Visible blood with clots, being unable to pass urine at all, or fever with back or flank pain are emergency signs. Call 911 or your local emergency number now.
Blood in the urine most often comes from somewhere along the urinary tract itself, and the common reasons are infection, stones, a recent hard training block, recent catheter use or injury, an enlarged prostate in older men, and menstrual blood mixing with the sample 1. Blood in the urine is described as visible, sometimes called gross, when the urine changes colour, and as microscopic when red cells are found only on testing 2.
A urinary tract infection irritates the bladder lining, so bleeding often arrives with burning, urgency and a need to pass urine more often than usual. Stones scrape the lining of the ureter or bladder as they move, which is why bleeding frequently turns up alongside waves of flank or groin pain and nausea. If that pattern sounds familiar, the warning signs are set out in more detail in kidney stone symptoms.
Training load matters more than most people expect. Research suggests that strenuous exercise can produce blood in the urine that settles within a few days of rest, a pattern long described in runners and other endurance athletes 3. Studies indicate that repeated impact, bladder wall contact and reduced blood flow to the kidneys during intense effort are among the explanations offered for exercise related bleeding 4. That does not make it something to shrug off. Bleeding after exercise still needs confirmation that it has cleared, because hard training can sit on top of another cause rather than replace it.
Several everyday things can also make urine look red without any blood being present. The most common are beetroot, blackberries, strong food colouring and concentrated urine after a long day with very little fluid. Some medicines can change urine colour or contribute to bleeding, so ask your prescriber rather than stopping anything on your own. Menstruation, recent sex and recent catheter use can all put a small amount of blood into a sample, which is one reason clinicians often repeat the test at a different moment in the month.
The kidneys themselves are the other broad source. When bleeding comes from the glomeruli, the tiny filters inside each kidney, blood often appears together with protein in the urine, and glomerular disease can present this way rather than with pain 5. Bleeding of that kind tends to be painless, may make urine look brown or cola coloured rather than bright red, and is usually picked up on a urine test rather than noticed by the person.
Age and smoking history are the reason clinicians take a painless, visible episode seriously even when someone feels completely well. Evaluation guidance describes older age and current or past smoking among the factors that raise concern for a urinary tract source such as bladder cancer, which is why an adult with blood in the urine is assessed rather than reassured by default 6. Being checked is routine. It is not a verdict, and most assessments find a benign explanation.
Blood tests cannot show where urinary bleeding starts, but two of them add context that changes what happens next. Creatinine reflects how well the kidneys are filtering, and the platelet count reflects one part of how readily blood clots. An initial assessment usually pairs urinalysis with microscopy and a blood check of kidney function, rather than relying on either alone 7.
| Marker | Why it is linked to this symptom | What a result can and cannot tell you |
|---|---|---|
| Creatinine | A waste product cleared by the kidneys, used to estimate filtration. A reduced filtration rate alongside blood and protein in the urine shifts attention toward the kidney filters rather than the bladder | Can suggest how well the kidneys are clearing waste right now and flag a change over time. Cannot show where bleeding comes from, cannot detect a stone or infection, and moves with muscle mass, recent heavy training and hydration |
| Platelets | The cell fragments that seal small vessel injuries. A low count is one possible reason bleeding appears more readily, including into the urine | Can show whether clotting capacity is reduced and whether a bleeding tendency deserves a closer look. Cannot locate the source, cannot replace a urine test, and shifts with infection, inflammation, alcohol intake and recent illness |
Typical lab reference ranges for these two markers are shown below. Ranges vary by lab, age and sex, so read your own report against the range printed on it.
| Marker | Typical lab reference range | Units |
|---|---|---|
| Creatinine (serum) | roughly 0.6 to 1.3, generally lower in women than men | mg/dL |
| Platelet count | roughly 150 to 400 | x10^9/L |
A result sitting slightly outside a range is a reason for a conversation, not a conclusion. One number taken on one morning is a snapshot, and the pattern across repeat testing carries far more meaning than any single value.
Yes, creatinine is the standard blood marker for kidney filtration, which is why it is commonly measured when blood in the urine is investigated 6. Creatinine is produced at a fairly steady rate as muscle turns over, and healthy kidneys clear it into the urine. When filtration slows, creatinine accumulates in the blood, so the level rises. Most labs also report an estimated glomerular filtration rate calculated from creatinine together with age and sex, which is easier to interpret than the raw number.
In the context of urinary bleeding, creatinine answers a specific question. It indicates whether the kidneys are keeping up, and it gives a baseline to compare against if bleeding recurs. When reduced filtration appears alongside blood and protein in the urine, attention moves toward the glomeruli, the pattern described in glomerular disease 5. When filtration looks normal, that is reassuring about kidney workload, though it says nothing at all about the bladder, the prostate or a stone sitting in a ureter.
Plenty of ordinary things move creatinine without any kidney problem. A larger muscle mass raises it, which is why strong lifters often sit at the upper end of a range and smaller people sit low. A big meat meal the day before, a heavy training session, hot weather and low fluid intake can all nudge it up temporarily. Age and sex shift the expected range. Some medicines also influence the result, so tell whoever orders the test what you take and ask your prescriber before changing anything.
A creatinine reading outside the standard range is best read as suboptimal and worth discussing with a clinician, particularly if it has drifted across repeat tests or arrives alongside swelling, foamy urine or newly raised blood pressure. You can read more about what the marker measures on the Creatinine page.
