Thyroid symptoms: the signs in women and men, and when to get tested

The thyroid is a small, butterfly-shaped gland at the front of the neck, just below the Adam's apple. It makes two hormones, T4 and T3, that set the pace of almost everything: how fast you burn energy, your heart rate, body temperature, digestion, periods, mood and how your skin and hair grow.

The gland is steered by TSH (thyroid-stimulating hormone) from the pituitary gland in the brain. When thyroid hormone runs low, TSH rises to push the thyroid harder; when it runs high, TSH falls. That's why TSH is the first blood test doctors use.

Thyroid problems are common, and far more so in women: the American Thyroid Association says women are five to eight times more likely than men to have one, and about one woman in eight will develop a thyroid disorder in her lifetime. In a study across eight Indian cities, about one adult in ten had an underactive thyroid, many without knowing it.

When the thyroid makes too little hormone, the body slows down. Symptoms usually come on so gradually that people put them down to age, stress or a busy life.

Common symptoms: tiredness, feeling cold, weight gain, constipation, dry skin, coarse or thinning hair, a puffy face, aching muscles, low mood, poor memory, heavy periods and a hoarse voice. Some people have no symptoms at all, and it's found on a routine blood test.

Common causes:

• Hashimoto's thyroiditis, where the immune system slowly damages the thyroid. It's the most common cause where diets have enough iodine, and it runs in families.
• Iodine deficiency, still the most common cause worldwide. Iodised salt has made it far rarer.
• Thyroid treatment or surgery, such as radioactive iodine for an overactive thyroid.
• Some medicines, including lithium and amiodarone.
• After pregnancy (postpartum thyroiditis), which is often temporary.

Treatment is usually a daily thyroid hormone tablet (levothyroxine), with the dose set and checked by your doctor through TSH tests. Most people feel well again once the level is right.

When the thyroid makes too much hormone, the body runs fast. It can feel like being permanently wired.

Common symptoms: weight loss despite a good appetite, a fast or irregular heartbeat, palpitations, feeling hot and sweaty, shaky hands, anxiety, irritability, poor sleep, frequent stools, muscle weakness and lighter periods. In Graves' disease, the eyes can feel gritty, look staring or bulge.

Common causes:

• Graves' disease, an immune condition and the most common cause.
• Thyroid nodules that make extra hormone on their own.
• Thyroiditis (an inflamed thyroid), including after pregnancy, which can cause a short overactive phase followed by an underactive one.
• Taking too much thyroid hormone medicine.

An untreated overactive thyroid strains the heart (including atrial fibrillation, an irregular heartbeat) and weakens bones over time, so it's worth treating. The options are medicines that calm the thyroid, radioactive iodine or surgery; your doctor (often an endocrinologist) will explain which fits.

Women are far more likely to have thyroid problems, and some symptoms show up in ways that are easy to miss:

• Periods: heavier or more frequent periods with an underactive thyroid; lighter, less frequent periods with an overactive one.
• Fertility: both can make it harder to get pregnant. Doctors often check TSH when periods are irregular or pregnancy is slow to happen.
• Pregnancy: the baby relies on the mother's thyroid hormone early on, so an untreated thyroid problem matters more in pregnancy. If you have a thyroid condition, or symptoms, tell your doctor or midwife as soon as you're pregnant or planning to be.
• After birth: postpartum thyroiditis affects about 5 to 10% of women in the year after having a baby. It's often mistaken for the exhaustion and low mood of new parenthood.
• Menopause: hot flushes, poor sleep, low mood and weight change overlap with thyroid symptoms, so a TSH test helps tell them apart.
• PCOS: irregular periods, weight gain and hair changes can come from either, and the two sometimes occur together.

An enlarged thyroid is called a goitre. It can happen with an underactive, overactive or normally working thyroid, and is often painless. A thyroid nodule is a lump within the gland.

Nodules are very common, especially with age, and more than 90% are benign (not cancer), according to the American Thyroid Association. Still, every new lump in the neck should be checked. The usual first steps are a TSH test and an ultrasound of the neck; some nodules then need a fine-needle sample.

See a doctor sooner if a lump is growing quickly, feels hard, or comes with a hoarse voice, trouble swallowing or trouble breathing.

Symptoms point the way, but a blood test decides:

• TSH is the first test. It's high when the thyroid is underactive and low when it's overactive. In most adults the normal range is about 0.4 to 4.0 mIU/L. See our TSH test guide for what each result means.
• Free T4 (and sometimes T3) shows how much thyroid hormone is actually in the blood.
• Thyroid antibodies (anti-TPO for Hashimoto's, TRAb for Graves') show whether the immune system is the cause.
• An ultrasound looks at the gland when there's a swelling or lump.

A few things can throw the results off: biotin supplements (often in hair and nail products) can make thyroid tests read wrongly, so tell the lab if you take them. A recent illness, pregnancy and some medicines also shift TSH.

• Get tested before you treat. Don't start thyroid tablets, iodine, kelp or "thyroid support" supplements on your own. Too much iodine can make some thyroid problems worse, and supplements can hide the real picture.
• Write your symptoms down, with when they started, and take the list (or the checklist above) to your appointment.
• If you're already on treatment and symptoms come back, ask for your TSH to be rechecked; the dose may need adjusting. Ask your pharmacist how to take thyroid tablets with food and other medicines.
• Use iodised salt in normal amounts. Foods like cabbage, broccoli and soy are fine to eat in a normal diet.
• Keep an eye on the heart and bones with an overactive thyroid: treatment protects both.