The Complete Guide to Thyroid Testing: Beyond TSH

Your thyroid is a small, butterfly-shaped gland in your neck that controls your metabolism, energy, mood, and so much more. Yet standard thyroid screening often only includes one test: TSH. For many women, that's not enough to get the full picture.

Why TSH Alone Isn't Enough

TSH (Thyroid Stimulating Hormone) is produced by your pituitary gland and tells your thyroid how much hormone to make. While it's a useful screening tool, it only shows one part of a complex system.

Think of it this way: TSH is like checking if your thermostat is working, but it doesn't tell you if the furnace is actually producing heat or if the heat is reaching every room in your house.

Many women with "normal" TSH levels still experience thyroid symptoms because:

• Their thyroid may be producing enough T4 but not converting it well to active T3
• They may have autoimmune thyroid disease that isn't yet affecting TSH
• TSH reference ranges are very broad and may not reflect optimal levels

The Complete Thyroid Panel

A comprehensive thyroid panel should include these markers:

TSH (Thyroid Stimulating Hormone)

The "master signal" from your pituitary gland. High TSH suggests your thyroid is underactive (hypothyroidism), while low TSH suggests it's overactive (hyperthyroidism). The standard reference range is 0.4-4.5 mIU/L, but many practitioners consider optimal to be 1.0-2.5 mIU/L.

Free T4 (Thyroxine)

The main hormone your thyroid produces. It's called "free" because it measures the unbound, available hormone. T4 is largely inactive and must be converted to T3 to be used by your cells.

Free T3 (Triiodothyronine)

The active thyroid hormone that actually affects your cells. This is arguably the most important marker for understanding how you feel, yet it's often left off standard panels. Low Free T3 with normal TSH and T4 can explain persistent symptoms.

Thyroid Antibodies (TPO and TgAb)

These indicate autoimmune thyroid disease, which affects up to 10% of women. Elevated antibodies can predict future thyroid problems even when other markers are normal. Testing includes:

• TPO Antibodies - Associated with Hashimoto's thyroiditis
• Thyroglobulin Antibodies - Can indicate autoimmune thyroid disease

Common Thyroid Symptoms in Women

Signs of Hypothyroidism (Underactive Thyroid)

• Fatigue and low energy
• Weight gain or difficulty losing weight
• Feeling cold when others are comfortable
• Dry skin and brittle nails
• Hair loss or thinning
• Brain fog and memory issues
• Depression
• Heavy or irregular periods
• Constipation

Signs of Hyperthyroidism (Overactive Thyroid)

• Rapid heartbeat or palpitations
• Unexplained weight loss
• Feeling hot or excessive sweating
• Anxiety or nervousness
• Trembling hands
• Difficulty sleeping
• Light or missed periods
• Frequent bowel movements

When to Test Your Thyroid

Consider thyroid testing if you:

• Experience symptoms listed above
• Have a family history of thyroid disease
• Are planning pregnancy or struggling with fertility
• Recently had a baby (postpartum thyroiditis is common)
• Are going through perimenopause or menopause
• Have another autoimmune condition
• Have been told your thyroid is "borderline"

Understanding Your Results

Thyroid testing is most useful when you look at all markers together, not in isolation. Here are common patterns:

Primary Hypothyroidism: High TSH + Low Free T4 and/or Free T3

Subclinical Hypothyroidism: Slightly elevated TSH + Normal Free T4 and T3

Hashimoto's Thyroiditis: Elevated TPO antibodies, often with hypothyroid pattern

Poor T4 to T3 Conversion: Normal TSH and T4 + Low Free T3

Taking Action

If your results suggest thyroid dysfunction, work with a healthcare provider who will consider your symptoms alongside your lab values. Treatment might include:

• Thyroid hormone medication
• Nutritional support (selenium, zinc, iron, vitamin D)
• Addressing underlying causes like gut health or stress
• Regular monitoring to optimize your levels