Hypothyroidism and thyroiditis: Clinical

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Hypothyroidism and thyroiditis: Clinical

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68-year-old man is brought to the physician by his partner because of increasing forgetfulness over the last 5 weeks. The patient is unable to finish his daily crossword puzzles and often has to call his partner when he is at the grocery store to help remember the list. He has had an 8-lb weight gain over this same time period. The patient has chronic hypertension, which is well-controlled with lisinopril, and he has also recently started taking laxatives several times a week to relieve constipation. Temperature is 36.5°C (97.7°F), pulse is 57/min, blood pressure is 128/86 mm Hg, and BMI is 27 kg/m2. The patient is alert and oriented to time, place, and person. Physical examination shows dry skin and a slightly distended abdomen. There is no mucosal pallor and capillary refill is less than 2 seconds. Deep tendon reflexes are delayed in the upper and lower extremities. Further testing confirms the diagnosis. Which of the following is the most appropriate pharmacotherapy for this patient?  


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Hypothyroidism is a condition that’s caused by having insufficient thyroid hormones.

Thyroid hormone production is under the control of the hypothalamus and the pituitary.

The hypothalamus secretes thyrotropin releasing hormone, or TRH, and TRH stimulates the anterior pituitary to secrete thyroid-stimulating hormone, or TSH.

TSH then binds to TSH receptors, which makes the thyroid secrete thyroxine, or T4 and triiodothyronine, or T3, in the blood. But this is not a one-way street - there’s also negative feedback happening, meaning when thyroid hormone levels rise, that inhibits the production of TSH and TRH, halting further production of T3 and T4 - to keep everything in balance.

Normally, some thyroid hormones travel through the bloodstream bound to thyroid binding globulin, and some are in their free form. And the thyroid actually makes more T4 than T3, and that T4 is converted to the more potent T3 in the periphery.

Thyroid hormones then increase the rate of metabolism in all cells, so they make us think, move, and talk faster, and they also increase heat generation. They also activate the sympathetic nervous system, the part of the nervous system responsible for our ‘fight-or-flight’ response, increasing cardiac output.

So with hypothyroidism, it’s like the entire body is functioning in slow motion - but this happens gradually, so it can take years before symptoms are even recognized. These include weight gain despite a loss in appetite because of the lower basal metabolic rate; cold sensitivity because the body is producing less heat; and slower heart rate, mental slowness, lethargy, and constipation because of the decreased effect of thyroid hormones on the sympathetic nervous system.


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