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Zorluk: OrtaOrdering Laboratory Tests

A 45-year-old man comes to the outpatient clinic reporting a 6-month history of worsening joint pain, generalized fatigue, and excessive sweating. He mentions that he had to have his wedding ring enlarged twice over the past year due to changes in his hands. His past medical history is significant for type 2 diabetes mellitus, which was diagnosed three months ago. Blood pressure is 152/94 mm Hg, heart rate is 78/min, and BMI is 29 kg/m 2^2. Physical examination reveals an enlarged, prominent jaw, macroglossia, and enlarged, doughy hands. Which of the following is the most appropriate next step in laboratory evaluation?

  1. Measurement of serum insulin-like growth factor 1Cevap
  2. B
    Oral glucose tolerance test with concurrent growth hormone measurement
  3. C
    Magnetic resonance imaging of the pituitary gland
  4. D
    Measurement of a random serum growth hormone level
  5. E
    Measurement of serum thyroid-stimulating hormone

Cevap

Measurement of serum insulin-like growth factor 1
The patient's clinical features (acral overgrowth, coarse facial features, hyperhidrosis, and new-onset diabetes) strongly suggest acromegaly, which is almost always caused by a growth hormone-secreting pituitary adenoma. The most appropriate initial step in laboratory evaluation is measuring the serum insulin-like growth factor 1 (IGF-1) level. Because growth hormone is secreted in a pulsatile fashion and has a short half-life, random growth hormone levels are unreliable. IGF-1, produced primarily by the liver in response to growth hormone, has a longer half-life and provides a steady, integrated assessment of growth hormone secretion.

Adım Adım Çözüm

1
Analyze the patient's clinical presentation.
The combination of enlarging hands (requiring ring resizing), prominent jaw, hyperhidrosis, macroglossia, and new-onset type 2 diabetes is a classic presentation of acromegaly.
Recognizing the syndrome correctly dictates the specific endocrine pathway that needs evaluation.
2
Determine the standard diagnostic sequencing for the suspected condition.
The workup for acromegaly requires a highly sensitive biochemical screening test first, followed by a specific confirmatory test, and finally imaging.
Adhering to proper test sequencing avoids unnecessary invasive testing, excessive costs, and diagnostic errors caused by false positives.
3
Select the most appropriate initial laboratory test.
Serum insulin-like growth factor 1 (IGF-1) is the correct choice because it does not fluctuate throughout the day, unlike growth hormone.
IGF-1 mediates most of the effects of growth hormone and provides a stable reflection of average growth hormone secretion over time.

Anahtar Kavram

The initial laboratory evaluation for suspected acromegaly is the measurement of serum insulin-like growth factor 1 (IGF-1).
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