Testing your thyroid: why you can't always trust the TSH

For years, my wonderful gastroenterologist was testing my thyroid (or so I thought) and the results were always "normal!" I thought nothing of it until last winter, when I became concerned that I felt crummy more often than not. Things I used to love doing now seemed like a huge chore, and housework and laundry felt like the most unsurmountable tasks ever.

My mom kept asking me, "Have you had your thyroid checked?" I insisted that yes, it's been checked, and yes, it's normal. She told me how unreliable the TSH can often be for some people, and I dismissed it as more of her "woo" medicine. Until I started making a mental note of how I felt and decided to look into it. What a shocker I was in for.

Many of the symptoms I was experiencing showed up on lists all over the internet, including an explanation of why the often-hailed TSH can sometimes leave many people under treated or even undiagnosed. I learned to be wary of doctors who told me that the TSH was the 'best way' to determine if you had a thyroid problem.

The TSH is kind of like a complex math problem: it's one component of the equation, but without the other numbers, it might not make much sense. It could look okay on its own, but not really be complete. By only looking at the TSH, it is a very misleading piece of the puzzle, when in fact there's much more that needs to be considered before solving the problem.

Photo credit: thevreelandclinic.wordpress.com

Before the TSH blood test was invented in the 1970s, doctors often paid attention to the symptoms a patient was experiencing. While not always a perfect science, I think it also reflected how more patient-centered the medical profession used to be; now with the advent of more tests and drugs to treat everything, we've definitely gone in the opposite direction. The TSH test was developed with a pool of approximately 200 volunteers (that's it?!) to test for 'normal' ranges of thyroid function, and has been used as a guideline ever since. The problem is, not everyone is the same - some people can feel relatively great with a higher TSH than others, and some feel like crap when their TSH is in the normal range. To confuse you even further, even though there are clear guidelines established, different labs use different "normal ranges."

Some thyroid advocates argue that since hypothyroidism is so prevalent, the volunteers themselves were not really 'normal' and our guidelines are false. As our medical community moved away from a more individualized approach to medicine and pharmaceuticals became more widely available, doctors treated blood tests as all-encompassing methods to diagnose patients, which has backfired for many who fall within gray areas of the spectrum.

Just among the friends that I've talked to, I know that my neighbor is on medication (a higher dose than I am, even) and yet she said she had no symptoms. Without trying to pry, I concluded that her TSH must have been high and that her doctor was simply doing routine blood work (wow!). Someone else I know said that her TSH "was at the high end of normal" and her doctor didn't think she needed medication just yet, even though she is the most miserably tired-looking person I think I've ever met. I tried to explain it to her gently, but of course since I'm not a doctor my opinion is invalid. She is definitely someone I think who could benefit from treatment, but I guess she'll just have to wait until her TSH explodes off the charts before she gets it.

Normal reference ranges for TSH function have been changed within the last few years, and are from 0.3-3.0. Before that, 0.5-5.0 were considered "normal." And still, I read of physicians who refuse to treat someone with a TSH hovering at 5.0, acting as if everything is all in the patient's head. In comments read around the web, one patient said her doctor routinely doesn't treat you until your TSH is above 10. Time to find a new doctor!

One patient tells her story about having trouble reaching her normal weight (that she had maintained for years) and asked her doctor about the possibility of a thyroid problem.

I scheduled an appointment with my doctor. I explained why I thought I may be having thyroid problems. He just laughed at me, when I suggested I might be hypothyroid. I even took my documented temperature readings, plus hypothyroid symptoms with me, but he discounted them all. He said temperature readings to test for hypothyroidism dated back to the 1920's. He intimated that since at 130lbs I wasn't "fat" by medical standards, I therefore couldn't possibly have a problem with my thyroid. I still insisted on blood tests to check TSH (thyroid stimulating hormone) levels. This test came back showing a TSH level of 6.7, and in Canada, the reference range of 0.5 - 4.5 means, "No Problem", 4.5 - 10 means "Euthryoid - perhaps there may be a problem developing" and > 10 means "Possibly we had better treat the patient." Now this is where the issue starts getting murky. You see, the American Endocrinology Association and the British Medical Journal have all (for years) been saying that these reference ranges are incorrect, that since thyroid problems are actually extremely common (especially in women), that these numbers include large numbers of people with underlying thyroid problems - thus the numbers are skewed and actually anything > 2 (some say 2.5) should be treated as "suspect".

So, anyhow, despite my many symptoms such as dry skin, thinning hair, memory problems, low temperature, emotional spells, low energy at times, and now a TSH of 6.72 (obviously greater than the new TSH reference ranges) my doctor was unimpressed and wrote "Euthryoid" on my form and sent me packing.

This attitude prevails, even though TSH guidelines have been lowered in an attempt to diagnose more missed patients who fall through the cracks.

If your TSH is within normal limits, they will often ignore your symptoms. If it's high, it often means the majority of the damage to your thyroid has already been done. It doesn't mean it's too late to treat it, but it often signifies that thyroid damage has slowly been occurring for years before you finally pieced two and two together and sought treatment. This is why the most common cause of hypothyroidism is Hashimoto's Disease, which is an autoimmune precursor that begins to destroy the thyroid gland first (more on this later).

If your TSH is normal, it doesn't mean that damage isn't occurring. It just means that oftentimes it's not that bad yet that it's registering on a blood test. There are other tests that can be done, including ones that examine each level of thyroid hormone and how your body is converting that hormone into energy. Also, antibody tests can be ordered (peroxidase and thyroglobulin) to determine if you have Hashimoto's. However, beware: a certain percentage of the population do have Hashi's but do not have elevated antibodies; just because you don't doesn't mean you don't have a thyroid disorder. If your doctor is reluctant to order any thyroid tests, or wants to adhere strictly to the TSH, question his position or find a new doctor who will take you more seriously.

If left untreated (or under-treated), thyroid disease can cause major complications such as heart disease, diabetes, depression, infertility and other autoimmune diseases. Unfortunately, the modern medical approach is to treat symptoms instead of the root cause, which could explain why so many Americans are being treated with expensive drugs for diabetes, depression and high cholesterol. In fact, upwards of 20 percent of people treated for depression may really have underlying hypothyroidism that is undiagnosed. There's also evidence to suggest that hypothyroidism "brain fog" can mimic symptoms of fibromyalgia Alzheimer's, which means more expensive medications to treat the symptom rather than the root cause (and true Alzheimer's can only be diagnosed with autopsy).

The bottom line: when it comes to thyroid disease, there is no "normal," it seems. Healthcare professionals are too quick to put you in a neat, tidy little box that explains - or dismisses - your symptoms entirely. This could explain why so many people say "My doctor refuses to order more blood tests," or "My doctor refuses to put me on medication" - because they're either stuck to ridiculous, often flawed guidelines or are attempting to treat something that they don't fully understand.

More reading:
Rethinking the TSH Test - Mary Shomon interviews Dr. David Derry