Which sign is most characteristic of hypothyroidism?

• A. Dry skin
• B. Irritability
• C. Palpitations
• D. Weight loss

Answer: (A)

The sign being tested is a skin change that reflects the slowed metabolism of hypothyroidism. Dry skin arises because reduced thyroid hormone lowers skin turnover and sweating, leading to xerosis and a rough, coarse texture. In more advanced cases, there can be myxedema from glycosaminoglycan buildup in the dermis, contributing to thickened, dry skin.

Irritability and palpitations are more characteristic of excess thyroid hormone (hyperthyroidism), which speeds up metabolism and often causes anxiety, tachycardia, and tremor. Weight loss is also typical of hyperthyroidism; hypothyroidism more commonly leads to weight gain or difficulty losing weight due to a lower metabolic rate.

So, dry skin best fits the profile of hypothyroidism.