Self-limited thyroid condition associated with a triphasic clinical course of hyperthyroidism, hypothyroidism, and return to normal thyroid function:subacute granulomatous thyroiditis.
Responsible for 15-20% of patients presenting with thyrotoxicosis and 10% of patients presenting with hypothyroidism.
In general, the following 3 forms of subacute thyroiditis are recognized:
Subacute granulomatous, subacute painful, or de Quervain thyroiditis, Lymphocytic thyroiditis (also known as subacute painless thyroiditis) and Subacute postpartum thyroiditis.
An inflammation of the thyroid gland.
It is thought to be a post viral inflammatory process, caused by common antigens in viruses and thyroid follicular cells.
Coxsackie and mumps virus and recently Covid-19 virus have been associated with subacute thyroiditis.
Am underreported process but is estimated to occur quite commonly, particularly following surgery in the neck.
Parathyroid surgery commonly results in transient or temporary post-operative thyroiditis.
Several types of thyroiditis exist.
Hashimoto’s thyroiditis, also called autoimmune or chronic lymphocytic thyroiditis, is the most common type of thyroiditis.
Hashimoto’s thyroiditis is the most common cause of hypothyroidism.
The thyroid gland is always enlarged in Hashimoto’s thyroiditis.
Presumably and the infection related antigen possesses structural similarity with thyroid follicular cells and the binding of the antigen to HLA-B35 on macrophages result in activation activation of cytotoxic T cells.
These T cells invade the thyroid and caused thyroid inflammation and proteolysis of stored thyroglobulin.
These findings result in a surge in T3 and T4 due to the release causing thyrotoxicosis.
Often the thyrotoxicosis is followed by a period of hypothyroidism until the thyroid gland recovers and TSH increases.
Euthyroidism eventually is achieved after 2-3 months.
The presenting symptom is usually anterior neck pain following infection and is occasionally associated with fever, fatigue and myalgia.
Fever is present in about 28% of patients.
Clinically the thyroid is firm or hard and tender or quite painful.
The thyroid is in large and tender.
TSH levels are suppressed and there is an absence of thyroid antibodies, increased thyroglobulin, and elevated ESR or C reactive proteins.
Radioactive iodine uptake is diffusely low: destructive subacute, thyroiditis results in thyrotoxicosis wave near absent radioactive iodine uptake.
Hypoechoic areas a present on thyroid ultrasound.
The ratio of total T3 to thyroxine is less than 20.
Treatment as supportive as the disease is self-limiting.
NSAIDs are used for neck pain and if this is insufficient low-dose steroids can be useful.
Beta blockade is useful for symptoms of thyrotoxicosis.
The radioactive iodine uptake may be paradoxically high while the patient is hypothyroid because the gland retains the ability to take-up or trap iodine even after it has lost its ability to produce thyroid hormone.
As the disease progresses, the TSH increases since the pituitary is trying to induce the thyroid to make more hormone, the T4 falls as the thyroid cannot manufacture it, and the patient becomes hypothyroid.
The above events occur over a relatively short span of a few weeks, or it may take several years.
Treatment with thyroid hormone replacement prevents or corrects the hypothyroidism, and generally keeps the gland from getting larger.
Once thyroid hormone replacement is started the thyroid gland will decrease in size.
Thyroid antibodies are present in 95% of patients with Hashimoto’s thyroiditis and serve as a marker in identifying the disease without thyroid biopsy or surgery.
Thyroid antibodies may remain for years after the disease has been adequately treated and the patient is on thyroid hormone replacement.
De Quervain’s subacute thyroiditis is much less common than Hashimoto’s thyroiditis.
With De Quervain’s subacute thyroiditis the thyroid gland generally swells rapidly and is very painful and tender.
As the gland discharges thyroid hormone into the blood and the patients become hyperthyroid with De Quervain’s subacute thyroiditis.
The thyroid gland takes up iodine very slowly and the hyperthyroidism generally resolves over the next several weeks.
De Quervain’s subacute thyroiditis is frequently associated with fever and prefer to be in bed.
Thyroid antibodies are absent in De Quervain’s subacute thyroiditis but the sedimentation rate is very high.
De Quervain’s subacute thyroiditis is not a result of infection, and antibiotics are of no use.
Treatment is usually bed rest and aspirin to reduce inflammation.
In prolonged cases corticosteroids are considered.
Nearly all patients recover, and the thyroid gland returns to normal after several weeks or months, and recurrences are uncommon..
A few patients with De Quervain’s subacute thyroiditis becomes hypothyroid once the inflammation settles down and therefore will need to stay on thyroid hormone replacement indefinitely.
Silent thyroiditis is the least common type of thyroiditis.
Silent thyroiditis resembles a combination of Hashimoto’s thyroiditis and De Quervain’s thyroiditis.
Like De Quervain’s thyroiditis the blood thyroid level is high
and the radioactive iodine uptake is low, but there is no pain and needle biopsy resembles Hashimoto’s thyroiditis.
The majority of patients with silent thyroid it is have been young women following pregnancy.
Silent thyroiditis usually needs no treatment, and 80% of patients show complete recovery and return of the thyroid gland to normal after 3 months.
Symptoms are similar to Graves’ disease except milder, with only a slightly enlarged thyroid and exophthalmos does not occur.
Bed rest and beta blockers to control palpitations may be helpful.
Thyroid inflammation can occur in response to vigorous movement of the thyroid gland during surgery in the neck for parathyroidectomy.
For those who develop dost-surgical thyroiditis, treatment is with medication for one to three months to help reduce the inflammation and restore the thyroid to healthy functioning.
Thyroiditis may occur in response to a viral infection or a bacterial infection, following radiation, or in response to certain medications.
The etiology appears to be different for the 3 subtypes, but the clinical courses are the same.
The high thyroid hormone levels are a result of destruction of the thyroid follicle and release of preformed thyroid hormone into the circulation.
Thyrotoxicosis develops in patients who is subacute thyroiditis caused by leakage of preformed hormone from thyroid follicles, resulting in transient hyperthyroid phase that lasts on average 2-8 weeks.
Eventually, thyroid hormone is depleted and the patient may become hypothyroid.
The hypothyroid phase may last up to 2 months, but 90-95% of patients return to normal thyroid function.
Subacute granulomatous thyroiditis symptoms typically include neck pain and tenderness.
Some patients experience difficulty swallowing or fever.
The cause of the condition is thought to be a virus.
Subacute granulomatous thyroiditis has a female-to-male prevalence ratio of 5:1, and lymphocytic thyroiditis occurs 2 times more often in women than it does in men.
Postpartum thyroiditis occurs 1-6 months after giving birth.
Postpartum thyroiditis may occur with all pregnancies.
Granulomatous thyroiditis usually occurs in adults aged 20-60 y.
No specific therapy is necessary in most patients.
Pain is usually managed with nonsteroidal, anti-inflammatory drugs, with glucocorticoids reserved for those who do not respond or have moderate to severe symptoms.