Do you recognize the chemical structure to the left? If you are hypothyroid, that’s what you’re probably taking: levothyroxine, the primary thyroid hormone in humans.
No doubt your doctor prescribed this medication, but the question is why? Were you overtly hypothyroid, with typical symptoms of fatigue, dry skin, constipation, decreased heart rate? Was your TSH significantly elevated with depressed T3 and T4 levels, or was your TSH just a little elevated with normal T3 and T4?
The most common reasons doctors prescribe Synthroid (Levothroid, levothyroxine) are: 1) mildly elevated TSH levels (with normal, compensated, T3 and T4); and 2) very high TSH levels (with normal T3 and T4, or depressed T3 and T4, with or without symptoms.)
In humans, when the production of thyroid hormones (T3 and T4) begins to wane, the pituitary increases the amount of TSH (thyroid stimulating hormone) in order to stimulate the thyroid gland to produce more hormone. Often this normalizes the level of circulating thyroid hormone in your blood. Sometimes the thyroid cannot keep up, and the TSH rises higher and higher and symptoms begin to develop. Occasionally a goiter (swollen thyroid) grows at the base of the neck.
Those with mildly elevated TSH levels (resulting in compensatory normalized T3 and T4 hormones) may not need medication. Those with very high TSH levels, especially with decreased thyroid hormone production and symptoms of hypothyroidism, require thyroid replacement therapy to lead a normal life.
The question is, which are you? If thyroid hormone therapy is unavailable, what will happen? Will you die?
If you’re one of the patients who has experienced symptoms of hypothyroidism and whose TSH was extremely high at the time of diagnosis, you already have your answer: you require medication. Likewise, if you had 100% of your thyroid surgically removed, you’re in the same boat. Without the medicine, symptoms will gradually develop, possibly leading to coma (and death, though I’ve never seen this happen).
But most patients that I see actually have subclinical hypothyroidism, that is, their TSH runs a bit high (say 2 to 10 mIU/L above normal), but they have no symptoms. Some of these patients I’ve observed over time without medication and have found that their TSH levels vary. If one thinks of the underlying problem as an autoimmune condition (which it often is), this makes sense. Other autoimmune diseases, such as arthritis, vary regarding severity of symptoms. If the thyroid is inflamed to varying degrees with time, just as acne flares on occasion, then the T3 and T4 output would vary. In response to this, the pituitary compensates by adjusting the output of thyroid stimulating hormone. All this is to say that many of these patients do not require medication. Compare this to another endocrine disease, that is, the patient with mild diabetes who requires little or no medication, and likely will never need insulin.
You may not know which class you fall in. Your doctor may not know either, if you were started on Synthroid long ago or with another doctor. It is, however, possible to find out.
To know if you are this type of patient you need to discuss the following experiment with your doctor. A patient’s dose of levothyroxine may be tapered or discontinued and the TSH monitored closely, perhaps once every month or two for a period of time. If lowering or decreasing the dose is going to be a problem, generally an elevated TSH would show up before a patient experiences symptoms, thus allowing treatment to be promptly reinitiated.
This depends, of course, on the patient. For a patient in whom I suspect a total lack of thyroid production, I would taper the dose more slowly and/or monitor the TSH every few weeks early on. An example of such a patient is one whose thyroid was irradiated for Grave’s disease. Such a patient may have residual functioning tissue. To determine if that is the case, the patient must be off medication (or on a reduced dose) to allow the TSH to rise, if it’s going to.
For a patient whom I diagnosed myself (or have documentation of a minimally elevated TSH level prior to therapy), simply stopping therapy and monitoring the result closely is an option.
Of course, patients do this all the time – they just don’t monitor their blood tests. They run out of medicine for a week or a month or longer and perhaps don’t feel any different. Rarely do they actually become symptomatic. It is possible to monitor your TSH level yourself, by collecting your blood and sending it to an accredited lab. (Check online for available services.)
If you find your TSH is elevated by a few points, even 10 or 20, but your thyroid hormone output remains normal, then discuss with your doctor whether taking medication is mandatory – it may not be.
I am not, however, suggesting you perform this experiment on yourself without physician supervision. If your doctor already has evidence for which type of hypothyroidism you have, there’s no need to experiment. But if not, please discuss the situation with him or her. Better to know now, when testing is readily available, than to guess later.
Although there are other rare forms of hypothyroid disorders, the above is applicable to the vast majority of patients.