We’re big believers in “evidence-based” medicine. Most recently, we questioned the fuzzy-science circumstances surrounding the death of Steve Jobs. But a recent article in The Atlantic by Megan McArdle reminds us that, sometimes, the art of medicine should play as large a role as that of science and that, ultimately, striking that balance requires the patient and the doctor to communicate well.
McArdle has lived with a thyroid condition for many years that requires periodic blood tests to determine how well that gland is functioning. For a long time, a normal thyroid was deemed to register between 0.5 and 5 for Thyroid Stimulating Hormone (TSH). But several years ago, the American Association of Clinical Endocrinologists Association of Clinical Endocrinologists lowered that threshold to between 0.3 and 3.
McArdle’s TSH levels were at the edge of the new, narrower range, and she had many of the symptoms associated with “underactive” thyroid-hair loss, fatigue, hoarseness, constantly feeling cold. (Overactive thyroid symptoms include insomnia, nervousness, heart palpitations, increased risk of bone fracture and a host of unpleasant and health-threatening problems.)
Her problem was that the numbers, the science, didn’t indicate how bad she was starting to feel.
The treatment for an underactive thyroid (hypothroidism) is a drug-thyroid hormone. And, like all drugs, it’s not without risk, so practitioners prescribe the lowest dosage possible to avoid them. As McArdle eloquently puts it, “There are real risks to taking too much thyroid hormone-it can cause heart palpitations and increase your risk of fractures. Unfortunately, too little thyroid hormone can leave you fat, bald, constipated, and depressed.”
Conservative TSH guidelines err on the side of hypothyroidism, McArdle writes, because “being hyperthyroid can kill you, while being hypothyroid just, well, makes you fat, bald, constipated, and depressed.” As long as TSH levels are under 5, many doctors believe, you are being treated appropriately, no matter how you feel.
Many primary care doctors have yet to adopt the more stringent levels recommended by the endocrinologists association, McArdle says, and even those whose patients’ blood tests show the new normal of 3 sometimes suggest these overweight, sluggish, cold people should just overcome their vanity or go to the gym more often.
“I can understand why doctors want to stick to the number: it is objective, while ‘I’m tired and kinda blue’ is not,” McArdle writes. “And presumably, you will get idiot patients who want to be thinner than is natural for them, and will lie about their symptoms in order to be prescribed dangerous levels of thyroid hormone.
“But this is not much comfort to the thyroid patient struggling to get enough energy to make it through the day.”
Which brings us back to the limitations of “evidence-based” medicine and the need for respectful, constant communication between patients and their doctors. “Evidence-based medicine works best on things that are very easy to measure, like blood levels.” McArdle says. “It is very easy to tell whether a statin reduces blood cholesterol levels. It took a lot longer to tell whether it actually reduced heart attacks.
“The more we rely on a central board to make decisions for huge numbers of people, the more tempted we are going to be to rely on metrics which can be collected, aggregated and mined for data. Where does that leave the thyroid patient with ‘normal’ blood levels . . . and a collection of vague, frustrating-but nonetheless very real–symptoms?”
McArdle found an endocrinologist willing to treat her more aggressively than mere numbers indicated to many of his colleagues. Three weeks after beginning her hormone regiment, she wasn’t so cold any more and her voice lost its scratchiness.
“I don’t want to come out against evidence-based medicine; we should always be trying to figure out what works and what doesn’t,” she writes. “But I do question what constitutes evidence. Will evidence-based medicine push us even more towards looking at numbers rather than listening to patients?”