Subacute lymphocytic thyroiditis can only be diagnosed correctly by taking a radioactive iodine uptake test (RAIU) test.

During the hyperthyroid phase, iodine uptake is increased, while during the hypothyroid phase, uptake is decreased.

This situation contrasts greatly with the elevated iodine uptake found in patients with Graves' disease.

Various tests can be chosen depending on the presenting symptoms. Doctors may search for Thyroid peroxidase Antibodies (TPOAb) when a person has symptoms of hypothyroidism, or when a person will be started on a drug therapy associated with risks of developing hypothyroidism, such as lithium or Interferon alfa. This antibody is related to Hashimoto's thyroiditis and Graves' disease. If the person presents symptoms of hyperthyroidism, doctors are more likely to test for Thyroid stimulating hormone receptor Antibodies (TRAb), and monitor the effects of anti-thyroid therapy, also associated with Graves' disease.

Doctors may check Thyroglobulin Antibodies (TgAb) also, whenever a thyroglobulin test is performed to see if the antibody is interfering. TgAb may also be ordered in regular intervals after a person has been diagnosed with thyroid cancer, and just like TPOAb, it can be associated with Hashimoto’s thyroiditis.

The most common and helpful way to diagnose thyroiditis is first for a physician to palpate the thyroid gland during a physical examination. Laboratory tests allow doctors to evaluate the patient for elevated erythrocyte sedimentation rates, elevated thyroglobulin levels, and depressed radioactive iodine uptake (Mather, 2007). Blood tests also help to determine the kind of thyroiditis and to see how much thyroid stimulating hormone the pituitary gland is producing and what antibodies are present in the body. In some cases a biopsy may be needed to find out what is attacking the thyroid.

Treatment is based on symptoms. Beta-blockers relieve rapid heart rate and excessive sweating during the hyperthyroid phase.

Diagnosis is usually made by detecting elevated levels of anti-thyroid peroxidase antibodies (TPOAb) in the serum, but seronegative (without circulating autoantibodies) thyroiditis is also possible.

Given the relatively non-specific symptoms of initial hypothyroidism, Hashimoto's thyroiditis is often misdiagnosed as depression, cyclothymia, PMS, chronic fatigue syndrome, fibromyalgia and, less frequently, as erectile dysfunction or an anxiety disorder. On gross examination, there is often presentation of a hard goiter that is not painful to the touch; other symptoms seen with hypothyroidism, such as periorbital myxedema, depend on the current state of progression of the response, especially given the usually gradual development of clinically relevant hypothyroidism. Testing for thyroid-stimulating hormone (TSH), free T3, free T4, and the anti-thyroglobulin antibodies (anti-Tg), anti-thyroid peroxidase antibodies (anti-TPO, or TPOAb) and anti-microsomal antibodies can help obtain an accurate diagnosis. Earlier assessment of the person may present with elevated levels of thyroglobulin owing to transient thyrotoxicosis, as inflammation within the thyroid causes damage to the integrity of thyroid follicle storage of thyroglobulin; TSH secretion from the anterior pituitary increases in response to a decrease in negative feedback inhibition secondary to decreased serum thyroid hormones. Typically T4 is the preferred thyroid hormone test for hypothyroidism. This exposure of the body to substantial amounts of previously isolated thyroid enzymes is thought to contribute to the exacerbation of tolerance breakdown, giving rise to the more pronounced symptoms seen later in the disease. Lymphocytic infiltration of the thyrocyte-associated tissues often leads to the histologically significant finding of germinal center development within the thyroid gland.

Hashimoto's when presenting as mania is known as Prasad's syndrome after Ashok Prasad, the psychiatrist who first described it.

Overt, symptomatic thyroid dysfunction is the most common complication, with about 5% of persons with subclinical hypothyroidism and chronic autoimmune thyroiditis progressing to thyroid failure every year. Transient periods of thyrotoxicosis (over-activity of the thyroid) sometimes occur, and rarely the illness may progress to full hyperthyroid Graves' disease with active orbitopathy (bulging, inflamed eyes). Rare cases of fibrous autoimmune thyroiditis present with severe dyspnea (shortness of breath) and dysphagia (difficulty swallowing), resembling aggressive thyroid tumors – but such symptoms always improve with surgery or corticosteroid therapy. Primary thyroid B cell lymphoma affects fewer than one in a thousand persons, and it is more likely to affect those with long-standing autoimmune thyroiditis.

