Hyperthyroidism and Diabetes
A while back, I wrote about hypothyroidism and diabetes. Recently, there was a press release from the American Association of Clinical Endocrinologists (AACE) about Hyperthyroidism: The Flip Side of the Thyroid Equation, and I decided to remind our readers that both hypo- (underactive) and hyperthyroidism (overactive thyroid functioning) are issues for people with diabetes (PWD).
It’s been known for years that diabetes and thyroid problems can go hand-in-hand. More specifically, type 1 diabetes, which itself is an autoimmune disorder, is frequently associated with other autoimmune disorders including autoimmune thyroid disorders. These autoimmune thyroid disorders may cause the thyroid to fail (in a disorder called Hashimoto’s thyroiditis, which leads to hypothyroidism), or, sometimes, to become overactive (in a disorder called Graves’ disease, which leads to hyperthyroidism). Both Hashimoto’s and Graves’ will have positive blood tests for thyroid antibodies.
In general, hypothyroidism is far more common than hyperthyroidism, and can occur in both T2DM and T1DM. For more information on hypothyroidism, please see my previous essay. Hypothyroidism can sneak up on people, with symptoms developing so slowly that frequently patients just assume they were growing old prematurely. Symptoms of hypothyroidism, no matter what the cause, include fatigue, dry, coarse skin and hair, inability to tolerate cold weather, weight gain, hoarse voice, and heavy or irregular menstrual periods. Blood levels of thyroid hormone are low and levels of TSH (thyroid stimulating hormone) are typically very elevated. Blood glucose control isn’t changed dramatically, but blood levels of cholesterol will become very elevated (and should return to normal with treatment of the hypothyroidism).
Hyperthyroidism’s symptoms are pretty much the reverse of those seen with hypothyroidism, and they can develop over a short period of time. Symptoms can include rapid heart rate, heart rhythm disturbances and palpitations, tremor, insomnia, anxiety or agitation, sweating, heat intolerance and abnormal ability to tolerate cold weather, weight loss, hair loss, and scant or absent menses. In older patients (older than about 70 years of age), the typical findings may be absent. Blood levels of thyroid hormone are elevated and levels of TSH are depressed. PWD usually also have deterioration of their blood glucose control. Sometimes, people without a prior diagnosis of diabetes may develop hyperglycemia as a result of their revved-up metabolism.
In patients with Graves’ disease, the thyroid gland (which is located in the front of the neck) may become noticeably enlarged (an enlarged thyroid gland is called a “goiter”). Another problem may occur in Graves’ disease: there may be swelling of the muscles and tissues around the eyes also may develop, causing the eyes to bulge forward.
Occasionally, hyperthyroidism may be caused by excessive thyroid hormone treatment in a patient who has a diagnosis of hypothyroidism. Decreasing the dose of thyroid hormone cures this form of hyperthyroidism.
In patients with hyperthyroidism, there may rarely be a sudden dramatic worsening of symptoms, resulting in a disaster called "thyroid storm" – with high body temperature, heart rhythm disturbances, vomiting and diarrhea, dehydration, coma, and death.
Concerning treatment of hyperthyroidism, AACE points out: "Before the development of current treatment options, those diagnosed with hyperthyroidism had a death rate as high as 50 percent. Today, treatment depends on the cause, the severity of symptoms and the patient’s age. For patients with sustained forms of hyperthyroidism, such as Graves’ disease, anti-thyroid medications are often used. Radioactive iodine, which is absorbed by the thyroid cells only, is the most widely recommended therapy for permanent treatment of hyperthyroidism." And occasionally, surgery to remove part of the thyroid gland may be recommended.
If you have diabetes, whether T1DM or T2DM, it seems reasonable that you should have a screening test for thyroid problems by having your TSH level checked every year or two. If it’s high or low, additional testing for thyroid hormone levels and possibly for thyroid antibodies should be done. If hypothyroidism is diagnosed, treatment with thyroid hormone replacement therapy is straightforward and rewarding. On the other hand, if hyperthyroidism is diagnosed, treatment options are more complex, and referral to an endocrinologist would be a good idea, especially if the patient has diabetes.
Bill Quick, M.D., is a physician who is living with diabetes. He is the editor of www.D-is-for-Diabetes.com. Dr. Quick wrote about diabetes for HealthCentral.