PANCE Blueprint Endocrinology (7%)

Thyroiditis (Lecture + ReelDx)


16 y/o with diaphoresis, weight loss, tremor, palpitations, and neck swelling

Patient will present as → a 37-year-old female with a 2-week history of a painful mass in her neck after having a sore throat and fever for 3 days. The patient reports the mass has slowly been enlarging over that time span and has become more painful to the touch. She also reports feeling hot, even when her coworkers feel cold, and reports loose stools over the past week. The patient’s vital signs are T 98.6F, BP 140/90, Pulse 110 bpm, and SpO2 100%. On exam, you note a diffusely enlarged thyroid that is painful to the touch. TSH is decreased, T4/T3 is elevated, and radioactive iodine uptake and scan at 24 hours reveals an uptake of 3% (normal 8-25%).

Thyroiditis is a general term that refers to inflammation of the thyroid gland and includes a group of individual disorders causing thyroidal inflammation but presenting in different ways

Hashimoto’s thyroiditis: an autoimmune form of thyroiditis ⇒ autoantibodies directed against thyroid ⇒ thyroid tissue is destroyed over time ⇒ chronic hypothyroidism

  • The most common cause of hypothyroidism in the United States
  • Hashimoto's thyroiditis may present similarly to subacute thyroiditis, but the presence of neck tenderness and a recent viral illness should make you think subacute thyroiditis.
  • Goiter on PE
  • High levels of anti-TPO antibodies
  • TX depends on whether hypothyroidism is present
    • euthyroid: no treatment
    • chronic hypothyroidism: lifelong substitution with T4

Postpartum thyroiditis

  • 2-12 months after giving birth
  • Immune system diminished during pregnancy ⇒ after childbirth, the immune system is more active and might attack the thyroid
  • Hyperthyroid phase 5-7 months after birth, followed by normal thyroid function

Subacute thyroiditis (Quervain's thyroiditis)

  • The most common cause of thyroid pain and has a greater incidence in women
  • Inflamed, painful thyroid, fever, and muscle aches
  • The etiology is often post-infectious and viral in origin
  • Usually following symptoms such as fever, myalgia, and pharyngitis
  • Early in the course may be hyperthyroid, followed by a period of hypothyroidism
  • Increased ESR (60-100)
  • Usually causes hyperthyroidism - TFTs (if abnormal) are usually hyperthyroid at presentation - ↓ TSH, ↑ T4, and ↑ T3

Drug-induced: Thyroiditis can also be seen in patients taking certain drugs

  • Antithyroid medications: methimazole and propylthiouracil
  • Lithium - bipolar disorder
  • Amiodarone - antiarrhythmic
  • Interferon alpha
  • Tyrosine Kinase Inhibitors (e.g., Sunitinib) - anti-cancer
  • Checkpoint inhibitors (e.g., Nivolumab, Pembrolizumab)
  • TSH should be checked every 6-12 months - T4 therapy given right away

Infectious bacterial thyroiditis (rare) is often due to the hematogenous spread of staph or strep

  • Its signs are the classic ones of inflammation: fever, heat, pain, redness, and swelling
  • ↑ WBC

Summary of thyroiditis:

Type Cause Features Diagnosis Duration and resolution
Hashimoto’s thyroiditis Anti-thyroid antibodies, autoimmune disease Hypothyroidism, rare cases of transient thyrotoxicosis Thyroid function tests, thyroid antibody tests

↑ anti-TPO antibodies

Hypothyroidism is usually permanent
Subacute thyroiditis (de Quervain’s thyroiditis) Possible viral cause Painful thyroid, thyrotoxicosis followed by hypothyroidism Thyroid function tests, sedimentation rate, radioactive iodine uptake

TFTs (if abnormal) are usually hyperthyroid at presentation - ↓ TSH, ↑ T4, and ↑ T3

Resolves to normal thyroid function within 12-18 months, 5% possibility of permanent hypothyroidism.
Silent thyroiditis, Painless thyroiditis Anti-thyroid antibodies, autoimmune disease Thyrotoxicosis followed by hypothyroidism. Thyroid function tests, thyroid antibody tests, radioactive iodine uptake Resolves to normal thyroid function within 12-18 months, 20% possibility of permanent hypothyroidism.
Postpartum thyroiditis Anti-thyroid antibodies, autoimmune disease Thyrotoxicosis followed by hypothyroidism Thyroid function tests, thyroid antibody tests, radioactive iodine uptake (contraindicated   if the hypothyroid woman is breast-feeding) Resolves to normal thyroid function within 12-18 months, 20% possibility of permanent hypothyroidism
Drug-induced Drugs include amiodarone, lithium, interferons, cytokines Either thyrotoxicosis or hypothyroidism. Thyroid function tests, thyroid antibody tests Often continues as long as the drug is taken
Radiation-induced Follows treatment with radioactive iodine for hyperthyroidism or external beam radiation therapy for certain cancers. Occasionally thyrotoxicosis, more frequently hypothyroidism Thyroid function tests Thyrotoxicosis is transient, hypothyroidism is usually permanent
Acute thyroiditis, Suppurative thyroiditis Bacteria mainly, but any infectious organism Occasionally painful thyroid, generalized illness, occasional mild hypothyroidism Thyroid function tests, radioactive iodine uptake, fine-needle aspiration biopsy Resolves after treatment of infectious cause, may cause severe illness

Lab values depend on the cause of thyroiditis and may be euthyroid

  • Other possibilities include ↑ ESR (subacute), ↑ WBC count (infectious), ↑ anti-TPO antibodies (Hashimoto's)
  • TFTs (if abnormal) are usually hyperthyroid at presentation - ↓ TSH, ↑ T4, and ↑ T3

