Undiagnosed Thyroid Disease and Depression

Mary Shomon


How Many of the 27 Million Americans on Antidepressants Actually Have Undiagnosed Thyroid Disease?

Tuesday August 4, 2009

According to news reports out today, the use of antidepressants doubled between 1996 and 2005. Today, 10% of the population is taking antidepressant medication — that’s an estimated 27 million Americans.

The question this raises for me is, how many of these people who have been diagnosed as “depressed” — usually by primary care and family doctors — are actually hypothyroid, but haven’t been properly tested and diagnosed? How many of the people taking antidepressants may actually be misdiagnosed?

It’s an important question. Because we know that depression can be a symptom of hypothyroidism. And we also know that there appears be a relationship between autoimmune thyroid disease/thyroid antibodies and depression. And we know that thyroid treatment can sometimes help as an adjunct to treatment for depression.

Consider the scenario. A woman goes to the doctor, complaining that she’s feeling more tired than usual lately. She’s gained a few pounds. And she feels down in the dumps, a bit blue and moody. Does the doctor think, “Hmm, fatigue, weight gain, depression — these could be signs of hypothyroidism. Let me run a complete thyroid panel?” Sometimes. But more often, the doctor thinks “fatigue, weight gain, depression — these are symptoms of depression, so I’ll write a prescription for an antidepressant.”

Why is this happening?

First, thyroid disease affects women, some eight to ten times more often than men. And women often describe our symptoms to doctors in a more emotional way. It’s not uncommon for a woman to say: “Doctor, I feel just awful. I’m so depressed, I feel like a blob, and I’m so tired I can’t think straight.” And when doctors hear symptoms described like this, the tendency may be to assume a mental health diagnosis, rather than consider the possibility of an underactive thyroid.

Second, the typical family practice doctor or GP doesn’t spend enough time in medical school studying thyroid disease or learning its many signs and symptoms. Much more time is spent, for example, on diabetes, which is actually less prevalent than thyroid disease.

Third, everyone who is depressed does not have a thyroid condition. (This is not an excuse to rule out thyroid disease as a cause of the depression, but it seems to be considered as much by some physicians.)

And finally, don’t overlook the financial aspect. Sad to say, but there is cost containment going on. No tests are needed, and it costs almost nothing for a doctor in an HMO or managed care environment to write a prescription for an antidepressant and send a patient on her way. But blood tests for thyroid disease, followup, and thyroid treatment — possibly even a referral to an endocrinologist for evaluation — all cost time and money.

Unfortunately, even if in our scenario, the doctor was one of the more enlightened physicians who hears “fatigue, weight gain, depression” and immediately thinks thyroid, the majority of those doctors will run only the Thyroid Stimulating Hormone (TSH) test, rather than a complete clinical and laboratory assessment of the thyroid.

And here, we have another challenge. Since late 2002, the endocrinology community has recommended that the normal reference range be changed for the TSH test. They recommended that the range — which usually runs from about 0.5 to 5.0 — be narrowed significantly, to 0.3 to 3.0. That debate has raged for more than six years. Today, millions of Americans fall into the limbo of a TSH level between 3.0 and 5.0 — where some doctors consider them hypothyroid and warranting treatment, and other doctors consider them “normal” and would assume depression to be primarily a mental health issue, and not a symptom of hypothyroidism. So the depressed patient with a TSH between 3.0 and 5.0 — who has a doctor who isn’t up on the latest thinking — is likely to be dismissed with an antidepressant prescription — and without thyroid treatment.

An added problem: Because laboratories like Quest and Labcorp are still using the old, outdated range, many doctors are not even aware of the TSH range controversy at all, because levels above 3.0 are not flagged on the lab reports as “high.”

I’d like to see all 27 million people on antidepressants have their thyroid levels tested. And no, not just TSH tests, but TSH, Free T4, Free T3 AND thyroid antibodies levels. I’ll bet that a significant percentage of the people on antidepressants have a TSH above 3.0, and/or antibodies indicative of autoimmune thyroid disease, or “normal” TSH but low or low-normal Free T4 and Free T3, and have never even been checked.

In my opinion, as a patient advocate, a complete thyroid panel should be required before any doctor prescribes an antidepressant. But, until it is a requirement, if you are experiencing depression, please ask for a complete thyroid evaluation — and not just a TSH test.


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Filed under Abbott, Autoimmune, Hypothyroidism, Synthroid

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