Excellent! We should definitely look for complement-mediated diseases in patients like this one with evidence of both nephrotic and nephritic syndrome. In this case, complements are normal with C3 109 mg/dL (ref: 90 – 180 mg/dL) and C4 14 mg/dL (ref: 10 – 40 mg/dL)

Though HIV is screening is important in all patients, HIV nephropathy is more likely to present with a pure nephrotic syndrome rather than nephritic syndrome. Try another test!

Without significant blood count abnormalities other than mild anemia, this test is less likely to provide high yield information. Pick again!

Diabetic nephropathy is unlikely to present with components of nephritic syndrome as our patient has here. Further, though the patient may have undiagnosed diabetes, there is no evidence to suggest this. Try again!

Given this patient’s presentation, this test is appropriate. You call the lab, and the result for this test will take 1 week. We’ll have to move on for now and try another test.

1:32 (reference: less than 1:80). It is reasonable to rule out systemic lupus erythematosus (SLE) given this patient’s presentation of a mixed nephritic & nephrotic syndrome.

Not the best test here; urine eosinophils are a poor diagnostic test that has been used in the past to diagnose acute interstitial nephritis, which is unlikely here (it may perform better, though, in patients with atheroembolic kidney disease).

Not the best test here; the urine osmolality gives us information about the kidney’s ability to concentrate urine. We’ve already seen a low urine specific gravity which suggests the concentrating ability may be impaired. This test is more useful in disorders of sodium balance.

Great choice – the ANCA screen for both p(erinuclear)-ANCA and c(ytoplasmic)-ANCA is negative.