The Gland That Controls Everything
Thyroid disorders affect an estimated 42 million Indians, but the majority remain undiagnosed. The symptoms — fatigue, weight gain, hair loss, feeling cold, irregular periods — are vague and easily attributed to stress, aging, or "just life."
You might be profoundly exhausted despite sleeping 9 hours. You may have gained weight despite not eating more. Your hair might be falling out in clumps. And doctor after doctor might suggest it's depression, stress, or that you should "exercise more and eat less."
A simple TSH test could reveal the truth: hypothyroidism that's been silently affecting you for years while your symptoms were dismissed as psychological.
What Your Thyroid Does
Your thyroid is a butterfly-shaped gland at the front of your neck. It produces hormones (T4 and T3) that control your metabolism — essentially, how fast your body runs.
Every cell in your body has thyroid hormone receptors. This gland affects:
- Metabolism and weight: How efficiently you burn calories
- Energy levels: Physical and mental stamina
- Heart rate: Speed and rhythm of the heart
- Body temperature: How warm or cold you feel
- Digestion: Speed of gut movement
- Brain function: Concentration, memory, mood
- Hair, skin, nails: Growth and quality
- Menstrual cycles: Regularity and flow
- Fertility: Both conception and pregnancy maintenance
When your thyroid malfunctions, virtually every body system is affected.
Understanding the Thyroid Panel
TSH (Thyroid Stimulating Hormone)
TSH is produced by the pituitary gland in your brain. It tells your thyroid how much hormone to make. This is the primary screening test.
The key insight: TSH works inversely.
- High TSH = Thyroid is underactive (hypothyroidism) — the brain is shouting at a lazy thyroid
- Low TSH = Thyroid is overactive (hyperthyroidism) — the brain is whispering because the thyroid is already running too fast
| TSH Level (mIU/L) | Interpretation | Typical Situation |
|---|---|---|
| Below 0.1 | Suppressed | Overt hyperthyroidism or overmedication |
| 0.1 - 0.4 | Low | Possible mild hyperthyroidism |
| 0.4 - 2.5 | Optimal | Healthy thyroid function |
| 2.5 - 4.0 | Upper normal | May warrant monitoring |
| 4.0 - 10.0 | Mildly elevated | Subclinical hypothyroidism |
| Above 10.0 | High | Overt hypothyroidism |
Free T4 (FT4) — The Main Hormone
T4 is the main hormone your thyroid produces. The "free" portion is what's available for your cells to use.
| Free T4 | Interpretation |
|---|---|
| Below 0.8 ng/dL | Low — confirms hypothyroidism if TSH is high |
| 0.8 - 1.8 ng/dL | Normal range |
| Above 1.8 ng/dL | High — confirms hyperthyroidism if TSH is low |
Free T3 (FT3) — The Active Hormone
T3 is the active form of thyroid hormone. Most T4 gets converted to T3 in your tissues. Sometimes T3 is checked when symptoms persist despite normal TSH and T4.
Thyroid Antibodies
These detect autoimmune thyroid disease:
| Antibody | What It Indicates |
|---|---|
| Anti-TPO (Thyroid Peroxidase) | Hashimoto's thyroiditis — autoimmune attack causing hypothyroidism |
| Anti-Thyroglobulin (Anti-Tg) | Also seen in Hashimoto's; used in thyroid cancer monitoring |
| TSH Receptor Antibodies (TRAb) | Graves' disease — autoimmune cause of hyperthyroidism |
Hypothyroidism: The Slow Thyroid
Hypothyroidism means your thyroid isn't producing enough hormone. Everything slows down.
Symptoms
- Fatigue, exhaustion — even after sleep
- Weight gain — despite not eating more
- Cold intolerance — feeling cold when others are comfortable
- Constipation — slow gut motility
- Dry skin, brittle nails
- Hair loss — especially outer third of eyebrows
- Brain fog — difficulty concentrating, memory problems
- Depression — low mood, apathy
- Muscle aches and stiffness
- Menstrual irregularities — heavy, irregular periods
- Infertility or recurrent miscarriage
- High cholesterol — thyroid affects lipid metabolism
Hashimoto's Thyroiditis
The most common cause of hypothyroidism in India is Hashimoto's disease — an autoimmune condition where the immune system attacks the thyroid. It's diagnosed by elevated Anti-TPO antibodies.
Having positive antibodies but normal TSH means increased risk of developing hypothyroidism in the future — monitoring is warranted.
Treatment
Levothyroxine (T4 replacement) is the standard treatment — a daily pill taken on an empty stomach. Properly treated, hypothyroid patients can live completely normal lives.
Taking Levothyroxine Correctly:
- Take on an empty stomach (at least 30-60 minutes before breakfast)
- Take at the same time daily
- Avoid calcium, iron, and antacids within 4 hours
- Coffee can interfere — wait 30+ minutes after taking the medication
Hyperthyroidism: The Overactive Thyroid
Hyperthyroidism means your thyroid produces too much hormone. Everything speeds up.
Symptoms
- Weight loss — despite eating more
- Rapid heart rate, palpitations
- Anxiety, nervousness, irritability
- Trembling hands
- Heat intolerance — excessive sweating
- Frequent bowel movements or diarrhea
- Muscle weakness
- Sleep problems
- Eye changes — bulging, irritation (in Graves' disease)
- Menstrual irregularities — light or absent periods
Graves' Disease
The most common cause of hyperthyroidism is Graves' disease — another autoimmune condition. The immune system produces antibodies that stimulate the thyroid to overproduce hormones.
