Seeing pink, red or brown urine is alarming. Hearing that a routine urine test found blood you could not see is confusing in a different way. Both have a name, hematuria, and both deserve follow-up. The cause can be as minor as a hard run or as serious as a tumor, and the only way to tell which is to look.

This guide explains the two kinds of hematuria, the common and the serious causes, and what the testing usually involves, based on guidance from the NIH’s kidney and urology institute (NIDDK) and MedlinePlus.

What is hematuria? The blood you see and the blood you do not

The NIDDK describes two types of hematuria:

  • Gross hematuria is blood you can see. It only takes a small amount of blood to change the color, and in most cases it causes no pain.
  • Microscopic hematuria is blood found only on a urine test or under a microscope. It does not change the color of urine and usually has no symptoms, so it tends to be found on a routine urine test.

For microscopic blood, the American Urological Association’s guideline panel defines it as 3 or more red blood cells per high power field on microscopic evaluation of a single specimen. The NIDDK notes that your clinician may repeat the urine test to confirm it before going further.

Is red urine always blood?

Not every red tinge is blood. MedlinePlus points out that urine can turn red from certain medicines, beets or other foods, and lists berries and rhubarb among the foods your provider may ask about. Blood can also come from somewhere other than the urinary tract and end up in the sample. The NIDDK notes that a menstrual period can make a urine test read positive, and the test is repeated after the period ends.

None of that is a reason to wait and see. If you notice red or brown urine and are not sure why, tell your doctor.

What causes blood in the urine?

The NIDDK lists these reasons for blood in the urine:

  • Infection or inflammation of the bladder, kidney, urethra or prostate
  • Urinary tract stones, or a recent procedure on the urinary tract
  • An enlarged prostate (BPH)
  • Vigorous exercise, such as long-distance running
  • Sexual activity, trauma or endometriosis
  • Some medicines, including blood thinners, certain antibiotics, and aspirin or other pain relievers

The more serious causes on the same list include cancer of the bladder, kidney or prostate, blood-clotting disorders, sickle cell disease, and kidney disease involving the glomeruli, the tiny filters inside each kidney. Inflammation of those filters is called glomerulonephritis.

Age and habits change the odds. The National Cancer Institute calls smoking a major risk factor for bladder cancer and notes that the risk rises with age. Workplace exposure to paints, dyes, metals or petroleum products is on that list too. The urology guideline above uses factors like these, along with how much blood was found and whether it persists, to sort people into low, intermediate and high risk groups.

If you take a blood thinner, keep taking it as directed and tell your doctor about the blood. Blood-thinning medicines are on MedlinePlus’s list of causes, but so are bleeding disorders and problems in the kidneys or bladder, and only testing tells them apart.

How is blood in the urine tested?

According to the NIDDK, the starting point is your medical history, a physical exam and a urinalysis. Expect questions like the ones MedlinePlus lists: when you first noticed it, the color, whether urinating hurts or happens more often, what medicines you take, and whether you have had kidney problems, surgery or an injury.

Depending on those answers, further tests may include:

  • A urine culture to look for infection.
  • Blood tests, such as creatinine to check kidney function and a complete blood count. Our guide to reading your kidney lab results explains eGFR.
  • A urine protein test. Protein leaking into the urine is an early sign of kidney damage; our guide to the UACR urine test explains it.
  • Imaging of the kidneys and bladder, such as an ultrasound or a CT scan.
  • Cystoscopy, in which a urologist uses a thin camera to look inside the bladder and urethra.
  • A kidney biopsy, when the results point to disease in the kidney itself.

How far the testing goes depends on your risk. The guideline panel recommends that cystoscopy and imaging be matched to each person’s risk and decided together with the patient.

How is it treated, and when should you call right away?

There is no treatment for hematuria itself. The NIDDK explains that clinicians treat the underlying cause, such as an infection or a stone, and that you may not need treatment at all if no serious condition is found. It also notes that diet has not been shown to cause or prevent hematuria.

MedlinePlus says never to ignore blood you can see in your urine. Get checked soon if it comes with discomfort when you urinate, frequent or urgent urination, or weight loss you cannot explain. Contact your provider right away if you also have:

  • Fever, nausea, vomiting or shaking chills
  • Pain in your abdomen, side or back
  • Blood clots in your urine
  • Trouble passing urine at all

If you have severe pain or cannot urinate, our guide to the ER, urgent care or calling your doctor can help you decide where to go.

Blood in the urine can be a bladder question, a kidney question or a medicine question. Some causes need a urologist’s camera; others show up in the kidney numbers on your blood work. Dr. Yana Shtern is board-certified in both Internal Medicine and Nephrology, so she can read the urine test, the kidney labs and your medicine list together and decide which specialist, if any, you need next. The kidney care page explains how she looks after kidney health at Legacy Medical, and members can usually be seen the same or next business day.

If a recent urine test came back with blood and you would like Dr. Shtern to look at it, start with a complimentary meet and greet at our Palm Beach Gardens office.

This article is general information, not advice for your situation. Members can call the office with questions about their own care.