A Newly Discovered Cause of Women’s Fatigue

Health Tips / A Newly Discovered Cause of Women’s Fatigue

Posted 12/12/2011

Given the number of women who walk around feeling tired all the time, it’s truly unfortunate that the important piece of research we’re discussing today didn’t generate more publicity.

Tucked away in the small-circulation medical journal Thyroid, whose readership is probably limited to endocrinologists specializing in thyroid disorders, there appeared an article about Hashimoto’s thyroiditis that really should have been published in a journal that every doctor reads, like JAMA or American Family Physician.

The autoimmune disorder Hashimoto’s thyroiditis is one of the most frequent causes of low-thyroid (hypothyroidism) conditions.

When you don’t have enough of the essential thyroid hormone, you’ll feel quite an assortment of symptoms, the most common by far being fatigue–a pervasive, 24/7 sense of never having enough energy to do the activities you enjoy. In fact, you may be so fatigued that your muscles actually feel weak.

Beyond fatigue, you may experience weight gain and have an impossible time trying to lose it. You might notice dry skin, dry hair, hair loss, and a peculiar thinning of the outer third of your eyebrows. You may feel mentally sluggish and constantly cold, even on a warm day. In the sack, your partner will shriek that your feet are like cakes of ice (and you really do prefer wearing socks to bed to keep your feet warm).

All this and more if you have low levels of thyroid hormone. You might notice puffiness around your eyes, your usually healthy glow replaced by a pasty complexion. You may be a bit constipated, and your periods have changed too. Having problems getting pregnant? Low thyroid can be involved. In people with severe hypothyroidism, this strange symptom occurs: your tongue actually feels too large for your mouth.

Tests for low thyroid

If you bring any or all of these symptoms to your doctor, any physician with a pulse will order a thyroid profile, a test that measures two thyroid hormones–T3 and T4–as well as a hormone from your pituitary gland that controls your thyroid, called TSH (thyroid-stimulating hormone).

With low thyroid, the T3 and T4 are low, the TSH (as your pituitary struggles valiantly to stimulate the thyroid) is high.

If your TSH is elevated and your T3/T4 low, your doctor might next order a test measuring anti-thyroid antibodies, which determines if Hashimoto’s thyroiditis is the cause of your underactive thyroid. Having your immune system create antibodies against any organ in your body is the very definition of an autoimmune disease. In this case these antibodies are targeting your thyroid—as though it were a sort of alien invader when it’s actually an utterly necessary part of your body.

Autoimmune disorders explained

We don’t know exactly what goes wrong with the immune systems of certain people, overwhelmingly women in a 20-to-1 ratio over men, but Hashimoto’s is one of several such autoimmune disorders, as are lupus, rheumatoid arthritis, and Sjögren’s syndrome.

It’s widely accepted that women’s immune systems are simply different from those of men, because the female immune system must adjust itself to the presence of a “foreign body” when a woman is pregnant.  Since half her embryo’s DNA is from a foreign source (dad), her immune system can’t simply reject this tissue or we’d never as a species be able to reproduce.

This difference in immunity somehow renders women more susceptible to all the autoimmune disorders, and Hashimoto’s thyroiditis is the most common.


When your doctor sees your elevated TSH and your similarly elevated thyroid antibodies, look carefully and you may see a subtle flicker of personal pride flashing across her face—she’s made a diagnosis of Hashimoto’s. She knows the source of your fatigue and that once you’re taking thyroid replacement hormone (Synthroid, Armour thyroid, etc.) you’ll feel better.

Your doctor may need to adjust your dose over time, using your steadily declining TSH as a guideline. As you take your thyroid replacement hormone, your levels of TSH will go down. This is because your pituitary gland no longer must flog your thyroid to get it to produce its hormone. Your smart pituitary recognizes that the thyroid replacement is in your system and is doing its job.

When your TSH is down to a normal level, you’ll be pronounced well and told that you’ll need to remain on a thyroid hormone for the remainder of your current incarnation.

“Sorry! Not quite as simple as that,” proclaimed researchers from the Medical University of Vienna, Austria, in their Thyroid journal article. What they discovered (and this is why the article is so important) is that, in women, the presence of thyroid antibodies themselves–even if you have completely normal levels of T3/T4–can cause symptoms identical to those of low thyroid.

It’s the presence of these antibodies as the newly discovered cause of fatigue that led to today’s health tip title. This is a very important piece of news and leads to a couple of serious possibilities:
• If a woman has all the symptoms of low thyroid but has normal hormone levels and normal TSH, she should not be hearing any doctor say “Your thyroid tests are normal. Whatever’s causing your fatigue, it’s not your thyroid.”

Instead, she should have her thyroid antibodies measured. If they’re elevated, her doctor should seriously consider prescribing thyroid hormone despite her normal hormone levels, using as a gauge to determine the correct dose how she feels (called “clinical response”) rather than hormone level tests. Unfortunately, women seeing their doctors for fatigue will find that virtually no physician routinely measures these antibodies.

• A woman diagnosed with Hashimoto’s thyroiditis whose antibody levels are especially high may need a higher dose of thyroid hormone than usual. And anyone tracking the fluctuations of her TSH as a guide to adjusting her thyroid hormone dose may prescribe an erroneously low dose of thyroid hormone for her particular situation.

A woman with high antibody levels may feel better on such a high dose that her lab test would register “hyperthyroid,” meaning overactive thyroid. In the past, when this occurred, doctors would lower the thyroid dose, but this article suggests “not so fast…”

We’re talking huge numbers of mainly women in this situation. Low thyroid probably affects up to 20% of women as they enter their forties. Of these, half have no access to our health care system, so they simply remain undiagnosed and tired all the time.

For those with insurance, we’ve added another large group of fatigued women: those who have been to their doctors, had their thyroid hormones tested, and were told they were normal. This group should return pronto, this health tip in hand, and say, “Listen, doc, I want you to test my thyroid antibodies. Let me show you this article…”

Be well,
David Edelberg, MD