ECG Challenge

September 28, 2018
Brady Pregerson, MD

Patient history
A 72-year-old woman presents to the emergency department for generalized weakness of approximately 1 week’s duration, with confusion since yesterday that according to her family seems to come and go. She denies pain, fever, vomiting, diarrhea, focal weakness or other complaints, but keeps asking for water to drink.

Vital signs and examination

Vital signs are normal except for a pulse of 48 beats/min. Blood pressure is slightly elevated. The physical examination is normal except for slightly dry mucous membranes and mild bradycardia.

Initial differential diagnosis
• UTI or other infection.
• Electrolyte abnormality
• Dehydration
• ~15 other things

Initial diagnostic testing
ECG obtained, results are shown in Figure 1, above. (Please double click to enlarge)


  • What does the EKG show? 
  • What should you do next? 

Please click here for answers and discussion.


What does the case image show?  The image shows bradycardia with first degree heart block and a prominent U-wave.
What should you do next?  Order laboratory studies: the potassium level was normal, but the calcium was over 15 mg/dL. Based on this evidence of hypercalcemia, you need to rehydrate, treat, and admit.


Hypercalcemia may present in a variety of ways but generalized weakness and dehydration from polyuria are probably the most common. Other symptoms may include abdominal pain and psychiatric symptoms. The many causes of hypercalcemia are listed in the highlighter area of the sample page in Figure 2, above (please double click to enlarge). 

ECG findings in hypercalcemia may include shortening of the ST segment and/or QT interval, elevation of the ST segment and/or J point and/or U wave, and finally lengthening of the PR and/or QRS interval. Ventricular fibrillation can also occur. In this patient’s ECG the findings were the elevated U wave and long PR interval. U waves are most famous in hypokalemia but other causes include hypercalcemia or hypomagnesemia, ischemia or LVH, and medications such as digoxin, amiodarone, quinidine, and neuroleptics.

Treatment of hypercalcemia is initiated with IV fluid repletion followed by medications such as calcitonin and/or zoledronic acid. Patients with levels >13 mg/dL should be hospitalized. For more details on testing, treatment and disposition see the list in the highlighted area of the sample page in Figure 2, above. (Please double click to enlarge.)


Calcium was 15.5 mg/dL; BUN/Cr were 60 mg/dL and 4.4 mg/dL, respectively. The cause was determined to be multiple myeloma.