From the Guidelines
For a patient with known hypothyroidism on Synthroid who has a mildly elevated TSH of 6.8, the recommended management is to increase the Synthroid dose by approximately 12-25 mcg daily. Yes, checking a free T4 level is appropriate to provide additional information about thyroid function, though it's not absolutely necessary for this mild elevation. The dose adjustment should be made based on the current dose; for example, if the patient is taking 100 mcg daily, increasing to 112 or 125 mcg would be reasonable. After making this adjustment, TSH should be rechecked in 6-8 weeks to ensure it has returned to the target range of 0.5-2.5 mIU/L. Before adjusting medication, it's essential to confirm the patient has been taking Synthroid consistently, on an empty stomach, and waiting 30-60 minutes before eating or taking other medications. Certain medications and supplements (like calcium, iron, and antacids) can interfere with Synthroid absorption if taken too close together. The elevated TSH indicates that the current dose is insufficient to provide adequate thyroid hormone replacement, causing the pituitary gland to produce more TSH in an attempt to stimulate additional thyroid hormone production.
Some key points to consider in managing this patient include:
- The primary treatment for hypothyroidism is oral T4 monotherapy (levothyroxine sodium) 1.
- The serum TSH test is the primary screening test for thyroid dysfunction, and follow-up testing of serum T4 levels can differentiate between subclinical and overt thyroid dysfunction 1.
- The optimal screening interval for thyroid dysfunction is unknown, but multiple tests should be done over a 3- to 6-month interval to confirm or rule out abnormal findings 1.
- For patients with subclinical hypothyroidism (TSH levels between 4.5 and 10 mIU/L), a trial of levothyroxine may be considered, but the likelihood of improvement is small, and it must be balanced against the inconvenience, expense, and potential risks of therapy 1.
Given the information provided and the current guidelines, the most appropriate course of action is to adjust the Synthroid dose and monitor the patient's TSH levels, while also considering the potential benefits and risks of treatment.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Management Options for Mildly Elevated TSH
- In a patient with known hypothyroidism on Synthroid, a mildly elevated TSH level of 6.8 may not necessarily require immediate adjustment of levothyroxine dosage 2, 3.
- The decision to adjust the dosage should be based on clinical and laboratory findings, rather than solely on the TSH level 2.
- According to some guidelines, treatment is not necessary unless the TSH exceeds 7.0-10 mIU/L 4.
- However, other studies suggest that levothyroxine therapy may be beneficial in patients with subclinical hypothyroidism, especially if the TSH level is above 10 mIU/L or if the patient has symptoms suggestive of hypothyroidism 2, 3.
Checking Free T4 Levels
- Free T4 levels can be useful in confirming the diagnosis of hypothyroidism and in monitoring treatment response 5.
- In patients with subclinical hypothyroidism, free T4 levels are typically normal, while TSH levels are elevated 2, 4.
- However, in some cases, patients may have resistance to exogenous thyroxine, characterized by elevated TSH and free T4 levels, and decreased T3/T4 and T3/rT3 ratios 6.
- Checking free T4 levels may be helpful in identifying these patients and guiding treatment decisions.
Treatment Considerations
- Levothyroxine therapy is the standard treatment for hypothyroidism, and the dosage should be adjusted based on TSH levels and clinical response 2, 3, 5.
- In some patients, combined treatment with levothyroxine and liothyronine may be preferred, especially in those with a polymorphism in type 2 deiodinase or resistance to exogenous thyroxine 4, 6.
- Treatment goals should be individualized, taking into account the patient's age, symptoms, and laboratory results 3, 4.