From the Guidelines
Subclinical hypothyroidism in levothyroxine-treated patients with overt hypothyroidism should be managed by adjusting the dosage of levothyroxine to bring the serum TSH into the reference range, with consideration of targeting the lower half of the range if symptoms persist 1. When managing subclinical hypothyroidism, it is essential to consider the patient's age, medical comorbidities, and symptoms.
- The dosage adjustment of levothyroxine should be based on the patient's individual needs, with minimal TSH elevations not requiring dosage adjustment in patients who feel well, particularly those with arrhythmias or other cardiac disorders 1.
- The target TSH level is controversial, but bringing the serum TSH into the lower portion of the reference range may be reasonable if patients continue to note symptoms suggestive of hypothyroidism 1.
- The rapidity of the dosage adjustment depends on the patient's age and medical comorbidities, with elderly patients or those with heart disease requiring more cautious adjustments 1. Key considerations in managing subclinical hypothyroidism include:
- Monitoring TSH levels regularly to adjust the levothyroxine dosage as needed
- Assessing the patient's symptoms and overall health to determine the optimal target TSH range
- Avoiding over-treatment, which can lead to adverse effects such as atrial fibrillation and osteoporosis
- Individualizing treatment based on the patient's unique needs and medical history 1.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Definition and Diagnosis of Subclinical Hypothyroidism
- Subclinical hypothyroidism is a biochemical condition defined by elevated serum thyroid-stimulating hormone (TSH) levels in the setting of normal levels of the peripheral thyroid hormones, thyroxine and triiodothyronine 2.
- The diagnosis is made based on the results of laboratory findings when the level of TSH reaches values above 4.0 mU/l 3.
- The condition is often asymptomatic, and the diagnosis is usually made during screening for thyroid disease 4.
Treatment of Subclinical Hypothyroidism
- Levothyroxine is the preferred therapy for patients with subclinical hypothyroidism, with the goal of maintaining serum TSH levels within the normal range 4.
- Treatment is generally not necessary unless the TSH exceeds 7.0-10 mIU/L 5.
- The decision to treat should be individualized based on patient age, degree of serum TSH elevation, symptoms, cardiovascular disease risk, and other co-morbidities 2.
- Treatment may be indicated for patients with subclinical hypothyroidism and serum thyrotropin levels of 10 mU/L or higher, or for young and middle-aged individuals with subclinical hypothyroidism and symptoms consistent with mild hypothyroidism 6.
Risks and Benefits of Treatment
- Treatment with levothyroxine may reduce the risk of cardiovascular disease in patients under age 65, but may be harmful in elderly patients 5, 2.
- Levothyroxine therapy may be associated with iatrogenic thyrotoxicosis, especially in elderly patients 6.
- There is no evidence that levothyroxine therapy is beneficial in persons aged 65 years or older 6.
- The potential benefits of treatment must be weighed against the potential risks, and further research is needed to determine the effects of treatment on cardiovascular disease risk and other outcomes 2, 3.
Special Considerations
- Patients with subclinical hypothyroidism and circulating thyroid peroxidase antibodies are at greater risk of progression to overt hypothyroidism 6.
- Middle-aged patients with subclinical hypothyroidism may have cognitive impairment, nonspecific symptoms such as fatigue, and altered mood 6.
- Treatment decisions should take into account the presence of symptoms, anti-thyroid antibodies, increased lipids, and other risk factors 3.