AVP and lung cancer: Excess ADH production can be documented in up to 70% of patients with lung cancer while SIADH is less common.[49] SAIDH is mainly associated with small cell lung cancer, although other malignant tumors of the lung may rarely be associated with this syndrome.[29, 31] In our study, hyponatremia was present in 56% of patients that may be due to increase production of ADH; however, SIADH was rarely seen.