Six Commonly Missed Diagnoses: Subtly Underactive Thyroid

I went to medical school in London for awhile and quite honestly didn’t learn much. But it was the 1960s and if you were going to be anywhere on the planet, central London was the place to be. The fact that the hospital to which I was assigned had a pub in its basement (where everyone, even a few patients, would gravitate around 4 pm) alerted me to the fact I wasn’t in Kansas anymore.

I finished my term with precisely two pieces of memorable knowledge. First, I was endlessly reminded by fellow students, “We’re not at all like you Americans. Medical students here learn to be gentlemen first, doctors second.” This was usually delivered in a waft of beer breath, so I couldn’t take it too seriously, but I liked the line. It went well with the phony British accent I was developing.
Second, and this from a highly respected (and genuine knighted “Sir”) inebriate with a W.C. Fields nose: “Lab tests. American doctors with their lab tests. If you listen to your patient long enough and use your brain, you’ll make the diagnosis without any of that foolishness.” And the equally valid corollary, “Never rely on a lab test for your diagnosis. Let the lab test confirm your diagnosis, not make it.”
These simple rules never did manage to cross the Atlantic. As a result, millions of women (and many men as well, but women are primarily affected) experience a wide spectrum of underactive thyroid symptoms yet perpetually hear, “Well, I know your symptoms do sound like low thyroid, but see for yourself–your tests are normal.”
Symptoms, causes, and sufferers
Fatigue, gradual weight gain and inability to lose it, dry skin and dry hair with hair thinning (and thinning of the outer third of your eyebrows), facial puffiness, mental sluggishness, cold hands, cold feet, being always the coldest one in a group of people, constipation. Having had low thyroid once myself, I can report it’s a strange sense of internal coldness. You’re outside and it’s in the 90s, yet you feel cold inside.
After age 40, it’s estimated about 25% of people have symptoms of diminished thyroid function, called hypothyroidism. There are two causes. First, a condition called Hashimoto’s thyroiditis, an autoimmune disorder in which the immune system starts creating antibodies against the thyroid gland (and only the thyroid gland), slowly but relentlessly destroying it. Most doctors won’t treat Hashimoto’s until hormone levels fall into the abnormally low range
Second, a controversial condition called thyroid fatigue. In this case, the gland is simply pooped out, exhausted (often along with your adrenal glands) from having received incessant fight-or-flight stress messages along the emergency path from your brain…via your master gland, the pituitary, which controls both thyroid and adrenals.
It’s been the medical profession’s over reliance on the familiar TSH test (thyroid-stimulating hormone), developed in the 1960s, that’s led to so much missed hypothyroidism. (You may need to read this next paragraph twice. It confuses medical students, too.) TSH is released by the pituitary to stimulate the thyroid to make more of its hormone. The pituitary has a hormone-sensing system, so when thyroid hormone levels are low TSH goes up to stimulate the thyroid to make more hormone.
Remember the rule: if you have a high TSH, your thyroid hormone is low. By the way, the opposite is also true. Too much hormone (hyperthyroidism) lowers TSH levels, sometimes as low as zero.  Uh, except not always.
Depending on the lab your doctor uses, the official normal range for TSH is generally between 1.0 and 5.0. If your TSH is above 5.0, you’re declared hypothyroid (have low thyroid) and started on thyroid replacement hormone. To this day, if you go to the doctor with every single symptom of hypothyroidism listed above and your TSH is 4.9, you’ll be told, “Let’s keep an eye on it” and leave the office untreated, feeling just as crappy as when you arrived.
It’s even worse if your hypothyroidism is due to thyroid fatigue, because in this situation, your pituitary, having been bombarded with stress messages from your brain, is fatigued and depleted as well. So you’ll have all the symptoms of low thyroid and a “mysteriously” low TSH. Your doctor may shake his head in wonderment, “I agree. You sure look hypothyroid, and your hormone levels are on the low side, too, but your TSH is so low, why, you’re almost hyperthyroid.” You hand him an article from the internet. “Thyroid fatigue? Never heard of it.”
Breakthrough recommendations
Recent research in laboratory testing has uncovered three important breakthroughs that haven’t filtered down to most conventional labs and therefore to most primary care offices.

The upper limit of normal for TSH should be lowered from 5.0 to 2.5  If this were enacted, the millions of patients with TSH ranges between 2.5 and 5.0 who’d been told they were normal would actually be diagnosed as hypothyroid. Most people feel best when their TSH is somewhere between 1.0 and 2.0.

When hypothyroidism is even remotely suspected check hormone levels and check for the presence of antibodies indicating Hashimoto’s. The presence of these antibodies alone, even with seemingly normal hormone levels, is enough to warrant starting thyroid replacement therapy. When thyroid antibodies are present, thyroid function will eventually diminish. Why postpone treatment?

Since there’s really no lab test for thyroid fatigue, we need to return to an old- fashioned but reliable means of testing thyroid function–namely, measuring basal body temperature. This is your temperature just as you emerge from sleep. Readings of 97.6 degrees or lower were, for your grandmother’s doctor, diagnostic of hypothyroidism, and she’d receive a bottle of Armour thyroid from her pharmacist to restore her thyroid hormone levels.



It’s estimated that tens of millions of people have undiagnosed mild hypothyroidism, all because their physicians weren’t in Professor (Sir) Carrick’s lecture hall that morning as I listened to the elderly bleary-eyed old debauchee raise his finger skyward and ring out with, “Treat the patient, not the lab test!”
It’s a pity we don’t.
Be well,
David Edelberg, MD