Leukocytes in urine: do you have a bladder infection?

The dipstick checks whether your urine contains leukocyte esterase. That is a substance released by white blood cells during inflammation. So the pad never sees the cell. It sees what the cell leaves behind.

That sounds like a detail, but it explains a lot. The pad can be positive while the sediment under the microscope counts almost nothing. The cells have already fallen apart. Perhaps your urine was very dilute, or the sample stood too long.

So there are two ways of looking at the same thing. The pad is fast and rough. The urine sediment actually counts the cells, in the lab.

You do not get a number with a unit back, but a scale:

That scale rises with the amount of substance, not with how serious something is. A 3+ deserves a doctor's explanation. But on its own it is not a diagnosis.

The honest summary: this pad is sensitive but not accurate. It rarely misses genuine inflammation. But it also turns positive without infection.

So the answer to 'do I have a bladder infection' is usually: maybe. What makes that more or less likely can be spelled out.

Do you have symptoms? Pain or burning when passing urine, a strong urge, cloudy urine. With symptoms, a positive pad counts for a good deal more than without.

Is the nitrite positive too? A positive nitrite test is less common, but far more convincing. Nitrite only appears once bacteria in the urine convert nitrate. Leukocytes and nitrite together, with symptoms, point strongly to a bacterial bladder infection.

Is the pad positive but the nitrite negative? Then it stays open. Not every bacterium produces nitrite.

That is why your doctor often requests a urine culture anyway. It shows which bacterium is involved, and which antibiotic works. A pad alone cannot establish that. The culture gives the answer; the pad only asks the question.

Sometimes the culture stays negative while leukocytes are present. That is called sterile pyuria. Investigation in a different direction is then needed. Think of an STI test, or looking at kidney stones and medication.

If a bladder infection goes untreated, it can travel up through the ureters to your kidneys. That is rare. But it is the reason to take fever and flank pain seriously.

One thing matters. A positive pad is never on its own a reason for antibiotics. In older people a positive result without symptoms is common, and usually needs no treatment.

Have this test done if you have symptoms that fit the urinary tract. Think of pain or burning when passing urine. Or going more often, a constant urge and cloudy urine. Lower abdominal pain counts too.

It is also a standard part of a wider urine screen. For instance when your kidneys are being checked.

How you collect matters more than the pad itself. Collect midstream urine. Let the first stream run and only then collect. That first stream flushes out the bacteria that entered the bladder through the urethra. Those say nothing about your bladder. Clean the area first and do not touch the inside of the container.

Morning urine is the most concentrated and usually the most useful.

Deliver your sample within two hours, or put it in the fridge. Urine that stands for a long time changes.

Are you on your period? Postpone the test. Blood in the sample makes the result unusable.

Do you have fever, chills, nausea or pain in your side? Then make contact the same day. You do not wait for a dipstick for that.