Haematuria

 

• Definition and classification

  • In health, <1 μL of blood per day in urine i.e. 1 million RBCs (≈ 1 RBC passed per glomerulus).
  • Can usually detect 1-5 RBC/μL on dipstick, or 3 RBC/high-powered field (HPF) on microscopy.
  • Classified as microscopic (invisible) or macroscopic (aka gross, frank), with colour from red to brown (tea or cola coloured).

• Differential diagnosis

  UTI:

  • Urethritis, cystitis, pyelonephritis, or prostatitis.
  • Often accompanied by frequency and dysuria.

  Cancer:

  • Bladder, prostate, kidney, urethral, or penile.
  • Often painless, but dysuria can occur.

  Stone:

  • Kidney, ureter, or bladder.
  • Often painful.

  Others:

  • Menstruation or rectal bleeding.
  • Glomerular disease. Commoner in younger patients.
  • Prostatic hypertrophy.
  • Cysts: polycystic kidney disease, simple renal cyst.
  • Alpert's syndrome: hearing loss also present.
  • Schistosomiasis

  Blood early in the flow suggests a urethral or prostatic problem while blood throughout suggests a bladder, ureteric, or kidney problem.

  Mimics:

  • Food e.g. beetroots.
  • Drugs: rifampicin, sulfasalazine.
  • Haemoglobinuria and myoglobinuria: brown urine, blood+ on dipstick, but no RBCs on microscopy.

• Nephritic syndrome

  Definition and pathophysiology

  • Haematuria along with proteinuria (milder than in nephrotic), RBC casts on microscopy, hypertension, and oliguria.
  • Pathophysiology: glomerular inflammation, due to local immune proliferation or immune infiltration (including immune complexes). Causes capillary wall damage and RBC leak.
  • Causes: primary glomerulonephritis (IgA nephropathy, postinfectious GN, rapidly progressive GN), HSP, HUS.

  Presentation

  PHRITIC:

  • Proteinuria. May lead to oedema (rare).
  • Haematuria
  • RBCs and RBC casts on microscopy.
  • Increased BP.
  • Trickle of urine (oliguria).
  • Investigate Cancer if older, as with all new unexplained haematuria.

• Investigations

  Urinalysis:

  • Dipstick any dark urine, to rule out food or drug mimics.
  • Microscopy: confirms haematuria if RBCs present, which are absent in haemoglobinuria and myoglobinuria. Deformed RBCs and RBC casts in glomerular disease.
  • Culture and sensitivity in suspected UTI.
  • Cytology in suspected cancer.

  Bloods:

  • FBC for anaemia.
  • U&E for renal function.

  Specialist referral and testing:

  • Refer older patients to urology as bladder or renal cancer more likely. Urologists will typically perform a CT urogram (to look for renal cell carcinoma) and cystoscopy (to look for bladder cancer).
  • Refer younger patients to nephrology as glomerular cause more likely. May lead to kidney biopsy.