Many thyroid patients—and even doctors—confuse two distinct terms: hyperthyroidism, which means “overactive thyroid gland,” and thyrotoxicosis, which means “too much thyroid hormone.” Hyperthyroidism and thyrotoxicosis are cousins that often pass as twins.
The overactive thyroid gland of hyperthyroidism classically causes too much thyroid hormone to be produced in your body. All the hyperthyroid symptoms you may have read about or heard about are, in fact, symptoms of too much thyroid hormone, which may indeed result from an overactive thyroid gland (hyperthyroid). But too much thyroid hormone can also result from other thyroid diseases—most commonly Graves’ disease—as well as too high a dosage of thyroid hormone taken as a medication.
Signs of Thyrotoxicosis
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The signs of hypothyroidism involve an overall slowing down. With hyperthyroidism, the opposite happens. When you have too much thyroid hormone in your body, everything speeds up.
Numerous physical symptoms can result, which are discussed here alphabetically. The good news is that the vast majority of these symptoms disappear once the cause of thyrotoxicosis is treated and your thyroid hormone levels are restored to normal.
The hormones released by the adrenergic system are called catecholamines. Two of these hormones are adrenaline (epinephrine) and noradrenaline (norepinephrine). High levels of thyroid hormone make you much more sensitive to the effects of your own adrenaline. Consequently, when thyroid hormone levels increase, your heart beats very fast from the combined effects of both adrenaline and thyroid hormone. Medications called beta-blockers are useful to help slow the heart down and prevent severe heart symptoms that can make thyrotoxicosis dangerous. You may notice the rapid heartbeat in thyrotoxicosis, or you may not. You may only notice it at bedtime when you are lying quietly and trying to go to sleep, as relayed by Sujata’s story. Once in a while, it may be severe enough to cause a heart rhythm problem called atrial ﬁ brillation.
Behavioral and Emotional Changes
Thyrotoxic people experience a range of emotional symptoms. Nervousness; restlessness, or the inability to sit quietly and calmly; anxiety; irritability; sleeplessness, or the inability to sustain sleep for long periods of time; and insomnia are common problems. A thyrotoxic person may exhibit some, all, or none of these symptoms; it depends on the individual.
Some thyrotoxic people are emotionally ﬁckle and easily angered.
Others may have disordered thoughts, sometimes severe enough to become frank paranoia. Some people have such severe behavioral problems that their thoughts become bizarre and delusional, although this is rare. This may warrant care by a psychiatrist until thyroid levels stabilize.
Psychiatrists see so many thyroid patients who have been referred to them as “psychiatric” patients that thyroid function tests have now become standard medical practice for most psychiatric referrals. When people experience the exhaustion of too much thyroid hormone and the natural anxiety that accompanies it, but they do not notice or report other physical manifestations such as a fast pulse or too-frequent bowel movements (which can also be attributed to anxiety), they are often misdiagnosed with anxiety or panic disorders.
Depression, which is more typically masked by, or confused with hypothyroidism, can also be masked by, or confused with hyperthyroidism. It can manifest with irritability, sadness, poor appetite, weight loss, sleeplessness, lack of energy, lack of sex drive, anxiety, and panic. Thyrotoxic symptoms unfortunately mimic these same manifestations. Finally, thyrotoxicosis can sometimes cause euphoric mood swings, a characteristic of a mania, which is present in bipolar disorder.