From the Guidelines
Thyrotoxicosis is diagnosed when a patient has elevated thyroid hormone levels in the blood (either free T4, free T3, or both) along with suppressed thyroid-stimulating hormone (TSH) levels, accompanied by clinical symptoms of thyroid hormone excess, as confirmed by the most recent guidelines from the Journal of Clinical Oncology in 2021 1.
Diagnosis and Evaluation
The diagnosis of thyrotoxicosis requires both laboratory confirmation and clinical evaluation. According to the guidelines, TSH and FT4 should be used for case detection in symptomatic patients, and T3 can be helpful in highly symptomatic patients with minimal FT4 elevations 1.
- Common symptoms include weight loss despite increased appetite, heat intolerance, sweating, palpitations, anxiety, tremors, fatigue, and menstrual irregularities.
- Physical examination may reveal tachycardia, hypertension, warm moist skin, fine tremor, hyperreflexia, and possibly goiter or eye abnormalities (in Graves' disease).
Additional Testing
Additional testing may include thyroid antibodies (such as TSI or TRAb for Graves' disease), radioactive iodine uptake scan, or thyroid ultrasound to determine the underlying cause, which could be Graves' disease, toxic nodular goiter, thyroiditis, or exogenous thyroid hormone intake, as suggested by the Society for Immunotherapy of Cancer in 2017 1.
- The diagnosis is important to establish promptly as thyrotoxicosis can lead to serious complications including cardiac arrhythmias, osteoporosis, and in severe cases, thyroid storm, which is a medical emergency requiring immediate treatment.
Management
The management of thyrotoxicosis depends on the severity of symptoms and the underlying cause, with guidelines recommending beta-blockers for symptomatic relief, hydration, and supportive care, and consideration of endocrine consultation for persistent thyrotoxicosis or severe symptoms 1.
- In cases of severe symptoms, hospitalization may be necessary, and additional medical therapies such as steroids, SSKI, or thionamide (methimazole or propylthiouracil) may be considered.
From the Research
Diagnosis of Thyrotoxicosis
Thyrotoxicosis is diagnosed based on clinical symptoms and laboratory tests. The commonest forms of thyrotoxicosis are:
- Toxic diffuse goiter (Basedow-Flajani-Graves disease)
- Toxic multinodular goiter
- Toxic adenoma Other less frequent forms include iodide-induced, Hashimoto thyroiditis, and inappropriate TSH secretion 2.
Clinical Presentation and Evaluation
The clinical presentation of thyrotoxicosis can vary, with classic symptoms often easily recognized by general practitioners. However, atypical presentations are common in the elderly 3. The diagnosis is predominantly clinical and confirmed by hormone level determination, associated with functional and morphofunctional tests (TRH test, scintigraphy, thyroid I uptake) and antithyroid antibody assay 2.
Laboratory Tests and Investigations
Following biochemical confirmation of thyrotoxicosis, a radionuclide thyroid scan is the most useful investigation in diagnosing the underlying cause 3. Other laboratory tests, such as TSH, free thyroxine (T4), and triiodothyronine (T3) concentrations, can help establish the diagnosis and guide treatment 4, 5.
Treatment and Management
The selection of treatment differs according to the cause of thyrotoxicosis and the wishes of the individual patient. The preferred treatment for Graves disease is usually antithyroid drug therapy, almost always carbimazole. The primary treatment of a toxic multinodular goitre or toxic adenoma is usually radioactive iodine therapy 3. Referral to an endocrinologist is recommended if thyroiditis is unlikely or has been excluded 3.