Thyrotoxicosis is a syndrome caused by either overproduction or excessive release of free thyroxine (T4) and/or triiodothyronine (T3) in the serum. The increased production of thyroid hormones is seen in toxic multinodular goiter, toxic adenoma, struma ovarii and Graves' disease while the excessive release of the hormone is secondary to inflammation or destruction of the thyroid glands e.g. autoimmune diseases, radiation, infection, chemical or mechanical injury. Increased intake of thyroid medication leads to factitious thyrotoxicosis.

Thyrotoxicosis occurs more frequently in women with Graves' disease presenting between the age of 20 and 40 years [1]. Toxic nodular goiter is prevalent amongst older adults and in individuals with low levels of iodine in their diet while autoimmune thyrotoxicosis is seen more often in those who smoke [1].

Typical manifestations of overt thyrotoxicosis are anxiety, palpitations, intolerance to heat, myopathy, asthenia, menstrual irregularities in women, tremors [2], excessive sweating, exophthalmos, tachycardia [3] and diffuse thyromegaly. Orbital involvement with protrusion of the eyeballs, diplopia, and dryness is noted in one-third of the patients with Graves' disease [3]. Sympathetic overstimulation and related symptoms like anxiety and tremors are found mostly in young thyrotoxic patients while the incidence of dyspnea, cardiac arrhythmias, atrial fibrillation (AF) and heart failure is higher in older patients [4].

Patients with subclinical thyrotoxicosis can present with non-specific symptoms although they have a higher risk of atrial fibrillation compared to patients with overt thyrotoxicosis.

The workup in thyrotoxicosis comprises of a thorough history of the symptoms, their onset, duration, progress, whether residing in iodine deficient regions, dietary and medication intake, exposure to toxic radiation/chemicals, family and occupational history. Patients with Graves' disease may provide a family history of autoimmune disorders like rheumatoid arthritis or vitiligo. Physical examination is likely to show a single thyroid nodule or a multinodular goiter [2] with resting tachycardia, visible pulsations, myxedema and skin changes. On palpation there may be thyroid tenderness in patients with thyroiditis and auscultation may reveal a bruit. Ophthalmopathy features are rarely noticed in toxic nodular goiter but are a frequent finding in Graves' disease [2].

Laboratory tests include complete blood cell count, serum thyroid-stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3) levels and tests for specific autoantibodies if autoimmune etiology is suspected. TSH levels are diminished in overt as well as subclinical thyrotoxicosis while FT4 and/or FT3 levels are elevated only in case of overt thyrotoxicosis. Only T3 levels may be elevated in mild thyrotoxicosis.

A radioactive iodine uptake or scintigraphy scan is indicated if the cause of thyrotoxicosis is not revealed by either history or examination [2]. It provides a differential diagnosis and helps in the subsequent treatment of the patient [5] [6] [7] [8] [9] [10]. Increased uptake is seen in Graves' disease, toxic nodular goiter, and toxic multinodular goiter while low uptake is seen in thyroiditis.

If scintigraphy is contraindicated, then color doppler ultrasonography can be performed for diagnosing thyrotoxicosis [6] and will show increased vascularity in most cases. Ultrasonography, if performed shows a normal sized gland or moderate thyromegaly in Graves' disease.

An electrocardiogram is obtained to detect AF while more tests can be ordered if indicated by clinical findings and laboratory studies.

The treatment of thyrotoxicosis depends on its cause, severity, and the patient's overall health. Common treatment options include:

• Antithyroid medications: Drugs like methimazole or propylthiouracil help reduce thyroid hormone production.
• Radioactive iodine therapy: This treatment involves taking radioactive iodine orally, which gradually destroys overactive thyroid cells.
• Beta-blockers: These medications help manage symptoms like rapid heart rate and tremors.
• Surgery: In some cases, part or all of the thyroid gland may be surgically removed.

The choice of treatment is tailored to the individual, considering factors such as age, pregnancy status, and the presence of other medical conditions.

With appropriate treatment, the prognosis for thyrotoxicosis is generally good. Most patients can achieve normal thyroid hormone levels and symptom relief. However, untreated thyrotoxicosis can lead to serious complications, such as heart problems or osteoporosis. Regular follow-up with a healthcare provider is essential to monitor thyroid function and adjust treatment as needed.

Thyrotoxicosis can result from various causes, including:

• Graves' disease: An autoimmune disorder where the immune system attacks the thyroid, causing it to produce excess hormones.
• Toxic adenoma or multinodular goiter: Benign growths in the thyroid that produce excess hormones.
• Thyroiditis: Inflammation of the thyroid gland, which can cause a temporary release of stored hormones.
• Excessive thyroid hormone intake: Overuse of thyroid hormone medication.

Identifying the underlying cause is crucial for effective management.

Thyrotoxicosis affects people worldwide, with varying prevalence depending on the population and underlying causes. It is more common in women than men and can occur at any age, though it is most frequently diagnosed in adults. Graves' disease is the most common cause of thyrotoxicosis in many regions.

The pathophysiology of thyrotoxicosis involves an excess of thyroid hormones, primarily thyroxine (T4) and triiodothyronine (T3), in the bloodstream. These hormones increase the metabolic rate, leading to the symptoms associated with the condition. The underlying mechanisms can vary, such as increased hormone production in Graves' disease or hormone release due to thyroid inflammation in thyroiditis.

Preventing thyrotoxicosis involves managing risk factors and underlying conditions. For example, regular monitoring and appropriate dosing of thyroid hormone medication can prevent iatrogenic thyrotoxicosis. In autoimmune conditions like Graves' disease, prevention may not be possible, but early detection and treatment can mitigate complications.

Thyrotoxicosis is a condition marked by an excess of thyroid hormones, leading to a range of symptoms affecting metabolism and other bodily functions. It can result from various causes, including autoimmune disorders, thyroid nodules, and medication overuse. Diagnosis involves clinical evaluation and laboratory tests, while treatment options include medications, radioactive iodine, and surgery. With proper management, the prognosis is generally favorable.

If you suspect you have symptoms of thyrotoxicosis, it's important to consult a healthcare provider for evaluation. They will conduct tests to determine if your thyroid hormone levels are elevated and identify the underlying cause. Treatment is available and can effectively manage symptoms and prevent complications. Regular follow-up is essential to ensure optimal thyroid function and adjust treatment as needed.

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