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Thyroid

TSH level: what does your result mean?

Your TSH level says how hard your pituitary is pulling on your thyroid. At the laboratory that runs the test the usual range runs from 0.27 to 4.20 mE/L. If your number is above it, your thyroid is probably running slow. Below it, and it is probably running fast. That feels back to front, and it is. TSH is the signal from your pituitary, not the thyroid hormone itself. One result is not a diagnosis. So always check the reference value on your own report.

Doctor's Assessment Included

Reference Ranges

See the value that applies to you:

Choose male or female — this range differs by sex.

Enter your age — this range changes with age.

This range also depends on context such as cycle phase or sample material; the highlighted rows apply to your group.

Male Your group
mu/l
Low 0.27 Normal 4.2 High
Female Your group
mu/l
Low 0.27 Normal 4.2 High

Reference ranges may vary between laboratories. When you order a test, a BIG-registered doctor assesses your personal results in context. For treatment decisions, discuss your results with your GP.

Check your own value

TSH (Thyroid Stimulating Hormone): what this test measures

This test measures the hormone TSH in your blood. Your pituitary makes TSH. It is a gland the size of a pea, at the base of your brain. Through TSH your pituitary tells your thyroid how much to produce. Your thyroid then makes T4 and T3. Those two set your pace: your temperature, your heart rate, your digestion and your energy.

Think of a thermostat. If the house gets too cold, the thermostat turns up. Your pituitary works the same way. If it senses too little thyroid hormone, it sends more TSH.

That is where the biggest confusion sits. A high TSH does not mean your thyroid is working too hard. It means your pituitary has to push harder. That happens when your thyroid makes too little hormone. So a high number means an underactive thyroid. A low number means an overactive one.

So what does TSH mean on a blood test? It is the most sensitive first test for your thyroid. Small changes get strongly amplified in it. That is why a problem often shows up before you notice anything.

You do not need to fast. Free T4 is usually measured in the same tube.

TSH (Thyroid Stimulating Hormone): why this value matters

Most people arrive here with one question. My number is outside the range, so what now?

The honest answer is that it is usually not alarming. A slightly abnormal result is far from always thyroid disease. There are three very ordinary explanations.

The first is the time of day. TSH is highest overnight and lowest in the early afternoon. The difference within one person is roughly 31 percent across a day. That is enough to land just above or just below a limit.

The second is illness. After flu or an infection your value can stay shifted for weeks.

The third is a supplement. Biotin, from hair and nail pills, can distort your result considerably.

That is why your GP almost always repeats the measurement. Not because something is badly wrong, but because one number is too little.

Your resultWhat that usually meansWhat usually happens
within 0.27 to 4.20your thyroid is probably just doing its jobno further investigation needed
just above the upper limitoften temporary; sometimes an early underactive thyroidrepeat after a few weeks, with free T4
clearly raised, with symptomsfits a thyroid making too little hormonediscuss it with your GP
just below the lower limitoften temporary, or the effect of medicationrepeat, with free T4 and free T3
very low, with palpitationsfits an overactive thyroiddo not leave this, call your GP

This is not a diagnosis and not a replacement for your doctor. It is here to help you understand your result before that conversation.

TSH (Thyroid Stimulating Hormone): when is testing worthwhile?

Have your TSH measured if you have symptoms that fit your thyroid. The best known are fatigue that will not lift, feeling cold and weight gain. On the other side sit palpitations, restlessness, sweating and losing weight instead.

If your GP saw a borderline result before, repeating is worthwhile too. And if thyroid disease runs in your family, a baseline is useful.

The time of day counts. Give blood in the morning if you can. Use around the same hour when you repeat it. You do not need to fast.

Just been ill? Wait a few weeks. An infection shifts the result and makes it hard to read.

On thyroid medication with a dose that was just changed? Wait 6 to 8 weeks. Measuring sooner gives a number that is still moving.

Always request free T4 alongside. TSH alone shows that something is going on; free T4 shows how much. If your doctor suspects an autoimmune cause, anti-TPO is added.

TSH (Thyroid Stimulating Hormone): symptoms of a high or low value

Low Levels

If your TSH is low, your thyroid is usually making too much hormone. Everything then runs a notch faster. Your heart pounds or skips, even when you sit still. You sleep worse and feel restless or short-tempered. You sweat sooner and cope badly with heat. Often you lose weight while eating normally. Trembling hands and more frequent toilet trips also occur. Not every low value means an overactive thyroid, though. Too high a dose of thyroid medication gives the same picture. And early in pregnancy a lower value simply belongs there. Do you have palpitations with a low result? Then do not wait, call your GP.

