Nephropathy (kidney damage)
- Nephropathy
- What is the significance of microalbuminuria?
- When to screen for microalbuminuria/ proteinuria?
- How to screen for microalbuminuria/ proteinuria?
- Factors affecting the urine protein excretion
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Nephropathy
Diabetes is one of the commonest causes of kidney failure requiring dialysis. About 20-25% of people with diabetes may develop kidney disease. This is due to damage to the small blood vessels in the kidney. The earliest sign of kidney damage is the presence of microalbuminuria. Microalbuminuria refers to the presence of a small amount of albumin in the urine, which cannot be detected with the usual urine dipstick. It occurs in 30% of type 1 diabetics 5 to 15 years after diagnosis but may be present at diagnosis in type 2 diabetics. |
What is the significance of microalbuminuria?
Microalbuminuria predicts the development of clinical diabetic nephropathy. 6 – 8 % of these diabetic patients evolve into kidney failure every year. Symptoms of kidney failure include tiredness, breathlessness, nausea and vomiting. This can be shown by increasing serum creatinine levels.
Microalbuminuria also predicts adverse cardiovascular morbidity and mortality in both Type 1 and Type 2 diabetics. |
When to screen for microalbuminuria/ proteinuria?
- Type 1 diabetes mellitus: over 5 years history of diabetes, or earlier in the presence of other cardiovascular risk factors such as hypertension, high serum lipids levels.
- Type 2 diabetes mellitus: from time of diagnosis of diabetes, following initial improvement in glycaemic control
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How to screen for microalbuminuria/ proteinuria?
Initially, urine should be screened for proteinuria with conventional dipstick on an early morning urine specimen. If urine dipstick for proteinuria is negative, screening for microalbuminuria should be performed. Thereafter the test should be done annually if the initial examination is normal. Urine dipstick for microalbuminuria is a convenient and an acceptable screening test e.g. Micral Test®. |
Factors affecting the urine protein excretion
There are various factors that may affect the urinary albumin excretion, e.g.
- Strenuous exercise
- Poorly controlled diabetes mellitus
- Heart failure
- Urinary tract infection
- Acute febrile illness
- Uncontrolled hypertension
- Haematuria
- Menstruation
- Pregnancy
Hence, early morning urine is used in order to minimise fluctuations in urinary concentration. Microalbuminuria is said to be present when albumin concentration is between 20 – 200 mg/l; overt proteinuria when albumin concentration >200 mg/l. |
