Thyroid disorders
Thyroid disorders — an underactive (hypothyroid) or overactive (hyperthyroid) thyroid — affect roughly 1 in 10 people in India, more often women, and are diagnosed with a simple blood test (TSH). In India specifically, autoimmune thyroiditis, not iodine deficiency (now largely resolved through salt iodization), is the leading cause of underactive thyroid — and treatment targets are individualized to your age, pregnancy status, and symptoms rather than one TSH number applying to everyone.
How we assess and manage thyroid disorders
Blood Testing
TSH, and thyroid hormone levels where needed, as the starting point.
Antibody Testing Where Indicated
Such as TPO antibodies, to confirm an autoimmune cause.
Determining Whether Treatment Is Needed
Especially important for borderline (subclinical) results, which aren't automatically treated.
Setting Your Personal TSH Target
Individualized to your age, pregnancy status, and symptoms.
Starting or Adjusting Treatment
Medication chosen and dosed to your specific situation.
Follow-Up Testing
Confirming you're at target and adjusting as needed.
Symptoms
- Underactive thyroid: fatigue, weight gain, cold intolerance, dry skin, constipation
- Overactive thyroid: weight loss, rapid heartbeat, heat intolerance, anxiety, tremor
- Changes in menstrual cycles
- A visible or palpable swelling in the neck (goiter), in some cases
Causes & risk factors
- Autoimmune thyroid conditions (the most common cause of both over- and underactive thyroid)
- A family history of thyroid disease
- Being female (thyroid disorders are more common in women)
- Certain medications and prior thyroid or neck radiation
Thyroid disorders affect an estimated 1 in 10 people in India (roughly 42 million people), with hypothyroidism affecting an estimated 10–12% of Indian women, more often past age 35. Self-reported rates in national health surveys are considerably lower (2.2% in NFHS-4, rising to 2.9% in NFHS-5), reflecting how much thyroid disease goes unrecognized without testing rather than a true low prevalence.
Underactive vs. overactive thyroid
These are opposite conditions with different symptoms and treatments, though both are diagnosed with the same starting blood test.
| Aspect | Underactive (hypothyroid) | Overactive (hyperthyroid) |
|---|---|---|
| Typical symptoms | Fatigue, weight gain, cold intolerance, constipation | Weight loss, rapid heartbeat, heat intolerance, tremor |
| Most common cause | Autoimmune thyroiditis (Hashimoto's) | Autoimmune disease (Graves') or thyroid nodules |
| Typical first treatment | Thyroid hormone replacement (levothyroxine) | Antithyroid medication (methimazole), with radioactive iodine or surgery as alternatives |
The gland itself
The thyroid can produce too little (underactive) or too much (overactive) hormone
Metabolic rate
Thyroid hormone sets your body's metabolic pace, affecting weight, energy, and temperature regulation
Heart rate
Both directions affect heart rate — usually slower with underactive, faster with overactive thyroid
Why autoimmune disease, not iodine deficiency, is now the main cause in India
This is a genuine, relatively recent shift in India's thyroid disease pattern, worth understanding directly.
A public health success story with a new implication
- India has completed its transition from iodine deficiency to iodine-replete status, largely through universal salt iodization
- As a result, autoimmune thyroiditis (Hashimoto's disease) — not iodine deficiency — is now the leading cause of underactive thyroid in India, as in other iodine-sufficient countries
- This matters practically: treatment addresses the autoimmune process and its consequences, not iodine intake, and dietary iodine supplementation isn't the answer for most patients diagnosed today
Understanding your TSH result
TSH (thyroid-stimulating hormone) is the primary screening test, but what counts as an appropriate result depends on your specific situation.
| Situation | General target or threshold |
|---|---|
| General adult range | Within your lab's standard reference range, interpreted alongside symptoms |
| Planning pregnancy | Below 2.5 mIU/L |
| Pregnant — by trimester | Roughly 0.1–2.5 (1st), 0.2–3.0 (2nd), 0.3–3.0 (3rd) mIU/L |
| Age 70–80 | A relaxed target of 4–6 mIU/L is often appropriate |
| Borderline ("subclinical") — TSH 4.5–10 | An individual decision based on symptoms, antibody status, and cardiovascular risk factors, not an automatic treatment threshold |
Treating an underactive thyroid
Levothyroxine (a synthetic form of thyroid hormone) is the standard treatment, dosed to bring your TSH to your individual target rather than a fixed dose for everyone.
Dosing is adjusted gradually based on follow-up blood tests, and taking it consistently (typically on an empty stomach, apart from certain other medicines and supplements) affects how reliably it works.
Treating an overactive thyroid
For Graves' disease and other causes of an overactive thyroid, methimazole is the preferred first-line antithyroid medication, typically continued for 12–18 months before assessing whether the condition has gone into remission.