A low platelet count is one possible contributor, though it is rarely the whole story. Platelets are the fragments that clump at the site of a small vessel injury and form the first plug, so when the count is low or platelet function is impaired, minor bleeding anywhere can become more visible. Bleeding and clotting disorders sit on the list of causes considered when blood in the urine is assessed in urgent settings 8.
The important nuance is that easier bleeding usually reveals a source rather than creating one. For that reason a low platelet count does not end the workup. It becomes one more thing a clinician factors in, alongside whether bruising, nosebleeds or heavy periods have also become more frequent.
Platelet counts move for many reasons that have nothing to do with the urinary tract. Recent infection and inflammation can push the count up or down, alcohol intake and nutritional status influence production, and conditions affecting the spleen or bone marrow change it more substantially. Counts also drift with recent hard endurance exercise and with the time of day a sample is drawn. Some medicines affect platelets as well, which again is a question for your prescriber rather than for the internet.
If your count sits below the typical range, that is worth discussing with a clinician promptly rather than monitoring alone, especially when bleeding is visible. The Platelets page covers what the marker measures and what a shifted count can reflect.
A completely normal blood panel does not rule out a urinary tract cause, because blood markers never see the bladder lining, the ureters or a stone. Several things that explain bleeding are invisible to blood work.
Urine microscopy looks at the red cells themselves, and the appearance of those cells carries information blood tests cannot provide. The finding of dysmorphic red cells or red cell casts is associated with bleeding originating in the glomeruli rather than lower in the urinary tract, which separates a kidney source from a bladder or prostate source 9. A urine culture is what identifies an infection. Neither appears on a standard blood panel.
Imaging of the kidneys and ureters, and direct inspection of the bladder, are used for selected adults depending on age and risk factors, because that is how structural causes are found 6. Bleeding can also be intermittent, so a single clear urine sample does not close the question, and repeat testing is part of how microscopic bleeding is confirmed or dismissed 2.
Blood tests also cannot tell you how much blood is present, how long it has been there, or whether an episode that happened last month was the same cause as one happening now. Treat the panel as context that sharpens the questions, not as a verdict on the urinary tract.
Some situations need emergency care rather than an appointment. Call 911 or go to an emergency department for visible blood with clots in it, an inability to pass urine at all, fever with back or flank pain, severe pain that is not controlled, heavy ongoing bleeding, or feeling faint, cold and clammy.
Arrange prompt review, within days rather than months, for any of the following. Visible blood even once, even if it was painless and cleared on its own. Blood found on two separate urine tests. Blood alongside ankle swelling, foamy urine or newly raised blood pressure, which can point toward the kidney filters 5. Blood with unexplained weight loss, or blood in an older adult or a current or former smoker, both of which are reasons assessment is recommended rather than deferred 6.
Two habits cause avoidable delay. The first is assuming that bleeding which stopped was nothing, when intermittent bleeding is exactly what several causes produce 2. The second is stopping a prescribed medicine without telling anyone. Some medicines can contribute, so ask your prescriber instead. Do not try to work out the cause yourself from a colour or a single number, and do not ignore an abnormal result because you feel well.
If you are having thoughts of self-harm, call or text 988 (US) or your local emergency number now.
Both markers sit on a standard baseline blood draw, and the FitScript Essential panel measures creatinine and platelets alongside the rest of a broad workup, with membership covering 150+ biomarkers tested per year. Atlas, FitScript's AI health advisor, explains what each result means in plain language and how it compares with your previous draws, so you arrive at an appointment with context rather than a sheet of numbers.
Blood work is one half of the picture for this symptom. Urine testing, culture and, where indicated, imaging answer questions that blood cannot, and a licensed clinician decides which of those apply to you. Treatment decisions belong to a licensed provider after they have reviewed your history, your examination and your results together.
This page is educational and not medical advice. Discuss your results and any next step with a clinician or licensed provider.
It means the dipstick detected blood, or something that reacts like blood, in that sample. It does not say where the blood came from or how much is present. The usual next step is a microscopic urine check to confirm red blood cells, often with a repeat sample. Your clinician decides what follows.
No. Hematuria blood in urine is called visible when the urine looks pink, red or brown, and microscopic when red cells show up only on testing. Microscopic bleeding is often picked up by chance on a routine urinalysis, and it is checked just as carefully, because colour alone does not reveal the cause.
It can, particularly after long or high impact sessions, and it usually clears within a few days of easier training. The catch is that exercise can coincide with another cause rather than rule one out. Get a repeat urine test to confirm it has resolved, and tell the clinician what your training week looked like.
A normal creatinine suggests filtration is keeping up at the moment the sample was taken. It does not rule out a stone, an infection, or a bladder source, and it can look normal early in some kidney conditions. It is most useful when tracked over time and read alongside a urine test.
A low count can make bleeding more visible, so it is one possible contributor. It rarely explains the whole picture on its own, which is why the urinary tract is still examined for a source. If your count is below the typical range, raise it with a clinician promptly, especially when bleeding is visible.
Yes, in almost every case. Blood markers show kidney filtration and clotting capacity, but only urine testing confirms red cells, identifies infection and shows the appearance of the cells themselves. Blood work and urine work answer different questions, and a clinician uses both together.
That decision belongs to the clinician reviewing you, not to a general rule. Many people are advised to ease off while the cause is being checked, so the test can be repeated without the confounding effect of a hard session. Bring your recent training details to the appointment.
Expect confirmation with microscopy, a culture to look for infection, and blood work including kidney function. Depending on your age, history and findings, imaging or a direct look at the bladder may be arranged. The sequence is decided by a clinician based on your individual picture.