The Governor General,
Michaëlle Jean
Photo by Sgt Éric
Jolin, Rideau Hall. |
Being the Queen's representative
on Canadian earth isn't all cocktail parties and red-carpet
events. At first it seemed our glamourous Governor General
Michaælle Jean's gruelling schedule visiting Canadian
troops and honouring the fallen soldiers at Vimy Ridge's
90th anniversary led to her near collapse from exhaustion.
Then her office made this announcement: "Her Excellency's
thyroid gland was not functioning normally, which caused
her to suffer from acute fatigue."
Her Excellency the Right Honourable
Governor General is far from alone in suffering from
thyroid dysfunction. According to the Thyroid Foundation
of Canada — of which Ms Jean happens to be patron
— roughly 30% of Canadians live with a thyroid
condition of one form or another. The disease, which
throws off the levels of the metabolism-regulating transcription
factors it secretes, commonly brings on the kind of
sudden exhaustion Ms Jean suffered, which could be caused
by both over- or under-activity of the gland.
"It's very common, especially in
women of her age," says Dr Jay Silverberg, a thyroid
specialist and associate professor of medicine at the
University of Toronto. "Roughly 3% of Canadians are
hypothyroid."
Common causes of hypothyroidism
include Hashimoto's thyroiditis and surgical or radiation
treatments for Grave's disease. In rarer instances,
a hypothyroid state can result from hypothalamic or
pituitary malfunction.
THE
DIAGNOSIS
Symptoms of fatigue, mental and physical sluggishness,
depression and weight gain often offer the first clue
that your patient's thyroid's acting up. A test of pituitary-secreted
thyroxine stimulating hormone (TSH) levels will usually
clinch your diagnosis.
TSH secretion causes the release
of thyroxine (T4) and iodothyroxidine (T3) from the
thyroid. Thyroid tissue dysfunction will result in a
drop of circulating thyroid hormone levels. "The loss
of these hormones causes uncontrolled release of TSH,
which is normally under their negative feedback regulation,"
explains ontolaryngologist Dr Jeremy Freeman of Mt Sinai
in Toronto. "TSH is a very accurate index of thyroid
hormone levels." Dr Silverberg adds that a cut-off value
of 10 mIU/L is typically used to diagnose hypothyroidism.
In rarer hypothyroid cases TSH will be below normal,
due to poor signalling by the hypothalamus or pituitary.
While hypothyroidism can warrant
decisive treatment, patients may also present with just
a slightly low thyroid tone. In these cases, intervention
with medications might do more harm than good, says
Dr Silverberg. "These patients should be monitored,
but not necessarily treated at just the slightest hint
of low TSH levels."
STANDARD
vs ALTERNATIVE Tx
"If someone doesn't produce enough T4, the hormone has
to be supplemented, or in the case of total thyroidectomy,
completely replaced," says Dr Freeman, who adds that
he's performed more thyroidectomies than anyone else
in Canada. The drug of choice for treating hypothyroidism
is synthetic thyroxine (T4), and is usually all that's
necessary, says Dr Silverberg.
"We generally discourage the use
of 'natural' and herbal remedies for hypothyroidism,"
cautions Dr Silverberg. "What could be more natural
than T4? It's synthesized, but it replaces exactly what
the thyroid should be producing, anyway. A lot of people
also take dessicated animal thyroid tissue. It may do
the job, but possibly not as well because it contains
impurities."
Patients may also ask you about
iodine supplementation, since iodine deficiency used
to be the leading cause of hypothyroidism. But nowadays,
most Canadians get more than enough in their normal
diet. Dr Silverberg adds that some thyroid conditions
can actually be worsened by iodine supplementation,
so he doesn't recommended it.
Calcium and iron supplements can
interfere with absorption of T4 pills, so warn your
patients not to take these together.
Treatment with T4 isn't without
risks. Watch out for overuse, which can render a state
not unlike hyperthyroidism, with its associated risks
of heart problems and osteoporosis.
FOLLOWUP
CARE
Dr Freeman and Dr Silverberg agree that hypothyroidism
should be pretty straightforward for you to manage.
Lifestyle changes required of patients will generally
centre around proper medication use. But Dr Silverberg
points out that many thyroid patients are not monitored
closely enough, and have TSH levels that are too high,
or too low. "Once you put a patient on T4, you can't
just forget about it." He advises you to schedule routine
annual checkups to monitor TSH levels. This will tell
you if the medications need to be adjusted or if the
condition changes, and assure you that patients are
sticking to their treatment regimen. T4 dosing should
be adjusted during pregnancy. Physicians should inform
hypothyroid women in their reproductive years to consult
with them if they become pregnant, for an increase of
their T4 dose.
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