Thyroid Radioiodide Uptake (RAIU) Curves

Thyroid uptake may be quantified at 4-6 hours and at 24 hours. The gray bars define the rough normal ranges at 4-6 hours (5%-20%) and 24 hours (10%-35%).

Hyperthyroid patients will have elevated 4-hour uptake values. In cases of rapidly turning over iodine pool (e.g., Graves disease), there will be an early peak followed by a gradual decline. In such cases, 24-hour uptakes may be in the normal range.

Patients with subacute thyroiditis (not shown) will be hyperthyroid clinically, but will demonstrate low or imperceptible uptake.

Patients with renal disease will have a prolonged uptake due to decreased urinary excretion of the iodine.

References

• Becker D, Charkes ND, Dworkin H, Hurley J, McDougall IR, Price D, Royal H, Sarkar S. Procedure guideline for thyroid uptake measurement: 1.0. Society of Nuclear Medicine. J Nucl Med. 1996 Jul;37(7):1266-8.
• Franklyn J and Shephard M. Evaluation of Thyroid Function in Health and Disease Revised 21 September 2000.