Test ID: B-220 | Sample Type: Dried Blood Spot | Test Method: LC-MS/MS | Results: 3–5 Working Days | Laboratory: ZRT Laboratory – CLIA Certified | Report: Specialist Doctor Comment Included | Suitable For: Women | Collect Sample At Home: No Clinic Visit Required
Could Your Thyroid Be Behind Your Fatigue, Weight Gain, or Low Mood?
Thyroid dysfunction is one of the most commonly missed conditions in women — affecting up to 1 in 8 at some point in their lives. Symptoms often develop gradually and are easily dismissed as stress, hormonal changes, or the demands of daily life. If you recognise any of the following, a comprehensive thyroid test could reveal the root cause:
- Persistent fatigue or exhaustion that sleep doesn’t fix
- Unexplained weight gain or difficulty losing weight
- Feeling cold all the time, or conversely, intolerance to heat
- Brain fog, poor concentration, or memory problems
- Low mood, depression, or anxiety
- Hair loss, thinning hair, or brittle nails
- Dry skin or puffy face
- Constipation or digestive sluggishness
- Irregular or heavy periods, PMS, or fertility concerns
- Difficulty conceiving or recurrent miscarriage
- Symptoms worsening around perimenopause or menopause
- Already on thyroid medication and wanting to monitor treatment
Why a Full Thyroid Panel Matters — Especially for Women
A standard GP thyroid test typically only measures TSH — which can miss significant thyroid dysfunction, particularly in women whose symptoms fluctuate with hormonal changes across the menstrual cycle, pregnancy, and menopause. This comprehensive panel measures six thyroid markers, giving a complete picture of thyroid hormone production, conversion, autoimmune activity, and iodine-related health:
- TSH (Thyroid Stimulating Hormone) — the primary screening marker; high TSH suggests hypothyroidism, low TSH suggests hyperthyroidism
- Free T4 (fT4) — the main hormone produced by the thyroid; assesses production capacity
- Free T3 (fT3) — the active thyroid hormone that drives energy, metabolism, and cellular function; many women have normal T4 but poor T4-to-T3 conversion, causing persistent symptoms despite apparently normal results
- Total T4 (TT4) — measures both bound and free thyroxine; provides a broader view of thyroid output
- TPO Antibodies (TPOab) — elevated levels indicate autoimmune thyroid disease such as Hashimoto’s thyroiditis, which is significantly more common in women
- Thyroglobulin (Tgbn) — linked to iodine storage and thyroid hormone production; elevated levels may suggest iodine deficiency or thyroid dysfunction
Thyroid Test Reference Ranges
| Test | Unit | Women | Men |
|---|---|---|---|
| Free Thyroxine (fT4) | ng/dL | 0.8–1.6 | 0.8–1.6 |
| Free Triiodothyronine (fT3) | pg/mL | 1.9–4.4 | 1.9–4.4 |
| Thyroglobulin (Tgbn) | ng/mL | 5–51 | 4–34 |
| Thyroid Peroxidase Antibodies (TPOab) | IU/mL | 0–150 | 0–150 |
| TPOab—Borderline | IU/mL | 70–150 | 70–150 |
| Thyroid-Stimulating Hormone (TSH) | μU/mL | 0.5–3.0 | 0.5–3.0 |
| Total Thyroxine (T4) | μg/dL | 5–10.6 | 5–10.6 |
What Conditions Can This Test Help Identify?
- Hypothyroidism — underactive thyroid; affects women up to 10x more often than men
- Hyperthyroidism — overactive thyroid, including Graves’ disease
- Hashimoto’s thyroiditis — autoimmune attack on the thyroid, disproportionately affecting women; often missed without TPO antibody testing
- Subclinical thyroid dysfunction — abnormal TSH with normal T4/T3; a common cause of unexplained symptoms in women
- T4-to-T3 conversion issues — normal T4 but insufficient active T3; frequently seen in women during hormonal transitions
- Thyroid-related cycle irregularities — thyroid imbalance can directly affect oestrogen, progesterone, and menstrual health
How It Works
- Order your kit — delivered to your door
- Collect your sample at home — a simple finger-prick dried blood spot; no clinic or GP visit needed
- Post your sample to ZRT Laboratory using the return instructions provided
- Receive your results by email within 3–5 working days of the lab receiving your sample
What You Receive
- All six thyroid markers displayed clearly in graphics and numbers with sex-specific reference ranges
- Written interpretation by a Hormone Specialist PhD Doctor
- Guidance on what your results mean and what to do next
- Laboratory fee included — no hidden charges
Why We Use ZRT Laboratory
All testing is performed by ZRT Laboratory — a globally recognised, CLIA-certified diagnostic laboratory founded in 1998 by Dr. David Zava, PhD. ZRT has performed over 11 million tests and is trusted by healthcare professionals in 96+ countries.
Frequently Asked Questions
Why is TSH alone not enough for women?
TSH reflects the pituitary’s signal to the thyroid but does not show whether the thyroid is producing adequate T4, whether T4 is converting to active T3, or whether an autoimmune process is attacking thyroid tissue. Many women with persistent fatigue, weight gain, hair loss, or mood changes have normal TSH but significant dysfunction in these downstream markers.
How does thyroid function affect fertility and periods?
Thyroid hormones directly interact with oestrogen and progesterone. Hypothyroidism and elevated TPO antibodies are associated with irregular cycles, heavy periods, difficulty conceiving, and increased miscarriage risk. Thyroid testing is strongly recommended for any woman with unexplained fertility concerns.
Does the price include the laboratory fee?
Yes. The full laboratory analysis fee is included. You are only responsible for posting your sample to the laboratory.
How long is the kit valid for?
The kit must be used within 12 months of the purchase date.
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