Case of the Month: Endocrine Board Review Online

endocrine review board

This issue highlights Endocrine Board Review Online. Test your clinical knowledge and prepare for your exam with access to live course session recordings and case questions. Available on the online store.

Clinical Vignette

A 24-year-old man is referred after an acute episode of renal colic. Imaging studies show bilateral kidney stones. Metabolic workup is consistent with primary hyperparathyroidism as illustrated by the following laboratory test results:

  • Serum calcium = 11.9 mg/dL (2.98 mmol/L) (reference range, 8.2-10.2 mg/dL [2.1-2.6 mmol/L])
  • Serum PTH = 112 pg/mL (112 ng/L) (reference range, 10-65 pg/mL [10-65 ng/L])
  • Urinary calcium excretion = 400 mg/24 h (10 mmol/d) (reference range, 100-300 mg/24 h [2.5-7.5 mmol/d])

Following a sestamibi scan that shows a “possible” adenoma in the right lower pole, the patient undergoes minimally invasive parathyroidectomy with resection of 1 enlarged parathyroid gland. Pathologic examination confirms a hyperplastic adenoma. Two weeks later, he returns for blood work while taking elemental calcium, 600 mg twice daily.

Laboratory test results 2 weeks after surgery:

  • Calcium = 11.8 mg/dL (2.95 mmol/L) (reference range, 8.2-10.2 mg/dL [2.1-2.6 mmol/L])
  • Phosphorus = 2.2 mg/dL (0.7 mmol/L) (reference range, 2.3-4.7 mg/dL [0.7-1.5 mmol/L])
  • Albumin = 4.2 g/dL (42 g/L) (reference range, 3.5-5.0 g/dL [35-50 g/L])
  • PTH = 120 pg/mL (120 ng/L) (reference range, 10-65 pg/mL [10-65 ng/L])
  • Serum creatinine = 1.0 mg/dL (88.4 mmol/L) (reference range, 0.6-1.1 mg/dL [53.0-97.2 mmol/L])

Which of the following should you do now?

  1. Genetic testing for mutations in the calcium-sensing receptor gene (CASR)
  2. Genetic testing for mutations in the multiple endocrine neoplasia type 1 gene (MEN1)
  3. 4D CT of the neck
  4. Another sestamibi scan
  5. Cessation of calcium supplementation and recheck of laboratory tests in 1 month