Congress of Endocrinology

Lisbon, Portugal
20 May 2017 - 23 May 2017

European Society of Endocrinology 

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