Blood in Urine (Hematuria) and Lab Testing

Hematuria is a medical term used for describing the presence of blood in the urine. It is not normal, but it’s not as uncommon as some might think. An individual who experiences blood in the urine might be worried, but it isn’t always a cause for alarm. It’s a symptom of something and not a disease. A healthcare practitioner will take it as a sign to further investigate to try and find the root cause of the problem. 

The presence of blood in urine isn’t always obvious as sometimes, the amount of blood is so tiny that its presence is only detected during an analysis performed as part of the overall health checkup. Typically, urine is transparent and a shade of yellow that ranges from pale straw to light amber. The shade of yellow depends on urine concentration. If blood is present in the urine, the urine color will be different, but it’s not always going to be red. 

Gross hematuria refers to visible levels of blood in the urine, and this type of urine is likely to be red tea or pink colored. In cases where blood clots are present in the urine, a person might be able to see the clots or drops of blood in the toilet while they are urinating. Microscopic hematuria refers to the type where blood can’t be seen with the naked eye, and this type of hematuria doesn’t affect the urine color. 

As far as the causes of hematuria are concerned, it typically involves issues with the urinary tract. The urinary tract consists of a bladder, a urethra, two ureters, and two kidneys. 

Kidneys continuously produce urine by filtering out the waste from the blood. Kidneys push the urine into the bladder through ureters, and the bladder stores the urine before it is pushed out of the body through urethra during urination. Blood in the urine can also be caused by conditions involving other bodily systems. Keep on reading to know more about the causes of this condition. 


Hematuria can have many causes. Some of these are temporary, benign states that don’t require any specific treatment and resolve on their own. However, it might also be a symptom of a more critical or chronic condition that needs immediate medical intervention and monitoring. 

Further investigation is the only appropriate measure to fully understand the severity or seriousness of hematuria in an individual. The healthcare practitioner will evaluate the medical history of the individual during the investigation, along with their physical examination and associated signs and symptoms to determine the underlying cause of hematuria. 

Some of the common questions that might be asked as part of the examination include: 

Is that really blood in the urine? 

Usually, the first question asked in the physical examination is whether it’s blood that is visible in the urine. 

There can be many sources of that reddish looking clot in the urine. Many foods such as rhubarb or beets can give that reddish-brown coloring to the urine. Certain drugs such as phenothiazine, phenazopyridine (most commonly), diphenylhydantoin, cascara, phenacetin, methyldopa, phenolphthalein, and phenindione can also cause red-colored urine. 

Another cause could be the presence of hemoglobin in the urine. Sometimes, red blood cells in the body are broken apart, which leads to the release of hemoglobin. As you are aware, hemoglobin is the iron-containing protein responsible for the red color of the red blood cells. This excess hemoglobin gets eliminated from the body through the urine, which makes the urine red or tea colored. Hemolytic anemia that also includes sickle-cell anemia, can also cause hemoglobinuria. 

Urine color can also be changed when the body eliminates certain other substances through urine. For instance, the liver typically removes bilirubin, but if the liver is diseased or damaged, it can lead to the accumulation of bilirubin, and it might make the urine dark amber in color. This is something that should be investigated, but it’s not hematuria. Myoglobin is a small oxygen-binding protein that is typically found in the heart as well as skeletal muscles. It is also eliminated through urine when kidneys filter the blood. If high levels of myoglobin are present in the urine, it might cause the urine to turn red, and that might be misinterpreted as blood in the urine. 

Source of Blood in the Urine 

Contaminated blood can become part of the urine through a variety of sources such as hemorrhoids as well as vaginal bleeding (menstruation). 

Can Infection Cause Hematuria? 

Sometimes, infections can lead to smelly and cloudy urine, as well as painful urination. It might also, sometimes, lead to blood in the urine. 

  • Urinary Tract Infections: These are infections that are typically caused by bacteria and mostly affect the bladder. These might lead to bladder inflammation (cystitis). 
  • Infection in Kidney: When an infection in the urinary tract spreads to the kidneys. 
  • Viral Infection: In certain cases, infections such as hepatitis, which leads to liver inflammation and liver disease might cause blood to be present in the urine. 

Blood in the Urine – Known Cause or Single Isolated Incident 

At times, blood might appear in the urine and disappear without the identification of the underlying cause. At other times, the presence of blood in the urine might be due to a self-limited, resolvable, or identifiable cause such as fever, strenuous exercise, or exposure to certain toxins such as dyes in radiologic procedures. 

Certain medications such as aspirin, Non-steroidal anti-inflammatory drugs, or blood thinners that prevent clotting might also cause the presence of blood in the urine. Another temporary cause of blood in the urine could be a medical procedure where some part of the urinary tract is involved, such as a kidney biopsy, surgery, or insertion of a urinary catheter. A physical injury to the bladder or kidney might also lead to a temporary presence of blood in the urine. 

Hematuria Causes – Irritation or Inflammation of the Urinary Tract or Prostate in Men or Passage of or Blockage by a Kidney Stone. 

