Case 27: Diagnostic Testing

Case 27 Index

Take a look at some initial diagnostic testing below!

Basic labs

The ED tells you that they have already given the patient 10 units of regular insulin, 1 g of intravenous calcium gluconate, and 30 g of kayexalate. 

Which of the following at the next best steps (more than one may be correct!)

Urgently place temporary dialysis catheter and arrange for hemodialysis against a potassium-free dialysate. 
Not so fast! There are a few more appropriate options here. 

Draw another sample to check a plasma potassium and walk it to the lab. 
Nailed it! This value is 4.2 meq/L. 

Repeat the plasma potassium and try to draw the sample without a tourniquet. 
The labs calls you urgently to tell you that the potassium is still very high. 

Check a serum potassium level in a tube with sodium citrate and EDTA (ethylenediaminetetraacetic acid)
Not quite…try again! 

Check a 12-lead electrocardiogram (ECG)
Great! A serum potassium of 7.5 meq/L should prompt an ECG in any patient. Here is the patient’s ECG:

Perform a kidney biopsy.
Ouch! This patient’s creatinine is within the normal range. We don’t have any other data suggesting that a kidney biopsy may be helpful here. Try again!

So what happened here? Click here to wrap up this case! 

Case 27 Index
Case 27 Introduction
Case 27 Physical Exam