A discoloration of urine may be due to a medication, something a person ate, or a variety of medical causes.
Blood in the urine (hematuria) commonly causes pink or red discoloration and should prompt medical evaluation.
Hematuria may be visible with the naked eye (gross hematuria) or visible only under a microscope (microscopic hematuria). The urine may look normal in patients who have have microscopic hematuria.
Hematuria is common, seen in 2% to 30% of the adult population. Older patients and smokers have higher rates of hematuria. Smokers are also at an increased risk of genitourinary cancer.
Hematuria can be caused by a number of different things, some of which are bladder or kidney stones; kidney disease; urinary tract infection, cystitis (bladder infection), or pyelonephritis (kidney infection); cancers of the urinary tract (kidney, bladder, prostate); trauma, injury, or urinary tract instrumentation; rigorous exercise; benign prostatic hyperplasia (enlarged prostate); and blood thinners (aspirin, warfarin, etc).
Hematuria can be confused with other urine discoloration caused by something other than blood in the urinary tract, such as foods like beets, bleeding from menstruation, blood from the gastrointestinal system, or medications.
If you see blood in your urine, you should tell your primary care doctor. Otherwise, hematuria is usually detected during routine evaluation and without any other signs or symptoms. Sometimes, this happens with a dipstick urine test, which can have high false-positive result rates. Therefore, all cases of hematuria must be confirmed in a laboratory by seeing 3 or more red blood cells in a sample under a microscope.
Doctors generally use practice guidelines as an aid to evaluation. At this time, national guidelines recommend a complete evaluation in all patients aged 35 years or older who have hematuria without an obvious benign cause. Patients are typically referred to a urologist (a surgeon of the urinary tract) and sometimes a nephrologist (a kidney specialist) for this evaluation.
A timely and complete evaluation of hematuria is essential because a delay in diagnosis can be serious. Your treatment team should coordinate an evaluation of the entire urinary system. This will likely include urinary tract imaging and a cystoscopy to help determine the cause of the hematuria.
Imaging of the urinary tract usually consists of a computed tomography (x-ray) scan or an ultrasound. The purpose of imaging is to see if there are any stones, kidney abnormalities, or tumors in the urinary tract. A cystoscopy is an examination of the bladder with a small telescope-like device through the urethra (the tube through which urine passes out of the body). This is typically performed in an office setting using a local anesthetic. The goal of the cystoscopy is to look for any small or flat tumors on the lining of the bladder that can be missed by imaging.
Even a thorough evaluation may not determine the cause of hematuria. Evaluations that find no causes are both common and encouraging. However, hematuria persists in some patients. Continued follow-up with a primary care doctor or specialist may be recommended for up to 3 years. You should tell your doctor about any changes in the frequency or severity of hematuria.
National Institute of Diabetes and Digestive and Kidney Diseaseswww.niddk.nih.gov/health-information/health-topics/urologic-disease/hematuria-blood-in-the-urine/Pages/facts.aspx
Urology Care Foundationwww.urologyhealth.org/urologic-conditions/hematuria
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Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.
Sources: Davis R, Jones JS, Barocas DA, et al. Diagnosis, evaluation and follow-up of asymptomatic microhematuria (AMH) in adults: AUA guideline. J Urol. 2012;188(6)(suppl):2473-2481.
Nielsen M, Qaseem A; High-Value Care Task Force of the American College of Physicians. Hematuria as a marker of occult urinary tract cancer: advice for high-value care from the American College of Physicians. Ann Intern Med. 2016;164(7):488-497.
Topic: Urological Disorders
Matulewicz RS, Meeks JJ. Blood in the Urine (Hematuria). JAMA. 2016;316(14):1508. doi:10.1001/jama.2016.4716