Treatment is as with hypothyroidism, daily thyroxine(T4) and/or triiodothyronine(T3).

Treatments for this disease depend on the type of thyroiditis that is diagnosed. For the most common type, which is known as Hashimoto's thyroiditis, the treatment is to immediately start hormone replacement. This prevents or corrects the hypothyroidism, and it also generally keeps the gland from getting bigger. However, Hashimoto's thyroiditis can initially present with excessive thyroid hormone being released from the thyroid gland (hyperthyroid). In this case the patient may only need bed rest and non-steroidal anti-inflammatory medications; however, some need steroids to reduce inflammation and to control palpitations. Also, doctors may prescribe beta blockers to lower the heart rate and reduce tremors, until the initial hyperthyroid period has resolved.

Diagnosis of autoimmune disorders largely rests on accurate history and physical examination of the patient, and high index of suspicion against a backdrop of certain abnormalities in routine laboratory tests (example, elevated C-reactive protein). In several systemic disorders, serological assays which can detect specific autoantibodies can be employed. Localised disorders are best diagnosed by immunofluorescence of biopsy specimens. Autoantibodies are used to diagnose many autoimmune diseases. The levels of autoantibodies are measured to determine the progress of the disease.

This condition is commonly undiagnosed by physicians due to either unfamiliarity with the disease, the subtlety of symptoms, or the attribution of the symptoms to the stresses of having a newborn. Usual screening begins with assessing the thyroid stimulating hormone (TSH) level. A suppressed TSH could represent the hyperthyroid phase, but warrants further testing to investigate for possible Graves' disease. A normal TSH with persistent symptoms could represent the shift between phases and requires repeat testing 4–6 weeks later; an elevated TSH at this time could indicate the hypothyroid phase.

Treatment is beta blockers, ASA, and NSAIDs (or corticosteroids if NSAIDs are ineffective).

In the initial phase of damage to the gland, preformed thyroid hormone will 'fall out' of the damaged cells. This leads to symptoms and biochemistry of an overactive thyroid (feels hot, trembly, anxious, loses weight, fast heart rate, sweaty, greasy hair), with raised free T3 and free T4, and a suppressed thyroid stimulating hormone (TSH) value. The damaged cells will no longer be able to take up iodine in order to manufacture further supplies of thyroid hormone, and thus in due course the patient comes to experience the symptoms of an underactive thyroid (feels cold, tired, depressed, gains weight, dry skin and hair) with low free T3 and free T4, and eventually increased TSH.

With the standard overactive thyroid, iodine uptake into the thyroid is avid, whereas if the cells are damaged, then uptake is poor. In this way, if there is doubt about whether the patient has too much thyroid hormone because of de Quervain's thyroiditis, then measuring radio-iodine uptake or technetium uptake gives a clear cut answer as it will be higher than normal in standard thyrotoxicosis and lower than normal in de Quervain's.

Thyroid autoantibodies appear mostly with the presence of lymphocytes in the targeted organ. Lymphocytes produce antibodies targeting three different thyroid proteins: Thyroid peroxidase Antibodies (TPOAb), Thyroglobulin Antibodies (TgAb), and Thyroid stimulating hormone receptor Antibodies (TRAb). Some patients who are healthy may be positive for more than one of these antibodies. Doctors who attend to such patients will most likely do routine follow-ups on the patient’s health since, even though it is highly unlikely that they will present any thyroid problems, there is still a chance that they will develop some type of dysfunction with time.

Therapy usually consists of prednisolone, nonetheless some cases may require surgery. Tamoxifen has been proposed as part of a treatment plan.

Treatment is directed to surgical relief of compressive symptoms. Tamoxifen may also be beneficial.

-Harrison's principle of internal medicine, 17th

The type of surgery which is indicated here is isthmectomy.

Riedel's thyroiditis is classified as rare. Most patients remain euthyroid, but approximately 30% of patients become hypothyroid and very few patients are hyperthyroid. It is most seen in women.

Outside Europe a goitrous form of autoimmune thyroiditis (Hashimoto's Thyroiditis) is more common than Ord's disease.

