What are the symptoms and treatment options for hypothyroidism?

Hypothyroidism: Symptoms and Treatment

Hypothyroidism is characterized by fatigue, weight gain, cold intolerance, constipation, hair loss, dry skin, cognitive issues, and menstrual irregularities, and is treated primarily with levothyroxine replacement therapy to normalize thyroid hormone levels. 1, 2

Clinical Presentation

Common Symptoms

• Fatigue (68%-83% of patients) 2
• Weight gain (24%-59% of patients) 2
• Cold intolerance 1
• Constipation 1
• Hair loss 1
• Dry skin (xeroderma) 3
• Cognitive issues (45%-48%) including memory loss and difficulty concentrating 2
• Voice changes and hoarseness 1, 4
• Depression 1

Advanced Symptoms

• With progression, patients may develop: 1
  • Voice changes
  • Intellectual slowness
  • Insomnia
  • Myxedema (in severe cases)

Physical Examination Findings

• Bradycardia 4
• Edema 4
• Firm and irregular thyroid on palpation (in Hashimoto's thyroiditis) 4
• Dry, coarse skin 3

Diagnosis

Laboratory Testing

• Thyroid-stimulating hormone (TSH) is the recommended initial screening test 4
• Elevated TSH with low free T4 confirms overt primary hypothyroidism 2
• Additional testing for thyroid antibodies such as thyroid peroxidase (TPO) antibody is warranted in confirmed cases 1

When to Test

• Testing is indicated in patients with unexplained fatigue, weight gain, hair loss, cold intolerance, constipation, depression, and other suggestive symptoms 1
• Targeted testing is recommended for high-risk individuals (e.g., patients with type 1 diabetes) 2
• Population-wide screening is not recommended for asymptomatic individuals 1, 2

Treatment

Levothyroxine Replacement

• First-line treatment is synthetic levothyroxine to normalize TSH levels 2, 5
• Initial dosing:
  • Standard starting dose: 1.5 to 1.8 mcg per kg per day 5
  • Lower starting doses (12.5 to 50 mcg per day) for patients over 60 years or with known/suspected ischemic heart disease 5
• Dosage adjustments:
  • Monitor TSH levels 6-8 weeks after initiating treatment or changing dose 2
  • Once stabilized, monitor annually to avoid over or undertreatment 2

Special Populations

• Pregnant women with hypothyroidism should increase their weekly dosage by 30% (take one extra dose twice per week), followed by monthly monitoring 5
• Patients with subclinical hypothyroidism (elevated TSH with normal T4) generally don't benefit from treatment unless TSH is >10 mIU/L or thyroid peroxidase antibody is elevated 5

Complications of Untreated Hypothyroidism

Cardiovascular Complications

• Increased risk for cardiovascular events, including heart failure 2
• Hyperlipidemia 4

Reproductive Health Issues

• Menstrual irregularities (approximately 23% of patients) including oligomenorrhea and menorrhagia 2, 4
• Disrupted ovulation and infertility 2
• Increased risk of miscarriage 2

Severe Complications

• Myxedema coma - a life-threatening condition with hypothermia, hypotension, and altered mental status 2
  • Requires treatment in intensive care unit
  • Has mortality rate of up to 30%

Common Causes

• Hashimoto's thyroiditis (autoimmune thyroiditis) - most common cause in areas with adequate iodine intake, accounting for up to 85% of cases 2
• Iodine deficiency - most common cause worldwide 1, 6
• Iatrogenic causes: 1
  • Radioactive iodine therapy
  • Thyroidectomy
• Medication-induced: 2
  • Immune checkpoint inhibitors
  • Amiodarone

Treatment Monitoring and Follow-up

• After initiating levothyroxine, check TSH in 6-8 weeks 2
• Once stable, annual TSH monitoring is recommended 2
• Persistent symptoms despite normalized TSH warrant reassessment for other causes or specialist referral 5

Important Considerations

• Levothyroxine bioavailability varies between preparations; designating a specific high-quality brand is appropriate 4
• Adding triiodothyronine (T3) is not recommended, even in patients with persistent symptoms and normal TSH levels 5
• Nearly one-third of treated patients may still exhibit symptoms despite normalized TSH levels 6