86.) A 35-year old woman experiences anterior pituitary hemorrhagic necrosis (Sh

Question

86.) A 35-year old woman experiences anterior pituitary hemorrhagic necrosis (Sheehan syndrome) after a postpartum hemorrhage. She feels light-headed, dizzy, and weak. Which of the following hormones most likely is responsible for her symptoms? A) ACTH GnRH &Prolactin; D) TSH GH 87) A 45-year-old woman is noted to have fatigue and cold intolerance and is diagnosed with hypothyroidism. Her physician suspects a pituitary etiology. Which of the following laboratory finding is most consistent with this condition? A) Low TSH, low free thyroxine B) Elevated TSH, low thyroxine C) Elevated TSH, elevated thyroxine D) Low TRH 88.) A 33-year-old chemist takes L-thyroxine (Synthroid) 1 ug orally each day. He asks how the thyroxine work a cellular level. Which of the following is the best explanation? A) It binds onto membrane surface receptor and activates protein synthesis. B) It binds onto membrane surface receptor and activates secondary messenger.u C) It binds onto a cytoplasmic receptor and the hormone-receptor complex diffuses to the nucleus to affect transcription. D) It has a direct effect on the hypothalamic nuclei affecting metabolism. 89.) A 33-year-old woman is noted by her physician to have some fatigue and some coarse skin. Her only medication is oral contraceptive agent. The following laboratories have been returned TSH 1.0mU/L (0.35-6.0mU/L) Free Thyroxine 1.0 ng/dL (0.8-2.7 ng/dL) Total thyroxine 13.0 ug/dL (4.5-12.0 ug/dL) Thyroid-binding globulin (TBG) 55ng/mL (15-34mg/L) Which of the following is the most likely diagnosis? A) Hyperthyroidism B) Hypothyroidism C) Normal thyroid status D) Transient hyperthyroidism

Explanation / Answer

86. If we are to choose one option only then answer must be TSH. TSH is the hormone which is responsible for maintaining the basal metabolic rate. It controls the whole body metabolism. And the symptoms mentioned here are indicative of hypothyroidism symptoms which is due to low TSH. Other hormones have other symptoms not mentioned here.[ ACTH will cause fluid retention, Prolactin will cause agalactorrhea, GnRH will cause amenorrhea]

87. B. Elevated TSH and low thyroxine ( this indicates primary hypothyroidism. Option A indicates central hypothyroidism which is a rare condition and not a recommended option here. We will choose the most common etiology and that is the option B ).

88. Option C is the answer [ T4 is transported to the target organ by TBG, taken into the cell--> binds to cytoplasmic receptors--. enters the nucleus---> activates DNA zone for protein synthesis ].

89. The answer is c. normal thyroid status [ as the patient is on contraceptive pills which is an estrogen, that suppresses the progesterone. This leads to an increase in TBG production from the liver which in turn increase the total thyroxine. But as you can see the free T4 and TSH level is normal, it is euthyroidism. The increased TBG and total thyroxine is due to oral contraceptive pills ]

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