Iodine (Serum)
The Serum Iodine test measures iodine levels in the blood. It helps assess iodine status and its role in thyroid hormone production.
Turnaround time
1 week
Biomarkers count
1
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Details about Iodine (Serum)
What is the Iodine (Serum) test?
The Iodine (Serum) test measures the concentration of iodine circulating in the bloodstream. Iodine is an essential trace element required for the production of thyroid hormones, which regulate metabolism, growth, and energy balance.
Adequate iodine intake is vital for normal thyroid function. Both iodine deficiency and excess can disrupt thyroid hormone synthesis, potentially leading to hypothyroidism or hyperthyroidism.
While urine iodine is often used for population-level assessment, serum iodine can provide useful insight in individual clinical and nutritional evaluations, especially when thyroid dysfunction is suspected.
Why do I need an Iodine (Serum) test?
Iodine imbalance can affect thyroid health, energy levels, and metabolic regulation. Testing helps identify deficiency or excess to guide appropriate intervention.
You may need a Serum Iodine test if you:
- Have thyroid dysfunction or abnormal thyroid tests
- Have symptoms of iodine deficiency or excess
- Follow a restricted or low-iodine diet
- Avoid dairy, seafood, or iodised salt
- Are pregnant or planning pregnancy
- Have unexplained fatigue or weight changes
- Are assessing nutritional micronutrient status
Symptoms associated with iodine imbalance may include:
- Fatigue
- Weight gain or loss
- Cold or heat intolerance
- Neck swelling (goitre)
- Hair thinning
- Menstrual irregularities
Benefits of the Iodine (Serum) test
- Assesses iodine status
Identifies deficiency or excess. - Supports thyroid function evaluation
Complements TSH, T3 and T4 testing. - Useful in nutritional assessment
Identifies micronutrient imbalance. - Relevant in pregnancy planning
Adequate iodine is essential for fetal development. - Helps guide dietary adjustments
Informs iodine intake optimisation. - Clinically recognised trace element test
Used in endocrine and nutritional medicine. - Supports investigation of goitre
Helps identify iodine-related causes. - Simple blood test
Requires only one sample.
Step by step – how the test works
You can access Serum Iodine testing UK-wide through two options:
- Clinic appointment
Attend your nearest UK clinic where a healthcare professional will take your blood sample. - At-home or hotel visit (£60 extra)
A qualified phlebotomist comes to your home or hotel, so you don’t need to travel.
Your sample is analysed in an accredited UK laboratory, and results are delivered securely.
Your results explained
Low serum iodine levels
May indicate iodine deficiency, which can impair thyroid hormone production.
Typical UK interpretation:
- Below laboratory reference range
Normal serum iodine levels
Suggest adequate iodine status for thyroid hormone synthesis.
Typical UK interpretation:
- Within reference range
High serum iodine levels
May indicate excess iodine intake, which can also disrupt thyroid function.
Typical UK interpretation:
- Above laboratory reference range
Results should be interpreted alongside thyroid function tests and dietary history.
How It Works
Simple steps to get your results
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Visit or Test at Home
Attend one of our UK or London clinics, arrange a home nurse visit, or use a finger-prick kit where available.
Get Your Results
Your sample is analysed by accredited UK laboratories, with secure results delivered directly to you.
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WhatsApp UsHow to Prepare for Your Test
Follow these guidelines for accurate results
Sample Timing
Where possible, attend your blood test between 7am and 12pm. Please wait until any short-term illness or infection has fully resolved before testing. Avoid intense exercise for 24–48 hours beforehand, as this can affect certain markers.
Fasting & Hydration
Fasting is not always required, but some tests may recommend it. If fasting is advised, avoid food for 8–12 hours before your appointment and drink water only. Stay well hydrated, as this helps with sample collection and accuracy.
Medications & Supplements
Continue prescribed medications unless advised otherwise by your clinician. Avoid vitamin, mineral, or biotin supplements for at least 24–48 hours before your test, as these can interfere with results. If you are unsure about any medication or supplement, please let us know before your appointment.
Hormones & Menstrual Cycle
For hormone-related tests, timing within your menstrual cycle may be important. If relevant, follow any specific guidance provided on your test page.
If you have any questions or special circumstances, our team is happy to advise before your appointment.