Clinical Nutrition Topic of the Day: Hypothyroidism

Throughout the week of my clinical nutrition rotation, I have noticed several patients suffering from a disorder called hypothyroidism. In fact, it is estimated that approximately 3-5% of the population suffer from hypothyroidism. Thus, I thought I would do some research on the topic.

Where is the thyroid?  The thyroid is a butterfly-shaped organ located in the front of the neck, in front of the windpipe (or trachea) and just below the voice box (larynx).

The thyroid gland.

What is the function of the thyroid?  The thyroid gland uses iodine from food to make two thyroid hormones:  thyroxine (T4) and triiodothyronine (T3). The thyroid gland stores these hormones and releases them as they are needed.  The hypothalamus in the brain regulates the thyroid hormone.  The hypothalamus releases thyrotropin-releasing hormone (TRH), which stimulates the pituitary gland to release thyroid-stimulating hormone (TSH). When the hypothalamus and pituitary are working normally, they sense the levels of thyroid hormone in the body and release the appropriate amount of TRH and TSH to either stimulate or reduce the thyroid’s production of thyroid hormones.

What are the roles of thyroid hormones?

  • Regulates the rate at which calories are burned, affecting weight loss or weight gain.
  • Can slow down or speed up the heartbeat.
  • Can raise or lower body temperature.
  • Influence the rate at which food moves through the digestive tract.
  • Control the way muscles contract.
  • The rate at which dying cells are replaced.

What is hypothyroidism?  A disorder when the thyroid is not making adequate amounts of thyroid hormones.  Chronic hypothyroidism can raise LDL cholesterol and increase the risk of CVD.  It may also cause other problem such as goiter, depression, and damage to the peripheral nerves.

Here are some common symptoms of hypothyroidism:

  • Feeling tired, weak, or depressed.
  • Dry skin and brittle nails.
  • Not being able to stand the cold.
  • Constipation.
  • Memory problems or having trouble thinking clearly.
  • Heavy or irregular menstrual periods.

What are the risk factors/causes of hypothyroidism?

  • Older age
  • Females>Males
  • Severe iodine deficiency
  • Autoimmune disease
  • Radiation
  • Thyroid surgery
  • Pregnancy

What types of medications are used to treat hypothyroidism?  Daily use of the synthetic thyroid hormone levothyroxine (Levothroid, Synthroid, others).

What type of dietary precautions should I take while taking thyroid hormone replacements?  Generally, patients should avoid consuming high fiber because it affects the absorption of the thyroid hormone.  Other foods that should be avoided are walnuts, soybean flour, iron supplements, calcium supplements, antacids containing Mg or Al, some ulcer meds (such as Carafate), and some cholesterol-lowering drugs.




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