Question

a 38-year-old female patient presents with fatigue and weight gain. her lab work reveals decreased trh, and decreased tsh and increased triiodothyronine. which of the following is the most helpful marker in making a diagnosis?
a) thyroid stimulating hormone
b) thyroid peroxidase
c) thyroxine
d) thyroglobulin
e) thyroid stimulating immunoglobulin

Explanation:

The patient has abnormal thyroid hormone levels (decreased TRH, TSH; increased Triiodothyronine). Thyroid - stimulating immunoglobulin (TSI) is associated with Graves' disease (a common cause of hyperthyroidism - though here the pattern with low TSH and high thyroid hormone could also relate to other hyperthyroid states, but TSI is a key diagnostic marker for autoimmune - mediated hyperthyroidism like Graves). TSH (option a) is already abnormal but not the best marker for diagnosis here. Thyroid peroxidase (option b) is more for autoimmune thyroiditis. Thyroxine (option c) is a thyroid hormone, but not the key diagnostic marker here. Thyroglobulin (option d) has limited diagnostic specificity in this context. So thyroid stimulating immunoglobulin is the most helpful marker.

Answer:

e) thyroid stimulating immunoglobulin