Lung carcinoma with paraneoplastic hyponatremia and hypercalcemia

Among the numerous paraneoplastic syndromes of the lung carcinoma, metabolic manifestations are of the particular clinical relevance. They are the consequence the prominent neurosecretory activity of certain peptides and hormones, mostly within amine precursor uptake and decarboxylation (APUD) secretion. Small cell lung carcinoma is the most common cause of paraneoplastic syndromes. Ectopically produced proteins by the tumor are structurally similar but biologically less active than the "true" hormones, which may be clinically manifested by absent, less frequent or milder symptoms of the hormonal imbalance.