PROTEINURIA - DIAGNOSIS & INVESTIGATIONS

A urine dipstick test is a simple method using a test strip immersed into a urine sample to detect the presence of protein in the urine. However, it only measures the concentration in that specific specimen. The concentration of urine passed varies throughout the day hence the urine dipstick is not a very accurate method. This method also is unable to detect microalbuminuria.


The most accurate method to detect proteinuria and microalbuminuria is by measuring the amount of protein excreted in the urine in a 24-hour period (24 hour Urine Total Protein). Collecting urine for 24 hours can be difficult and inconvenient, so the physician often uses a spot urine test in which one sample of urine is analyzed. Healthy kidneys continually remove creatinine from the blood to maintain a stasis between blood levels and urine levels. The ratio of protein to creatinine in the urine is closely related to the 24 hour proteinuria result and hence provide the physician with a good idea of how much protein is being excreted over 24 hours.

INVESTIGATING PROTEINURIA

There are many causes of proteinuria and the treatment will depend on the underlying cause and degree of protein leak. A series of investigations may be required to ascertain the cause:

1. Blood test to assess the kidney function, ie. blood creatinine level

2. Ultrasound of the kidneys

3. Kidney biopsy may be indicated in some cases for more specific diagnosis and prognosis

PROTEINURIA - TREATMENT

If a person has diabetes, hypertension, or both, the first goal of treatment will be to control blood sugar and blood pressure. People with diabetes should test their blood glucose often, follow a healthy eating plan, take prescribed medicines, and get the amount of exercise recommended by their doctor.

A person with diabetes and high blood pressure may need a medicine from a class of drugs called angiotensin-converting enzyme (ACE) inhibitors or a similar class called angiotensin receptor blockers (ARBs). These medicines have been found to protect kidney function even more than other drugs that provide the same level of blood pressure control as well as reducing the proteinuria. Many patients with proteinuria but without hypertension may also benefit from the use of ACE inhibitors or ARBs. The American Diabetes Association and the American College of Cardiology recommend that people with diabetes keep their blood pressure below 130/80.

Patients who have high blood pressure and proteinuria, but not diabetes, also benefit from taking an ACE inhibitor or ARB. The Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure recommends that people with kidney disease keep their blood pressure below 130/80. To maintain this target, a person may need to take a combination of two or more blood pressure medicines.

In addition to blood glucose and blood pressure control, the National Kidney Foundation recommends restricting dietary salt and protein. A doctor may refer a patient to a dietitian to help develop and follow a healthy eating plan.

Find a Renal Physician

Expert Author:

Dr Roger Tan, Consultant Nephrologist