Case 53: Diagnostic Testing

Case 53 Index

Take a look at some data from POD #1!
Basic labs
Kidney ultrasound (Foley catheter in place)
Urine sediment
After centrifuge  : Image courtesy of Ruth Schulman Stained (Sternheimer Malbin stain); Bright field (400x) Image courtesy of Vipin Varghese   Left: Bright field microscopy; Right: Phase contrast microscopy. (400x) Image courtesy of Jose Tesser Poloni


Basic Lab Ref

Choose the highest yield tests below (more than one choice may be correct)!
Haptoglobin & lactate dehydrogenase (LDH)
Excellent! The haptoglobin is undetectable and the LDH is 1,545 U/L (normal: 140 – 280 U/L).
Peripheral blood smear
In this patient with new anemia, AKI, and the urine findings above, this is a potentially helpful test. Image courtesy of the American Society of Hematology & Peter Maslak
Creatine phosphokinase (CPK)
A good idea, given the large blood without significant hematuria and the appearance of the urine supernatant after centrifuge. CPK for this patient is within the normal range.
Kidney biopsy
Not so fast…Take a closer look at the data we have so far.
Urine hemoglobin & myoglobin levels
Great choice! Hemoglobin is detected in the urine and myoglobin is undetectable.
Urine culture
This patient’s history and urinalysis are not suggestive of a urinary tract infection. Pick again!
Urine eosinophils
Even though this is a cheap, non-invasive test, the utility of this test is very low for this patient. Give it another shot!
Hepatitis B virus, hepatitis C virus, and human immunodeficiency virus (HIV) serologies
These viruses may be associated with various glomerular diseases – these serologies may not be the most helpful tests here. Try again!
With this new data, what’s the diagnosis here? Pick 1!
Contrast-induced nephropathy (CIN)
Volume depletion
Obstructive nephropathy
Acute tubular necrosis (ATN)  
Acute interstitial nephritis (AIN)
Hypertensive sclerosis
Pigment-induced nephropathy
Membranous nephropathy
Post-infection glomerulonephritis
Diabetic nephroapthy

Confident in your diagnosis? Click here to wrap this case up!

Case 53 Index
Case 53 Introduction
Case 53 Physical Exam