By Alan S. Peterson, MD

What Is Microscopic Hematuria?

Microscopic Hematuria is a small amount of red blood cells in your urine that can only be seen under the microscope. The amount of blood is so small that it does not change the color of your urine and the only way that it can be known is to be found in a urinalysis by your doctor.

What Causes Microscopic Hematuria?

Some causes of microscopic hematuria are:

• Bladder or kidney infection
• Kidney stone
• Swelling of your kidneys
• Harmless conditions that may run in your families (a benign familial hematuria is known in several families in the southern end of Lancaster County)
• A tumor anywhere in your urinary tract, which may or may not be malignant
• Heavy exercise just before giving a urine sample
• Some medicines

What Will My Doctor Do About the Blood in My Urine?

Your doctor will ask you questions about your medical history. Your doctor may also examine you to decide which test is right for you and if you are more likely to have a serious health problem because of this.

Your doctor may take pictures of your urinary tract. These may be x-rays or ultrasound images.

Your doctor may send your urine to a laboratory for more tests. These may look for cancer cells.

You may need to see a special doctor who can use a small camera and a light to look inside your bladder. A urologist does this procedure called a cystoscopy.

Your doctor may have you repeat some of the same tests several months later. This depends upon your risk of getting a serious health problem.

If you have an infection, your doctor will give you medicine. After taking this medicine, the blood in your urine should go away, unless there is another reason for the blood.

• Being older than 40 years of age
• Smoking
• Being in contact with certain chemicals at work (for example, leather dye, rubber, or tires)

What Is Benign Familial Hematuria?

When I was a resident in the Lancaster General Hospital Family Practice Residency program in the early 1970’s, I did a research study on several families in the southern end who had what is called Benign Familial Hematuria. This is microscopic red blood cells in the urine that is inherited down through various family members. We found that this did not increase the risks of serious health problems in these patients. This problem could be found in both males and females in the family, but did not have to occur in all family members. It also was of interest that this microscopic hematuria could be present at some times, but not every time, the urine was checked. Certainly family members, who are aware that this has been diagnosed by a physician in their family, should alert other family members to this hereditary familial form of benign blood in their urine.

One of the important issues, of course, is that if the person is at low risk for other serious problems of urinary tract disease, knowing that this is in the family may decrease the amount of testing that the physicians need to do. Obviously, people who have benign hematuria can at times also develop other reasons for blood in their urine that could be serious. Therefore, at times, your physician may want to do further studies even knowing that you or your family had benign red blood cells in urine in the past.

We did not find out, however, in studying these families with benign familial hematuria that there was an increased risk (over the general population) for other serious urinary tract causes for blood in the urine.

One of the interesting families with benign hematuria in Lancaster County was traced back to Jefferson, North Carolina. Any of you who have relatives in that area should ask your physician to check your urine for red blood cells, if that has not already been done.