Evidence has evolved here: longer, continuous courses of methimazole (five years or more, in appropriately selected patients) have been shown to achieve substantially better sustained remission than the conventional shorter course, which is discussed as an option where relevant. Radioactive iodine treatment or surgery remain established alternatives, particularly if medication doesn't control the condition or isn't well tolerated.
Follow-up and monitoring
Thyroid treatment is adjusted gradually over time using follow-up blood tests — not set once and left unchanged — since dose needs can shift with weight change, pregnancy, aging, and other factors.
How it’s diagnosed
Diagnosis is based on blood tests (TSH and thyroid hormone levels), sometimes alongside antibody testing or imaging depending on the findings.
How it’s treated
Underactive thyroid is typically treated with thyroid hormone replacement; overactive thyroid has several treatment paths depending on the cause. Treatment is individualized — including your personal TSH target — and monitored with regular blood testing.
When to seek care
- A rapid or irregular heartbeat alongside other thyroid symptoms
- Significant unexplained weight change
- A new lump or swelling in the neck
- Severe fatigue, confusion, or feeling extremely cold — a rare but serious complication of untreated underactive thyroid
- High fever, a rapid heartbeat, agitation, or confusion — a rare but serious complication of untreated overactive thyroid
FAQ
Is thyroid testing part of routine diabetes care?
Thyroid conditions are more common in people with diabetes, particularly type 1, so your care team may check thyroid function periodically as part of overall metabolic assessment.
What's the difference between hypothyroidism and hyperthyroidism?
Hypothyroidism is an underactive thyroid producing too little hormone, causing fatigue, weight gain, and cold intolerance. Hyperthyroidism is an overactive thyroid producing too much, causing weight loss, a rapid heartbeat, and heat intolerance.
What causes thyroid disorders in India today?
Autoimmune thyroiditis (Hashimoto's disease) is now the leading cause of underactive thyroid in India, since the country has become iodine-replete through universal salt iodization — iodine deficiency is no longer the main driver it once was.
What is Hashimoto's thyroiditis?
It's an autoimmune condition where the immune system gradually damages the thyroid gland, reducing its ability to produce hormone — it's the most common cause of underactive thyroid in iodine-sufficient countries, including India.
What is Graves' disease?
It's an autoimmune condition that causes the thyroid to become overactive, producing excess hormone — the most common cause of hyperthyroidism.
What is a normal TSH level?
This depends on your lab's reference range and your specific situation — general adult ranges differ from targets used in pregnancy or in older adults, which is why your result is interpreted individually rather than against one universal number.
Why might my target TSH be different from someone else's?
Targets are individualized by age, pregnancy status, and symptoms — for example, a relaxed target is often appropriate for adults aged 70–80, while a stricter target applies during pregnancy or when planning one.
Does pregnancy change my thyroid target?
Yes — pregnancy uses trimester-specific TSH ranges, generally stricter than standard adult targets, and women planning pregnancy are typically managed to a TSH below 2.5 mIU/L beforehand.
What is subclinical hypothyroidism, and does it need treatment?
It's a mildly elevated TSH (roughly 4.5–10 mIU/L) with normal thyroid hormone levels. Treatment isn't automatic at this range — the decision depends on your symptoms, thyroid antibody status, and cardiovascular risk factors, individualized rather than based on the TSH number alone.
How is an underactive thyroid treated?
With levothyroxine, a synthetic thyroid hormone, dosed to reach your individual TSH target and adjusted over time based on follow-up blood tests.
How is an overactive thyroid treated?
Methimazole is the preferred first-line antithyroid medication, typically for 12–18 months before assessing remission; radioactive iodine treatment or surgery are established alternatives depending on your situation and response.
Can hyperthyroidism go into remission?
Yes, for many patients — antithyroid medication aims for remission, and evidence shows longer, continuous treatment courses can achieve meaningfully better sustained remission than shorter conventional courses in appropriately selected patients.
How often should thyroid levels be checked?
This depends on whether you're newly diagnosed, adjusting treatment, pregnant, or stable long-term — your care team will advise a specific schedule suited to your situation.
Does a thyroid nodule mean cancer?
No — most thyroid nodules are not cancerous. If one is found, it's evaluated individually (sometimes with imaging or further testing) to determine its nature, rather than assumed to be either harmless or concerning without assessment.
Medical disclaimer: Content on this page is for general education and is not a substitute for individualized medical advice, diagnosis, or treatment. Outcomes vary between patients. Boston Diabetes Center is outpatient / day-care specialty centre with an on-site diagnostic lab and pharmacy — no inpatient beds; imaging and inpatient care are coordinated through partner facilities.