A 45-year-old African American woman presents to her primary care physician for not feeling well. She states she has had a cough for the past week. She also has abdominal pain and trouble focusing that has been worsening and has lost 5 pounds recently. Her gastroesophageal reflux disease (GERD) has been poorly controlled recently. The patient is a non-smoker and has a history of GERD for which she takes antacids. Her temperature is 98.6°F (37°C), blood pressure is 115/71 mmHg, pulse is 72/min, and respirations are 12/min. A physical exam is within normal limits. Laboratory studies are ordered and are below:

Serum:
Na+: 139 mEq/L
K+: 4.1 mEq/L
Cl-: 101 mEq/L
HCO3-: 24 mEq/L
Urea nitrogen: 12 mg/dL
Glucose: 70 mg/dL
Creatinine: 0.9 mg/dL
Ca2+: 12.5 mg/dL
Alkaline phosphatase: 150 U/L
Phosphorus: 2.0 mg/dL

Urine:
Color: amber
Nitrites: negative
Sodium: 5 mmol/24 hours
Red blood cells: 0/hpf

Which of the following is the most likely explanation of this patient's current presentation?
Increased parathyroid hormone
Malignancy
Viral illness
Antacid overuse
Increased parathyroid hormone
This patient is presenting with hypercalcemia and low phosphate levels suggesting a diagnosis of hyperparathyroidism.

Hyperparathyroidism can cause hypercalcemia which typically presents with "bones, stones, moans, and groans," which corresponds to symptoms of bone pain (increased bone resorption), kidney stones, GI pain, and change in mental status/trouble focusing. The increased PTH results in renal phosphate wasting, increased production of 1,25-dihydroxy vitamin D, and increased renal calcium reabsorption. It also results in increased osteoclast activity resulting in increased bone breakdown. This will lead to laboratory changes of hypercalcemia and hypophosphatemia.

Taniegra reviews the evidence regarding hyperparathyroidism. She discusses how this disease is usually discovered asymptomatically with routine blood work. She recommends surgical treatment with intractable cases as success rates are high.

Figure A is a chest radiograph that is within normal limits. No masses are seen which suggests that malignancy is a less likely diagnosis.

Incorrect Answers:
Answer A: Antacid overuse for this patient's GERD can lead to a milk-alkali syndrome which presents with hypercalcemia and metabolic alkalosis. This patient does not have metabolic alkalosis. Treatment is with the discontinuation of the offending agent.

Answer B: Increased 1,25-dihydroxy vitamin D occurs in sarcoidosis which presents with cough, fatigue, and weight loss in an African American woman. Increased vitamin D by itself will result in hypercalcemia, and hyperphosphatemia rather than hypophosphatemia. Treatment is supportive and/or with corticosteroids.

Answer D: Malignancy (lung or renal cancer) is possible given this patient's presentation. Hypercalcemia of malignancy is a common feature with PTH-related protein effects; however, the patient's normal urinalysis and normal chest radiograph as well as non-smoking history point more toward a diagnosis of increased PTH.

Answer E: Viral illness is possible given this patient's systemic symptoms; however, it does not explain this patient's hypercalcemia and hypophosphatemia. Treatment of seasonal viruses is generally supportive though specific viruses such as influenza have agents such as oseltamivir that may be helpful.

Bullet Summary:
Hyperparathyroidism presents with "bones, stones, moans, and groans," as well as laboratory findings of hypercalcemia and hypophosphatemia.