Iodide in Blood

Beschrijving

What it measures

• Iodide circulating in the blood (either in serum or whole blood).
• Reflects the amount of iodine available for immediate thyroid hormone synthesis and transport.

Why it matters

• Unlike urine tests, which show how much iodine is excreted, blood iodide reflects current circulating levels and may indicate whether enough is available for thyroid uptake.
• Whole blood iodide includes both plasma and intracellular fractions, giving a more stable picture than serum alone.

Clinical applications

• Assessing acute iodine status in patients with thyroid symptoms.
• Monitoring iodine supplementation (together with thyroid function tests).
• Complementary to urine testing:

1. Urine = output/excretion (how much iodine leaves the body).
2. Blood = circulating availability (how much iodine is currently accessible to the thyroid).

• Useful in patients with kidney disease, where urinary iodine might be misleading.

Practical details

• Sample type: Whole Blood or capillary blood via Tasso device (for at-home collection).
• Turnaround time: 7–10 working days.
• Reference values: Typically around 40–90 µg/L for serum iodide (may vary by lab population).

Limitations

• Whole blood iodide is stable but requires careful sample handling.
• Should always be interpreted alongside thyroid hormones (TSH, free T4, free T3).

• Sample requirement: Whole blood sample

Suitable for postal submission.