What are the symptoms and management of hypothyroidism?

Symptoms of Hypothyroidism

The most common symptoms of hypothyroidism include fatigue, cold intolerance, weight gain, dry skin, constipation, hair loss, menstrual irregularities, depression, brain fog, and hoarseness. 1, 2, 3

Clinical Presentation

Hypothyroidism presents with a constellation of symptoms that result from decreased metabolic rate:

• Common symptoms:

  • Fatigue and lethargy
  • Cold intolerance
  • Weight gain (typically mild to moderate)
  • Dry skin (xeroderma)
  • Constipation
  • Hair loss
  • Menstrual irregularities
  • Depression and poor concentration
  • Brain fog and mental impairment
  • Hoarseness
  • Muscle aches (myalgias)
  • Edema (especially periorbital)

• Physical examination findings:

  • Firm and irregular thyroid on palpation (in Hashimoto's thyroiditis) 4
  • Bradycardia
  • Delayed relaxation phase of deep tendon reflexes
  • Puffy face and periorbital edema

It's important to note that symptoms are often nonspecific and subtle, especially early in the disease, making laboratory confirmation essential 2.

Diagnosis

Diagnosis is primarily biochemical and includes:

• TSH measurement - the most sensitive test for both hypo- and hyperthyroidism 4
• Free T4 level - typically low in overt hypothyroidism

Diagnostic criteria:

• Overt hypothyroidism: Elevated TSH with low free T4
• Subclinical hypothyroidism: Elevated TSH with normal free T4 2, 5

Management

The standard treatment for hypothyroidism is levothyroxine replacement therapy:

• Starting dose:

  • Adults: 1.5-1.8 mcg/kg/day 2
  • Elderly (>60 years) or patients with heart disease: Lower starting dose (12.5-50 mcg/day) 2

• Dose adjustments:

  • Titrate to achieve normal TSH levels (0.4-4.0 mIU/L) 6
  • Recheck TSH in 6-8 weeks after dose changes 1

• Special populations:

  • Pregnant women: Increase weekly levothyroxine dosage by 30% (take one extra dose twice weekly) 2
  • Monitoring during pregnancy: Check TSH and free T4 each trimester 7

• Monitoring:

  • Stable patients: Evaluate clinical and biochemical response every 6-12 months 1
  • Adjust doses in 5-25 mcg increments (approximately 12.5% of current dose) 1

Complications of Untreated Hypothyroidism

If left untreated, hypothyroidism can lead to:

• Cardiovascular disease
• Infertility and menstrual irregularities
• Myxedema coma (rare but life-threatening)
• Neurocognitive impairment
• In infants: Mental retardation and delayed milestones 1, 3

Pitfalls and Caveats

• Symptoms of hypothyroidism are nonspecific and may overlap with other conditions, making laboratory confirmation essential 3
• Bioavailability varies between levothyroxine preparations; designating a specific high-quality brand is appropriate 4
• Adding T3 (triiodothyronine) is not recommended, even in patients with persistent symptoms and normal TSH levels 2
• Estrogen increases thyroid binding globulin levels, so women on hormone replacement therapy, oral contraceptives, or who are pregnant typically have total T4 levels above the reference range 4
• Overtreatment with levothyroxine can lead to iatrogenic hyperthyroidism, which can cause cardiac complications, especially in elderly patients 1

Hypothyroidism affects approximately 4-10% of the population, with higher prevalence among women and older individuals 4, 3. With appropriate treatment, most patients can lead normal, healthy lives, but lifelong medication and regular monitoring are typically required.