What are the symptoms of low TSH?

Weight loss, Rapid heartbeat, Anxiety, Tremors, Heat intolerance, Insomnia

What is the optimal range for TSH?

The optimal range for TSH is 1-2.5 mIU/L.

What causes high TSH?

Weight gain, Fatigue, Cold intolerance, Depression, Dry skin, Constipation

Thyroid

What is TSH? Optimal Ranges & Function

Normal Range:0.4-4 mIU/L

Optimal Range:1-2.5 mIU/L

What is TSH?

Thyroid Stimulating Hormone (TSH) is produced by your pituitary gland and signals your thyroid to produce hormones. It's the primary screening test for thyroid function.

Why TSH Matters

TSH is inversely related to thyroid hormone levels—high TSH often indicates an underactive thyroid, while low TSH may suggest an overactive thyroid. Both affect metabolism, energy, and mood.

Symptoms of Low TSH

Weight loss
Rapid heartbeat
Anxiety
Tremors
Heat intolerance
Insomnia

Symptoms of High TSH

Weight gain
Fatigue
Cold intolerance
Depression
Dry skin
Constipation

Reference Ranges

0.4 mIU/L4 mIU/L

2.5

Standard Lab Range

BioStack Optimal

Range Type	Minimum	Maximum	Unit
Normal Range	0.4	4	mIU/L
Optimal Range	1	2.5	mIU/L

Related Biomarkers

T3 Free T4

When to Request Additional Tests

If Your TSH is High

When TSH is elevated, consider testing the following markers to get a more complete picture:

Free T4 — Evaluate thyroid hormone production
T3 — Check conversion to active hormone

If Your TSH is Low

When TSH is below optimal, these additional tests can help identify the underlying cause:

Free T4 — Evaluate thyroid hormone production
T3 — Check conversion to active hormone

Analyze Your TSH Levels

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