High Levels

If your TSH is high, your thyroid is usually making too little hormone. Everything then runs a notch slower. You are tired, even after a good night. You feel cold sooner than the people around you. Your skin gets drier, your hair breaks more easily and your bowels slow down. Many people gain weight slowly without anything having changed. Low mood and slower thinking belong with it too. Importantly, with a mildly raised value you often notice nothing at all. Your thyroid hormone itself is then usually still normal. That is called subclinical, and it often does not progress. So a result like that gets repeated before anything happens.

TSH (Thyroid Stimulating Hormone): what to do about an abnormal value

Male

If Low

Low TSH may indicate hyperthyroidism. Consider thyroid function panel (Free T4, Free T3) and consultation with an endocrinologist.

If High

High TSH indicates hypothyroidism. Consider thyroid hormone replacement therapy and consultation with an endocrinologist.

Female

If Low

Low TSH may indicate hyperthyroidism. Consider thyroid function panel (Free T4, Free T3) and consultation with an endocrinologist.

If High

High TSH indicates hypothyroidism. Consider thyroid hormone replacement therapy and consultation with an endocrinologist.

TSH (Thyroid Stimulating Hormone): lifestyle and this value

There is no pill or diet that neatly steers your TSH level. What you can do is make sure the measurement is right. Four things genuinely help.

Stop biotin for a few days. It is in almost every hair, skin and nail supplement, often at 5 to 10 milligrams. It can falsely lower your TSH and falsely raise your free T4. Your result then looks like an overactive thyroid while nothing is wrong. Two to three days off is usually enough. You do not need to stop an ordinary multivitamin.

Give blood at around the same time each time. That matters more than you think, because your value drops over the course of the day.

Do not measure just after flu. Wait a few weeks until you have properly recovered.

Tell them which medicines you take. Lithium and amiodarone can disturb your thyroid. Stomach protectors, calcium and iron slow the absorption of thyroid medication. If you take levothyroxine, take it after the blood draw. And never adjust your own dose based on a test you requested yourself. Discuss that with your GP.

TSH (Thyroid Stimulating Hormone): frequently asked questions

What is the ideal TSH level?
There is no ideal number that fits everyone. At the laboratory that runs the test the usual range runs from 0.27 to 4.20 mE/L. Anywhere inside that is fine. What counts as a good TSH level also depends on your age. Pregnancy and medication shift the picture too. So look at the reference column on your own result.
What happens if your TSH is too low?
Usually your thyroid is making too much hormone. Your heart runs faster, you sleep worse, you sweat more and you often lose weight. Sometimes it is caused by too high a dose of thyroid medication. Early in pregnancy a lower value is actually normal. If you have palpitations with it, call your GP.
What is a TSH level, in plain language?
It is the signal from your pituitary to your thyroid. Your pituitary works like a thermostat. If there is too little thyroid hormone, it sends more TSH. So the number mainly says how hard the pulling is. It does not directly say how much hormone you have.
Why does my GP want to measure it again?
Because one result is too little to conclude anything. Your value varies with the time of day. A recent infection and supplements such as biotin shift it too. Measuring again after a few weeks shows whether it is genuinely so. Free T4 is usually measured at the same time.
Should I worry about a slightly high value?
Usually not straight away. A mildly raised value with a normal free T4 is called subclinical. Many people notice nothing, and it often does not progress. Your GP looks at your symptoms, your age and the repeat measurement before anything happens.
Can I compare my result with numbers online?
Better not. Labs use different analysers and different limits, for example 0.4 to 4.0 instead of 0.27 to 4.20. So a normal TSH level is not the same number everywhere. Compare your result with the reference column printed on your own report.

Test Products

This marker is included in the following test panels.

InsideTracker

InsideTracker

An InsideTracker blood test with 35 biomarkers: heart, hormones, metabolism, inflammation, recovery and iron status. Measured in the Netherlands.

