The thyroid gland is a small organ on the front surface of the neck, in front of the trachea, which produces hormones that affect heart rate, body temperature, and basal metabolism. When its function slows down or speeds up, symptoms can resemble fatigue, stress, or other conditions. We break down how to distinguish hypothyroidism and hyperthyroidism by their manifestations and which examinations a doctor usually suggests.
Gland function and hormones
The thyroid gland consists of two lobes and an isthmus, is located on the front surface of the neck, and regulates basal metabolism. Its follicles produce thyroid hormones — thyroxine (T4) and triiodothyronine — and C cells produce calcitonin, which is involved in regulating calcium metabolism. Hormone synthesis requires iodine, which comes from food. When the gland produces too few hormones, it is called hypothyroidism; when too many — hyperthyroidism.
What to remember: hypothyroidism is reduced thyroid function, hyperthyroidism is increased.
Hypothyroidism: when the gland slows down
Symptoms of reduced thyroid function can be mild and unnoticeable, developing gradually. Common manifestations include pronounced fatigue, feeling cold more often than usual, weight gain, constipation, difficulty concentrating, depressed mood, dry skin and hair or hair loss, a hoarse voice, irregular or heavy menstruation. The main cause is the autoimmune disease Hashimoto's, in which the immune system attacks the gland; it occurs more often in women and usually begins at age 30–50. Other causes include other thyroid conditions, such as thyroiditis, surgery or radiation to the neck, treatment of hyperthyroidism, insufficient iodine intake from food, and taking certain medications. Untreated hypothyroidism increases the risk of heart disease, in particular coronary heart disease and heart failure, and osteoporosis, and during pregnancy — of complications such as high blood pressure, birth defects, premature birth, or miscarriage.
What to remember: gradual fatigue, cold, and weight gain are a reason to see a family doctor, who will decide whether TSH and T4 are needed.
Hyperthyroidism: when the gland speeds up
An excess of thyroid hormones can produce many different manifestations: nervousness, anxiety and irritability, mood swings, difficulty sleeping, constant fatigue and weakness, sensitivity to heat, swelling in the neck due to an enlarged gland (goiter), irregular or too-fast heart rhythm (palpitations), tremor, weight loss. Hyperthyroidism can occur in anyone, but about 10 times more often in women, typically at age 20–40. The most common cause is Graves' disease, an autoimmune condition in which antibodies force the gland to produce too many hormones; about 4 out of 5 people with hyperthyroidism have Graves' disease. Other causes are nodules on the gland and certain medications, in particular amiodarone. Without treatment or with poor control, hyperthyroidism can cause eye problems — irritation, double vision, bulging eyes — and pregnancy complications such as high blood pressure, premature birth, or miscarriage.
What to remember: palpitations, tremor, and sensitivity to heat are a reason to see a doctor.
Nodules and goiter
Enlargement of the gland (goiter) may be noticeable as swelling in the neck. Nodules are additional gland tissue that can produce hormones and raise their levels. A doctor may examine the neck to determine whether the gland is enlarged.
What to remember: a doctor evaluates neck swelling by examination, not only by tests.
Which tests a doctor evaluates
In addition to symptoms and family history, the doctor asks whether there has been a recent pregnancy — this affects further examinations.
- Asking about symptoms and family history
- Neck examination to detect an enlarged gland
- Blood test for TSH and T4
- Referral to a specialist to clarify the cause
What to remember: the basic tests are TSH and T4, then a specialist if needed.
When to see an endocrinologist
See a family doctor if you notice symptoms of reduced or increased thyroid function: some of them also occur with other conditions, but it is appropriate to check them. The doctor will decide whether tests are needed and, if necessary, refer you to an endocrinologist. If you have hypothyroidism and are planning a pregnancy or are already pregnant, tell your doctor — additional examinations will be needed.
What to remember: tell your family doctor about such symptoms, and discuss pregnancy with hypothyroidism with them separately.
Call an ambulance immediately (103 or 112) in case of loss of consciousness, difficulty breathing, severe chest pain, or seizures. Thyroid storm (a sudden severe exacerbation of hyperthyroidism) and myxedema coma (a rare complication of severe hypothyroidism, more often in older people) are treated only in hospital.
This material is for reference and does not replace a doctor's consultation.
Sources
Update history
This content is for reference and does not replace a doctor's consultation. Medical disclaimer