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Old 10-18-2011
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Thyroid Which thyroid function test will be low?

A 38-year-old woman comes to the physician complaining of increasing weight loss and anxiety. She had started a weight loss program approximately 6 months ago and had been quite successful with the weight loss. She began to notice changes in her body, however, and increasing weight loss after resumption of a regular diet. In particular, she noticed that her hair has become thinner over the last 6 months and has started to gray quite rapidly. She notes that she has become quite sensitive to heat and prefers cool environments; she also finds herself sweating much more often that she has in the past. She also has noted that she has been unable to sleep regularly, finding herself sleeping 2-4 hours a night. On review of systems, she notes that her heart occasionally races. She also has noted that her menstrual flow has lightened. She denies any medication or substance use and denies any additional or increased stress in her personal or professional life. Her vital signs are: temperature 37.2 C (99.0 F), blood pressure 128/56 mm Hg, pulse 110/min, and respirations 16/min. Physical examination shows a prominent stare with a lid lag and noted conjunctival injection. She has a diffusely enlarged anterior neck mass with a bruit heard over the area when auscultated. There is a 2/6 systolic flow murmur, fine, graying hair with small patches of alopecia on the scalp, thickened, reddish skin on the patient’s anterior legs, and separation of her nails from her nail bed. She has a mild tremor and weakness in her proximal arms and thighs. Which of the following findings is most likely to be decreased?

A. T3 resin uptake test
B. Thyroid radioactive iodine uptake
C. Thyroid stimulating hormone
D. Thyroid stimulating immunoglobulins
E. Triiodothyronine (T3) and thyroxine (T4) levels
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Old 10-18-2011
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I agree

i think tsh
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Old 10-19-2011
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C. Thyroid stimulating hormone
I'm Predictable In The Unpredictable Future !
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Old 10-19-2011
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Graves disease

TSH will be supressed
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Old 10-19-2011
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Correct Answer Answer

The correct answer is C. This woman has the classic history, signs, and symptoms of Graves' disease (diffuse toxic goiter). A triad of hyperthyroidism with a goiter, ocular pathology (usually exophthalmos), and dermatologic findings (nail findings, pretibial myxedema), characterizes Graves' disease. Patients often have symptoms of hyperthyroidism that classically include weight loss, heat intolerance, skin changes, and resting tremor. In addition, the presence of goiter with bruit on physical examination and proximal muscle weakness also lends credence to a hyperfunctioning thyroid gland. Usually the diagnosis can be made by using the triad criteria, but most often, diagnosis is confirmed with thyroid functioning tests, showing very low levels of thyroid stimulating hormone and high levels of T3 and T4 and resin T3 uptake.
T3 resin uptake test(choice A) determines the distribution of radiolabeled T3 between an absorbent resin and the unoccupied thyroid hormone binding proteins in the patient's plasma. the binding of the labeled T3 to the resin is increased when there is reduced unoccupied protein binding sites (e.g., TBG deficiency) or increased total thyroid hormone in the patient's plasma; it is decreased under the opposite circumstances.
Graves' disease is characterized by an enlarged gland and increased tracer uptake that is distributed homogeneously. Toxic adenomas appear as focal areas of increased uptake, with suppressed tracer uptake in the remainder of the gland. In toxic multinodular goiter, the gland is enlarged-often with distorted architecture- and there are multiple areas of relatively increased or decreased uptake (choice B).
If there is uncertainty about the nature of precipitating factors, the pathogenic process leading to hyperthyroidism is no longer in doubt. This depends on the presence of antibodies directed against the thyroid follicular cell surface membrane TSH receptor; they are usually of the IgG1 subclass and in binding to the TSH receptor activate the adenylate cyclase system, and thus stimulate thyroid function in vitro and in vivo. The levels of antibody correlate with thyroid function, and in humans the innoculation in vivo with purified antibody preparations leads to increased thyroid activation; and in the offspring of mothers with high levels of antibodies, passage of these antibodies across the placenta leads to transient neonatal hyperthyroidism (choice D).
Triiodothyronine (T3) and thyroxine (T4) levels (choice E) are elevated in Graves disease and in most hyperthyroid, hyperfunctioning states, causing the symptoms seen in this patient.
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Endocrinology-, Internal-Medicine-, Step-2-Questions

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