What are the symptoms and treatment options for hypothyroidism?

Symptoms of Hypothyroidism

The classic symptoms of hypothyroidism include fatigue, weight gain, cold intolerance, constipation, dry skin, depression, hair loss, and irregular menstrual cycles, with diagnosis confirmed by laboratory tests showing high TSH and low free T4 levels. 1, 2, 3, 4

Common Clinical Manifestations

Physical Symptoms

• Fatigue and lethargy
• Weight gain despite no change in diet
• Increased sensitivity to cold (cold intolerance)
• Constipation
• Dry skin (xeroderma)
• Hair loss
• Hoarseness or voice changes
• Muscle weakness, aches, tenderness and stiffness
• Edema, particularly periorbital
• Bradycardia
• Decreased sweating

Neuropsychiatric Symptoms

• Depression
• Irritability
• Memory problems
• Difficulty concentrating
• Mental slowing

Reproductive Symptoms

• Irregular or heavy menstrual periods
• Reduced fertility
• Decreased libido

Laboratory Diagnosis

Diagnosis is primarily based on laboratory tests, not symptoms alone 1, 2:

Test	Result in Hypothyroidism	Notes
TSH	Elevated	Primary diagnostic marker
Free T4	Low	Confirms overt hypothyroidism
Free T3	Normal or low	May be checked in some cases
Thyroid antibodies (TPO)	Often elevated	Indicates autoimmune etiology

• Primary hypothyroidism: Elevated TSH with low free T4
• Subclinical hypothyroidism: Elevated TSH with normal free T4
• Secondary (central) hypothyroidism: Low/normal TSH with low free T4 2

Causes of Hypothyroidism

1. Autoimmune thyroiditis (Hashimoto's thyroiditis) - most common cause in iodine-sufficient areas 5
2. Iatrogenic causes:
   • Post-thyroidectomy
   • Radioactive iodine treatment
   • Radiation therapy to the neck
3. Medications:
   • Amiodarone
   • Lithium
   • Immune checkpoint inhibitors 1
   • Beta-blockers
   • Corticosteroids 2
4. Iodine deficiency - historically the most common cause globally 6
5. Congenital hypothyroidism
6. Pituitary or hypothalamic disorders (secondary/tertiary hypothyroidism)

Treatment

Standard Treatment Approach

• Levothyroxine (T4) monotherapy is the standard treatment 2, 7, 8, 4
• Initial dosing:
  • Adults: 1.5-1.8 mcg/kg/day 4
  • Elderly (>60 years) or those with heart disease: Start lower at 12.5-50 mcg/day 4
  • Adjust dose in 12.5-25 mcg increments 2

Monitoring and Dose Adjustments

• Check TSH and free T4 every 6-8 weeks during dose adjustments 2
• Once stabilized, monitor TSH every 6-12 months
• Target TSH within normal reference range

Special Considerations

• Pregnancy: Increase weekly dosage by 30% (take one extra dose twice weekly) 4
• Elderly: Use lower starting doses to avoid cardiac complications 7
• Heart disease: Start with lower doses and titrate slowly 7

Complications of Untreated Hypothyroidism

• Cardiovascular disease
• Infertility
• Pregnancy complications (preeclampsia, preterm delivery, miscarriage) 2
• Myxedema coma (rare but life-threatening)
• Mental health issues
• Decreased quality of life

When to Refer to an Endocrinologist

Consider referral when:

• Diagnosis is unclear
• Poor response to standard treatment
• Pregnancy with hypothyroidism
• Secondary or tertiary hypothyroidism
• Severe hypothyroidism or myxedema coma

Hypothyroidism is a common endocrine disorder that affects multiple body systems. Early recognition of symptoms, proper laboratory diagnosis, and appropriate treatment with levothyroxine can effectively manage the condition and prevent complications in most patients.