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Complications of Diabetes

Microalbuminuria

What is microalbuminuria?

Albumin is a protein which is present in the blood. The kidneys act as a filter for waste products in the blood. Protein is not allowed to spill over into the urine unless the filter system is ‘leaky’.

Microalbuminuria refers to the appearance of small but abnormal amounts of albumin in the urine. If measured, this protein excretion is between 30 and 300 mg during a 24 hour period.

How is it detected?

This requires special methods of testing as tiny amounts of albumin are not detectable by standard urine tests which are traditionally used to check for protein.

A random sample of urine is often used to measure the albumin-to-creatinine ration (ACR.

At least two or three measurements should be made before the diagnosis of persistant microalbuminuria is made.

A 24 hour urine collection of the estimation of the ‘albumin excretion rate’ (AER) is the best method of assessing albumin excretion, though this is time consuming and expensive and therefore not suitable for large scale screening.

What is a ‘normal’ ACR?

The Albumin-Creatinine Ratio varies according to age and sex. As a general rule men should have an ACR less than 2.5, whereas women should measure less than 3.5.

What is the significance of microalbuminuria?

Microalbuminuria often heralds the onset of diabetic nephropathy. It is also an independent risk factor for cardiovascular disease. It is important to identify the risk of both these conditions so you have the best chance of preventing them.

Who is likely to develop microalbuminuria?

Microalbuminuria is almost unheard of in childhood, before adolescence. Studies have shown that development of microalbuminuria is closely linked to long term blood sugar control. This risk is increased by:

  1. duration of diabetes
  2. high blood pressure
  3. genetic susceptibility

What can be done to prevent the onset of microalbuminuria?

Good long term blood sugar and blood pressure control. Don’t smoke. Regular exercise.

Who should be tested?

People with type 1 diabetes for over five years.

People with type 2 diabetes at time of diagnosis and on an annual basis therafter.

Is it possible to have a positive microalbuminuria test without having diabetic nephropathy?

Yes. False positive tests may occur after strenuous exercise and in the presence of other kidney disorders, such as glomerulonephritis or infections.

Why screen for microalbuminuria?

  • evidence that treatment with an ACE inhibitor or A-II anatagonist is effective in slowing progress to nephropathy.
  • microalbuminuria is the strongest independent risk factor of cardiovascular disease.
  • screening identifies an increased risk of proliferative retinopathy.

What does the presence of microalbuminuria indicate in someone with type 2 diabetes?

Microalbuminuria rates are very high in type 2 diabetes. Many people with T2D have microalbuminuria at the time of diagnosis. If you have T2D, you should have a test for microalbuminuria at the time of diagnosis and thereafter on an annual basis. In T2D, having microalbuminuria is a powerful message that you have an increased risk of heart disease.

I have a positive test – what now?

For reasons outlined above the following measures are advisable:

  • tighten up your blood sugar control
  • blood pressure lowering if high
  • stop smoking
  • exercise
  • lipid lowering treatment
  • discuss drug therapy with your doctor
  • low dose aspirin
  • ACE inhibitors or AII antagonists

 

Dr Nishan Wijenaike
Consultant Diabetologist
West Suffolk Diabetes Service
November 2003