Non visible haematuria

non-visible haematuria

Also known as microscopic haematuria or 'dipstick positive haematuria', non visible haematuria is further sub-divided into:

• symptomatic Non-Visible Haematuria (s-NVH) - symptoms such as voiding lower urinary tract symptoms (LUTS): hesitancy, frequency, urgency, dysuria
• asymptomatic Non-Visible Haematuria (a-NVH) - incidental detection in the absence of LUTS or upper urinary tract symptoms (1)

There is no consensus as to what the 'normal' upper limit for red blood cells in the urine should be. Established definitions have used threshold values of ≥3 RBCs per high-power field (hpf) and ≥5 RBCs/hpf (2).

The significance of microscopic haematuria varies with age:

• in young people
  • urinary tract malignancies are uncommon in this age group, hence prevalence of significant underlying pathology for haematuria found at screening is low (in the range 0-7.2%)
  • glomerula causes are mainly responsible for haematuria
• prevalence of significant pathologies is said to increase with age
  • in patients over 60 years who were screened positive for macroscopic haematuria, 5% had bladder tumours

Causes of non-visible haematuria include:

• transient
  • urinary tract infections
  • exercise related
• spurious
  • menstrual contamination
  • sexual intercourse
  • foods such as beetroot, blackberries and rhubarb
  • rhabdomyolysis
  • drugs - doxorubicin, cholorquine, rifampicin
  • chronic lead or mercury poisoning (2)

Reference:

• (1) Renal Association and British Association of Urological Surgeons (2008). Joint Consensus Statement on the Initial Assessment of Haematuria
• (2) Kelly JD, Fawcett DP, Goldberg LC. Assessment and management of non-visible haematuria in primary care. BMJ. 2009;338