Inflammation in the concentrating tissue of the kidney can produce a range of manifestations:

  • Proteinuria
  • Haematuria (microscopic, ie on dipstick/microscopy only, or frank macroscopic)
  • Nephrotic syndrome
  • Acute nephritis

Protein in urine is not usually symptomatic in itself, the urine may seem more frothy.  It would not be until the loss of a substantial amount of protein leads to hypoalbuminaemia and oedema (nephrotic syndrome) that it would be apparent.


Accompanying symptoms will tend to guide you to a diagnosis eg purpuric rash (HSP), photodermatitis and/or arhtritis (SLE), heavy proteinuria without haematuria (minimal change glomerulonephropathy).

Dipstick testing is sensitive for proteinuria and haematuria, but urine protein/albumin:creatinine ratio is more reliable.  On microscopy, red and white cell casts are pathognomic.  Presence of red cells useful to exclude other causes of apparent haematuria.

Complement – some characteristic patterns.

If isolated low C3, and fits with PSAGN, diagnosis is clear.  But check it normalizes in 3/12, else biopsy.

Biopsy – for definitive diagnosis.  Although some conditions have patchy changes so sampling error possible.