What are the symptoms of hypothyroidism?

Symptoms of Hypothyroidism

Hypothyroidism presents with a constellation of nonspecific symptoms resulting from decreased metabolic rate, with fatigue being the most common manifestation affecting 68-83% of patients. 1

Metabolic and Constitutional Symptoms

The hallmark symptoms of hypothyroidism reflect systemic metabolic slowing and include:

• Fatigue and lethargy are the most prevalent symptoms, affecting multiple body systems due to decreased metabolic rate and reduced thyroid hormone activity 2, 1
• Weight gain and difficulty losing weight occur in 24-59% of patients due to decreased fat-burning rate 2, 1, 3
• Cold intolerance results from decreased heat production by the body 4, 3
• Somnolence (excessive sleepiness) is commonly reported 2

Cognitive and Psychiatric Symptoms

• Cognitive impairment including memory loss, difficulty concentrating, and intellectual slowness affects 45-48% of patients 2, 1, 5
• Depression is a recognized symptom of hypothyroidism 2, 5

Dermatologic and Physical Examination Findings

• Dry skin (xeroderma) and coarse skin are characteristic dermatologic manifestations 2, 4, 3
• Hair loss occurs commonly 2
• Myxedema (non-pitting edema/swelling) and periorbital puffiness represent more severe manifestations 2
• Hoarseness and voice changes occur due to low metabolic rate 2, 4

Gastrointestinal Symptoms

• Constipation results from slowed gastrointestinal motility 2, 4, 3

Cardiovascular Manifestations

• Bradycardia (slow heart rate) is a common finding 2, 6
• Mild hypertension (often diastolic) and narrowed pulse pressure can occur 2
• Pericardial effusions may develop in severe cases 2
• Heart failure is a serious complication of untreated hypothyroidism 2, 1

Musculoskeletal Symptoms

• Muscle cramps and muscle weakness (particularly proximal) are frequently reported 2
• Myalgias (muscle pain) can occur 6
• Delayed ankle reflex and slow movement are examination findings 2

Reproductive and Endocrine Effects

• Menstrual irregularities including oligomenorrhea and menorrhagia affect approximately 23% of women with hypothyroidism 1, 5, 6
• Infertility and increased risk of miscarriage can result from untreated hypothyroidism 1, 3, 6

Laboratory Findings

• Elevated thyroid-stimulating hormone (TSH) is the primary diagnostic marker 2, 4
• Low free thyroxine (T4) confirms overt primary hypothyroidism 2, 4
• Hyperlipidemia may be present 6
• Insulin resistance and hyperglycemia can occur in patients with diabetes 1

Critical Complication

Myxedema coma represents severe, life-threatening hypothyroidism characterized by hypothermia, hypotension, and altered mental status, with mortality rates up to 30% requiring intensive care unit treatment 1, 4. Early recognition is essential for survival.

Important Clinical Caveats

The symptoms of hypothyroidism are nonspecific and nondiagnostic, especially early in disease presentation, which makes clinical diagnosis challenging without biochemical confirmation 4. These symptoms can overlap with many other conditions and may go unnoticed or be subtle 5, 3. Diagnosis must be based on laboratory testing (elevated TSH and low free T4), not symptoms alone 4. Women and older adults are disproportionately affected 1, 5, 4.