Three years ago, Ruth Hertz, 66, a self-described little old lady, began feeling lousy. An avid tennis player, she found herself dragging around the court. "The tiredness sort of seemed to come on suddenly," she recalled last week.
In fact, Hertz was "more than tired. I was lethargic. I was doing a lot of sleeping," she says, "and I was beginning to be a little depressed."
She finally confided her growing list of symptoms to another woman in her water aerobics class who immediately -- and correctly -- diagnosed her problem: an underactive thyroid gland.
Thyroid troubles, especially the mild, early stages of hypothyroidism or underactive thyroid, are among the most common and easily missed of medical problems, especially for older women, whose complaints of fatigue or malaise may be dismissed as anxiety, loneliness or part of menopause.
Yet more than 6 million Americans, most of them women, suffer from hypothyroidism. Another million have the opposite problem, hyperthyroidism, in which the butterfly-shaped thyroid gland in the neck makes too much, not too little, hormone.
And while some women do encounter thyroid problems right after childbirth, many more -- an estimated 10 percent to 20 percent -- first begin having thyroid abnormalities around age 60.
But increasingly, doctors are getting better not just at diagnosing these problems, but also at avoiding what used to be a major pitfall: overtreating hypothyroidism, which can cause osteoporosis, or bone loss.
Today, thanks to increasingly sophisticated versions of a sensitive test called TSH, doctors can adjust medications precisely, allowing virtually all patients to maintain normal thyroid function.
Researchers also have a more detailed picture of what causes most thyroid troubles in the first place. As we age, the immune system, for unclear reasons, sometimes begins to attack organs in the body, especially in women.
In hypothyroidism, immune cells mistakenly attack the thyroid gland, a process known as Hashimoto's thyroiditis.
Hyperthyroidism can also be caused by an auto-immune disorder -- Graves' disease -- in which antibodies attack the thyroid.
The half-ounce thyroid gland is far more important than its diminutive size would suggest. In fact, the iodine-laced hormone it makes, thyroxine, is essential -- and not just in humans.
It is thyroxine that turns tadpoles into frogs, notes Dr. Reed Larsen, chief of the thyroid division at Brigham and Women's Hospital in Boston. If tadpoles' thyroid glands are removed, they keep growing -- up to a foot long -- but never change into frogs.
Thyroid hormone is also essential for bone growth and for maintaining the basal metabolic rate -- the speed at which the body uses sugars, fats and proteins.
With increasing age, perhaps 50 percent of us develop nodules in the thyroid that doctors can feel. These usually do not interfere with thyroid function and are almost always benign, but occasionally, larger nodules may contain cancer. This is rarely fatal and can be treated by removing the affected part of the gland and treating with replacement hormones.
But it's usually the tiny, non-life-threatening changes in hormone function that cause most people misery.
If your aging immune system goes bonkers and attacks your thyroid, you may suffer fatigue, weight gain, intellectual dullness, depression, a tendency to feel cold, constipation, dry skin and other signs of an underactive thyroid. An overactive thyroid can cause fatigue, heart failure and heart palpitations, mood swings, nervousness, weight loss, heat intolerance and other problems.
And how much hormone you produce is controlled by the pituitary gland, which lies just underneath the brain.
If the pituitary senses that the thyroid gland is not making enough hormone, it puts out extra TSH, or thyroid stimulating hormone. If the pituitary senses the thyroid is making too much hormone, it decreases TSH to damp the system down.
In the old days, before TSH testing allowed doctors to measure minuscule changes in thyroid function, the only way doctors could assess function was by measuring blood levels of a thyroid hormone called T4. And the only remedy they could offer was a dessicated powder made from the thyroid glands of pigs or cows, which varied greatly in strength from dose to dose.
"But now there are better ways both to test for and treat thyroid problems," says Dr. Gilbert Daniels, co-director of Thyroid Associates at Massachusetts General Hospital.
Now, most patients' blood is tested for TSH levels, which is "much more sensitive" than T4 testing at detecting minuscule changes in thyroid function, he says. If the test shows you have hypothyroidism, the solution is straightforward.
"Just give back thyroxine," says Larsen of the Brigham. Nowadays, most doctors prescribe synthetic hormones such as Synthroid, which costs roughly $10 for a month's supply, or Levoxyl and Levothroid, which cost $5 and $7 respectively.