What are the symptoms and treatment of hypothyroidism?

Symptoms of Hypothyroidism

The common symptoms of hypothyroidism include fatigue, weight gain, cold intolerance, constipation, hair loss, dry skin, voice changes, mental slowness, muscle cramps, and menstrual irregularities. 1

Common Clinical Manifestations

• Fatigue and lethargy are among the most frequent symptoms, affecting 68-83% of patients with hypothyroidism 2
• Weight gain is reported in 24-59% of patients and is typically mild to moderate 2, 3
• Cold intolerance occurs due to decreased heat production in the body as a result of lower metabolic rate 1, 4
• Constipation is a common gastrointestinal manifestation 1, 3
• Skin and hair changes include dry skin (xeroderma) and hair loss 1, 3
• Cognitive issues affect 45-48% of patients and include memory loss, difficulty concentrating, and mental slowness 1, 2
• Voice changes, particularly hoarseness, may be present 1, 3
• Menstrual irregularities occur in approximately 23% of women, including oligomenorrhea and menorrhagia 1, 2
• Muscle cramps and myalgias are common musculoskeletal symptoms 1, 3
• Edema can occur in some patients 3

Diagnosis

• TSH testing is the initial screening test for hypothyroidism 1
• Overt primary hypothyroidism is confirmed by elevated TSH with low free T4 levels 1, 2
• Subclinical hypothyroidism is defined as elevated TSH with normal T4 levels 1
• Additional testing for thyroid antibodies (TPO) may help identify autoimmune causes like Hashimoto's thyroiditis 1

Treatment

• Levothyroxine (synthetic T4) is the first-line treatment for hypothyroidism 5, 2
• The goal of treatment is to normalize TSH levels 2
• Initial dosing should be tailored to patient-specific factors:
  • Standard starting dose for adults with overt hypothyroidism is typically 1.6 μg/kg/day 6
  • Lower starting doses should be used for older patients or those with cardiovascular conditions like atrial fibrillation and coronary artery disease 2
• TSH monitoring should be performed 6-8 weeks after initiating treatment or changing the dose, then annually once levels stabilize 2
• Liothyronine (T3) may be used in specific situations, particularly for patients allergic to desiccated thyroid or thyroid extract derived from pork or beef 7

Special Considerations

• Pregnancy: Levothyroxine requirements often increase during pregnancy, requiring close monitoring of TSH levels and dose adjustments 5
• Pediatric patients: Rapid restoration of normal T4 levels is essential to prevent adverse effects on cognitive development and physical growth 5
• Elderly patients: Treatment should begin at less than the full replacement dose due to increased prevalence of cardiovascular disease 5

Complications of Untreated Hypothyroidism

• Worsening symptoms affecting quality of life 1
• Cardiovascular complications including heart failure 2
• Reproductive health issues in women, including disrupted ovulation, infertility, and increased risk of miscarriage 2
• Myxedema coma, a severe complication with hypothermia, hypotension, and altered mental status, which has a mortality rate of up to 30% 1, 2
• Mental retardation and delayed milestones in infants 4

Common Pitfalls in Diagnosis and Management

• Symptoms of hypothyroidism are often nonspecific and subtle, which can lead to delayed diagnosis 3, 8
• Overtreatment can cause iatrogenic hyperthyroidism with risk of atrial arrhythmias, especially in elderly patients 1, 5
• Nearly one-third of patients with treated hypothyroidism still exhibit symptoms despite normalized TSH levels 6
• Bioavailability can vary between different levothyroxine preparations, so using a specific high-quality brand and monitoring TSH is important 3