A 51-year-old woman comes to the office due to feeling "very fatigued and achy" for the past 2-3 months. She also has vague upper abdominal pain for which she has taken over-the-counter antacids without relief. The patient has no hemoptysis, chest pain, or weight loss. She has a 15-pack-year smoking history and quit 10 years ago. Her grandmother died of kidney cancer at age 65.
The patient's blood pressure is 142/90 mm Hg and pulse is 84/min. BMI is 34 kg/m². The lungs are clear to auscultation. Neck examination is unremarkable. The abdomen is soft and nontender. Laboratory results are as follows:

Chest x-ray is normal. Repeat serum calcium is 11.1 mg/dL. Parathyroid hormone is 85 pg/mL (10-65 pg/mL) . 25-hydroxyvitamin D is 10 ng/mL (30-74 ng/mL) .
Which of the following is the most likely cause of this patient's hypercalcemia?

Question

A 51-year-old woman comes to the office due to feeling "very fatigued and achy" for the past 2-3 months. She also has vague upper abdominal pain for which she has taken over-the-counter antacids without relief. The patient has no hemoptysis, chest pain, or weight loss. She has a 15-pack-year smoking history and quit 10 years ago. Her grandmother died of kidney cancer at age 65.
The patient's blood pressure is 142/90 mm Hg and pulse is 84/min. BMI is 34 kg/m². The lungs are clear to auscultation. Neck examination is unremarkable. The abdomen is soft and nontender. Laboratory results are as follows:

Chest x-ray is normal. Repeat serum calcium is 11.1 mg/dL. Parathyroid hormone is 85 pg/mL (10-65 pg/mL) . 25-hydroxyvitamin D is 10 ng/mL (30-74 ng/mL) .
Which of the following is the most likely cause of this patient's hypercalcemia?

Quizplus · Accepted Answer

11ec193a_97b4_8399_853d_537575092772_MD0002_00 The evaluation of hypercalcemia depends on parathyroid hormone (PTH) levels. Hypercalcemia with an elevated or inappropriately normal PTH (PTH-dependent) is caused by very few disorders, mainly primary hyperparathyroidism (PHPT). Parathyroid adenoma causes nearly 90% of PHPT. Other etiologies include parathyroid hyperplasia and carcinoma. Parathyroidectomy is indicated for patients with PHPT who have: Age <50 (and are therefore likely to develop eventual complications)Osteoporosis (T score <-2.5 at the hip, spine, or forearm)Serum calcium >1 mg/dL above the upper limit of normalRenal insufficiency (creatinine clearance <60 mL/min) Age <50 (and are therefore likely to develop eventual complications) Osteoporosis (T score <-2.5 at the hip, spine, or forearm) Serum calcium >1 mg/dL above the upper limit of normal Renal insufficiency (creatinine clearance <60 mL/min) Less common causes of PTH-dependent hypercalcemia include familial hypocalciuric hypercalcemia (FHH), lithium-induced hypercalcemia, tertiary hyperparathyroidism (in renal failure patients), and ectopic PTH production by malignant tumors (rare). FHH is a rare autosomal dominant disorder caused by an abnormal calcium-sensing receptor on the parathyroid cells. FHH can be differentiated from PHPT by measuring urinary calcium excretion, which is markedly low in FHH but normal to high in PHPT. (Choice A) Granulomatous disease (eg, sarcoidosis, tuberculosis) causes hypercalcemia due to increased production of 1,25-dihydroxyvitamin D, which leads to increased intestinal calcium absorption. The hypercalcemia is associated with low PTH levels (PTH-independent). (Choice B) Excessive ingestion of calcium carbonate (eg, antacid medications) can cause PTH-independent hypercalcemia, which is often associated with metabolic alkalosis and renal insufficiency (milk-alkali syndrome). This patient has normal bicarbonate, elevated PTH, and a normal serum creatinine level. (Choice D) Squamous cell carcinoma can cause hypercalcemia from osteolytic metastatic lesions or by secreting parathyroid hormone-related peptide (PTHrP). Serum calcium in malignant hypercalcemia is usually much higher than in PHPT and is PTH-independent. (Choice E) Vitamin D deficiency is common in patients with PHPT and can complicate assessment; it can lead to decreased urinary calcium excretion, causing PHPT to appear like FHH. However, vitamin D deficiency itself causes hypocalcemia (with secondarily elevated PTH). Educational objective: The evaluation of hypercalcemia depends on parathyroid hormone (PTH) levels. Hypercalcemia with an elevated or inappropriately normal PTH (PTH-dependent) is caused by very few disorders, mainly primary hyperparathyroidism. __________ References: Diagnosis of asymptomatic primary hyperparathyroidism: proceedings of the third international workshop. (http://www.ncbi.nlm.nih.gov/pubmed/19193909)

A 51-Year-Old Woman Comes to the Office Due to Feeling