Proteinuria

Any abnormal proteinuria is a significant risk factor for both renal disease and for cardiovascular morbidity and mortality. Unlike haematuria, proteinuria almost always has a renal origin. Management should include

  • Quantitate albumin/creatinine or protein/creatinine ratio (ACR or PCR)
  • Test for haematuria
  • Measure serum creatinine and eGFR

The risk of renal failure is greater in younger patients. The risk of dying from heart disease is greater in older patients. Risks may be altered by therapy.

How to measure it

  • Measurements should not be make during an acute illness or menstruation
  • ACR/PCR is more reproducible and generally useful than 24h collections
  • Units are mg/mmol (mg protein: mmol creatinine)
  • A PCR of 100, or ACR of 70, is approximately equal to 1g of protein per 24h. Below this level the conversion is non-linear.

What to do about it

A number of thresholds have been recommended, as summarised here:

ACR
(mg/mmol)

PCR
(mg/mmol)

Implication
>2.5/3.5 >15 Abnormal (ACR values are for male, female): adequate to define CKD 1 or 2.
Commence ACEI/ARB if diabetic(**).
30 50 Favour ACE inhibitor/ ARB if hypertensive
Suffix 'p' on CKD stage
70 100 Stricter BP limits apply
Referral threshold in non-diabetics
>250 >300 Approximately 'nephrotic range' proteinuria

Long term implications are important when considering assessment and management. For example, young adults will have many more years at risk and lower levels of proteinuria are more important.

Ratios at lower levels than above

Bearing in mind the above, usually manage as CKD, according to stage:


In patients with diabetes

Microalbuminuria (ACR>2.5/3.5)* is an indication for

  • treatment with ACE inhibitors (or Angiotensin receptor blockers if those are not tolerated), with titration up to full dose irrespective of initial blood pressure: more information on treatment with ACEIs and ARBs
  • Plus control of hypertension to target (more info)
  • Good glycaemic control
  • ACR or PCR and serum creatinine should be measured annually
  • Referral to nephrology only if fulfil usual criteria (more info)

Information for patients

Information for patients about proteinuria from EdREN.
Information for patients about haematuria from EdREN.

* error corrected 30.6.09. Previously stated 30mg/mmol: should read 2.5/3.5 (male/female). Thanks to Andrew Moncrief for pointing this out. NT

** error corrected 10.8.09. Similarly, threshold for ACEI/ARB in diabetes was placed too high in this table. Thanks to Cathy Twomey for pointing this out. NT

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