SHBG (Sex Hormone Binding Globulin) TSH (Thyroid Stimulating Hormone) ALT (Alanine Aminotransferase) LDL Cholesterol GGT (Gamma-Glutamyl Transferase) Cortisol DHEA-S Estradiol (E2) Free Testosterone Total Testosterone Folate (Folic Acid) Vitamin B12 Calcium Ferritin Iron (Serum) Magnesium Potassium Progesterone Sodium Transferrin CRP (C-Reactive Protein) Glucose (Fasting) HbA1c (Glycated Hemoglobin) ApoB (Apolipoprotein B) HDL Cholesterol Total Cholesterol Albumin AST (Aspartate Aminotransferase) Vitamin D (25-OH) Insulin (Fasting) Leukocyte Differential Creatine Kinase (CK) Transferrin Saturation Triglycerides Basic Blood Count
€399,-
Whoop

Whoop

A 43-biomarker comprehensive health panel inspired by WHOOP Advanced Labs — a deep look at metabolism, cardiovascular risk, hormones, liver, kidney and inflammation.

SHBG (Sex Hormone Binding Globulin) TSH (Thyroid Stimulating Hormone) ALT (Alanine Aminotransferase) LDL Cholesterol Cortisol DHEA-S Estradiol (E2) Free Testosterone FSH (Follicle Stimulating Hormone) LH (Luteinizing Hormone) Total Testosterone Bicarbonate Calcium Chloride Ferritin Iron (Serum) Magnesium Potassium Sodium Transferrin CRP (C-Reactive Protein) Homocysteine Glucose (Fasting) HbA1c (Glycated Hemoglobin) ApoB (Apolipoprotein B) HDL Cholesterol Total Cholesterol Albumin HOMA-IR ALP (Alkaline Phosphatase) AST (Aspartate Aminotransferase) Bilirubin (Total) Total Protein Urea (BUN) Creatinine Vitamin D (25-OH) eGFR (Estimated Glomerular Filtration Rate) Insulin (Fasting) Leukocyte Differential Transferrin Saturation Lipoprotein(a) Triglycerides Basic Blood Count
€499,-
Whoop

Whoop Heart Health

A 45-biomarker heart health panel inspired by the WHOOP Heart Health Panel — an advanced look at cholesterol, lipoproteins, inflammation and kidney function.

Complete Blood Count (CBC) Leukocyte Differential ALP (Alkaline Phosphatase) ALT (Alanine Aminotransferase) AST (Aspartate Aminotransferase) Albumin Total Protein Bilirubin (Total) ApoB (Apolipoprotein B) Total Cholesterol LDL Cholesterol HDL Cholesterol Triglycerides Lipoprotein(a) Urea (BUN) Creatinine eGFR (Estimated Glomerular Filtration Rate) Calcium Bicarbonate Chloride Sodium Potassium Magnesium Cortisol DHEA-S Estradiol (E2) FSH (Follicle Stimulating Hormone) LH (Luteinizing Hormone) SHBG (Sex Hormone Binding Globulin) Total Testosterone Free Testosterone TSH (Thyroid Stimulating Hormone) Glucose (Fasting) HbA1c (Glycated Hemoglobin) Insulin (Fasting) HOMA-IR CRP (C-Reactive Protein) Homocysteine Ferritin Iron (Serum) Transferrin Transferrin Saturation Vitamin D (25-OH) Cystatin C Uric Acid
€629,-
Whoop

Whoop Performance Health

A 50-biomarker performance panel inspired by the WHOOP Performance Health Panel — recovery, blood production, thyroid, hormones, iron and nutrient status for people who train.

Complete Blood Count (CBC) Leukocyte Differential ALP (Alkaline Phosphatase) ALT (Alanine Aminotransferase) AST (Aspartate Aminotransferase) Albumin Total Protein Bilirubin (Total) ApoB (Apolipoprotein B) Total Cholesterol LDL Cholesterol HDL Cholesterol Triglycerides Lipoprotein(a) Urea (BUN) Creatinine eGFR (Estimated Glomerular Filtration Rate) Calcium Bicarbonate Chloride Sodium Potassium Magnesium Cortisol DHEA-S Estradiol (E2) FSH (Follicle Stimulating Hormone) LH (Luteinizing Hormone) SHBG (Sex Hormone Binding Globulin) Total Testosterone Free Testosterone TSH (Thyroid Stimulating Hormone) Glucose (Fasting) HbA1c (Glycated Hemoglobin) Insulin (Fasting) HOMA-IR CRP (C-Reactive Protein) Homocysteine Ferritin Iron (Serum) Transferrin Transferrin Saturation Vitamin D (25-OH) IGF-1 (Insulin-like Growth Factor) Creatine Kinase (CK) Reticulocytes Free T3 (Triiodothyronine) Free T4 (Thyroxine) Vitamin B12 Folate (Folic Acid)
€689,-
Whoop

Whoop Metabolic Health

A 51-biomarker metabolic panel inspired by the WHOOP Metabolic Health Panel — blood sugar regulation, insulin, thyroid, liver and the mineral cofactors behind your metabolism.

