A 28-year-old woman comes to the office due to unintentional weight loss, fatigue, and sweating. The patient has no neck pain. Two months before this visit, she delivered a healthy male baby without complications. The patient has no chronic medical conditions and takes no medications. Blood pressure is 140/70 mm Hg, pulse is 110/min, and respirations are 16/min. Oxygen saturation is 98% on room air. Neck examination shows mild, diffuse enlargement of the thyroid gland with no tenderness. The remainder of the physical examination is normal. Laboratory evaluation shows low serum TSH and elevated serum thyroxine (T4) and triiodothyronine (T3). Thyroid ultrasound with Doppler flow reveals a mildly enlarged gland with decreased blood flow. Which of the following is most likely responsible for this patient's disorder?

Question

A 28-year-old woman comes to the office due to unintentional weight loss, fatigue, and sweating.  The patient has no neck pain.  Two months before this visit, she delivered a healthy male baby without complications.  The patient has no chronic medical conditions and takes no medications.  Blood pressure is 140/70 mm Hg, pulse is 110/min, and respirations are 16/min.  Oxygen saturation is 98% on room air.  Neck examination shows mild, diffuse enlargement of the thyroid gland with no tenderness.  The remainder of the physical examination is normal.  Laboratory evaluation shows low serum TSH and elevated serum thyroxine (T4) and triiodothyronine (T3).  Thyroid ultrasound with Doppler flow reveals a mildly enlarged gland with decreased blood flow.  Which of the following is most likely responsible for this patient's disorder?

Quizplus · Accepted Answer

11ec160b_3acb_d162_9249_a3d069be35ed_MD0001_00 This patient has postpartum thyroiditis (PPT) presenting with hyperthyroidism (ie, elevated thyroid hormone levels, suppressed TSH) and a diffuse, nontender goiter. The clinical course typically has 3 phases: hyperthyroid phase (1-3 months) due to release of preformed thyroid hormone, hypothyroid phase (4-8 months) due to depletion of thyroid hormone stores, and recovery phase with return to euthyroid state. Not all 3 phases occur in all patients. PPT is an autoimmune disorder characterized by lymphocytic thyroid inflammation. By convention, it occurs within 12 months of pregnancy. PPT is part of a group of lymphocytic/autoimmune thyroid disorders that also includes silent thyroiditis (sporadic, not related to pregnancy) and chronic lymphocytic (Hashimoto) thyroiditis (usually diagnosed in hypothyroid phase, which may be permanent). These disorders share a characteristic pattern in diagnostic testing: Positive thyroid peroxidase antibody, a nonspecific marker for autoimmune thyroid disease Elevated serum thyroglobulin due to destruction of follicles and release of colloid in the hyperthyroid phase Low radioiodine uptake due to decreased organification of iodine and synthesis of new thyroid hormone Diffuse swelling and decreased thyroid blood flow on ultrasound (Choices A and B) Graves disease is caused by autoantibodies that bind and stimulate the TSH receptor (ie, thyrotropin receptor antibodies/thyroid-stimulating immunoglobulins) on thyroid follicular cells. Toxic adenoma and toxic nodular goiter are characterized by autonomous thyroid hormone synthesis. Because of the increased metabolic activity in these conditions, Doppler ultrasound reveals increased, not decreased, blood flow. Radioiodine uptake is also increased. (Choice C) Thyrotoxicosis due to exogenous thyroid hormone use (eg, erroneous levothyroxine dosing, surreptitious use of thyroid hormone supplements) would show suppression of TSH and decreased blood flow in the thyroid, but goiter would not be present (thyroid atrophy is more likely). (Choice E) Subacute (ie, postviral/granulomatous/de Quervain) thyroiditis is thought to be due to a viral infection in the gland or a secondary inflammatory response to viral antigens. Patients may experience a transient hyperthyroid phase, but the thyroid gland is characteristically painful and tender to palpation. Educational objective: Postpartum thyroiditis occurs within 12 months of pregnancy and is characterized by autoimmune destruction of thyroid follicles. It typically has a hyperthyroid phase due to release of preformed thyroid hormone, followed by a hypothyroid phase due to depletion of thyroid hormone stores and eventual return to a euthyroid state. Thyroid metabolic activity during the hyperthyroid phase is suppressed, and glandular blood flow and radioiodine uptake are low.

A 28-Year-Old Woman Comes to the Office Due to Unintentional