# Graves' disease and hyperthyroidism

Source: https://nuclide.cc/indications/graves-hyperthyroidism/  
Nuclide record `graves-hyperthyroidism` (Indication). Data CC BY-NC 4.0, attribute "Data from Nuclide (nuclide.cc)"; commercial use needs a licence.

## TL;DR

An overactive thyroid gland makes too much thyroid hormone, speeding up the whole body. A drink or capsule of radioactive iodine can shrink and quieten the gland from the inside, without surgery.

## Summary

Graves' disease, an autoimmune condition in which antibodies stimulate the TSH receptor, is the most common cause of hyperthyroidism, accounting for 60-80% of cases. Oral radioactive iodine-131 has been used to treat it since the 1940s: because the thyroid concentrates iodine, an orally administered dose is taken up almost exclusively by thyroid tissue, which is then irradiated from within by the beta particles, over weeks progressively destroying overactive follicular cells.

Work-up before therapy establishes that the gland is actually iodine-avid: thyroid function tests, and a radioiodine uptake measurement (with I-123 or I-131) or Tc-99m pertechnetate scan, distinguish Graves' disease and toxic nodules (high uptake) from destructive thyroiditis or factitious thyrotoxicosis (low uptake), which will not respond to I-131. Dosing is either a fixed empiric activity or calculated from gland size and the 24-hour uptake to target roughly 2.96-7.4 MBq per gram of thyroid tissue; a serum TSH above about 30 mIU/mL maximises uptake. Antithyroid drugs (methimazole or propylthiouracil) are often used first, or stopped a few days before treatment, to reduce the risk of a transient post-therapy surge in circulating hormone.

The intended endpoint is a non-hyperthyroid state, and permanent hypothyroidism requiring lifelong levothyroxine is the expected outcome in most patients rather than a complication - it is easier to manage than recurrent thyrotoxicosis. Alternatives are long-term antithyroid drugs or thyroidectomy; the choice among the three is guided by goitre size, ophthalmopathy, pregnancy plans and patient preference rather than by radiopharmaceutical availability. Graves' orbitopathy can worsen after I-131 and this needs to be discussed and sometimes covered with steroids beforehand.

## Fields

- Kind: Indication
- Last checked: 2026-09-22
- Tags: thyroid; benign disease; SPECT
- Group: thyroid
- Burden: Graves' disease affects an estimated 1-1.5% of people worldwide, with an annual incidence of roughly 20-50 new cases per 100,000, and is 5-10 times more common in women; hyperthyroidism from all causes affects about 1.2% of the US population.

## Standard of care

- Confirmed Graves' disease or toxic nodular goitre, iodine-avid on uptake study: Oral I-131 sodium iodide, dosed empirically or by calculated activity per gram of thyroid tissue, as one of three first-line options alongside antithyroid drugs and thyroidectomy. ([Radioactive iodine (I-131)](https://nuclide.cc/drugs/radioactive-iodine/))
- Diagnostic work-up before any hyperthyroidism therapy: Thyroid function tests plus a radioiodine uptake measurement or Tc-99m pertechnetate scan to confirm iodine avidity and exclude thyroiditis or factitious thyrotoxicosis before committing to I-131. ([Radioactive iodine (I-131)](https://nuclide.cc/drugs/radioactive-iodine/))
- After I-131 therapy: Structured follow-up of thyroid function, with levothyroxine started once TSH rises, since iatrogenic hypothyroidism is the expected and accepted outcome of an effective dose.

## State of the art

- The SNMMI/ACR/ACNM/ARS practice parameter and the older SNMMI procedure standard for I-131 sodium iodide therapy set the modern framework: confirm iodine avidity, stop iodine-blocking medications and antithyroid drugs before dosing, verify the prescribed activity in a dose calibrator, and follow written radiation-safety instructions after a therapeutic dose.
- Dosing methods still vary between fixed empiric activities (for example roughly 370-555 MBq for Graves' disease per American Thyroid Association ranges) and calculated activities based on gland size and 24-hour uptake; no single method has been shown clearly superior for achieving euthyroidism versus planned ablation to hypothyroidism.

## Open problems

- No consensus on whether to aim for a euthyroid outcome or deliberately over-treat to hypothyroidism, which trades a higher chance of needing thyroid hormone replacement against a lower chance of needing a second treatment.
- Radiation thyroiditis can transiently worsen thyrotoxicosis after treatment, occasionally precipitating thyroid storm in patients with large glands or cardiac disease, who need pre-treatment with antithyroid drugs and beta-blockers.
- Graves' orbitopathy may worsen after I-131 in a subset of patients, and the decision to add prophylactic corticosteroids is individualised rather than protocol-driven.

## Sources

- SNMMI procedure standard: therapy of thyroid disease with I-131 (sodium iodide), version 3.0: https://jnm.snmjournals.org/content/53/10/1633
- ACR-ACNM-ARS-SNMMI-SPR practice parameter for treatment of benign and malignant thyroid disease with I-131 sodium iodide: https://gravitas.acr.org/PPTS/GetDocumentView?docId=29
- Graves' disease: review of disease characteristics, burden and treatments (2026): https://pmc.ncbi.nlm.nih.gov/articles/PMC13530974/

## Connected records

- indications: [Functional assessment of thyroid nodules](https://nuclide.cc/indications/thyroid-nodule-assessment/)
- isotopes: [Iodine-123](https://nuclide.cc/isotopes/i-123/), [Iodine-131](https://nuclide.cc/isotopes/i-131/), [Technetium-99m](https://nuclide.cc/isotopes/tc-99m/)
- technologies: [Radioiodine therapy and whole-body iodine scanning](https://nuclide.cc/technologies/radioiodine-therapy/)
- drugs: [Radioactive iodine (I-131)](https://nuclide.cc/drugs/radioactive-iodine/), [Thyrotropin alfa](https://nuclide.cc/drugs/thyrotropin-alfa/)
- terms: [Half-life](https://nuclide.cc/terms/half-life/), [Radioiodine therapy (I-131)](https://nuclide.cc/terms/radioiodine-term/)

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