Subclinical Hyperthyroidism

GENERAL INFORMATION:

What is subclinical hyperthyroidism?

• Subclinical hyperthyroidism is a condition where the amount of thyroid stimulating hormone (TSH) in your blood is slightly lower than normal. This hormone is produced by the brain, in the hypothalamus and the pituitary gland. The TSH controls how the thyroid gland works by telling it how much thyroid hormones to make. The thyroid gland is a butterfly-shaped organ that is located in the front part of your neck. Thyroid hormones help control body functions such as heart rate, growth, and body temperature. The thyroid hormones also control how your body uses energy, and affects weight gain and loss.
  
  
• There are two forms of thyroid hormones in the blood, the T3 and T4. When these hormones become low, the brain releases more TSH to tell the thyroid to make more hormones. If the thyroid hormone levels are too high, the brain slows down making TSH. With subclinical hyperthyroidism, the TSH is slightly lower than normal while the thyroid hormone levels are normal.

What causes or increases my risk of having subclinical hyperthyroidism?

• Autoimmune disease: The immune system is the part of your body that fights infection. A problem with the immune system may make your body attack even its own cells. The most common autoimmune disease that may cause this condition is early Grave's disease.
  
  
• Diet: Having too much or too little iodine in your diet and taking medicines with iodine may cause this condition. Iodine is an important mineral used by the thyroid gland to work correctly.
  
  
• Family history: Having a family member with thyroid disease or autoimmune disease may increase your risk.
  
  
• Medicines: This includes taking steroids or certain medicines for heart problems. Taking too much thyroid hormones to treat other thyroid diseases, such as hypothyroidism, also increases your risk.
  
  
• Other diseases: These include having conditions that affect the pituitary, hypothalamus, or thyroid gland.

What are the signs and symptoms of subclinical hyperthyroidism? You may have no signs and symptoms, or you may have general signs and symptoms of hyperthyroidism. These may include losing too much weight, having problems falling asleep, or feeling nervous and restless. You may also feel warm when other people feel cold, and have shortness of breath or a very fast heartbeat. You may have more signs and symptoms over time if your condition worsens.

How is subclinical hyperthyroidism diagnosed? You may need any of the following:

• Blood tests: You may need blood taken for tests. These tests tell your caregiver what the levels of TSH and thyroid hormones are in your blood. This information may also be used to see how well any treatments are working.
  
  
• Thyroid scan: This test shows caregivers how well your thyroid is working. Radioactive dye is put into your IV or is given to you to drink. The working part of the thyroid gland absorbs (soaks up) the dye. Two to 48 hours later, caregivers put a machine called a scintillator over your neck. The machine takes pictures showing the areas of your thyroid that absorbed the dye.
  
  
• Thyroid ultrasound: This is a test using sound waves to look at your thyroid gland. Pictures of your thyroid gland show up on a TV-like screen.

How is subclinical hyperthyroidism treated? Treatment depends on your levels of TSH and thyroid hormones, your age, signs and symptoms, and other factors. You may not need any treatment, or you may need one or more of the following:

• Medicines:
  
  
  • Antithyroid medicines: These medicines act on the thyroid and stop it from making too much thyroid hormone. They may also decrease and prevent the signs and symptoms of hyperthyroidism.
    
    
  • Others: You may be given medicines to control your signs and symptoms. This includes medicines to treat fast a heartbeat, or tremors (shakiness). If another disease or condition is seen, such as low bone density, it will also be treated.
  
  
• Radioactive iodine: The thyroid gland is the only organ in the body that can absorb iodine. A radioactive form of iodine is given to damage or kill some thyroid gland cells. This may decrease the amount of thyroid hormones made by the thyroid gland. If you are a woman, tell your caregiver if you know or think you might be pregnant.
  
  
• Surgery: You may need surgery to remove all or part of your thyroid gland. By making the thyroid gland smaller, the amount of thyroid hormones produced will also decrease.

Where can I find more information?

• American Academy of Family Physicians
  PO Box 11210
  Shawnee Mission, KS 66207-1210
  Phone: 1-913-906-6000
  Web Address: http://www.aafp.org
  

• American Thyroid Association
  6066 Leesburg Pike, Suite 550
  Falls Church, VA 22041
  Phone: 1-703-998-8890
  Phone: 1-800-849-7643
  Web Address: www.thyroid.org
  

CARE AGREEMENT:

You have the right to help plan your care. To help with this plan, you must learn about your health condition and how it may be treated. You can then discuss treatment options with your caregivers. Work with them to decide what care may be used to treat you. You always have the right to refuse treatment.

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