Final answer:
The syndrome associated with flushing, diarrhea, palpitations, and elevated 5-HIAA levels is Carcinoid Syndrome, not hyperthyroidism. Elevated 5-HIAA levels indicate a serotonin-secreting neuroendocrine tumor.
Step-by-step explanation:
The syndrome that presents with symptoms such as flushing, diarrhea, and palpitations, along with elevated levels of 5-HIAA, is not hyperthyroidism but rather a condition known as Carcinoid Syndrome. While hyperthyroidism does involve an abnormally elevated level of thyroid hormone in the blood and can cause symptoms such as an increased metabolic rate, excess body heat, sweating, diarrhea, weight loss, and increased heart rate, it does not typically cause elevated 5-HIAA levels. Elevated 5-HIAA is usually indicative of a serotonin-secreting neuroendocrine tumor, which is characteristic of Carcinoid Syndrome.