Ultrasound and radioactive iodine scanning have little value in this setting and are not warranted

  • If performed, a radioactive iodine (RAI) scan will reveal diminished uptake

If there is PAIN think:

  • Painful subacute - De Quervain's (granulomatous) usually post viral
  • Infectious - bacterial mainly - strep or staph most common
  • Radiation
  • Trauma

If there is NO PAIN, think

  • Postpartum - 1-2 months of hyperthyroidism after delivery
  • Drug-induced - the most common cause of drug-induced thyroiditis is Lithium or Amiodarone
  • Hashimoto thyroiditis

Hashimotos: TX depends on whether hypothyroidism is present

  • euthyroid: no treatment
  • chronic hypothyroidism: lifelong substitution with T4

Subacute and postpartum thyroiditis usually resolve on their own after 12-18 months; often only need pain management

  • Beta-blockers during hyperthyroid state
  • T4 for several months during hypothyroid phase until TSH normalizes then can be stopped
  • Occasionally permanent hypothyroidism
  • Aspirin for pain and inflammation

Drug-induced: Stop offending drugs *lithium *Amiodarone - will usually return to euthyroid state once the meds are stopped

Infectious bacterial thyroiditis: The treatment is that for any febrile disease, including specific antibiotic drugs if the invading organism has been identified and its sensitivity to the drug established. Surgical drainage if abscess present

osmosis Osmosis
Question 1
A 31-year-old woman returns to your clinic after being seen for a viral upper respiratory infection three weeks ago. She reports initial improvement, followed by the development of a painful neck, fatigue, and weight gain. She also mentions experiencing dry skin and cold intolerance. On examination, you note mild, diffuse tenderness over the thyroid gland. What is the most likely diagnosis?
Grave's disease
Graves' disease is an autoimmune disorder that leads to hyperthyroidism. It typically presents with symptoms like weight loss, heat intolerance, and palpitations, and the thyroid is usually not tender.
Hashimoto thyroiditis
This is an autoimmune disorder leading to hypothyroidism. While it can cause symptoms like fatigue and weight gain, the thyroid gland is usually not painful.
Subacute thyroiditis
Papillary thyroid carcinoma
While this is the most common type of thyroid cancer, it typically does not present with a painful thyroid gland or a pattern of symptoms consistent with both hyperthyroidism and hypothyroidism.
Thyroid lymphoma
This is a rare form of thyroid cancer and typically presents with a rapidly enlarging, painless goiter. It is not typically associated with a preceding viral infection.
Question 1 Explanation: 
Subacute thyroiditis, also known as De Quervain's thyroiditis, often follows a viral upper respiratory infection. It is characterized by a painful, tender thyroid, and can initially present with symptoms of hyperthyroidism (such as palpitations), followed by symptoms of hypothyroidism (such as fatigue, weight gain, dry skin, and cold intolerance). The course of the disease typically involves an initial thyrotoxic phase followed by a hypothyroid phase, before eventually returning to normal thyroid function.
Question 2
A 45-year-old man presents with a painful, tender thyroid gland, fever, and malaise. He recently recovered from a viral upper respiratory infection. His thyroid function tests reveal elevated free T4 and low TSH. What is the most appropriate diagnostic test to confirm the suspected condition?
Thyroid ultrasound
Thyroid ultrasound is useful in evaluating thyroid nodules but less helpful in acute thyroiditis.
Radioactive iodine uptake test
Radioactive iodine uptake test would show low uptake in subacute thyroiditis but is not necessary for diagnosis.
Fine-needle aspiration biopsy
Fine-needle aspiration biopsy is more appropriate for evaluating thyroid nodules or suspected thyroid cancer.
Anti-thyroid peroxidase (anti-TPO) antibodies
Anti-TPO antibodies are associated with Hashimoto's thyroiditis, not subacute thyroiditis.
Erythrocyte sedimentation rate (ESR)
Question 2 Explanation: 
The patient's clinical presentation is suggestive of subacute (De Quervain's) thyroiditis, which typically follows a viral infection and presents with a painful, tender thyroid gland, fever, and transient hyperthyroidism. An elevated ESR is a hallmark of this condition and helps confirm the diagnosis.
Question 3
A 33-year-old woman, previously diagnosed with subacute thyroiditis, now presents with laboratory findings confirming a hypothyroid state. She complains of persistent fatigue, weight gain, and cold intolerance. What is the most appropriate management for her current condition?
Initiate radioactive iodine therapy
This is not indicated in subacute thyroiditis, as it is typically a self-limiting condition and radioactive iodine is used in the treatment of hyperthyroid states.
Start thyroid hormone replacement and monitor thyroid function regularly
Reassure and observe without treatment, as the condition is self-limiting
While subacute thyroiditis is often self-limiting, treatment for symptomatic hypothyroidism during its course is necessary to alleviate symptoms.
Inform the patient that thyroid function will normalize spontaneously within a few weeks
While thyroid function may eventually normalize, this patient's current symptoms warrant treatment.
Order a thyroid ultrasound for further evaluation
While a thyroid ultrasound can be useful in the diagnosis of thyroid conditions, it is not necessary in this case where the diagnosis is clear and the focus is on managing the hypothyroid phase.
Question 3 Explanation: 
In cases of subacute thyroiditis, patients may go through a phase of hypothyroidism. If the hypothyroid symptoms are significant, as in this patient, starting thyroid hormone replacement therapy is appropriate. Regular monitoring of thyroid function tests is essential to adjust the dosage and to assess if the thyroid function returns to normal, at which point the replacement therapy might be tapered or discontinued.
There are 3 questions to complete.
Shaded items are complete.

References: Merck Manual · UpToDate

Hypothyroidism (Lecture) (Prev Lesson)
Back to PANCE Blueprint Endocrinology (7%)