Severe Hyponatremia Due to Paraneoplastic SIADH Revealing Occult Small Cell Lung Carcinoma

Lordian Nunci, Olta Ajasllari, Deniona Nunci, Klara Ajasllari, Krenar Lilaj, Prof. Dr. Ditila Doracaj

Abstract: This case study aims to highlight the diagnostic complexity and clinical management of a comatose patient with hyponatremia, ultimately diagnosed with paraneoplastic SIADH secondary to small-cell lung carcinoma. A 52-year-old male chronic smoker presented in a comatose state due to severe hyponatremia, with serum sodium measured at 109 mmol/L. Initial neuroimaging excluded intracranial pathology, while thoracic CT and bronchoscopy revealed an infiltrative lesion in the right upper lobe. Histopathology confirmed small cell lung carcinoma (SCLC) with neuroendocrine features. Laboratory findings supported a diagnosis of syndrome of inappropriate antidiuretic hormone secretion (SIADH). Initial treatment with hypertonic saline failed to improve sodium levels. A modified protocol involving fluid restriction, oral sodium supplementation, loop diuretics, and desmopressin led to controlled correction. This case underscores the importance of recognizing paraneoplastic SIADH as a potential initial presentation of SCLC and highlights the value of a multidisciplinary approach to diagnosis and management.

Keywords: small cell lung carcinoma, SIADH, severe hyponatremia, desmopressin therapy, paraneoplastic syndrome

How to Cite?: Lordian Nunci, Olta Ajasllari, Deniona Nunci, Klara Ajasllari, Krenar Lilaj, Prof. Dr. Ditila Doracaj, "Severe Hyponatremia Due to Paraneoplastic SIADH Revealing Occult Small Cell Lung Carcinoma", Volume 15 Issue 1, January 2026, International Journal of Science and Research (IJSR), Pages: 1296-1297, https://www.ijsr.net/getabstract.php?paperid=SR26119031145, DOI: https://dx.doi.org/10.21275/SR26119031145