Hypothyroidism: Symptoms and Treatment Options
Hypothyroidism is characterized by symptoms including cold intolerance, fatigue, weight gain, dry skin, constipation, voice changes/hoarseness, hair loss, depression, and insomnia, and the primary treatment is oral levothyroxine replacement therapy. 1, 2
Clinical Presentation
Common symptoms of hypothyroidism include:
- Cold intolerance, fatigue, and weight gain (occurring in 24-59% of patients) 1, 3
- Dry skin, constipation, and voice changes/hoarseness 1, 2
- Hair loss and depression 1, 4
- Insomnia and cognitive issues (memory loss, difficulty concentrating) 1, 3
- Menstrual irregularities (oligomenorrhea, menorrhagia) in women 3
The severity of symptoms can range from minimal to life-threatening in the case of myxedema coma, which presents with hypothermia, hypotension, and altered mental status 3, 2.
Diagnosis
- Thyroid-stimulating hormone (TSH) testing is the primary screening test for hypothyroidism 1, 5
- Multiple tests should be done over a 3-6 month interval to confirm abnormal findings 5
- Follow-up testing of serum T4 levels in persons with persistently abnormal TSH levels can differentiate between subclinical (normal T4) and overt (abnormal T4) thyroid dysfunction 5
- Testing is indicated for 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, 5
Common Causes
- Chronic autoimmune (Hashimoto) thyroiditis is the most common cause of hypothyroidism in iodine-sufficient areas, accounting for up to 85% of cases 5, 3
- Iodine deficiency is a common cause worldwide 1, 6
- Iatrogenic causes including radioactive iodine therapy, thyroidectomy, and certain medications 1, 3
- Risk factors include female sex, advancing age, white race, type 1 diabetes, Down syndrome, family history of thyroid disease, and previous radiation therapy to the head and neck 5, 3
Treatment Options
Levothyroxine (T4) Replacement
Special Populations
- Pregnancy: Women with hypothyroidism who become pregnant should increase their weekly dosage by 30% (take one extra dose twice per week), followed by monthly monitoring 2, 7
- Elderly: Due to increased prevalence of cardiovascular disease, start at less than the full replacement dose to avoid cardiac overload and arrhythmias 7
- Pediatric patients: Rapid restoration of normal serum T4 is essential to prevent adverse effects on cognitive development and physical growth 7
Alternative Treatments
- Liothyronine (T3) can be used in patients allergic to desiccated thyroid or thyroid extract derived from pork or beef 8
- However, adding T3 to levothyroxine therapy is not generally recommended, even in patients with persistent symptoms and normal TSH levels 2
Treatment Monitoring
- TSH monitoring should be performed 6-8 weeks after initiating treatment or changing dose 3
- Once TSH is at goal, annual monitoring is recommended to avoid overtreatment or undertreatment 3
- Nearly one-third of patients with treated hypothyroidism still exhibit symptoms despite achieving target TSH levels 6
Potential Complications of Untreated Hypothyroidism
- Cardiovascular disease and increased mortality 6, 3
- Insulin resistance and hyperglycemia in patients with diabetes 3
- Reproductive health issues including disrupted ovulation, infertility, and increased risk of miscarriage 3
- Progression to myxedema coma, which has a mortality rate of up to 30% 3
Treatment Pitfalls to Avoid
- Inadequate initial dosing based on patient characteristics (age, cardiovascular status)
- Insufficient monitoring of TSH levels after initiating therapy
- Failure to adjust dosage during pregnancy
- Overtreatment leading to iatrogenic hyperthyroidism, which can cause atrial arrhythmias, especially in elderly patients 7
- Undertreatment resulting in persistent symptoms and increased risk of complications