Complete Blood Count (CBC) Leukocyte Differential ALP (Alkaline Phosphatase) ALT (Alanine Aminotransferase) AST (Aspartate Aminotransferase) Albumin Total Protein Bilirubin (Total) ApoB (Apolipoprotein B) Total Cholesterol LDL Cholesterol HDL Cholesterol Triglycerides Lipoprotein(a) Urea (BUN) Creatinine eGFR (Estimated Glomerular Filtration Rate) Calcium Bicarbonate Chloride Sodium Potassium Magnesium Cortisol DHEA-S Estradiol (E2) FSH (Follicle Stimulating Hormone) LH (Luteinizing Hormone) SHBG (Sex Hormone Binding Globulin) Total Testosterone Free Testosterone TSH (Thyroid Stimulating Hormone) Glucose (Fasting) HbA1c (Glycated Hemoglobin) Insulin (Fasting) HOMA-IR CRP (C-Reactive Protein) Homocysteine Ferritin Iron (Serum) Transferrin Transferrin Saturation Vitamin D (25-OH) Leptin Zinc Selenium Iodine Copper Free T3 (Triiodothyronine) Free T4 (Thyroxine) GGT (Gamma-Glutamyl Transferase)
€799,-
Whoop

Whoop Women's Health

A 53-biomarker women's health panel inspired by the WHOOP Women's Health Panel — fertility, cycle and thyroid hormones plus a complete metabolic and nutrient base.

Complete Blood Count (CBC) Leukocyte Differential ALP (Alkaline Phosphatase) ALT (Alanine Aminotransferase) AST (Aspartate Aminotransferase) Albumin Total Protein Bilirubin (Total) ApoB (Apolipoprotein B) Total Cholesterol LDL Cholesterol HDL Cholesterol Triglycerides Lipoprotein(a) Urea (BUN) Creatinine eGFR (Estimated Glomerular Filtration Rate) Calcium Bicarbonate Chloride Sodium Potassium Magnesium Cortisol DHEA-S Estradiol (E2) FSH (Follicle Stimulating Hormone) LH (Luteinizing Hormone) SHBG (Sex Hormone Binding Globulin) Total Testosterone Free Testosterone TSH (Thyroid Stimulating Hormone) Glucose (Fasting) HbA1c (Glycated Hemoglobin) Insulin (Fasting) HOMA-IR CRP (C-Reactive Protein) Homocysteine Ferritin Iron (Serum) Transferrin Transferrin Saturation Vitamin D (25-OH) AMH (Anti-Müllerian Hormone) Progesterone Prolactin TPO Antibodies Free T3 (Triiodothyronine) Free T4 (Thyroxine) Leptin Vitamin B12 Folate (Folic Acid) Phosphorus
€709,-
Whoop

Whoop Men's Health

A 48-biomarker men's health panel inspired by the WHOOP Men's Health Panel — testosterone, PSA and prostate health plus a complete metabolic and hormone base.

Complete Blood Count (CBC) Leukocyte Differential ALP (Alkaline Phosphatase) ALT (Alanine Aminotransferase) AST (Aspartate Aminotransferase) Albumin Total Protein Bilirubin (Total) ApoB (Apolipoprotein B) Total Cholesterol LDL Cholesterol HDL Cholesterol Triglycerides Lipoprotein(a) Urea (BUN) Creatinine eGFR (Estimated Glomerular Filtration Rate) Calcium Bicarbonate Chloride Sodium Potassium Magnesium Cortisol DHEA-S Estradiol (E2) FSH (Follicle Stimulating Hormone) LH (Luteinizing Hormone) SHBG (Sex Hormone Binding Globulin) Total Testosterone Free Testosterone TSH (Thyroid Stimulating Hormone) Glucose (Fasting) HbA1c (Glycated Hemoglobin) Insulin (Fasting) HOMA-IR CRP (C-Reactive Protein) Homocysteine Ferritin Iron (Serum) Transferrin Transferrin Saturation Vitamin D (25-OH) PSA (Prostate-Specific Antigen) Prolactin Leptin Uric Acid Zinc
€659,-

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Medical standards

Dr. Naimi oversees the medical standards behind our content and assessments.

Medical policy
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TSH (Thyroid Stimulating Hormone)

€26,-