Subacute thyroiditis is a form of thyroiditis that can be a cause of both thyrotoxicosis and hypothyroidism. It is uncommon and can affect individuals of both sexes and people of all ages. The most common form, subacute granulomatous, or de Quervain's, thyroiditis manifests as a sudden and painful enlargement of the thyroid gland accompanied with fever, malaise and muscle aches. Indirect evidence has implicated viral infection in the aetiology of subacute thyroiditis. This evidence is limited to preceding upper respiratory tract infection, elevated viral antibody levels, and both seasonal and geographical clustering of cases. There may be a genetic predisposition.

Nishihara and coworkers studied the clinical features of subacute thyroiditis in 852 mostly 40- to 50-year-old women in Japan. They noted seasonal clusters (summer to early autumn) and most subjects presented with neck pain. Fever and symptoms of thyrotoxicosis was present in two thirds of subjects. Upper respiratory tract infections in the month preceding presentation were reported in only 1 in 5 subjects. Recurrent episodes following resolution of the initial episode were rare, occurring in just 1.6% of cases. Laboratory markers for thyroid inflammation and dysfunction typically peaked within one week of onset of illness.

Types include:

- Subacute granulomatous thyroiditis (De Quervain thyroiditis)

- Subacute lymphocytic thyroiditis

- Postpartum thyroiditis

- Palpation thyroiditis

The diagnosis of autoimmune hepatitis is best achieved with a combination of clinical, laboratory, and histological findings after excluding other etiological factors (e.g. viral, hereditary, metabolic, cholestatic, and drug-induced diseases).

A number of specific antibodies found in the blood (antinuclear antibody (ANA), anti-smooth muscle antibody (SMA), anti-liver kidney microsomal antibodies (LKM-1, LKM-2, LKM-3), anti soluble liver antigen (SLA), liver–pancreas antigen (LP), and anti-mitochondrial antibody (AMA)) are of use, as is finding an increased Immunoglobulin G level. However, the diagnosis of autoimmune hepatitis always requires a liver biopsy.

Expert opinion has been summarized by the International Autoimmune Hepatitis Group, which has published criteria which utilize clinical and laboratory data that can be used to help determine if a patient has autoimmune hepatitis.

A calculator based on those criteria is available online.

Overlapping presentation with primary biliary cirrhosis and primary sclerosing cholangitis has been observed.

Four subtypes are recognised, but the clinical utility of distinguishing subtypes is limited.

1. positive ANA and SMA, elevated immunoglobulin G (classic form, responds well to low dose steroids);

2. positive LKM-1 (typically female children and teenagers; disease can be severe), LKM-2 or LKM-3;

3. positive antibodies against soluble liver antigen (this group behaves like group 1) (anti-SLA, anti-LP)

4. no autoantibodies detected (~20%) (of debatable validity/importance)

Screening for hypothyroidism is performed in the newborn period in many countries, generally using TSH. This has led to the early identification of many cases and thus the prevention of developmental delay. It is the most widely used newborn screening test worldwide. While TSH-based screening will identify the most common causes, the addition of T testing is required to pick up the rarer central causes of neonatal hypothyroidism. If T determination is included in the screening done at birth, this will identify cases of congenital hypothyroidism of central origin in 1:16,000 to 1:160,000 children. Considering that these children usually have other pituitary hormone deficiencies, early identification of these cases may prevent complications.

In adults, widespread screening of the general population is a matter of debate. Some organizations (such as the United States Preventive Services Task Force) state that evidence is insufficient to support routine screening, while others (such as the American Thyroid Association) recommend either intermittent testing above a certain age in both sexes or only in women. Targeted screening may be appropriate in a number of situations where hypothyroidism is common: other autoimmune diseases, a strong family history of thyroid disease, those who have received radioiodine or other radiation therapy to the neck, those who have previously undergone thyroid surgery, those with an abnormal thyroid examination, those with psychiatric disorders, people taking amiodarone or lithium, and those with a number of health conditions (such as certain heart and skin conditions). Yearly thyroid function tests are recommended in people with Down syndrome, as they are at higher risk of thyroid disease.

During pregnancy, immunologic suppression occurs which induces tolerance to the presence of the fetus. Without this suppression, the fetus would be rejected causing miscarriage. As a result, following delivery, the immune system rebounds causing levels of thyroids antibodies to rise in susceptible women.

