Over 13 million people in the United States suffer from thyroid disorders, according to the American Association of Clinical Endocrinologists. The thyroid gland at the base of the neck controls critical processes in the body, including metabolism. If the thyroid doesn't work properly, prescription thyroid hormone can help. Since the medication is actually thyroid hormone, the symptoms of too much thyroid medicine are identical to those of an overactive thyroid gland, in which the body makes too much thyroid hormone.
Heart Symptoms
Manifestations of disease that a patient feels or experiences are called symptoms, whereas those seen by a doctor are called signs.
The most frightening, and among the most common, symptoms that occur from too much thyroid hormone involve the heart, as reviewed in the journal article "Thyroid Disease and the Heart" in the journal Circulation in 2007. Too much thyroid hormone causes the heart rate to speed up. The patient might experience palpitations as the sensation of a racing or pounding heart.
Digestive System Problems
The symptoms of too much thyroid medication are identical to an overactive thyroid gland, a disorder called hyperthyroidism.
When too much thyroid hormone circulates and the body operates in a hyper-metabolic state, an increased appetite and frequent bowel movements become prominent, as elucidated in a 2009 study by Ronald Daher and colleagues, published in the World Journal of Gastroenterology. The article explains that the complex mechanisms by which nearly all parts of the digestive system can be affected remain poorly understood.
Sweating and Heat Intolerance
Hyperthyroidism, whether caused by an overactive gland or by too much TH medication, speeds up metabolism and energy consumption by the body. This situation results in heat production, and the body responds by sweating, a natural cooling mechanism, as discussed on the website Drugs.com. Patients also often complain of feeling hot when those around them seem comfortable. For patients taking too much thyroid medicine, this may be one of the earliest symptoms.
Other symptoms
As discussed in Harrison's "Textbook of Internal Medicine," patients who suffer from primary hyperthyroidism or take too much thyroid hormone report feeling anxious, jittery and irritable, and may suffer from insomnia and increased appetite. Tremors or trembling may become noticeable and bothersome as well.
If excess thyroid hormone is taken over a longer time, weight loss may occur despite increased calorie consumption. Muscle weakness becomes more prominent, and patients complain of fatigue and hair loss.
Acute Overdose
In an acute overdose, meaning a toxic dose of thyroid hormone suddenly ingested, thyroid storm becomes a concern, manifest by seizures and delirium, as well as heart arrhythmias and coma. However, in 2008, although there were over 9,000 overdoses of thyroid hormone, only three major adverse events and no deaths resulted, according to the annual report of the American Association of Poison Control Centers' National Poison Data System (NPDS).
References
- American Association of Clinical Endocrinologists, Public Awareness Information
- "The World Journal of Gastroenterology"; Consequences of Dysthyroidism on the Digestive Tract and Viscera; Daher, Ronald, et al; 2009
- "Circulation"; Thyroid Disease and the Heart; Irwin Klein, MD and Sara Danzi, PhD.; 2007
- Drugs.com; Sweating
- "Harrison's Textbook of Internal Medicine, 17th edition"; Anthony Fauci, Eugene Braunwald, et al, editors; 2009
