Leukocytes and red blood cells in urine: when to worry?

White blood cells play a role in the body’s immune defense. If their number increases, it may mean the body is defending itself against infection. Red blood cells are red blood cells. If their number is higher, this may reflect hematuric cystitis, bleeding disorder, stones or other pathologies. What do elevated leukocyte and red blood cell values ​​in urine mean? How do you interpret your test results? When (really) to worry? Answers.

What do elevated leukocyte and red blood cell values ​​mean in urine?

THE white blood cells (leukocytes) normally circulate in the blood, but can also be present in the urine. This is completely normal. On the other hand, too many leukocytes in the urine reflect leukocyturia. In the vast majority of cases, leukocyturia highlights a urinary tract infection. Indeed, during an infection, our immune system is solicited and particularly the leukocytes, which will thus multiply to fight the infection. Red blood cells are red blood cells. If their number is higher, this may reflect a hematuric cystitis, bleeding disorder, stones or other pathologies. Additional examinations will guide the diagnosis.

What are the normal blood cell values ​​in urine?

The number of white blood cells in the urine is normally less than 10,000/ml of urine in men or women, but this standard may vary slightly depending on the technique used in the laboratory. It is therefore important to rely on the standards indicated on your examination report. Above 10,000/ml, it is considered that there is a leukocyturia : that is, the number of white blood cells in the urine is abnormal. We are talking about high pyuria if there is the presence of pus, which corresponds to altered leukocytes in the urine. Normally, the red blood cells (red blood cells) are rarely greater than 1,000/ml of urine.

What test should be done to check red and white blood cells in urine?

Leukocytes can be identified and counted in the urine during an examination called “Cyto-Bacteriological Examination of Urine” (ECBU). Simple and common, this examination is prescribed by a doctor during a consultation or at the hospital if the latter suspects a urinary tract infection. It allows to identify the germ responsible for the infection and to propose the most effective treatment to cure it. But in order to make a diagnosis of UTI, the result of the urine sample is never analyzed alone, it must be compared to the number of bacteria found in the urine, their type and the symptoms from which the patient suffers. If in most cases, the ECBU highlights a urinary tract infection, it can also detect another pathology related to urinary disorders such as cystitis, pyelonephritis or prostatitis.

Urine collection can be done in a laboratory, but it is possible to do it at home. For that :

► You need provide a sterile analysis bottle approximately 20 to 30 ml, available in a laboratory or at the pharmacy.

► Ideally when waking up, collect your urine in the bottle by standing over the toilet without sitting on the bowl.

► The method of “medium jet” is the most reliable : it is enough to eliminate the first jet of urine in the toilets then, to urinate directly in the bottle. Fill it halfway and finish urinating in the toilet.

► Write your first and last name on the bottle and bring it to the laboratory as soon as possible, with your vital card and your medical prescription. (If you cannot get to the lab immediately, the vial can be stored for 24 hours in the refrigerator). The laboratory may ask you for the time of the sample, the context of the prescription (suspicion of an infection, control, etc.), if you are pregnant, diabetic, treated with an antibiotic, etc.

In case of urinary tract infection, the levels of red blood cells and leukocytes increase.

The urine is then analyzed in the laboratory under a microscope to look for the presence of white blood cells, red blood cells and any microbes. This will identify the germ responsible for the infection. In uninfected urine called “sterile and normal”, the number of white blood cells is respectively less than 10,000, the red blood cells less than 1,000 and there is no germ. On the other hand, if the number of white or/and red blood cells is too high and the presence of germs is noticed, the results are considered abnormal and must be the subject of a medical follow-up. The culture of the germs present is essential to specify the bacterial species and quantify the bacteriuria (presence of bacteria in the urine):

• If the number of germs is less than 1,000 CFU/ml and you do not have antibiotic treatment in progress: you don’t have a urinary tract infection.
• If the red blood cell count is over 10,000/ml, the white blood cell count is over 10,000/ml, and the germ count (often E Coli bacteria) is over 1,000 CFU/ml (as well as certain clinical signs such as cloudy urine), then you may have a urinary tract infection.

Transmitted 24 to 48 hours after the sample, the culture and the antibiogram (laboratory examination aimed at determining the sensitivity of a bacterium to different antibiotics), the results of the urine sample must be compared to the clinical signs of the patient and possibly to other examinations in order to prescribe an appropriate treatment (prescription of antibiotics for example).

What does high germ-free white blood cells mean?

In some cases, the results indicate a low leukocyte count, but a significant presence of germs. This may mean that the ECBU was performed too early or using poor technique. But also that the urine may have been contaminated by a germ from the rectum or vagina. It is then advisable to repeat a urine sample to deepen the results. Conversely, it may be that the level of leukocytes is very high and that we do not see any germs : in this case, the patient may have taken antibiotics for suspected urinary tract infection before the sample was taken, which falsifies the results. But in humans, it can also be another pathology such as urethritis, prostatitis, posthitis (inflammation of the foreskin), or an inflammatory disease, but this is very rare.

Learn more: Institute of Clinical Biology – Free University of Brussels