Hypothyroidism: complete guide

Thyroid problems are so common in India that most families know someone who takes a small tablet every morning. An eight-city Indian study found hypothyroidism in about one in ten adults, with women affected around three times as often as men, and roughly a third of those people had not been diagnosed before. If you have just been told your thyroid is “low”, you are in very large company.

What hypothyroidism is

The thyroid is a butterfly-shaped gland at the front of the neck. Its hormones, mainly T4 and T3, set the pace of your metabolism: how fast your heart beats, how warm you feel, how quickly food moves through your gut, and how much energy you have. In hypothyroidism the gland makes too little hormone, so the body slows down. The pituitary gland in the brain notices and releases more TSH (thyroid-stimulating hormone) to push the thyroid harder, which is why a high TSH is the usual sign.

Symptoms of hypothyroidism

Symptoms usually creep in over months or years, which is why they are so often missed. Common ones include:

• Tiredness and sleepiness that rest does not fix
• Weight gain, often modest, and puffiness of the face
• Feeling cold when others are comfortable
• Constipation
• Dry skin, brittle nails and hair fall
• Low mood, slow thinking or poor memory
• Muscle aches, cramps and joint stiffness
• Heavier or irregular periods, and difficulty getting pregnant
• A hoarse voice or a swelling in the neck (goitre)
• A slow pulse

In women, period changes, fertility problems and hair fall are often what first lead to a test. In older adults, symptoms can be very mild or look like ageing: forgetfulness, slowing down, or feeling low.

What causes it?

• Hashimoto's thyroiditis is the most common cause in India today. The immune system slowly damages the thyroid. Anti-TPO antibodies in a blood test point to it. It often runs in families and is more common in people with other autoimmune conditions, such as type 1 diabetes, vitiligo or coeliac disease.
• Iodine deficiency used to be a major cause in India, especially in hilly regions. Iodised salt has made it much less common, but it still matters in pregnancy and in some areas.
• Treatment for an overactive thyroid, such as radioactive iodine or surgery, often leads to hypothyroidism later.
• Some medicines, such as lithium and amiodarone, and radiotherapy to the neck.
• After pregnancy: some women develop a temporary thyroid inflammation (postpartum thyroiditis). See our guide to thyroid and pregnancy.
• Rarely, a problem with the pituitary gland.

How it is diagnosed

A simple blood test is enough to diagnose hypothyroidism. Doctors look at TSH and free T4 together:

An anti-TPO antibody test can show whether Hashimoto's is the cause. Our guide to thyroid tests explained (TSH, T3, T4) walks through each number on your report, and what can throw them off, such as biotin supplements.

Subclinical hypothyroidism

Many people in India are told they have “borderline thyroid”: a TSH a little above the lab range with a normal free T4. This is subclinical hypothyroidism. It is common, it often causes no symptoms, and a single result can be temporary, for example after an illness. Doctors usually repeat the test after a few weeks to a few months before deciding anything.

Whether it needs treatment depends on how high the TSH is, whether it stays high, your symptoms, antibodies, age, and whether you are pregnant or planning a pregnancy. Many people with a mildly raised TSH are simply checked again from time to time. If you are trying for a baby or are pregnant, the thresholds are different, so tell your doctor.

Treatment with thyroxine

Hypothyroidism is treated with levothyroxine (often called thyroxine), a tablet that replaces the T4 your thyroid is not making. It is the same hormone your body makes, so when the dose is right it should not cause side effects. For most people with Hashimoto's, treatment is lifelong.

• Your doctor sets the dose based on your weight, age, heart health and how high your TSH is, and adjusts it over time.
• How you take it affects how well it works. Food, tea and coffee, and some tablets (such as calcium, iron and antacids) can reduce absorption. Ask your doctor how to time your tablet around meals and other medicines, and then keep the routine the same every day.
• Stick to one brand if you can. Indian pharmacies stock many brands and strengths. Switching between them can shift your TSH, so tell your doctor if your pharmacy changes the brand.
• Symptoms improve gradually over weeks; energy often returns before weight or hair changes.

Combination T4 and T3 treatment, and natural or “desiccated” thyroid products, are not recommended for routine use by thyroid guidelines. Do not add supplements that claim to “boost” the thyroid; some contain thyroid hormone or iodine in unknown amounts.

Follow-up tests

TSH takes several weeks to settle after any change, so doctors usually recheck it about 6 to 8 weeks after starting treatment or changing the dose, and then once or twice a year once you are stable. Tell your doctor about pregnancy, big weight changes and new medicines, because each can change how much thyroxine you need.

Living with hypothyroidism

Once treated, most people feel well and live completely normal lives. There is no special “thyroid diet” to follow; our guide to thyroid diet myths and facts sorts out the cabbage and soy worries. Regular activity, enough sleep and a balanced diet help energy and weight. If you still feel tired with a normal TSH, ask your doctor to look for other common causes in India, such as anaemia, vitamin B12 or vitamin D deficiency, diabetes and sleep problems.

Questions to ask your doctor

• Is my hypothyroidism overt or subclinical, and what is causing it?
• Should I have an anti-TPO antibody test?
• How should I take my tablet around meals, tea and other medicines?
• When should I repeat my TSH, and what TSH are we aiming for?
• What should I do if I plan to get pregnant?

Frequently asked questions

Sources

1. Unnikrishnan AG, et al. Prevalence of hypothyroidism in adults: an epidemiological study in eight cities of India. Indian J Endocrinol Metab 2013;17(4):647–652.
2. Jonklaas J, et al. Guidelines for the Treatment of Hypothyroidism: prepared by the American Thyroid Association Task Force on Thyroid Hormone Replacement. Thyroid 2014;24(12):1670–1751.
3. Garber JR, et al. Clinical practice guidelines for hypothyroidism in adults: cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association. Thyroid 2012;22(12):1200–1235.
4. US Food and Drug Administration. Biotin may interfere with lab tests.

This article is general information for adults in India and is not a diagnosis or a treatment plan. Always discuss results and any changes with your own doctor. Read our editorial policy.