Final answer:
Hypothyroidism is defined as low thyroid hormone levels due to an underactive thyroid gland, leading to a decrease in metabolism and symptoms such as weight gain and fatigue, as seen in Patient A. Hyperthyroidism, on the other hand, results from an overactive thyroid gland, contributing to weight loss and increased metabolism, as demonstrated by Patient B's symptoms.
Step-by-step explanation:
What is Hypothyroidism? Hypothyroidism is a condition characterized by low thyroid hormone levels, specifically thyroxine (T4) and triiodothyronine (T3) which can lead to a decreased metabolism. Patient A showcasing symptoms of weight gain, cold sensitivity low heart rate and fatigue is likely experiencing hypothyroidism. Conversely Patient B demonstrates symptoms that are indicative of hyperthyroidism such as weight loss, profuse sweating, increased heart rate, and difficulty sleeping.
It's important to understand that when the thyroid gland is underactive as in hypothyroidism, it does not produce sufficient amounts of these crucial hormones affecting various bodily functions. This contrasts with hyperthyroidism, the opposite condition where the thyroid gland is overactive.To further clarify Hypothyroidism is the answer to the initial multiple-choice question which is option C: Low thyroid hormone levels.