Thyroid Disorders in Women: A Complete Guide to Understanding Your Butterfly Gland

The short answer: The thyroid is a small butterfly-shaped gland in your neck that sets the speed of your body. It can run slow (hypothyroidism, the common one) or fast (hyperthyroidism, the rarer one). In a study across eight Indian cities, about 1 in 9 adults had an underactive thyroid, and women were affected about three times as often as men. One blood test called TSH is the starting point. If you are tired, gaining weight, feeling cold, or your periods have changed, ask for that test.

What does the thyroid actually do?

Your thyroid sets your body's speed. It sits low in the front of your neck, shaped like a small butterfly, and it makes two hormones called T4 and T3. These hormones reach almost every cell you have.

They decide how fast you burn food, how warm you feel, how quickly your heart beats, how regular your periods are, and how clearly you think. When the thyroid makes too little hormone, everything slows down. When it makes too much, everything races.

Above the thyroid, the pituitary gland in your brain watches the level and sends an instruction hormone called TSH. This is the part women find confusing, so hold on to it: TSH goes UP when the thyroid is slow. A high TSH means your brain is shouting at a sleepy gland. A low TSH means the brain has gone quiet because there is already too much hormone around.

How common are thyroid problems in India?

Common enough that I check for them often. A study across eight Indian cities tested 5,360 adults and found an underactive thyroid in 10.95%, which is about 1 in 9. In the same study, women were affected far more than men: 15.86% of women against 5.02% of men.

Another 8.02% had subclinical hypothyroidism, which means a raised TSH with normal thyroid hormone levels. And nearly 22% carried anti-TPO antibodies. Those antibodies point to thyroid autoimmunity, but on their own they do not mean the gland is underactive. TSH and free T4 are what show whether it actually is.

The number I want you to hold on to is this one. Of that 10.95%, only 7.48% already knew. The remaining 3.47% were found by the study itself. So roughly one in three women and men with an underactive thyroid were walking around with no idea. These adults came forward to health camps, so the true rate in the general population may be lower, but the pattern of missed diagnoses is real.

An often-quoted estimate from Indian endocrinologists puts around 42 million people in India living with some form of thyroid disorder. One detail surprises most women: in that eight-city study, inland cities had slightly more hypothyroidism than coastal ones, 11.73% against 9.45%. So living near the sea is not protection.

Both of these are older studies, from 2011 and 2013, and they remain the most widely cited Indian figures we have. Treat them as the shape of the problem rather than today's exact count.

Why do women get thyroid disease so much more than men?

The honest answer is that we do not fully know. The best explanation we have is autoimmunity. The commonest cause of an underactive thyroid is Hashimoto's disease, in which the immune system mistakes the thyroid for an intruder and attacks it, and autoimmune conditions of this kind are much more common in women.

The American Thyroid Association reports a large gap between women and men in the United States. Women there are five to eight times more likely to have a thyroid problem. It also estimates that one in eight women will develop one during her life.

Those are American numbers, so read them as the size of the gap, not as an Indian rate. For India, the eight-city study is the better guide: 15.86% of women against 5.02% of men.

The year after childbirth is a well recognised time for thyroid trouble to appear, because the immune system shifts after delivery. In my clinic I often see women who put months of tiredness down to "just the baby" or "just my age" when a simple blood test would have given them the answer.

Slow thyroid or fast thyroid? The symptom difference

The two problems are near opposites. Doctors call the slow one hypothyroidism and the fast one hyperthyroidism. Reading them side by side is the quickest way to recognise yourself.

Please notice how ordinary this list is. Tiredness, weight change and low mood belong to a hundred other things too, from anaemia to plain lack of sleep. That is exactly why guessing does not work here. As the American Thyroid Association says, a blood test is the only way to know for sure.

What causes each one

An underactive thyroid is most often Hashimoto's disease, an autoimmune condition where antibodies slowly damage the gland. It can also follow thyroid surgery, radioactive iodine treatment, or certain medicines. In parts of India where iodine intake is still low, iodine deficiency plays a part too, which is why iodised salt matters.

An overactive thyroid is most often Graves' disease, another autoimmune condition, where antibodies push every thyroid cell to overproduce. It runs in families and appears more in younger women. The American Thyroid Association estimates Graves' disease affects about 1% of the population.

Which thyroid test do I need?

For most adults, start with TSH. It is one tube of blood, it is cheap, and it is the most sensitive early signal we have. Your doctor usually adds further tests only if the TSH is off. There are exceptions: if a pituitary problem is possible, TSH and free T4 are checked together, because in that situation the TSH can look normal while the thyroid hormone is low.

A word on the full panel some labs sell. A package with T3, T4, TSH, antibodies, reverse T3 and a scan sounds thorough, and mostly it is money you did not need to spend. Start with TSH. Let the result decide the next step.

How to read your TSH report

Most Indian labs print a normal range next to your number, commonly somewhere around 0.4 to 4.5 mIU/L. That range is set by each laboratory, not by a national guideline, so always read your own report's range rather than a number you saw online.

• TSH high, thyroid hormone low: hypothyroidism. Treatment is usually straightforward.
• TSH high, thyroid hormone normal: subclinical hypothyroidism. Whether to treat depends on how high the number is, whether you have antibodies, your symptoms, and whether you are planning a pregnancy.
• TSH low, thyroid hormone high: hyperthyroidism. This needs a specialist.
• Borderline: repeat it. TSH moves with illness, stress, pregnancy and even time of day. One odd number is not a diagnosis.

