Final answer:
A patient with the syndrome of inappropriate secretion of antidiuretic hormone would typically exhibit hyponatremia, demonstrated by a serum sodium level of 115 mEq/L.
Step-by-step explanation:
The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is characterized by the excessive release of antidiuretic hormone (ADH), also known as vasopressin, which leads to water retention and dilution of electrolytes, particularly sodium. Consequently, a common laboratory finding in a patient with SIADH is hyponatremia, or lower-than-normal levels of sodium in the blood. Therefore, the value that would be found in a patient with SIADH out of the given options is a serum sodium of 115 mEq/L, which indicates hyponatremia.