Case 4: Additional Testing

Case 4 Index

Choose ONE of the following tests to make the diagnosis here:
 Creatine phosphokinase (CPK)
Great choice! Yikes, the creatine phosphokinase (CPK), also known as the creatinine kinase (CK), is through the roof at 225,000 units/L (reference range: 22 – 198 U/L).
Bone marrow biopsy
You consult your hematology colleagues for help with a bone marrow biopsy, but they’re not convinced it will be helpful in this case as there are not significant abnormalities in the complete blood count. Let’s try a less invasive test.
Complement levels (C3, C4)
Both C3 and C4 are within the normal range, there is no evidence of hypocomplementemia. Complement-mediated kidney diseases often present with an active urine sediment (the presence of cells, casts, or proteinuria) which we did not see here. Pick another test!
Serum uric acid and phosphorus levels
The lab quickly tells you that both the uric acid and phosphorous levels are elevated when compared to the reference range for these tests. As both can be elevated in acute kidney injury, this information might not be the most helpful diagnostic test in this case. Try again!
Now it’s time to lock in your final diagnosis. What do you think?
Post-infectious glomerulonephritis (PIGN)
Obstructive nephroprathy
Acute interstitial nephritis (AIN)
Systemic lupus erythematosus (SLE) nephritis
Anti-nuclear cytoplasmic antibody (ANCA) associated glomerulonephritis
Acute tubular necrosis (ATN)
IgA nephropathy

Click here when you’re confident in your final diagnosis!

Case 4 Index
Case 4 Introduction
Case 4 Physical Exam
Case 4 Diagnostic Testing