From the Guidelines
Hypothyroidism is characterized by clinical findings such as fatigue, feeling cold, weight gain, hair loss, and constipation.
Clinical Findings
- Fatigue
- Feeling cold
- Weight gain
- Hair loss
- Constipation These symptoms are often relatively subtle and nonspecific, and may not be present in all patients with hypothyroidism 1.
Biochemical Definition
Hypothyroidism is defined biochemically by an elevated TSH level and a low T4 level, with TSH levels between 4.5 and 10.0 mIU/L or greater than 10.0 mIU/L considered abnormal 1.
Subclinical Hypothyroidism
Subclinical hypothyroidism is defined as a TSH level between 4.5 and 10.0 mIU/L, with normal T4 and T3 levels, and may be associated with symptoms such as fatigue and weight gain, although these symptoms are often mild and nonspecific 1.
Diagnosis and Screening
The US Preventive Services Task Force recommends screening for thyroid dysfunction in asymptomatic populations, with a focus on detecting abnormal TSH levels and confirming the diagnosis with further testing 1.
High-Risk Populations
Certain populations, such as the elderly, postpartum women, and those with a history of radiation exposure, are at higher risk for thyroid dysfunction and should be evaluated for symptoms of hypothyroidism 1.
From the Research
Clinical Findings of Hypothyroidism
The clinical findings of hypothyroidism can vary depending on the age, sex, and severity of the condition. Some common symptoms include:
- Fatigue and lethargy 2, 3
- Weight gain due to a decrease in fat-burning rate 2
- Cold intolerance due to a decrease in heat production by the body 2, 4
- Constipation and irregular bowel movements 2, 3
- Dry skin (xeroderma) 2, 3
- Change in voice 3
- Bradycardia (slow heart rate) 4, 5
- Pretibial oedema (swelling of the legs) 4
- Delayed ankle reflex 4, 5
- Coarse skin 4, 5
- Puffy face 5
- Slow movements 5
Diagnosis and Treatment
The diagnosis of hypothyroidism is based on laboratory tests that measure the levels of thyroid hormones (T3 and T4) in the blood 2, 4. Treatment typically involves lifelong hormone replacement therapy with synthetic thyroid hormone replacement medication, such as levothyroxine 2, 4, 3, 6. The initial dose of levothyroxine is adjusted based on the age and general condition of the patient, and the duration and severity of hypothyroidism 4.
Subclinical Hypothyroidism
Subclinical hypothyroidism is characterized by a normal serum level of T4, an increased level of TSH, and the absence of clinical symptoms 4, 6. This condition can be a precursor to overt hypothyroidism and may require treatment with levothyroxine 6.
Variability in Clinical Presentation
The clinical presentation of hypothyroidism can vary significantly depending on the age, sex, and severity of the condition 3, 6. Some patients may not exhibit any symptoms, while others may experience severe symptoms 3. The diagnosis of hypothyroidism can be challenging, and clinicians cannot rely exclusively on physical examination to confirm or rule out the condition 5.