Thyroiditis

Question 1

Define thyroiditis.

Answer 1

Broad category of inflammatory diseases of the thyroid gland.

Question 2

What is the aetiology of thyroiditis?

Answer 2

Causes can be:

1. Autoimmune disease - anti thyroid antibodies. FH common.
2. Viral or bacterial infection
3. Medication - interferon and amiodarone

Question 3

Name 7 causes of thyroiditis.

Answer 3

1. Hashimoto’s thyroiditis - autoimmune
2. Drug induced thyroiditis e.g. amiodarone, lithium, interferons, cytokines
3. Radiation induced
4. Acute suppurative thyroiditis

Subacute types:

1. Subacute thyroiditis (de Quervain’s thyroiditis/ subacute granulomaous)
2. Silent/painless thyroiditis
3. Post partum thyroiditis

Question 4

What are 3 types of subacute thyroiditis?

Answer 4

Question 5

Describe how the thyroid hormones become disregulated in each cause of thyroiditis.

Answer 5

Thyrotoxicosis in ALL.

1. Hashimoto’s - hypothyroidism (+/- transient thyrotoxicosis)
2. de Quervain’s - transient thyrotoxicosis followed by transient hypothyroidism then normal
3. Silent/painless - transient thyrotoxicosis followed by hypothyroidism which may remain
4. Post partum thyroiditis - thyrotoxicosis followed by hypothyroidism which may remain
5. Drug induced - either thyrotoxicosis or hypothyroidism
6. Radiation induced - mostly hypothyroidism but sometimes thyrotoxicosis
7. Acute suppurative - occasional mild hypothyroidism

Question 6

What causes Hashimoto’s thyroiditis? What are the clinical features? How is it diagnosed?

Answer 6

Hashimoto’s - AI-mediated lymphocytic inflammation of the thyroid causing destructive thyroiditis. Antibodies bind to and block the TSH receptor this causes a decrease in thyroid hormone production and secretion. Initially preformed T3 and T4 may leak into circulation from damaged cells.

RF: It is 15-20 times more common in women. Usually affects those 30-50yrs.

Symptoms: Thyroid may enlarge rapidly causing dysphagia/dyspnoea and pain may persist. Mild thyrotoxicosis can occur in early stages. Symptoms of hypothyroidism may develop slowly.

Diagnosis: TSH levels raised; anti-thyroid peroxidase and anti-thyroglobulin (anti-TPO and anti-TG) antibodies; US thyroid.

Treatment: levothyroxine for life; surgery if dyspnoea/dysphagia

Question 7

What causes subacute thyroiditis/de Quervain’s? What are the clinical features? How is it diagnosed?

Answer 7

Subacute thyroiditis - sel-limited condition associated with 4-phased clinical course and return to normal thyroid function. Usually caused by viral illness causing URTI. NOT AI, but presence of antibodies may be found in the acute phase.

Course: Destruction of the thyroid follicles causes high thyroid hormone levels (lasting 4-10weeks). This undergoes spontaneous remission in 4-8 weeks but the thyroid is depleted of colloid so hypothyroidism occurs which may last up to 2 months (this is usually mild)

Symptoms: may cause pain which shifts to different locations in the thyroid.

Diagnosis:

• thyroid scintigraphy: globally reduced uptake of iodine-131

Management: self-limiting +/- NSAIDs, steroids in severe cases.

Question 8

What causes silent/painless thyroiditis? What are the clinical features? How is it diagnosed?

Answer 8

aka Painless lymphocytic thyroiditis - AI mediated inflammation of thyroid gland which causes transient hyperthyroidism, then hypothyroidism and recovery of normal thyroid function.

Causes: sporadic, postnatal, lithium or immunomodulatory therapy. Considered a variant of Hashimoto’s. Most patients have anti-TPO, although these antibodies may be present in low titres.

Diagnosis: confirmed by a 4-, 6-, or 24-hour radioiodine uptake of <1% during the hyperthyroid phase of the illness. TSH variable, T3 and T4 variable, TPO may be present and TRAb antibodies negative (+ve in Graves’).

Treatment: Treatment, if needed, includes beta-blockers for the hyperthyroid phase and levothyroxine for the hypothyroid phase of the illness.

Question 9

What causes acute thyroiditis? What are the clinical features ? How is it diagnosed?

Answer 9

Acute thyroiditis -

Causes: Bacteria mainly, but any infectious organism. Thyroid is usually resistant to haematogenous spread of infection.

Symptoms: Occasionally painful thyroid, generalized illness, occasional mild hypothyroidism

Diagnosis: Laboratory abnormalities in acute thyroiditis reflect the acute systemic illness; findings include leukocytosis with a left shift and an increased ESR;TFTs results are within the reference range

Management: parenteral antibiotics e.g. penicillin or ampicillin to cover gram-positive cocci and the anaerobes that are the usual causes of the disease. Recovery is usually complete and thyroid function remains normal.

Question 10

Summarise thyroiditis.

Answer 10

Question 11

What cancer is associated with Hashimoto’s?

Answer 11

MALT lymphoma - non-gastric variants are associated with autoimmune diseases, such as Hashimoto’s thyroiditis. The gastric MALT lymphomas are most commonly caused by H. pylori infection.

Question 12

What are the general treatments for thyroiditis?

Answer 12

• Beta blockers
• Thyroxine for thyrotoxic phase - but remember that you want to withdraw the levothyroxine eventually
• NSAIDs - avoid aspirin
• High dose steroids

Not in use anymore:

Gastrograffin - stops T4 to T3 conversion