Which of the following can be considered a direct consequence of untreated Hyperthyroidism?

Untreated hyperthyroidism can lead to several direct consequences due to the physiological effects of excess thyroid hormones on the body. One such consequence is the development of cardiac arrhythmias. Hyperthyroidism accelerates the metabolism and increases heart rate, leading to elevated cardiac output and overall changes in cardiovascular function. This heightened activity can cause irregular heart rhythms, also known as arrhythmias, including atrial fibrillation, which is a common and serious complication associated with this condition.

While weight reduction can occur in hyperthyroidism due to increased metabolism, it is not considered a consequence of untreated hyperthyroidism; rather, it's typically a symptom. Severe hypothyroidism and autoimmune diseases, while they can be related to thyroid dysfunction, are not direct consequences of untreated hyperthyroidism. In fact, severe hypothyroidism represents an opposite condition to hyperthyroidism, and autoimmune diseases are more complex, often involving the immune system rather than a direct consequence of thyroid hormone levels.