Signs and Symptoms of Hypothyroidism
Hypothyroidism presents with relatively subtle and nonspecific clinical symptoms including fatigue, feeling cold, weight gain, hair loss, and constipation, all resulting from decreased metabolic rate. 1
Core Clinical Manifestations
Metabolic and Constitutional Symptoms
- Fatigue and lethargy are the most prevalent symptoms, affecting 68-83% of patients due to decreased metabolic rate and reduced thyroid hormone activity 2, 3
- Weight gain and difficulty losing weight occur in 24-59% of patients as a result of decreased fat-burning rate 2, 3
- Cold intolerance develops from decreased heat production by the body 4, 5
- Intellectual slowness and cognitive issues (memory loss, difficulty concentrating) affect 45-48% of patients 2, 3
Dermatologic Manifestations
- Dry skin (xeroderma) is a common finding 4, 6
- Coarse skin and periorbital puffiness develop as the condition progresses 2
- Hair loss occurs as a direct consequence of thyroid hormone deficiency 1, 2
Gastrointestinal Symptoms
Cardiovascular Signs
- Bradycardia (slow heart rate) is a characteristic finding 2
- Mild hypertension, often diastolic can be present 2
- Narrowed pulse pressure occurs in affected patients 2
- Pericardial effusions may develop in severe cases 2
Neuromuscular Symptoms
- Muscle cramps and muscle weakness, particularly proximal muscle weakness 2
- Delayed ankle reflex and slow movement are objective findings on physical examination 2
Reproductive and Endocrine Effects
- Menstrual irregularities (oligomenorrhea and menorrhagia) occur in approximately 23% of women 3
- Infertility and disrupted ovulation can result from untreated hypothyroidism 3
Other Clinical Features
- Depression is a recognized symptom of hypothyroidism 2
- Somnolence (excessive sleepiness) beyond normal fatigue 2
- Hoarseness and voice changes develop from metabolic slowing 2
- Myxedema (non-pitting edema/swelling) represents more advanced disease 2
Important Clinical Caveats
The symptoms of hypothyroidism are often nonspecific and may overlap with other conditions, making diagnosis challenging based on clinical presentation alone. 4 The clinical manifestations can differ with age and sex, requiring careful consideration of the patient's demographic characteristics 5.
Biochemical confirmation is essential for diagnosis, as symptoms alone are insufficient—elevated TSH with low free T4 confirms overt primary hypothyroidism 3, 6. The condition exists on a spectrum from asymptomatic biochemical changes to clinically symptomatic disease 1.
Severe Complications if Untreated
- Heart failure can develop as a serious complication 2, 3
- Myxedema coma represents life-threatening decompensation with hypothermia, hypotension, and altered mental status, carrying up to 30% mortality 3
- Cardiovascular events including increased risk for heart failure and other cardiac complications 3
- Insulin resistance and hyperglycemia in patients with diabetes 3