Depression and Thyroid Illness
Introduction
Depression may be the first sign of an overactive or underactive
thyroid. The nervousness, anxiety, and hyperactivity of hyperthyroidism
often interfere with a person's ability to function in normal daily
activities. Both anxiety and depression can be severe, but should
improve once the hyperthyroidism is recognized and treated.
Depression is more commonly associated with hypothyroidism with
its fatigue, mental dullness and lethargy leading to depression
which is often profound and severe enough that a physician may mistakenly
treat the patient first for depression without testing for underlying
hypothyroidism. Since most hypothyroidism begins after age fifty,
the symptoms are often attributed to aging, menopause and/or depression.
Postpartum Depression
Approximately one in twenty women experience a change in thyroid
function following pregnancy. Since this is a time when the responsibilities
of the young mother are considerable, she may attribute the fatigue
and emotional symptoms as a natural result of her increased duties
and lack of sleep. Some physicians have suggested, however, that
every young mother who experiences depression should have a TSH
test to be sure her thyroid function is normal.
Bipolar Mood Disorders and Thyroid Disease
Bipolar is a relatively new term that psychiatrists are using
to describe individuals whose emotions tend to swing from highs
to lows, elation to the blues. A subgroup of this population experience
rapid cycling, meaning that they have at least four major highs
and lows per year. Studies of patients with rapid cycling bipolar
disorder, (80% of whom are women) have shown that 25-50% have evidence
of thyroid deficiency. Some feel well, and their only evidence of
thyroid failure is an increased level of TSH in their blood. Others
are clearly hypothyroid.
Lithium: A problem for some patients
Physicians have prescribed lithium in the treatment of depression
for years. It has a low incidence of side effects and a high success
rate in treating depression, especially bipolar disorders including
the rapid cycling described above.
Unfortunately, in individuals with an underlying tendency toward
thyroid dysfunction, lithium may cause hypothyroidism. Since most
physicians are aware of this relationship, it is now common for
a physician to first check the serum TSH levels of a patient before
prescribing lithium, repeating the thyroid test periodically while
the patient is on the medication.
Are you at risk?
Not all individuals with depression have a thyroid problem. Nevertheless,
because thyroid dysfunction can be so difficult to recognize yet
so responsive to treatment, most physicians will order an initial
serum TSH test to evaluate thyroid function.
You are at increased risk if you or a close relative has had a
thyroid problem. Your risk is also increased if you have a related
autoimmune condition such as diabetes requiring insulin treatment,
pernicious anemia, or the white skin spots of vitiligo. You are
also more likely to develop thyroid dysfunction if you or a close
relative have had prematurely gray hair (one gray hair before thirty)
or any degree of ambidexterity or left-handedness.
But why risk missing a thyroid problem if you are depressed? Discuss
these concerns with your physicians and be sure that your TSH has
been checked before you are treated for depression.
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