Choice Case Study

Choice "A" is the best answer. Both hyperthyroidism and hypothyroidism are common causes of menstrual cycle disturbances and amenorrhea, and thyroid function screening is warranted in the workup of an adolescent patient with secondary amenorrhea. This patient exhibits classic signs of hyperthyroidism, such as sleep disturbance, weight loss, tachycardia, and systolic hypertension, as well as lid lag on physical examination. The combination of laboratory findings of hyperthyroidism (low TSH, high FT4) and essentially no uptake on radioiodine scan is suggestive of either subacute thyroiditis (see below for the differentiation between granulomatous and lymphocytic thyroiditis) or exogenous thyroid hormone use.

The patient’s low thyroglobulin
Graves disease is the most common cause of hyperthyroidism, and is an autoimmune disease in which autoantibodies (thyroid-stimulating immunoglobulins) cause inappropriate thyroid gland enlargement and increased thyroid function. Graves disease can be diagnosed in the setting of clinical and laboratory findings of hyperthyroidism (low TSH, high T3 and/or T4) when thyrotropin receptor antibodies (TRAb) are positive (a specific finding in Graves disease) or radioactive iodine scanning demonstrates diffusely increased uptake in a non-nodular pattern. In addition, multiple physical examination findings are specifically seen in Graves disease that are not associated with non-Graves hyperthyroidism reflective of the underlying autoimmune process: exophthalmos, periorbital edema, and infiltrative dermopathy (pretibial
Hashimoto thyroiditis is the most common cause of hypothyroidism in the United States. It is an autoimmune-mediated gradual destruction of the thyroid with gradual thyroid failure, with or without goiter formation. This process causes clinical and laboratory hypothyroidism (high TSH) that leads to permanent thyroid failure, with lifelong thyroid hormone replacement indicated. Hashimoto thyroiditis is typically associated with positive thyroid autoantibodies, including antithyroglobulin and antithyroid peroxidase antibodies. Radioactive iodine uptake is variable in Hashimoto thyroiditis and is not part of the diagnostic workup of hypothyroidism.

Choice "D" is not the best answer. Polycystic ovarian syndrome (PCOS) is a common endocrinopathy of reproductive-age women characterized by anovulation, androgen excess, and polycystic ovaries. Patients commonly exhibit hirsutism, alopecia, obesity, diabetes, and oligomenorrhea/amenorrhea as part of the syndrome. PCOS is a diagnosis of exclusion, with the patient’s symptoms better explained by the abnormal thyroid laboratory values and other workup. Elevation of free testosterone is sensitive for detecting androgen excess, but in this patient, this value was