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Soru

Zorluk: KolayEndocrinology and Metabolism

An evaluation for recurrent nephrolithiasis is being conducted for a 51-year-old male. Over the past six months, he has passed two calcium oxalate stones. He reports no major medical history but mentions a recent onset of constipation and generalized bone aches. Vital signs are within normal limits. Blood tests reveal a serum calcium concentration of 11.411.4 mg/dL (normal: 8.4−10.28.4-10.2 mg/dL) and a serum phosphorus concentration of 2.22.2 mg/dL (normal: 2.7−4.52.7-4.5 mg/dL). Which of the following is the most appropriate next step in the diagnostic evaluation of this patient's metabolic abnormality?

  1. Measurement of intact parathyroid hormone (PTH)Cevap
  2. B
    Measurement of 1,25-dihydroxyvitamin D
  3. C
    24-hour urine calcium collection
  4. D
    Sestamibi parathyroid scan
  5. E
    Measurement of parathyroid hormone-related peptide (PTHrP)

Cevap

Measurement of intact parathyroid hormone (PTH) is the most appropriate next step.
The correct response is the measurement of intact parathyroid hormone (PTH). In any patient with confirmed hypercalcemia, the first and most critical branching point in the diagnostic workup is determining whether the elevated calcium is PTH-mediated (primary or tertiary hyperparathyroidism, familial hypocalciuric hypercalcemia) or non-PTH-mediated (malignancy, vitamin D toxicity, granulomatous disease). Measuring intact PTH accurately establishes this distinction and dictates all subsequent steps.

Adım Adım Çözüm

1
Identify the primary laboratory abnormality in the context of the patient's symptoms.
The patient has hypercalcemia (11.411.4 mg/dL) and hypophosphatemia (2.22.2 mg/dL), presenting with classic symptoms of 'stones, bones, and groans'.
Recognizing the metabolic state is necessary to select the correct diagnostic algorithm.
2
Determine the first branching point in the standard diagnostic algorithm for this laboratory abnormality.
The initial step in evaluating any hypercalcemia is to distinguish whether the condition is driven by the parathyroid glands (PTH-mediated) or by another source (non-PTH-mediated).
Measuring intact parathyroid hormone (PTH) is the most direct and accurate way to make this differentiation.
3
Select the option that matches this diagnostic protocol.
Measurement of intact parathyroid hormone (PTH) is selected as the correct next step.
This aligns exactly with medical guidelines for the workup of hypercalcemia.

Anahtar Kavram

The initial diagnostic step for any confirmed hypercalcemia is the measurement of serum intact parathyroid hormone (PTH) to differentiate between PTH-mediated and non-PTH-mediated causes.
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Endocrinology and Metabolism

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