Here are some of the reasons that might lead to blood in the urine accompanied by painful urination, radiating pain, urinary hesitancy, and/or urinary urgency: 

  • Urethritis: It refers to inflammation of the urethra which is a duct responsible for carrying urine collected in the bladder out of the body 
  • Prostatitis: It refers to prostate inflammation. The prostate is the organ surrounding the urethra in men 
  • Bladder or kidney stones 
  • Benign Prostate Hyperplasia 
  • Hematuria Causes : Condition Causing Kidney Damage or Some Kind of Kidney Disease 

Many kidney diseases can lead to hematuria. For example, glomerulonephritis is a kidney disease that is associated with filtering units in the kidneys known as glomeruli. Another cause could be kidney disease that happens after a strep throat, and it is known as post-infectious glomerulonephritis, and it can lead to the presence of blood in a child’s urine.  

Hypertension or high blood pressure and diabetes are also known to cause kidney damage, and these can also sometimes lead to hematuria. Polycystic kidney disease might cause the formation of cysts in the kidneys, which can cause kidney disease. It is an inherited disorder. 

Hematuria Causes – Diseases or Conditions Involving the Urinary Tract. 

If the urinary tract has some structural abnormalities, these can lead to bleeding. Sometimes, blood clots form in the urinary tract, and that can cause blood in the urine. 

A condition known as endometriosis can also lead to hematuria. It is a condition where a tissue that typically lines the uterus starts to grow in other places such as the bladder. 

Hematuria Causes – Inherited and/or Chronic Disorder 

Hematuria could also be caused by an underlying disorder affecting the whole body (systemic) that causes the presence of excess blood in the urinary tract. Some of these conditions include: 

Bleeding Disorders – Bruising, bloody, or prolonged bleeding are some common disorders causing excessive bleeding throughout the body. Some of the common examples of these disorders include hemophilia and thrombocytopenia. 

Alport Syndrome – It’s an inherited disorder that causes the presence of blood and protein in the urine. 

Autoimmune Diseases – It’s a group of disorders where the immune system in the body starts attacking the body itself, and that causes damage to various organs and tissue in the body, including the kidneys. 

Hematuria Causes – Cancer. 

Cancers associated with the prostate and urinary tract can also lead to hematuria. Some of the common examples include prostate cancer, kidney cancer, and bladder cancer. 

Symptoms and Signs of Hematuria 

Many people with hematuria won’t show any signs or symptoms. However, people typically display symptoms associated with another underlying condition. Some of the common examples of signs and symptoms include back pain, abdominal pain, urgent and/or frequent urination, painful urination, fever with infections, severe pain due to kidney stones, swelling of the ankles, legs or feet (edema) as well as urinary hesitancy which means difficulty in urination or flow interruption. 

Laboratory Testing 

Tests are performed to identify and address the root cause of the problem and to determine the severity, extent, and persistence of blood in the urine. Typically, an initial set of tests will be performed by a health practitioner to determine the prevalence of hematuria and to rule out and identify some of the common causes. The findings of these initial tests, combined with the medical history and signs and symptoms shown by the affected individual, will determine the need for a more extensive workup. 

Initial Testing 

  • Urinalysis – It is the primary test through which the presence of hematuria is confirmed. It involves chemical and visual examinations for the identification of gross hematuria through visual examination of the urine color and a chemical test strip. In case of any abnormal findings, a further microscopic examination is done. Multiple samples of urine might be tested. 

As per the American Urological Association, microscopic hematuria is confirmed when there are three or more red blood cells present in the high-powered microscope field in two of the three urine samples. Results from the urinalysis (presence of protein) might also help in determining the underlying cause. 

  • Urea Nitrogen and Creatinine – These blood tests are performed to evaluate kidney function. These tests might form part of the comprehensive metabolic panel or basic metabolic panel. 
  • CBC or Complete Blood Count – This test is done to check the number of platelets and blood cells. The health practitioner might ask for this test for a general evaluation of health or when they suspect a blood cell abnormality or infection or anemia. 

Follow-Up Testing – Kidney Health and Kidney Function 

  • Urine Culture – This test is done to determine the presence of bacterial infection. 
  • Cystatin C – This test might be performed as an alternative to the blood creatinine test and for calculation of estimated glomerular filtration rate (eGFR). 

Urine cytology – This test is performed for the identification and presence of any abnormal cells in the urine sample. 

The health practitioner might order further tests based on the initial test results along with your medical history, physical examination as well as other signs and symptoms. These tests are only done when indicated and to help investigate the root cause of the presence of blood in your urine. Some examples of these non-routine tests include: 

Analysis of Kidney Stone: It is performed to check the kidney stone composition passed into the urine. The stone itself is tested. 

  • Sickle Cell Tests – This test is performed to check whether sickle cell disease is the root cause of hemoglobin in urine. 
  • Hemoglobinopathy Evaluation – These tests are performed for identifying various inherited disorders that affect red blood cells. 
  • Autoantibody Testing – This test is performed for the identification of autoimmune disorders. 
  • Kidney Biopsy: This test is sometimes used for evaluating the nature and extent of structural damage to the kidney.