Please replace question 291 in Internal Medicine Board-Style Questions & Answers Volume 4 (Books/CD-ROM/Download) with the question presented below. The ECG shown in the original question is incorrect and shows QT interval prolongation, which is consistent with HYPOcalcemia, not hypercalcemia. Additionally, portions of the explanation accompanying the original question are incorrect.

291.

A 74-year-old lethargic female is brought to the ED complaining of nausea, vomiting, and abdominal pain. She has been having vague muscle and joint pains for several days prior to admission. On exam, she has hyperreflexia, and you notice that she has fasciculations of the tongue. A cardiac tracing shows a shortened QT interval without significant change in the T wave.

Which of the following is the most likely diagnosis?

A. Hypercalcemia
B. Hypocalcemia
C. Hyperkalemia
D. Hypokalemia
E. Carbon monoxide poisoning

Answer: A. Hypercalcemia.

Hypercalcemia is most commonly caused by hyperparathyroidism or malignancy (usually breast or lung cancer or multiple myeloma), but can also be caused by sarcoidosis and other granulomatous diseases.

When caused by hyperparathyroidism, the hypercalcemia is usually mild; this is also known as primary hyperparathyroidism. This occurs more often in women, and its incidence increases with age. The increase in calcium is due to the hypersecretion of parathyroid hormone (PTH), which causes an increase in the absorption of calcium in the intestine, as well as decreased excretion of calcium at the renal tubule. The osteoclasts in the bones are not involved in this process.

When caused by cancer, the hypercalcemia is usually more severe. It is due to increased osteoclastic activity within the bone (non-PTH mediated). This affects men and women equally, and increases in incidence with increasing age (as does the occurrence of these tumors).

Symptoms of hypercalcemia include nausea, vomiting, abdominal pain, altered mentation, and lethargy. Some patients report muscle and joint pains. Physical findings may include hyperreflexia and tongue fasciculations, but usually physical findings are absent. Laboratory testing shows elevated calcium. An ECG may show a shortened QT interval.

The treatment is to rapidly correct the hypercalcemia. The prognosis depends on the underlying cause. If caused by a malignancy, the prognosis is usually poor.

Hyperkalemia usually causes peaked T waves and a shortened QT interval on ECG. As the condition worsens, the PR interval and QRS widens. Hyporeflexia and muscle weakness can be observed when levels exceed 7.0 meq/L.

Hypocalcemia is incorrect because low calcium levels are associated with circumoral paresthesias and tetany (not fasciculations). You normally see prolongation, not shortening, of the QT interval.

Hypokalemia is associated with muscle weakness that begins distally and progresses to the trunk, with abdominal pain, nausea, vomiting and muscle cramping or tetany. The ECG is variable (ectopy, bradycardia, AV blocks and ventricular arrhythmias). Major changes include ST segment depression and reduced amplitude T waves. On occasion, the rare lateral U wave can be seen. Shortening of the QT interval is not a common feature, however.

Carbon monoxide poisoning is not associated with this clinical presentation, and ECG traditionally shows evidence of ischemia or ventricular arrhythmias.

Board Testing Point: Recognize the clinical findings of hypercalcemia and interpret an electrocardiogram showing a shortened QT interval.

Question # 260 should read: "Which of the following  is consistent with a patient with Type 1 RTA and recurrent nephrolithiasis?"
This question asks you to utilize the urine pH and anion gap to differentiate diarrhea from RTA.

Please replace Question #278 and its associated explanation with the following corrected text:

Which of the following disease states is not caused by an abnormality in the adrenal gland itself?

A. Cushing disease
B. Pheochromocytoma
C. Aldosteronoma (Conn syndrome)
D. Adrenal tumor-secreting deoxycorticosterone (DOC)
E. Adrenal carcinoma

Answer: A. Cushing disease.

Explanation: Adrenal carcinomas, Conn syndrome, pheochromocytomas and adrenal deoxycorticosterone (DOC)-secreting tumors all arise within the adrenal gland.
Cushing disease, however, is caused by an ACTH-secreting pituitary adenoma. The ACTH stimulates cortisol release by the adrenal glands and resultant hypertension. Cushing disease is the most common cause of Cushing syndrome.

Board Testing Point: Recognize that Cushing disease is a secondary disorder of the adrenal gland (the primary lesion is in the pituitary gland).