If you are pregnant or trying to conceive, the rules are stricter. Your lab should use a pregnancy-specific range where it has one. Where it does not, a TSH above 4 mU/L is treated as abnormal, and if you are on treatment the aim is to keep TSH between the lower end of the normal range and 2.5 mU/L. I cover pregnancy, diet and daily management in detail in my guide to living with a thyroid condition.

How thyroid problems show up in a woman's cycle

Often the periods change before anything else does. An underactive thyroid tends to make periods heavier, longer or irregular. An overactive thyroid tends to make them lighter or skip them.

Both can make ovulation unreliable, which is why thyroid testing is part of a proper fertility check-up. Untreated overt hypothyroidism in pregnancy raises the risk of miscarriage, early delivery and problems with the baby's development, which is exactly why we treat it seriously.

Here is a nuance worth knowing, because it saves you an unnecessary test. If heavy periods are your ONLY problem, guidelines say not to test the thyroid unless there are other thyroid signs as well. Heavy bleeding much more often comes from fibroids, hormone imbalance or the lining of the womb. I go through those causes in my guide to heavy periods and what causes them. If your periods are irregular rather than heavy, my complete guide to irregular periods works through the whole list, thyroid included.

Thyroid problems also sit alongside PCOS quite often, and the two get confused because both cause irregular cycles, weight change and hair problems. They are different conditions with different treatments, and you can have both. That is why I check TSH whenever I am working up a PCOS diagnosis.

Who should get tested, even without symptoms

There is no recommendation to screen every adult in India. But I lower my threshold a lot for these women, and I would ask for a TSH test if you are one of them.

• Planning a pregnancy, currently pregnant, or within a year of delivery
• A mother, sister or daughter with thyroid disease
• Any other autoimmune condition, such as type 1 diabetes or coeliac disease
• Being investigated for infertility or repeated miscarriage
• Unexplained tiredness, weight change or persistent low mood that has lasted months
• A neck swelling, or previous thyroid surgery or radiation to the neck

Your questions, answered

What is a normal TSH level?

Most laboratories use a range of roughly 0.4 to 4.5 mIU/L, but each lab prints its own range on your report, so read that one. A single borderline value should be repeated rather than acted upon, because stress, illness and pregnancy all shift it.

Do I need to fast for a thyroid test?

No, a thyroid test does not need fasting. If the same blood sample is being used for sugar or cholesterol tests, follow the fasting instruction for those. It is sensible to give the sample in the morning, and to use the same lab each time so your numbers stay comparable.

Can a thyroid problem be cured?

An underactive thyroid caused by autoimmune damage is usually lifelong, but it is very well controlled with one tablet a day. An overactive thyroid can often be brought under control or permanently resolved with medicines, radioactive iodine or surgery, and your specialist will explain which suits you.

Is my hair fall because of my thyroid?

It can be, but hair fall has many causes, and in Indian women low iron is a very common one. A TSH test and a haemoglobin and ferritin check together answer this much better than either alone. My guide to iron deficiency in Indian women explains that side.

Should I get a thyroid scan along with my blood test?

Not routinely, and it depends which scan. A thyroid ultrasound is mainly for a lump or a swelling, not for diagnosing an underactive gland; the blood tests do that job. If blood tests confirm an overactive thyroid, a specialist may order a different test called an uptake scan to find the cause. Uptake scans are not used in pregnancy or while breastfeeding.

My TSH is slightly high but I feel fine. Do I need treatment?

Not always. That picture is called subclinical hypothyroidism, and the decision depends on how high the number is, whether you carry thyroid antibodies, and whether you are planning a pregnancy. If you are pregnant or trying, the bar for treating is much lower.

Does stress cause thyroid disease?

Stress does not create an autoimmune thyroid condition on its own, but it worsens the symptoms and can be the last push that makes a hidden problem show. Sleeping badly and living in constant tension makes every hormone harder to steady, which is why I talk about it in my guide to managing stress.

Sources for this article (9)

1. Unnikrishnan AG et al., Prevalence of hypothyroidism in adults: an epidemiological study in eight cities of India, Indian Journal of Endocrinology and Metabolism, 2013 (accessed July 2026)
2. Unnikrishnan AG, Menon UV, Thyroid disorders in India: an epidemiological perspective, Indian Journal of Endocrinology and Metabolism, 2011 (accessed July 2026)
3. American Thyroid Association, General information and thyroid disease statistics (accessed July 2026)
4. American Thyroid Association, Hypothyroidism: patient information (accessed July 2026)
5. American Thyroid Association, Hyperthyroidism: patient information (accessed July 2026)
6. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), Hypothyroidism: symptoms and causes (accessed July 2026)
7. NHS, Symptoms of an underactive thyroid (accessed July 2026)
8. American Thyroid Association, Management of hypothyroidism during pregnancy (accessed July 2026)
9. NICE guideline NG88, Heavy menstrual bleeding: assessment and management (accessed July 2026)

This article is for your information and learning. It is not a substitute for a consultation. For advice about your own health, talk to me or your own doctor.