RAIU
Pronunciation: RAY-you
Also written as: RAIU — Radioactive Iodine Uptake
Radioactive iodine uptake test. Measures how much radioactive iodine the thyroid gland absorbs from the bloodstream.
Full Definition
Radioactive iodine uptake (RAIU) is a nuclear medicine test that measures the percentage of administered radioactive iodine (typically I-123) that is absorbed by the thyroid gland over a specific time period, usually 4, 6, or 24 hours. This test helps distinguish between different causes of hyperthyroidism and assesses thyroid function. High uptake suggests conditions like Graves' disease or toxic nodular goiter, while low uptake may indicate thyroiditis or exogenous thyroid hormone intake. RAIU results influence treatment decisions, particularly regarding radioactive iodine therapy candidacy and surgical planning.
Usage
Usage note: Always specify the time point (4, 6, or 24 hours) when reporting RAIU values.
In Context
- "The RAIU was elevated at 45% at 24 hours, consistent with Graves' disease." — Nuclear medicine report
- "Low RAIU of 2% suggested thyroiditis rather than Graves' disease." — Endocrinology note