title: Asymptomatic isolated microscopic haematuria: long-term follow-up.
abstract: BACKGROUND
  Evidence to support current diagnostic and management approaches to asymptomatic haematuria is lacking and based on short-term clinical observation.
  
  
  OBJECTIVE
  To ascertain the natural history and long-term outcome of asymptomatic and isolated haematuria, and to determine the clinical correlates of adverse renal events.
  
  
  METHODS
  Prospective observational referral-based study.
  
  
  METHODS
  We evaluated 90 consecutive patients with isolated microscopic haematuria, first seen between 1985 and 1996 at an out-patient nephrology clinic. We defined adverse renal events as the development of proteinuria (> 0.5 g/24 h) on two consecutive occasions, development of hypertension, or impaired renal function characterized by glomerular filtration rate (GFR) of <60 ml/min/1.73 m(2) for 3 months or more.
  
  
  RESULTS
  There were 24 males and 66 females, median follow-up 5.2 years (total 442 patient-years). Mean age at presentation was 39 +/- 13 years. Fifteen (17%) had complete resolution of microscopic haematuria. One (1%) had transitional cell carcinoma of urinary bladder 20 months after initial presentation. Twelve (13%) developed hypertension, and 10 (11%) proteinuria. Only one developed chronic renal failure, 2.3 years after initial presentation. Altogether, 16 (19%) developed at least one adverse event, after a mean 42 months. Neither history of renal biopsy nor histological diagnosis of glomerular disease was predictive of renal events. Three independent variables were predictive of adverse renal events: baseline proteinuria (RR per 0.1 g/day 2.04; 95%CI 1.13-3.68; p = 0.018); MDRD-estimated GFR at presentation (RR per 10 ml/min/1.73 m(2) decrement 2.01; 95%CI 1.09-3.71; p = 0.025); and baseline serum urate (RR per 100 micromol/l 1.02; 95%CI 1.01-1.03; p = 0.009).
  
  
  CONCLUSIONS
  Asymptomatic microscopic haematuria can lead to adverse renal events, and warrants nephrologist evaluation and regular follow-up. Its isolated microscopic haematuria is closely related to early hints of chronic kidney disease, such as low-grade proteinuria and renal insufficiency, as well as hyperuricaemia.
authors.affiliation: Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, SAR, China.
authors.forename: K M
authors.initials: KM
authors.lastname: Chow
authors.forename: B C
authors.initials: BC
authors.lastname: Kwan
authors.forename: P K
authors.initials: PK
authors.lastname: Li
authors.forename: C C
authors.initials: CC
authors.lastname: Szeto
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D018450:Disease Progression; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006417:Hematuria / Q000209:etiology*; D006801:Humans; D033461:Hyperuricemia / Q000150:complications; D007676:Kidney Failure, Chronic / Q000150:complications; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D011507:Proteinuria / Q000150:complications; D012307:Risk Factors