because the heart is less able to respond to exercise. Make sure your dose of thyroid is correct if you’re receiving treatment for hypothyroidism.
The nervous system and muscles If you have hyperthyroidism, your fingers have a fine tremor when you hold your hands out. The loss of muscle tissue leads to weakness, especially in the muscles that are closer to the center of the body. Your reflexes increase; some patients can’t sit still. In Chapter 15, I discuss the psychological changes associated with hyperthyroidism. Basically, if you’re hyperthyroid, most likely you’re nervous, you don’t sleep as much as you used to, and you have rapidly changing emotions, from exhilaration to depression. You may find that you can’t perform mentally at the high level that you did before you developed hyperthyroidism. Several of my patients, law students and medical students, couldn’t take examinations successfully and had to take several months off of school to recover before they could return to their studies. You may also tire much earlier than you used to.
The reproductive system Hyperthyroidism can cause a decrease in fertility, because it interferes with ovulation. However, pregnancy can occur. Miscarriage is more common, especially if the hyperthyroidism goes uncontrolled. Menstrual flow decreases as well and may cease. I discuss more about hyperthyroidism and pregnancy in Chapter 17. Males with hyperthyroidism have trouble having an erection in half the cases. They often experience infertility with reduced sperm count. The sperm appear abnormal when looked at under a microscope. All changes in the reproductive system disappear with successful treatment.
The stomach, intestines, and liver If you’re hyperthyroid, food moves more quickly through your intestines than it used to, and you have more frequent bowel movements or even diarrhea. You may experience nausea and vomiting. Your appetite greatly increases, and you eat more but don’t gain weight. Your doctor may tell you that your liver is enlarged. Blood tests of the liver suggest a picture of hepatitis, but when the thyroid is under control, the liver returns to normal.