Review Question - QID 214509

This patient who presents with symptoms of hypercalcemia such as constipation, weakness, flank pain, and depression most likely has primary hyperparathyroidism given the high calcium and low phosphate levels. Primary hyperparathyroidism can be caused by the development of a hyperfunctioning parathyroid adenoma.

Primary hyperparathyroidism results from the development of parathyroid hyperplasia or a hyperfunctioning adenoma. Abnormally increased activity of the parathyroid hormone results in hypercalcemia due to calcium retention and hypophosphatemia due to phosphate wasting. The high levels of calcium can result in the formation of calcium oxalate kidney stones that cause colicky flank pain as well as cysts in the bone known as osteitis fibrosa cystica. Patients with hypercalcemia should be treated with intravenous fluid resuscitation as they are usually profoundly dehydrated. The hyperfunctioning gland can then be identified by a sestamibi scan and surgically removed.

Incorrect Answers:
Answer 2: Ingestion of supplement can result in hypercalcemia with hypervitaminosis D; however, this condition would usually present with normal or elevated levels of phosphate because vitamin D leads to increased absorption of both calcium and phosphate.

Answer 3: Medication side effect can result in hypercalcemia with the use of thiazide diuretics; however, neither lisinopril nor metformin are associated with symptomatic hypercalcemia. Thiazide-induced hypercalcemia is usually also associated with smaller increases in calcium levels compared with primary hyperparathyroidism.

Answer 4: Paraneoplastic syndrome can cause hypercalcemia because of PTH-related protein release from squamous cell carcinomas of the lung. Squamous cell carcinoma is found almost exclusively in heavy smokers and is very unlikely in this patient. Furthermore, the calcium elevation in malignancy is usually over 12.0 mg/dL as opposed to the mild elevation found in this patient.

Answer 5: Renal failure can result in secondary hyperparathyroidism because the kidney is unable to properly reabsorb calcium and hydroxylate vitamin D; however, this disease would present with signs of hypocalcemia such as twitching of the face when tapping over the facial nerve (Chvostek) or twitching of the arm when taking a blood pressure (Trousseau) rather than hypercalcemia.

Bullet Summary:
Primary hyperparathyroidism will present with signs of hypercalcemia such as constipation, depression, kidney stones, weakness, and osteitis fibrosa cystica.