Specifically, the immunohistological features of susceptible women are indicated by:

- antibodies to thyroglobulin (TgAb)

- antibodies to thyroid peroxidase (TPOAb)

- increase in TPOAb subclasses IgG-IgG

- lymphocyte infiltration and follicle formation within thyroid gland (Hashimoto's thyroiditis)

- T-cell changes (increased CD4:CD8 ratio)

- TSH-receptor antibodies (TSH-R Abs)

Autoantibodies to the thyroid gland may be detected in various disease states. There are several anti-thyroid antibodies, including anti-thyroglobulin antibodies (TgAb), anti-microsomal/anti-thyroid peroxidase antibodies (TPOAb), and TSH receptor antibodies (TSHRAb).

- Elevated anti-thryoglobulin (TgAb) and anti-thyroid peroxidase antibodies (TPOAb) can be found in patients with Hashimoto's thyroiditis, the most common autoimmune type of hypothyroidism. TPOAb levels have also been found to be elevated in patients who present with subclinical hypothyroidism (where TSH is elevated, but free T4 is normal), and can help predict progression to overt hypothyroidism. The American Association Thyroid Association thus recommends measuring TPOAb levels when evaluating subclinical hypothyroidism or when trying to identify whether nodular thyroid disease is due to autoimmune thyroid disease.

- When the etiology of hyperthyroidism is not clear after initial clinical and biochemical evaluation, measurement of TSH receptor antibodies (TSHRAb) can help make the diagnosis. In Grave's disease, TSHRAb levels are elevated as they are responsible for activating the TSH receptor and causing increased thyroid hormone production.

Treatments for autoimmune disease have traditionally been immunosuppressive, anti-inflammatory, or palliative. Managing inflammation is critical in autoimmune diseases. Non-immunological therapies, such as hormone replacement in Hashimoto's thyroiditis or Type 1 diabetes mellitus treat outcomes of the autoaggressive response, thus these are palliative treatments. Dietary manipulation limits the severity of celiac disease. Steroidal or NSAID treatment limits inflammatory symptoms of many diseases. IVIG is used for CIDP and GBS. Specific immunomodulatory therapies, such as the TNFα antagonists (e.g. etanercept), the B cell depleting agent rituximab, the anti-IL-6 receptor tocilizumab and the costimulation blocker abatacept have been shown to be useful in treating RA. Some of these immunotherapies may be associated with increased risk of adverse effects, such as susceptibility to infection.

Helminthic therapy is an experimental approach that involves inoculation of the patient with specific parasitic intestinal nematodes (helminths). There are currently two closely related treatments available, inoculation with either Necator americanus, commonly known as hookworms, or Trichuris Suis Ova, commonly known as Pig Whipworm Eggs.

T cell vaccination is also being explored as a possible future therapy for autoimmune disorders.

Cerebrospinal fluid findings:

- Raised protein (25% cases)

- Negative for 14–3–3 protein

- May contain antithyroid antibodies

- Magnetic resonance imaging abnormalities consistent with encephalopathy (26% cases)

- Single photon emission computed tomography shows focal and global hypoperfusion (75% cases)

- Cerebral angiography is normal

Thyroid hormone abnormalities are common (>80% cases):

- subclinical hypothyroidism (35% cases)

- overt hypothyroidism (20% cases)

- hyperthyroidism (5% cases)

- euthyroid on levothyroxine (10% cases)

- euthyroid not on levothyroxine (20% cases)

Thyroid antibodies – both anti-thyroid peroxidase antibodies (anti-TPO, anti-thyroid microsomal antibodies, anti-M) and antithyroglobulin antibodies (anti-Tg) – in the disease are elevated but their levels do not correlate with the severity.

Electroencephalogram studies, while almost always abnormal (98% cases), are usually nondiagnostic. The most common findings are diffuse or generalized slowing or frontal intermittent rhythmic delta activity. Prominent triphasic waves, focal slowing, epileptiform abnormalities, photoparoxysmal and photomyogenic responses may be seen.

The goal of treatment is the induction and maintenance of remission so as to prevent progression of fibrosis and organ destruction in affected organ(s).

An international panel of experts have developed recommendations for the management of IgG4-RD. They concluded that in all cases of symptomatic, active IgG4-RD that treatment is required. Some cases with asymptomatic IgG4-RD also require treatment, as some organs tend to not cause symptoms until the late stages of disease. Urgent treatment is advised with certain organ manifestations, such as aortitis, retroperitoneal fibrosis, proximal biliary strictures, tubulointerstitial nephritis, pachymeningitis, pancreatic enlargement and pericarditis.