Treatment Options
- Anti-thyroid medications: Methimazole or carbimazole — reduce hormone production
- Radioactive iodine: Destroys overactive thyroid tissue (usually causes eventual hypothyroidism)
- Surgery: Thyroidectomy in specific cases
- Beta-blockers: Control symptoms like rapid heart rate while awaiting treatment effect
Subclinical Thyroid Disease: The Gray Zone
Sometimes TSH is abnormal but T4 remains normal. This is "subclinical" disease.
Subclinical Hypothyroidism
TSH elevated (typically 4-10 mIU/L) but Free T4 normal.
Treatment decisions depend on:
- Degree of TSH elevation
- Presence of symptoms
- Presence of thyroid antibodies (suggests progression)
- Pregnancy status or planning
- Cardiovascular risk factors
When to Treat Subclinical Hypothyroidism:
- TSH above 10: Most guidelines recommend treatment
- TSH 4-10 with symptoms: Consider treatment trial
- TSH 4-10 with positive antibodies: Monitor closely; may progress
- Pregnancy or trying to conceive: Treat if TSH above 2.5
Thyroid and Pregnancy
Thyroid function is critical during pregnancy:
- Untreated hypothyroidism increases risk of: Miscarriage, preeclampsia, preterm birth, low IQ in children
- TSH targets are stricter: Below 2.5 mIU/L in first trimester, below 3.0 in second and third
- Dose requirements increase: Many women need 25-50% more levothyroxine during pregnancy
- Test early: All pregnant women should have TSH checked in the first trimester
Women with known thyroid disease should have levels optimized before conception.
The "Normal" TSH Controversy
The standard reference range for TSH (0.4-4.0 or 0.4-4.5 mIU/L) is debated:
- Derived from population studies that included people with undiagnosed thyroid disease
- Many experts consider TSH above 2.5 suboptimal
- Symptoms may occur at TSH levels within the "normal" range
What matters is the individual picture: TSH level, symptoms, antibody status, and how you feel. A TSH of 3.5 with fatigue and weight gain warrants attention, even if technically "normal."
When to Test Your Thyroid
Screen if you have:
- Unexplained fatigue, weight changes, or mood changes
- Family history of thyroid disease
- Previous thyroid problems
- Other autoimmune conditions (Type 1 diabetes, celiac, rheumatoid arthritis)
- Neck radiation history
- Fertility problems or recurrent miscarriage
- Irregular menstrual cycles
- Unexplained high cholesterol
Routine screening recommended for:
- Women over 35 (every 5 years)
- All pregnant women (first trimester)
- Women trying to conceive
- People over 60
Complete Thyroid Panel: What to Request
| Test | When It's Needed |
|---|---|
| TSH | Always — the primary screening test |
| Free T4 | If TSH is abnormal, or monitoring treatment |
| Free T3 | If symptoms persist with normal TSH/T4; hyperthyroidism evaluation |
| Anti-TPO | To diagnose Hashimoto's; if TSH borderline/elevated |
| Anti-Thyroglobulin | Sometimes with Anti-TPO; thyroid cancer monitoring |
| TSH Receptor Antibodies | If Graves' disease suspected |
Common Mistakes in Thyroid Management
1. Testing Only TSH
TSH alone can miss cases where T4 to T3 conversion is impaired. If symptoms persist, complete panel is warranted.
2. Not Retesting After Dose Changes
After any dose change, wait 6-8 weeks before rechecking TSH — it takes time to stabilize.
3. Ignoring Symptoms with "Normal" Numbers
Reference ranges are population averages. An individual may feel best at a different level within (or slightly outside) the range.
4. Taking Levothyroxine Incorrectly
Taking with food, coffee, or supplements dramatically reduces absorption.
5. Forgetting About Iodine
Both deficiency and excess iodine can cause thyroid problems. Most Indians get adequate iodine from iodized salt, but those avoiding salt or on special diets may be at risk.
Your Thyroid Action Plan
| Your TSH | What It Means | What To Do |
|---|---|---|
| 0.4 - 2.5 mIU/L | Optimal | Healthy thyroid; rescreen in 3-5 years if no symptoms |
| 2.5 - 4.0 mIU/L | Upper normal | Monitor; check antibodies if symptoms present |
| 4.0 - 10.0 mIU/L | Subclinical hypothyroid | Check Free T4 and antibodies; discuss treatment if symptomatic |
| Above 10.0 mIU/L | Overt hypothyroidism | Start levothyroxine; investigate cause |
| 0.1 - 0.4 mIU/L | Subclinical hyperthyroid | Check Free T4/T3; may need further evaluation |
| Below 0.1 mIU/L | Overt hyperthyroidism | Full thyroid panel; TRAb; possible thyroid scan |
Key Takeaways:
- Thyroid disorders are common and underdiagnosed — don't dismiss vague symptoms
- TSH is the key screening test — but sometimes the full panel is needed
- High TSH means low thyroid, low TSH means high thyroid — the inverse relationship
- Autoimmune thyroiditis is the most common cause — check antibodies
- Pregnancy requires stricter targets — optimize before conception
- Treatment is highly effective — once diagnosed, hypothyroidism is very manageable
Track your thyroid health with ExaHealth. Upload your lab reports and monitor your TSH, T4, and T3 levels over time — because catching thyroid dysfunction early prevents years of unexplained symptoms.
