What condition is characterized by weight loss, hand tumors, and an irregular heartbeat?

The condition characterized by weight loss, hand tumors, and an irregular heartbeat is hyperthyroidism. This condition occurs when the thyroid gland produces excessive amounts of thyroid hormones, leading to an accelerated metabolism. Symptoms such as weight loss are common because the body's metabolic rate increases, causing it to burn calories more rapidly.

Hand tumors, specifically in the context of hyperthyroidism, may refer to the presence of nodules or increased growth of tissue, which can sometimes be related to conditions like toxic nodular goiter or Graves' disease. The irregular heartbeat, or palpitations, is also a well-known manifestation of hyperthyroidism due to the increased stimulation of the heart by elevated hormone levels.

In contrast, Addison's disease involves adrenal insufficiency and is characterized by symptoms such as fatigue, weight loss, and low blood pressure, but does not typically present with hand tumors or an irregular heartbeat. Hypothyroidism results in weight gain and a slow metabolism rather than weight loss. Diabetes mellitus, primarily characterized by high blood sugar levels and related complications, does not align with the symptoms described either. Thus, hyperthyroidism is the condition that best encapsulates all the provided symptoms.