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Zorluk: OrtaDiagnostic Workup and Test Sequencing

A 38-year-old man comes to the outpatient clinic reporting a one-year history of worsening joint pain, excessive sweating, and frequent headaches. He mentions that he recently had to have his wedding band resized because it would no longer fit his finger. He has no significant past medical history and takes no medications. Vital signs show a blood pressure of 152/95 mmHg, heart rate of 78/min, and respiratory rate of 14/min. Physical examination reveals coarse facial features, a prominent jaw, and widening of the spaces between the lower incisors. His hands and feet appear enlarged with thickened skin. Which of the following is the most appropriate next step in the diagnostic workup?

  1. Measurement of serum insulin-like growth factor 1 concentrationCevap
  2. B
    Measurement of serum growth hormone following an oral glucose load
  3. C
    Magnetic resonance imaging of the brain with contrast
  4. D
    Measurement of a random serum growth hormone concentration
  5. E
    Initiation of a nonsteroidal anti-inflammatory drug and routine follow-up

Cevap

Measurement of serum insulin-like growth factor 1 concentration
The correct next step is the measurement of serum insulin-like growth factor 1 (IGF-1) concentration. This patient's presentation of acral enlargement (needing a ring resized, enlarged hands and feet), coarse facial features, widening of the teeth, excessive sweating, and hypertension is the classic clinical picture of acromegaly. Acromegaly is typically caused by a growth hormone (GH)-secreting pituitary adenoma. Because GH is secreted in a pulsatile manner and has a short half-life, random serum GH levels fluctuate widely and are unreliable for diagnosis. Instead, the initial screening test of choice is the measurement of serum IGF-1. IGF-1 is synthesized by the liver in response to GH, has a longer half-life, and remains consistently elevated in patients with acromegaly, providing an accurate reflection of integrated GH secretion over time.

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1
Identify the clinical syndrome based on the patient's presentation.
The combination of acral enlargement (growing ring size, enlarged hands/feet), coarse facial features, macrognathia, diaphoresis, headaches, and new-onset hypertension is highly characteristic of acromegaly.
Recognizing the classic phenotype of excess growth hormone (GH) secretion is the first step in determining the diagnostic pathway.
2
Determine the optimal initial biochemical screening test for the suspected condition.
Measurement of serum insulin-like growth factor 1 (IGF-1) is the recommended initial screening test.
GH is secreted from the pituitary in a pulsatile fashion with a short half-life, making random GH levels unreliable. IGF-1 is produced by the liver in response to GH and provides a stable, integrated marker of GH secretion over time.
3
Sequence the subsequent diagnostic steps to follow the initial screen.
If IGF-1 is elevated, the next step is a confirmatory oral glucose suppression test. If GH fails to suppress, magnetic resonance imaging of the pituitary is then indicated.
Adhering to proper test sequencing avoids unnecessary imaging (which may reveal incidentalomas) and prevents the misinterpretation of fluctuating hormone levels.

Anahtar Kavram

The initial diagnostic test for suspected acromegaly is the measurement of serum insulin-like growth factor 1 (IGF-1) concentration, followed by an oral glucose suppression test if the IGF-1 level is elevated.
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Diagnostic Workup and Test Sequencing

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