Final answer:
SIADH is an oncological emergency because it results in low sodium levels, known as hyponatremia, which can cause neurological symptoms and life-threatening complications.
Step-by-step explanation:
SIADH (syndrome of inappropriate antidiuretic hormone) is considered an oncological emergency because it results in low sodium levels, known as hyponatremia. When ADH is excessively released and water is retained, sodium becomes diluted in the body, leading to low sodium levels. This can cause neurological symptoms and potentially life-threatening complications.