Symptoms of Hypothyroidism
Hypothyroidism presents with a constellation of nonspecific symptoms related to metabolic slowing, most commonly including fatigue (68-83% of patients), cold intolerance, constipation, weight gain (24-59%), hair loss, and depression. 1, 2
Core Clinical Manifestations
The American Academy of Family Physicians identifies the following characteristic symptoms 1:
- Cold intolerance - one of the hallmark features
- Constipation - due to decreased gastrointestinal motility
- Hair loss - affecting scalp and body hair
- Depression - can be a prominent presenting feature
- Voice changes and hoarseness - from myxedematous infiltration of vocal cords
- Insomnia - despite overall fatigue
Additional Common Symptoms
Beyond the classic presentation, patients frequently experience 2, 3:
- Cognitive impairment (45-48% of patients) - including memory loss and difficulty concentrating
- Menstrual irregularities (approximately 23%) - such as oligomenorrhea and menorrhagia
- Mild to moderate weight gain - typically modest despite metabolic slowing
- Dry skin - from decreased sweating and skin metabolism
- Myalgias - muscle aches and stiffness
- Bradycardia - slowed heart rate
Important Clinical Context
These symptoms are notably nonspecific and nondiagnostic, especially early in disease presentation, which is why diagnosis must be based on biochemical testing (TSH and free T4 levels) rather than clinical symptoms alone. 4, 5
The U.S. Preventive Services Task Force emphasizes that even "overt" hypothyroidism (defined biochemically by elevated TSH and low T4) does not require the presence of symptoms and encompasses a range of presentations from asymptomatic to symptomatic disease 4.
Serious Complications if Untreated
Untreated hypothyroidism can progress to severe manifestations 2, 3:
- Cardiovascular complications - including heart failure and increased cardiovascular event risk
- Myxedema coma - a life-threatening decompensation with hypothermia, hypotension, and altered mental status; mortality rate up to 30%
- Reproductive health issues - disrupted ovulation, infertility, increased miscarriage risk
- Metabolic disturbances - insulin resistance and hyperglycemia in diabetic patients
Diagnostic Approach
The American College of Physicians recommends TSH testing as the initial screening test for hypothyroidism in patients with unexplained fatigue, weight gain, hair loss, cold intolerance, constipation, depression, and other suggestive symptoms. 1 Population-wide screening is not recommended for asymptomatic individuals 1.
Additional testing for thyroid peroxidase (TPO) antibody is warranted in confirmed cases to identify autoimmune etiology 1.