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Zorluk: OrtaDiagnostic Workup and Test Sequencing

A 54-year-old man is evaluated in the outpatient clinic for a 6-month history of episodic facial flushing, intermittent severe diarrhea, and abdominal cramping. He reports that the flushing episodes are frequently triggered by emotional stress or consuming alcohol. He has lost 4 kg (8.8 lb) over this period. Medical history is unremarkable, and he takes no daily medications. Vital signs are temperature 37.0°C (98.6°F), blood pressure 118/76 mmHg, pulse 82/min, and respiratory rate 14/min. Physical examination reveals telangiectasias over the cheeks and nose. Cardiac auscultation reveals a grade 2/6 holosystolic murmur at the left lower sternal border that becomes louder with inspiration. Abdominal examination shows mild diffuse tenderness but no hepatosplenomegaly or palpable masses. Which of the following is the most appropriate next step in the diagnostic workup?

  1. 24-hour urine collection for 5-hydroxyindoleacetic acidCevap
  2. B
    Computed tomography scan of the abdomen and pelvis
  3. C
    Somatostatin receptor scintigraphy
  4. D
    Colonoscopy with terminal ileum intubation
  5. E
    Measurement of serum vasoactive intestinal peptide

Cevap

24-hour urine collection for 5-hydroxyindoleacetic acid
The patient's presentation of episodic facial flushing, secretory diarrhea, telangiectasias, and a tricuspid regurgitation murmur (holosystolic at the left lower sternal border, increasing with inspiration) is highly characteristic of carcinoid syndrome. Carcinoid tumors secrete excessive vasoactive substances, predominantly serotonin. A fundamental principle in the diagnostic workup of neuroendocrine tumors is that biochemical confirmation must precede anatomic or functional localization. Therefore, the most appropriate initial diagnostic step is to measure the 24-hour urinary excretion of 5-hydroxyindoleacetic acid (5-HIAA), which is the primary metabolite of serotonin.

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1
Analyze the patient's clinical presentation.
The patient exhibits episodic flushing, secretory diarrhea, telangiectasias, and a tricuspid regurgitation murmur (holosystolic, louder with inspiration).
These findings represent the classic constellation of carcinoid syndrome, complicated by carcinoid heart disease (plaque-like deposits on right-sided heart valves due to elevated circulating serotonin).
2
Determine the standard diagnostic sequencing protocol for suspected neuroendocrine tumors.
The protocol dictates that biochemical confirmation must be established before anatomic or functional imaging.
Neuroendocrine tumors can be small and difficult to locate. Imaging beforehand is low-yield and constitutes premature overutilization of healthcare resources.
3
Identify the optimal initial diagnostic test for this specific syndrome.
A 24-hour urine collection for 5-hydroxyindoleacetic acid (5-HIAA) is required.
5-HIAA is the primary end-product of serotonin metabolism and serves as a highly sensitive and specific initial biochemical marker for carcinoid tumors.

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Diagnostic Workup and Test Sequencing
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Diagnostic Workup and Test Sequencing

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