Examkin

Soru

Zorluk: KolayPharmacologic Interventions

A 26-year-old primigravid woman at 8 weeks gestation presents to the clinic for a routine prenatal visit. Over the past three weeks, she has experienced frequent palpitations, heat intolerance, excessive sweating, and a 2.3-kg (5-lb) weight loss despite an increased appetite. Her blood pressure is 128/78 mmHg, pulse is 112/min, and respirations are 16/min. Physical examination reveals mild exophthalmos and a diffusely enlarged, non-tender thyroid gland. A fine bilateral hand tremor is noted when her arms are outstretched. Laboratory studies show:

Thyroid-stimulating hormone (TSH): 0.01 µU/mL (normal: 0.1-2.5 µU/mL)
Free thyroxine (T4): 2.9 ng/dL (normal: 0.8-1.5 ng/dL)
Thyroid-stimulating immunoglobulin: Elevated

Which of the following is the most appropriate pharmacologic intervention for this patient's underlying condition?

  1. PropylthiouracilCevap
  2. B
    Methimazole
  3. C
    Radioactive iodine-131
  4. D
    Levothyroxine
  5. E
    Surgical referral for total thyroidectomy

Cevap

The most appropriate pharmacologic intervention is propylthiouracil.
The correct answer is propylthiouracil (PTU). This patient is presenting with symptomatic Graves' disease during the first trimester of pregnancy (8 weeks gestation). The management of hyperthyroidism changes during pregnancy to minimize harm to the developing fetus. PTU is the drug of choice during the first trimester because methimazole is associated with an increased risk of severe congenital malformations, specifically aplasia cutis (a congenital absence of skin, typically on the scalp) and choanal atresia, which occur during critical organogenesis in the first trimester. After the first trimester, patients are often transitioned back to methimazole due to PTU's higher risk of severe maternal hepatotoxicity.

Adım Adım Çözüm

1
Interpret the patient's clinical presentation and laboratory results.
The patient has symptomatic thyrotoxicosis with a suppressed TSH, elevated free T4, and positive thyroid-stimulating immunoglobulin.
These findings confirm the diagnosis of Graves' disease.
2
Identify the patient's specific physiological context.
The patient is a primigravida at 8 weeks gestation (first trimester of pregnancy).
Pregnancy status directly dictates which pharmacologic agents are safe to use for hyperthyroidism.
3
Select the guideline-concordant antithyroid medication for this gestational age.
Propylthiouracil (PTU) is selected.
PTU is the preferred thioamide in the first trimester to avoid the specific teratogenic effects of methimazole (aplasia cutis, choanal atresia).

Anahtar Kavram

In the first trimester of pregnancy, propylthiouracil (PTU) is the preferred pharmacologic treatment for hyperthyroidism (Graves' disease) due to the teratogenic risks associated with methimazole.
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