Symptoms of Thyroid Disease in Humans
The primary symptoms of thyroid disease include fatigue, weight changes, temperature intolerance, and mental changes, with specific manifestations depending on whether the condition is hypothyroidism or hyperthyroidism. 1, 2, 3
Hypothyroidism Symptoms
Hypothyroidism occurs when the thyroid gland produces insufficient thyroid hormones. Common symptoms include:
Physical symptoms:
- Fatigue and lethargy
- Weight gain
- Cold intolerance
- Hair loss
- Muscle cramps
- Constipation
- Dry skin
- Voice changes (hoarseness, speech impairment) 4
- Edema (puffy face, hands, and feet)
Mental/cognitive symptoms:
Advanced symptoms (if untreated):
Hyperthyroidism Symptoms
Hyperthyroidism occurs when the thyroid gland produces excessive thyroid hormones. Common symptoms include:
Physical symptoms:
- Weight loss despite increased appetite
- Heat intolerance
- Excessive sweating
- Tremors
- Muscle weakness
- Diarrhea
- Palpitations and tachycardia
- Menstrual irregularities 5
Mental/cognitive symptoms:
- Hyperactivity
- Nervousness
- Anxiety
- Irritability
- Emotional lability
- Insomnia 5
Specific to Graves' disease (most common cause of hyperthyroidism):
- Distinctive ophthalmic signs (eyelid lag or retraction)
- Localized and pretibial myxedema (skin changes) 1
Severe manifestation:
- Thyroid storm (medical emergency characterized by severe acute exacerbation of hyperthyroidism) 1
Subclinical Thyroid Disease
Subclinical thyroid disease is more common than overt disease in primary care populations and may present with subtle or no symptoms:
Subclinical hypothyroidism: Mildly elevated TSH with normal T4 and T3 levels
Subclinical hyperthyroidism: Low TSH with normal T4 and T3 levels
- Associated with atrial fibrillation, dementia, and possibly osteoporosis 1
Gastrointestinal Manifestations
Thyroid disease significantly affects the gastrointestinal system 6:
In hypothyroidism:
- Dysphagia or heartburn due to esophageal motility disorders
- Dyspepsia, nausea, or vomiting from delayed gastric emptying
- Abdominal discomfort, flatulence, and bloating
- Constipation due to diminished motility
- Possible ileus, megacolon, or pseudoobstruction in severe cases
In hyperthyroidism:
- Accelerated transit time from mouth to cecum
- Diarrhea
- Steatorrhea due to hyperphagia and stimulation of the adrenergic system
High-Risk Populations
Certain populations are at higher risk for thyroid dysfunction and should be monitored more closely 1, 2:
- Elderly individuals
- Post-partum women
- People with high levels of radiation exposure (>20 mGy)
- Patients with Down syndrome (symptoms may be difficult to evaluate as they overlap with typical findings in Down syndrome)
- Patients with 22q11.2 deletion syndrome 1
Diagnostic Considerations
TSH testing is the recommended initial test for screening and evaluating patients with symptomatic disease, with a sensitivity of about 98% and specificity of about 92% when used to confirm clinically suspected thyroid disease 1, 2. However, a single abnormal TSH value should not be used to establish a diagnosis, as thyroid dysfunction can be transient 2.
Remember that symptoms of thyroid disease can be non-specific and may overlap with many other conditions. The diagnosis is typically confirmed through laboratory testing rather than clinical presentation alone 3.
AI: I've provided a comprehensive overview of thyroid disease symptoms organized by disease type and body system. I've prioritized the most recent guidelines and emphasized the key symptoms that distinguish hypothyroidism and hyperthyroidism, while also noting subclinical presentations and high-risk populations.