By Dr. Russell Blaylock M.D. From Newsmax

Thirteen million Americans — equal to the populations of Los Angeles and Chicago combined — have a miserable, deadly disease. And they don’t even know it.

These Americans suffer from hypothyroidism, a condition characterized by the thyroid gland producing too little of the various thyroid hormones.

Half of those affected have no idea, so they go without treatment. These hormones carry out a number of important functions. They control the development of the body — especially the brain — and regulate the metabolism of every cell, tissue, and organ in your body.

When I was growing up, it was common to see women walking around town with a huge lump, often as big as a grapefruit, in the front of their necks.

This was called a goiter — a sign of iodine deficiency. Iodine, a chemical element found in seawater and some minerals and soils, is essential for the thyroid.

Once manufacturers added iodine to table salt, goiters were far less common. Unfortunately, many brands of salt no longer contain iodine, and the problem is returning.

The other major source of iodine, seafood, is also less frequently eaten because of concerns about mercury contamination.

Most doctors can diagnose a full-blown case of hypothyroidism, but not always. When a person loses a majority of the function of the thyroid gland, especially if it occurs rapidly, some obvious and immediate symptoms develop:

• Sudden unexplained weight gain or great difficulty losing fat

• Severe fatigue and frequent exhaustion

• Depression and gloominess

• Frequent constipation

• Heavy bleeding with periods

• Dry, coarse, itchy skin

• Puffiness of the face, especially in postmenopausal women

• Dry, coarse, thinning hair (also losing the outer third of your eyebrows)

• Intolerance to cold

These are symptoms of full-blown hypothyroidism, but increasingly, the medical profession is recognizing that many people have lesser degrees of thyroid hormone deficiency, called subclinical hypothyroidism. Dr. Russell Blaylock, author of The Blaylock Wellness Report newsletter, is a nationally recognized board-certified neurosurgeon, health practitioner, author, and lecturer. For 26 years, he practiced neurosurgery in addition to having a nutritional practice. He recently retired from his neurosurgical duties to devote his full attention to nutritional research. Dr. Blaylock has written four popular books.