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Screening for proteinuria and hematuria

By Dr Harold Dion

Dr Harold DionHarold Christian Dion studied medicine at the University of Ottawa and Family Medicine at McGill University.

He has worked at the Clinique médicale l’Actuel in Montreal for the past 25 years.

He is also co-editor-in-chief of “e-Relais VIH”, a Canadian bilingual online publication for patients living with HIV.

Over the past 10 years, Dr. Dion has published several articles on various health issues, for both general public (Coup de pouce, 7 Jours, Reader’s Digest) and healthcare professionals (L’actualité médicale, Le Clinicien, l’Omnipraticien, MedActuel FMC, Le Médecin du Québec). 

In my last column, I talked about a session on bone and renal co-morbidities, that I attended at the 20th International AIDS conference in Melbourne and that I found particularly interesting. I also mentioned that I would develop further on screening for proteinuria and hematuria…

What if the urine dipstick is negative for protein, blood and glucose?

  • Repeat every 3-6 months.
  • Consider annual albumin/creatinine (Acr) ratio and/or protein/creatinine (Pcr) ratio if patient is a smoker, or takes tenofovir, or has:
    • Hypertension
    • Diabetes
    • Dyslipidemia
    • Cardiovascular disease
    • HCV/HBV co-infection

What if the urine dipstick is positive for any or all of protein, blood and glucose?

  • Confirm with repeat urine dipstick and if :

The urine dipstick is positive for protein?

  • Order urine ACr and/or PCr (see table 1):

 Table 1 : Urine Positive for Protein

  • Identify pattern of proteinuria
    • Glomerular (albumin is the predominant protein – if ACr/PCr ratio > 0.4 likely glomerular)
    • Tubular or overflow (non-albumin proteins are the predominant proteins – if ACr/PCr ratio < 0.4 likely tubular or overflow)
    • Consider ruling out monoclonal gammopathy (ie. serum protein electrophoresis)
  • Evaluate GFR
  • Search for signs of proximal tubular dysfunction
  • Look for reversible causes of proteinuria (ie. NSAIDs, severe hypertension, congestive heart failure, systemic inflammation, etc.)
  • Manage risk factors for cardiovascular disease
  • Consider treating individuals with hypertension or diabetes with an ACE inhibitor or ARB
  • Consider referral to a nephrologist if presence of :
    • Rapid decline in eGFR
    • ACr ratio ≥ 60 mg/mmol or PCr ratio ≥ 100 mg/mmol)
    • Uncontrolled hypertension
    • Signs of systemic disease

The urine dipstick is positive for blood?

  • Consider ordering an urine culture and a renal ultrasound (see table 2):

Table 2 – Urine Positive for Blood

  • Rule out:
    • Menstruation
    • Infection (urinary tract infection, sexually transmitted infection, prostatitis)
      • Order appropriate cultures
    • Urological cause
    • Renal cause
      • Order eGFR, ACr and/or PCr
    • Coagulopathy
      • Order CBC, INR/PTT

The urine dipstick is positive for glucose?

  • Rule out diabetes:
    • Evaluate GFR
    • Screen for proteinuria (ACr and/or PCr)
    • Screen for proximal tubular dysfunction:
      • Increased urine creatinine
      • Euglycemic glucosuria
      • Proteinuria
      • Hypophostatemia and posphaturia (see table 3)

Table 3 : Serum Phosphate

  • If normal (0.8 – 1.5 mmol/L)
    • Monitor every 3-6 months
  • If low (< 0.7 mmol/L)
    • Order urinary fractional excretion of phosphate
    • If abnormal (> 10%), look for signs of tubular dysfunction
    • If signs of proximal tubular toxicity, consider also myeloma or vitamin D deficiency

The urine dipstick is positive for white blood cells only?

  • Consider urethritis, prostatitis or interstitial nephritis.

 

Reference
Bone and Renal Co-morbidities in HIV: The Osteo-Renal Exchange Program. AIDS 2014. 20th International AIDS Conference. July 20-25, 2014. Melbourne. Abstract MOSA01.