From the Guidelines
In a 92-year-old patient with elevated Thyroid-Stimulating Hormone (TSH) and normal Thyroxine (T4) levels, the recommended workup includes:
- Repeat TSH and free T4 (FT4) measurements to confirm the results, as the serum TSH test is the primary screening test for thyroid dysfunction 1.
- Check for the presence of antithyroid antibodies (e.g., anti-thyroid peroxidase, anti-thyroglobulin) to evaluate for autoimmune thyroiditis, which is the most common cause of hypothyroidism in the United States 1.
- Consider a thyroid ultrasound to assess thyroid gland morphology and rule out nodules or other abnormalities.
- Evaluate for non-thyroidal illness (NTI) or sick euthyroid syndrome, which can cause elevated TSH with normal T4 in elderly patients.
- Review medications that may affect thyroid function, such as amiodarone, lithium, or iodine-containing agents.
Given the patient's age and elevated TSH, it is essential to exercise caution before initiating thyroid hormone replacement therapy. If the patient is asymptomatic and has no evidence of cardiovascular disease, it may be reasonable to monitor the patient's thyroid function tests and clinical status closely rather than starting treatment immediately 1. However, if the patient has symptoms suggestive of hypothyroidism or significant cardiovascular disease, levothyroxine (e.g., Synthroid) may be initiated at a low dose (e.g., 12.5-25 mcg daily) and titrated based on clinical response and thyroid function tests 1. The dose should be adjusted based on the patient's response, and it is recommended to start with a lower dose in elderly patients with known cardiovascular disease 1.
From the Research
Diagnostic Workup
- The diagnostic workup for a 92-year-old patient with elevated Thyroid-Stimulating Hormone (TSH) and normal Thyroxine (T4) levels should include confirmation of the elevated TSH level through repeated testing, as well as measurements of serum levels of T4 and thyroid peroxidase antibodies to verify, quantify, and subclassify the abnormality 2.
- It is essential to consider the natural trend toward higher values of circulating TSH with aging, and to verify carefully the diagnosis of subclinical hypothyroidism (sHT) to tailor an appropriate follow-up and ad hoc therapy, avoiding unnecessary or excessive treatment 3, 4.
- The possibility of macro-TSH, a complex of TSH and anti-TSH IgG autoantibody, should be considered in cases with unexpectedly high TSH values, especially in autoimmune thyroidal disorders 5.
Therapeutic Approach
- The treatment of choice for hypothyroid patients is hormone replacement with levothyroxine (LT4), but it is crucial to consider multiple factors before commencing therapy, including age-dependent TSH increase, the presence of an actual thyroid disease, and comorbidities 3, 4.
- A tailored therapy should be chosen, considering poly-pharmacy and frailty, and a careful follow-up and treatment re-assessment should be always considered to avoid the risk of over-treatment 3, 4.
- The initial replacement dose of LT4 should be low, especially if heart disease is suspected, and small dosage adjustments may be performed by adding or withdrawing a tablet once or twice weekly 2.
Monitoring and Follow-up
- Patients with subclinical hypothyroidism should be informed about the disease and offered the possibility of replacement, and only some patients treated for subclinical hypothyroidism will feel better after therapy 2.
- In elderly patients on replacement therapy, care should include estimation of serum TSH level once or twice a year, with small dosage adjustments of LT4 to keep serum TSH level within the normal range 2.
- The stability of TSH levels in patients treated with different LT4 formulations, such as tablet or liquid, should be monitored, and further large, prospective, longitudinal studies are needed to evaluate the stability of TSH in hypothyroid patients treated with different LT4 formulations 6.