What is the clinical presentation of Hashimoto's (Hashimoto's thyroiditis) thyroiditis?

Clinical Presentation of Hashimoto's Thyroiditis

Hashimoto's thyroiditis presents with a triphasic pattern of thyroid dysfunction, beginning with potential thyrotoxicosis, followed by hypothyroidism, and in some cases progressing to permanent hypothyroidism requiring lifelong thyroid hormone replacement therapy. 1

Common Clinical Manifestations

Initial Presentation

Hashimoto's thyroiditis can present in three distinct clinical phases:

1. Thyrotoxic Phase (Hashitoxicosis)

   • Occurs when stored thyroid hormones are released from destroyed thyroid follicles 2
   • Symptoms may include:
     • Tachycardia
     • Palpitations
     • Heat intolerance
     • Weight loss
     • Anxiety
   • This phase is typically transient

2. Euthyroid Phase

   • Preserved thyroid tissue compensates for destroyed thyrocytes 2
   • Patients may be asymptomatic or have mild symptoms
   • Often detected incidentally through laboratory testing
   • May present with painless goiter

3. Hypothyroid Phase

   • Most common clinical presentation
   • Develops when thyroid hormone production becomes insufficient 2
   • Symptoms include:
     • Fatigue
     • Muscle cramps
     • Constipation
     • Cold intolerance
     • Hair loss
     • Voice changes
     • Weight gain
     • Intellectual slowness
     • Insomnia 3

Physical Examination Findings

• Painless goiter (most common physical finding)
• Pale and round face (in advanced cases)
• Bradycardia
• Pseudohypertrophy of calf muscles (rare) 4
• Dry skin
• Delayed relaxation of deep tendon reflexes

Laboratory Findings

• Elevated TSH: Primary screening test for thyroid dysfunction 3
• Normal or low Free T4: Depending on disease severity 5
• Positive thyroid autoantibodies:
  • Thyroid peroxidase antibodies (TPOAbs) - most sensitive marker
  • Thyroglobulin antibodies (TgAbs) - less specific
• Other potential findings:
  • Dyslipidemia
  • Elevated liver enzymes (transaminases)
  • Low serum ceruloplasmin (rare) 4

Special Populations

Children and Adolescents

• Most commonly presents as subclinical hypothyroidism (39.5%) or euthyroidism (36.5%) 6
• Overt hypothyroidism occurs in approximately 18.5% of pediatric cases 6
• May affect growth and development if left untreated

Pregnant Women

• TPOAbs associated with 2-4 fold increased risk of recurrent miscarriages and preterm birth 2
• Requires careful monitoring and management

Elderly Patients

• May present with atypical symptoms
• Often mistaken for normal aging
• Treatment decisions should be individualized based on clinical presentation 5

Associated Conditions and Complications

• Increased risk of other autoimmune disorders:

  • Type 1 diabetes
  • Celiac disease
  • Pernicious anemia
  • Vitiligo
  • Rheumatoid arthritis 7

• Increased cancer risk:

  • 1.6 times higher risk of papillary thyroid cancer
  • 60 times higher risk of thyroid lymphoma compared to general population 2

• Cardiac complications:

  • Pericardial effusion (in severe cases) 4
  • Increased risk of atherosclerosis with prolonged hypothyroidism

• Myxedema:

  • Advanced form of hypothyroidism
  • Medical emergency requiring immediate treatment 5

Monitoring and Progression

• Regular thyroid function tests (TSH and Free T4) should be performed every 4-6 weeks initially, then every 6-12 months if stable 5
• Approximately 48.4% of patients can be monitored without treatment, while 47.6% require levothyroxine therapy 6
• Autoantibody levels may decrease over time, particularly by year five of follow-up 6

Diagnostic Pitfalls

• Multiple tests should be done over a 3-6 month interval to confirm abnormal findings 3
• TSH alone is insufficient; Free T4 should also be measured for accurate diagnosis 5
• Subclinical hypothyroidism (elevated TSH with normal Free T4) is common and may progress to overt hypothyroidism
• Hashimoto's can coexist with other thyroid disorders, complicating the clinical picture

Hashimoto's thyroiditis is the most common cause of hypothyroidism in industrialized nations, affecting women 7-10 times more frequently than men 3, 2. The clinical presentation varies widely, and diagnosis requires careful laboratory assessment and monitoring over time.