Whether it’s overactive or underactive, a misbehaving thyroid gland has to be checked out
By Wendy Haaf
When Linda Rooker of Qualicum Beach, BC, began to experience brief episodes of a racing heartbeat a few years before retiring in 2003, she initially thought menopause might be the culprit. When these bouts grew longer and were joined by other niggling issues including stomach problems, her doctor, who insisted that they consider only one symptom at a time, recommended cutting back on caffeine.
When in his late 40s Ben Benedict of London, ON, began noticing small, nagging complaints such as chest pain, recurring dizzy spells, and feeling cold, he put it down to what he says he thought was “normal aging.”
In both cases, the real problem was a malfunctioning thyroid, a butterfly-shaped gland in the neck that regulates metabolism and produces hormones that virtually every cell in our bodies needs to function normally. According to the Thyroid Foundation of Canada, one person in 10 has some type of thyroid condition at some point during his or her life, up to 50 per cent of which go undiagnosed.
Five to eight times more common among women than men, thyroid disorders also become increasingly prevalent with age, affecting one in five people aged 75 or older and up to 25 per cent of residents in long-term care. And not only can the symptoms—which can come on very gradually—be mistaken for those of everyday ailments such as viral infections or age-related changes, they can be much more subtle in older people. “I didn’t know I was sick until I started feeling better,” Benedict says.
What can go wrong with your thyroid? And when should you suspect something might be amiss? To find out, we spoke with several experts from across Canada.
“With thyroid disease, you can have a disease that’s related to function that is abnormal or to structure that is abnormal,” says Dr. Terri Paul, a professor of endocrinology and metabolism at Western University’s Schulich School of Medicine & Dentistry and an endocrinologist at St. Joseph’s Health Care London, ON. The most common type of functional thyroid disorder is hypothyroidism—an underactive thyroid gland producing little or no hormone.
This undersupply can cause a range of issues, including fatigue, depression-like symptoms, difficulty concentrating or thinking clearly, constipation, dry skin, a hoarsening of the voice, weight gain, and muscle weakness. An abnormally high blood cholesterol level is another potential clue. “People can get muscle pain, as well,” notes Dr. Ally Prebtani, an endocrinologist and professor of medicine at McMaster University in Hamilton, ON. These changes can creep up slowly and incrementally, and may be few or mild or both in people over 55.
If you experience such symptoms, it’s worth raising the issue with your doctor. As part of an effort to get to the bottom of what’s going on, he or she will likely order a simple blood test called the TSH (for thyroid stimulating hormone) to find out if the gland is functioning normally. “It’s a fairly accurate test, and it’s not super-expensive, so it’s an easy thing to check,” Paul says.
One important note about TSH testing: taking supplements containing the B vitamin biotin can throw off the results.
A high TSH level indicates that the thyroid isn’t making enough thyroid hormone. “The thyroid is like the heater in the room and the TSH, which is produced by the pituitary gland, is like the thermostat,” explains Dr. Christopher Kovacs, a professor and researcher in the Faculty of Medicine, Endocrinology, at Memorial University of Newfoundland in St. John’s. In this scenario, thyroid hormone (actually two forms, called T4 and T3) is the temperature in the room. Just as the thermostat will switch the furnace on if the temperature in the room dips below a certain level, if the level of thyroid hormone drops, the pituitary churns out more TSH. Ordinarily, this prompts the thyroid to produce enough thyroid hormone to bring levels up into a normal range. (What’s considered a normal TSH measurement varies a little from lab to lab, and by age, but generally, it’s between 0.3 and anywhere from 3.0 to 5.0 mIU/L. “There’s a bit of a range,” Prebtani says: one person might feel fine at 5.0, while another might start developing symptoms at 3.5.)
If the thyroid is underactive, however—for example, because it’s under attack by the immune system (as occurs in Hashimoto’s thyroiditis, the most frequent cause of hypothyroidism)—the TSH levels continue to climb.
“If the TSH is abnormally high, that tells you the thyroid’s not working,” Kovacs says. “In a lot of labs, they’ll do only the TSH first, and then if that’s abnormal, they’ll do free T4 and maybe free T3,” he adds. “How abnormal the free T4 and free T3 are gives you an idea of how badly off the patient is, and gives you a guide for whether to treat and how much.” It was an abnormal TSH test, run as part of a checkup after he turned 50, that led to Ben Benedict being diagnosed with hypothyroidism caused by Hashimoto’s. After having been without a regular physician for a few years, “I had found a doctor and I just went in to get my oil checked, and they discovered my hormone level was really off,” he says.
The mainstay of treatment is replacing the body’s own supply of thyroid hormone (T4) with a pill such as Synthroid or Eltroxin. “It is a bioidentical hormone—in other words, chemically exactly the same as what your body makes,” says Dr. Andrea Opgenorth, an associate clinical professor of endocrinology and metabolism in the Department of Medicine at the University of Alberta in Edmonton. (By contrast, desiccated pork or beef thyroid—used to treat hypothyroidism before it was possible to make the bioidentical version—contains three to four times more T3 than the human variety, and the dose can vary from pill to pill and batch to batch, so desiccated thyroid is generally no longer recommended.) “Straightforward Hashimoto’s thyroiditis, straightforward thyroid replacement, is generally very well managed by family doctors,” Opgenorth says, and the condition rarely requires referral to a specialist.
Typically, the physician will estimate the dose needed based on the patient’s free T4 and T3 levels, his or her age, overall heart health status, and weight, Prebtani says. “It’s initially a guesstimate, and there’s often tweaking to get to the right dose.”
“If I have someone who’s elderly and profoundly hypothyroid,” Paul says, “I start with a very low dose and gradually increase it, because if they have been hypothyroid, their heart has been hypothyroid, too, and as it speeds up, they could get angina, chest pain, or even a heart attack.”
In Benedict’s case, “it took about two years to get the dosage right,” he says. While he still has occasional bouts of dizziness and fatigue and has had to give up vigorous gym workouts, he lives an active life and, having returned to school at 50, just completed his master’s thesis.
While most people with hypothyroidism fare well with thyroid hormone replacement, some struggle with lingering symptoms such as fatigue. In such cases, it’s important to rule out correctable issues, such as medication interactions and improper storage of medication. For example, you should take Synthroid and iron or calcium at different times of day since these nutrients can bind with thyroid hormone. In addition, since Synthroid and Eltroxin are sensitive to light, heat, and moisture, “thyroid tablets can become completely inactive after two months if they’re kept in common places such as on the kitchen windowsill, next to the stove, or in the bathroom,” Kovacs cautions. “The solution is either to store the tablets in a cool, dark place not subject to extremes in humidity or to get only a month’s supply at a time.” (Missing the odd dose is less of a problem, since it takes a week after completely stopping the medication for levels to drop by half in the blood, Kovacs says.)
If symptoms persist, there are two possible explanations. “One is that maybe the tiredness isn’t due to the thyroid,” Kovacs says, but to something entirely unrelated, such as an age-related decrease in sleep quality. “Or it may be there’s something the thyroid produces that we’re not fully making up for when we give the T4 back.”