What are the physical signs of thyrotoxicosis?

Physical signs that may become apparent in patients who develop thyrotoxicosis reflect exposure to excess amounts of thyroid hormone. Patients who develop thyrotoxicosis may be noted to have an accelerated heart rate as a result of increased stimulation of the cardiovascular system. If measurement of the pulse reveals that a patient's heart is beating at a rate faster than 100 beats per minute, this acceleration is called tachycardia. Increased stimulation of the cardiovascular system may also lead to the development of abnormal heart rhythms called arrhythmias. An arrhythmia may first be detected as an irregular pulse. In most situations when an irregular pulse is detected, an electrocardiogram must be performed to determine if an underlying arrhythmia is present. Different types of arrhythmias that may be develop in the setting thyrotoxicosis include sinus tachycardia, atrial fibrillation, atrial flutter, and paroxysmal atrial tachycardia. Examination of patients who develop thyrotoxicosis may reveal warm moist skin that is very smooth in texture. Characteristic skin changes may be related to increased blood flow in the tissues supporting the skin and increased stimulation of the sweat glands. Neurologic testing of patients who develop thyrotoxicosis may reveal characteristic findings related to increased stimulation of the nervous system. Testing of the reflexes may reveal sharp forceful contraction of muscles when tendons in the arms, knees, and ankles are tapped with a reflex hammer. Further testing may reveal evidence of a fine tremor when a patient is asked to hold a hand out to keep it steady. Muscle strength may be noted to be decreased when a patient is asked to push or pull against fixed resistance. Increased contraction of the muscles that open the upper eyelids may be associated with a finding called retraction. This may become apparent when examination of the eyes reveals a delay in closure of the upper eyelids. This delay is called lid lag. Patients with retraction and lid lag may look like they are staring, even when they are completely relaxed.