Case 5: Diagnostic Testing

Take a look at some initial diagnostic testing below.
Urinalysis/microscopy, urine electrolytes
Urine sediment
Basic labs
 
Kidney Ultrasound

Basic Lab Ref

Some additional tests are now ready for you! Choose the highest yield (more than one may be correct).
Complement levels (C3, C4)
Patients with a pure nephrotic syndrome without hematuria are less likely to have a kidney disease associated with hypocomplementemia. Let’s try a different test.
HIV 1/2 ELISA
Negative. HIV nephropathy often presents with nephrotic syndrome – this is a high yield test for this case.
Repeat Hemoglobin A1C
5.8% (ref: 4 – 5.6%)
Anti-phospholipase A2 receptor (PLA2R) antibody
This is a reasonable diagnostic test for this patient, though the lab tells you that the result from this test won’t be ready for a few days.
Hepatitis C Antibody
Hepatitis C infection is usually associated with membranoproliferative glomerulonephritis with cryoglobunlinemia, and a nephritic syndrome. As our patient here has a nephrotic syndrome, try a higher yield test.
Hepatitis B Antibody
Negative. Good thought, hepatitis B is typically associated with membranous nephropathy and nephrotic syndrome.
Anti-nuclear antibody (ANA)
1:320 (reference: less than 1:80). In a women of this age and an active urine sediment, autoimmune disease such as systemic lupus erythematosus should be on our differential.  This is a high yield test.
Anti-double stranded DNA (anti-DS DNA)
Negative. In a women of this age and an active urine sediment, autoimmune disease such as systemic lupus erythematosus should be on our differential.  This is a high yield test.
Serum protein electrophoresis and free light chains
No evidence of monoclonal protein (no M-spike), normal ratio of kappa and lambda light chains. Though more likely to be diagnosed in an older patient, monoclonal gammopathies are associated with glomerular disease and nephrotic syndrome.
Lipid panel
LDL 307 mg/dL, HDL 59 mg/dL, total cholesterol 398 mg/dL, triglycerides 160 mg/dL. In patients with nephrotic syndrome, hypoalbuminemia (low albumin levels) and low oncotic pressure lead to reactive hepatic synthesis – and subsequently increased synthesis of lipoproteins.

Take a moment to reassess your differential diagnosis.

What are the top 2 diagnoses on your differential now?
Post-infectious glomerulonephritis (PIGN)
Primary membranous nephropathy
Systemic lupus erythematosus (SLE) nephritis
Diabetic nephropathy
Hepatitis-C associated glomerular disease
Hepatitis-B associated glomerular disease
Focal segmental glomerulosclerosis (FSGS)
Anti-glomerular basement membrane (GBM) disease
Acute tubular necrosis (ATN)
IgA nephropathy
Minimal change disease

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Case 5 Index
Case 5 Introduction
Case 5 Physical Exam