Microalbuminuria and risk

Current situation

  • Diabetic nephropathy, which is originally microvascular in nature, is an important complication of diabetes.
  • Microalbuminuria is the presence of 20–200µg/min levels of albumin in the urine.
  • It is an important indicator of increased cardiovascular risk and is associated with increased mortality.
  • Half of patients with diabetes develop microalbuminuria.

What is the evidence?

  • One longitudinal study has shown that macro- and microalbuminuria are associated with an increased risk of cardiovascular and all-cause mortality, with a greater effect conferred by the presence of greater proteinuria (Br J Vasc Dis 2005; 5: 334–40).
  • A number of trials have shown that the progress of existing microalbuminuria and proteinuria can be slowed by the use of both ACE inhibitors and angiotensin-II receptor blockers (ARBs).
  • Patients with type-2 diabetes experience regression or remission of microalbuminuria, especially when blood glucose is carefully controlled, according to one report (Diabetes 2005; 54: 2,983–7).
  • A review of randomised trials has demonstrated that ACE inhibitors are the only agents with proven survival benefit in patients who have diabetes with microalbuminuria (J Am Soc Nephrol 2006; 17 (4 Suppl 2): S153–5).
  • The Bergamo Nephrologic Diabetes Complications Trial found that a significant decrease of the development of persistent microalbuminuria could be achieved by using an ACE-inhibitor, trandolapril alone or in combination with verapamil in hypertensive type-2 diabetic patients with normoalbuminuria (J Am Soc Nephrol 2006; 17 (4 Suppl 2): S90–7).
  • One study showed that rosiglitazone reduces microalbuminuria and blood pressure independently of glycaemia in patients with type-2 diabetes with microalbuminuria (J Hypertens 2006; 24: 2,047–55).

Implication for practice

  • No studies address whether screening for microalbuminuria once a patient is taking an ACE inhibitor or ARB improves outcomes. Evidence and expert opinion suggest it may be beneficial to continue microalbuminuria surveillance (J Fam Pract 2007; 56: 145–6).

Available guidelines

  • The prescribing of ACE inhibitors or ARBs for diabetic patients with microalbuminuria is a GMS quality target.
  • BHS and NICE guidelines state that an ACE inhibitor or ARB should be used as first-line treatment in patients with diabetes and microalbuminuria or proteinuria.

Useful websites

www.nice.org.uk — NICE

www.bhsoc.org — British Hypertension Society

Dr Louise Newson is a GP in the West Midlands and author of ‘Hot Topics for MRCGP and General Practitioners’ PasTest 2006

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