High RBC in Urine: Causes, What the Numbers Mean, and Next Steps

Clinically reviewed by Dr. Ponlawat Pitsuwan, Physician, Doctor Bangkok. Last reviewed: August 2026

You got your health check results back. Everything looks fine except one line: RBC in urine, flagged high. You feel completely normal. No pain, no change in colour when you use the bathroom. So you start Googling at your desk and end up more confused than when you started.

This is one of the most common scenarios I see at Doctor Bangkok. Patients come in with a Thai lab printout, a number circled in red, and no idea what it means or what to do next. The good news is that most causes are benign. The important news is that some are not, and you cannot tell the difference without a proper follow-up.

What High Red Blood Cells in Urine Actually Means

Red blood cells belong in your blood, not your urine. When a urine test shows more than 2 RBCs per high-power field (HPF), that is flagged as abnormal. The American Urological Association defines microhematuria as 3 or more RBCs per HPF. That is blood you cannot see with the naked eye.

Thai health check reports express this in different ways. You might see "RBC 3+" or "TNTC," which stands for "too numerous to count." Some reports write a number like "15 RBC/HPF." All of these mean the same thing: there are red blood cells in your urine that need to be explained.

Two Types of Hematuria and Why It Matters

Gross hematuria is blood you can actually see. Your urine looks pink, red, or the colour of cola. This always warrants same-day evaluation. Microscopic hematuria is invisible and only shows up on a lab test.

Both types need investigation. Visible blood, especially if there are clots or it came on without any pain, is a more urgent red flag. Painless visible hematuria can be an early sign of bladder or kidney cancer, which is exactly why it should not be left until it is convenient.

Where the Blood Is Coming From Changes Everything

Not all high red blood cells in urine come from the same place. The shape of the red blood cells under a microscope helps identify the source. That distinction shapes everything that comes next.

Glomerular Hematuria

This means blood is leaking from the kidney’s filtering units. The red blood cells get distorted as they pass through damaged tissue, so under the microscope they look twisted and irregular. You may also see protein in the urine or clusters of cells that formed inside the kidney’s tiny tubes. This pattern points toward kidney conditions such as IgA nephropathy or glomerulonephritis, which is a type of kidney inflammation.

Non-Glomerular Hematuria

Here the red blood cells look normal and round. They entered the urine from the bladder, ureter, urethra, or the kidney’s drainage system rather than its filtering units. This pattern fits better with infections, stones, tumours, or trauma.

Common Causes of High Red Blood Cells in Urine

Urinary tract infections are the most frequent cause I see, especially in women. The infection irritates the lining of the bladder or urethra, and red blood cells leak through. Kidney stones can cause hematuria even before they cause pain, as the stone scratches the walls of the urinary tract as it moves.

An enlarged prostate, known as BPH, is a common cause in men over 40. IgA nephropathy is one of the most common kidney diseases worldwide and often shows up as microscopic hematuria after a respiratory infection. Blood-thinning medications like warfarin do not cause hematuria on their own, but they can expose an underlying source of bleeding that would otherwise go unnoticed. Bladder and kidney cancers are less common but are one reason painless hematuria in someone over 40 should always be followed up properly.

What Can Look Like High RBCs But Is Not

A dipstick urine test can flag positive for blood even when there are no actual red blood cells present. The test reacts to a protein released from muscle during intense exercise or muscle injury, and the strip turns positive without any true hematuria.

Red or pink urine with no blood at all is also possible. Beetroot, certain berries, and some food dyes can turn urine red for a day or two. The antibiotic rifampicin, used in tuberculosis treatment, turns urine orange-red. A urinary pain reliever called phenazopyridine, sometimes sold in pharmacies here in Bangkok, turns urine bright orange. Menstrual contamination is another common false positive in women. This is why a clean-catch midstream sample matters and why a dipstick result alone is never the full picture.

Bangkok and Travel-Related Causes Worth Knowing

If you have been travelling outside Bangkok to rural areas, lakes, or countries in sub-Saharan Africa or the Middle East, schistosomiasis is worth mentioning to your doctor. It is a parasitic infection that specifically causes blood in urine and is one that most online resources miss entirely because they are written for Western populations.

Dengue fever can also cause microscopic hematuria during the acute phase, which is directly relevant in Bangkok given the city’s seasonal transmission patterns. Vigorous exercise, including long-distance running or heavy gym sessions, can cause transient hematuria that clears within 48 hours. If you trained hard the day before your health check, mention it.

When to Act Urgently vs When to Book a Routine Appointment

See a doctor the same day if you have visible blood in your urine, especially with clots. The same applies if you have flank or back pain, a fever alongside urinary symptoms, difficulty passing urine, or significant unintended weight loss. These combinations should not wait.

Asymptomatic microhematuria found on a routine health check, in someone under 35 with no risk factors, is less urgent but still needs follow-up. A single positive dipstick that is not confirmed on microscopy is often not true hematuria at all. The right next step is a repeat urinalysis done properly, then further workup if the finding persists.

Do not ignore a result just because you feel fine. Some of the more serious causes produce no symptoms at all in the early stages.

How Hematuria Is Investigated at a Private Clinic in Bangkok

You do not need a referral or a Thai-speaking GP to get this sorted. At Doctor Bangkok, you walk in, see an English-speaking physician, and have a urinalysis with microscopy done on-site. Results are typically ready within the same visit.

If the finding is confirmed, next steps depend on what the microscopy shows. A urine culture checks for infection. Blood tests assess kidney function and your full blood count. If stones or a structural problem is suspected, an ultrasound of the kidneys and bladder is arranged. Higher-risk presentations, such as visible hematuria in someone over 40, may need a CT urogram, which is a detailed scan of the urinary tract, or a cystoscopy, which is a camera examination of the bladder. Doctor Bangkok can coordinate same-day or next-day referrals for imaging when needed.

DR Ponlawat

Dr. Ponlawat Pitsuwan is a physician at Doctor Bangkok, a private clinic in central Bangkok. He sees expats, residents, and medical tourists for general medicine, wellness consultations, and IV therapy. His focus is straightforward, evidence-based care delivered in plain language.