Question of the Week #484

A 50-year-old African american woman presents to your clinic with increased thirst and increased urination. You review her old records and it appears like she had a Chest X-ray in the ER last year that showed bilateral hilar lymphadenopathy. She was advised follow-up but she did not comply at that time. Upon examination, you discover some subcutaneous skin nodules and biopsy of one of these comes back positive for non-caseating granulomas.

Laboratory studies from a week ago show:

Hemoglobin 15.2gm%

Calcium : 11.6mg%

Creatinine : 1.0mg%

Which of the following investigations may explain the underlying mechanism of her Hypercalcemia?

A. Biopsy of Hilar Lymph Node

B. 25 Hydroxy Vitamin D Level

C. PTH related peptides

D. 1,25 di-hydroxy Vitamin D level

E. Serum Protein Electrophoresis

7 Responses

  1. A. Sarcoidosis is a diagnosis of exclusion, but hilar lymph node biopsy is used to rule out infectious etiologies ie. TB.

    • With regard to Diagnosis you are right. Skin nodule already gave us a Sarcoid diagnosis. Additional biopsy is not needed. Sarcoid can caus Hypercalcemia but how do we prove this is what is doing it here – what’s that mechanism? The question asks “Mechanism” of her Hypercalcemia

  2. D The mechanism responsible for the abnormal calcium metabolism in granulomatous disease has been most completely evaluated in sarcoidosis. Approximately 30 to 50 percent of patients with this disorder have hypercalciuria, and 10 to 20 percent have hypercalcemia, which is aggravated by exposure to sunlight. Increased intestinal calcium absorption induced by high serum calcitriol concentrations (1,25-dihydroxyvitamin D, the most active metabolite of vitamin D) is the primary abnormality, although a calcitriol-induced increase in bone resorption may also contribute

  3. We check 25 OH vit D level as it will be low in sarcoidosis
    Unknown mechanism one proposed is that activated macrophages in granuloma converts 25 to 1 25 so it gets depleted

  4. C

  5. D

  6. D

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