Depression, the thyroid and hormones
Depression is a common symptom of an underactive thyroid, also called hypothyroidism.
A doctor will want to rule out other causes of the depression, and diagnosis of underactive thyroid may be reached once other symptoms have been explored, such as tiredness and weight gain.
Mood swings, irritability and nervousness are more common with overactive thyroid, or hyperthyroidism, than underactive thyroid.
Other underactive thyroid symptoms
When the thyroid gland does not produce enough hormone, the body uses energy at a slower pace than it should. This condition, underactive thyroid, is called hypothyroidism. Symptoms that may indicate hypothyroidism include:
- Dry, coarse skin and hair
- Frequent, heavy menstrual periods
- Hoarse voice
- Inability to tolerate cold
- Weight gain
Some of these symptoms - fatigue, irritability, weight changes, sleep problems - are symptoms that may also indicate depression.
Your doctor may arrange blood tests to determine levels of certain hormones, including:
- Thyroid stimulating hormone (TSH)
- Triiodothyronine (T3)
- Thyroxine (T4)
What causes thyroid disease?
There are many different reasons why either hyperthyroidism or hypothyroidism might develop. Hyperthyroidism affects up to one in 50 people and is ten times more common in women than in men. It can occur at any age but is most common between the ages of 20 and 40. Hypothyroidism is 15 times more common in women than in men and is most common in people over the age of 40. People of all ages and races can get thyroid disease. Some babies born with a non-functioning thyroid gland may have thyroid disease from the beginning of life. Hypothyroidism may be caused by:
- Thyroiditis, an inflammation of the thyroid gland that can affect the level of thyroid hormone production
- Hashimoto's thyroiditis, a painless autoimmune disease
- Post-partum thyroiditis, which occurs in five to nine percent of women who have given birth and is usually temporary
Hypothyroidism can also be caused by the side effect of certain drugs, such as lithium and amiodarone, and by iodine deficiency. The thyroid gland uses iodine to make hormones. According to the NHS, this cause of hypothyroidism is practically unheard of in Britain, as even very poor diets contain enough iodine. However, iodine deficiency is a problem world-wide.
Hyperthyroidism may be caused by:
- Graves' disease, an enlarged thyroid gland (also called diffuse toxic goitre)
- Nodules that may form in the thyroid and may cause it to be overactive
- Thyroiditis, an inflammation of the thyroid gland that can cause the release of stored hormones (If thyroiditis causes all the hormones to be released, hypothyroidism can follow.)
- Excessive iodine, which might be found in certain drugs and some cough syrups