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Zorluk: KolayOrdering Laboratory Tests

A 35-year-old woman presents to the outpatient primary care clinic with a 3-month history of worsening fatigue, a 5-kg (11-lb) weight gain despite no change in her appetite, constipation, and feeling cold all the time. She also reports that her menstrual cycles have become heavier over the past few months. Vital signs show a temperature of 36.5°C (97.7°F), a heart rate of 54/min, a blood pressure of 110/70 mm Hg, and a respiratory rate of 14/min. On physical examination, her skin is cool and dry. The thyroid gland is palpable, firm, and non-tender without distinct nodules. Neurologic examination reveals a delayed relaxation phase of the Achilles tendon reflexes. Which of the following is the most appropriate next step in laboratory evaluation?

  1. Serum thyroid-stimulating hormone levelCevap
  2. B
    Serum free thyroxine (T4) level
  3. C
    Antithyroid peroxidase (anti-TPO) antibodies
  4. D
    Complete blood count
  5. E
    Thyroid ultrasound

Cevap

Serum thyroid-stimulating hormone level
The correct answer is a serum thyroid-stimulating hormone (TSH) level. This patient presents with classic signs and symptoms of primary hypothyroidism, which include fatigue, unexpected weight gain, cold intolerance, constipation, heavy menstrual bleeding, bradycardia, and a delayed relaxation phase of deep tendon reflexes. In the ambulatory setting, the most sensitive and cost-effective initial laboratory test to evaluate for suspected thyroid dysfunction is a serum TSH level. If the TSH is elevated, a serum free T4 level is subsequently checked to confirm and determine the severity of primary hypothyroidism.

Adım Adım Çözüm

1
Analyze the patient's clinical presentation.
The patient exhibits fatigue, weight gain, cold intolerance, constipation, menorrhagia, bradycardia, dry skin, and delayed deep tendon reflexes.
Identifying the constellation of signs and symptoms is necessary to formulate a primary working diagnosis.
2
Synthesize the clinical findings into a suspected diagnosis.
The clinical picture is highly classic for primary hypothyroidism.
Grouping systemic symptoms directs the clinician toward the appropriate organ system and functional defect.
3
Determine the most appropriate initial diagnostic laboratory test.
Select a serum thyroid-stimulating hormone (TSH) level as the first test.
TSH is the most sensitive screening test for primary thyroid dysfunction and is the standard initial step in the diagnostic algorithm.

Anahtar Kavram

The initial laboratory evaluation of suspected primary hypothyroidism is a serum thyroid-stimulating hormone (TSH) level.
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Ordering Laboratory Tests

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