Red Urine as a Red Flag for Kidney Cancer

Your body’s renal system works overtime to perfectly filter waste from your blood daily into urine, but when that crystal-clear stream turns reddish – it could be a signature indicator of kidney cancer. 

What Is Haematuria? 

Blood in urine, also known as haematuria, comes in two forms.  

1. Gross Haematuria: blood is visible to the naked eye and urine appears pink/red/cola-coloured 

2. Microscopic Haematuria: blood is detectable only under a microscope and

   urine appears normal coloured 

While potentially scary to witness, blood in urine is actually a common clinical finding that is often benign and linked to multiple conditions.  For example, Urinary Tract Infections account for 30-40% of microscopic cases, and kidney stones cause trauma and visible blood in 15-20% of gross cases. 

Even overexercising can cause haematuria, but now recent studies with population-level data now establish it as a significant predictor of renal cell carcinoma (RCC), the most prevalent form of kidney cancer notorious for difficult early diagnosis. 

What’s RCC and why are Kidney Cancers so Dangerous? 

RCC is the most common form of kidney cancer, accounting for about 90% of cases in adults and the 14^th most common cancer worldwide. It originates from cells mutating and growing uncontrollably to form a tumour in the kidney, where urine is filtered and formed.  

What makes kidney cancers so dangerous is their often-silent nature—they frequently show no early symptoms, leading to diagnosis at advanced stages when the cancer has spread (metastasized) to other organs like the lungs, bones, or liver. At that point, treatment becomes more complex, and cure rates drop significantly. For instance, localized tumours have a 93% five-year survival rate, but this falls to about 14% if distant metastases occur.  

Just imagine living your daily life happily when you’re suddenly handed a 14% survival rate without warning. What a shock! Overall, kidney cancer causes around 15,000 U.S. deaths annually, underscoring the need for awareness of the more subtle predictors of this type of tumour. 

How can RCC cause Haematuria? 

RCCs are usually located near the outer layers of the kidney, and as the tumour grows, the mass erodes into the bloodstream, breaking into the fragile blood vessels of the kidney. This causes red blood cells to leak out into the urine, leading to haematuria. While these tears may clot to prevent continuous bleeding, new tears may form as the RCC grows, leading to intermittent haematuria. 

A landmark Danish cohort study involving almost 140,000 adults revealed a twofold elevated risk of bladder and kidney cancers occurring 1 to 5 years following an initial hospital-based haematuria diagnosis. 

Notably, patients who received cystoscopy within 3 months of diagnosis exhibited substantially reduced risks compared to those who did not. 

A systematic review of 20 studies developing risk prediction models for kidney cancer found that haematuria was not only the strongest clinical predictor, with those having haematuria being up to 26 times more likely to develop kidney or bladder cancer compared to those without, but it was also the most common, being included in all models at the end of the study. 

These findings strongly suggest that haematuria acts as a critical early warning sign for kidney cancers like RCC, highlighting the importance quick medical checks like cystoscopy to lower risks and catch issues early for better treatment outcomes.  

Early Screening for RCC 

To combat the stealthy threat of kidney cancers like RCC, prioritizing early screening is essential, especially for those with risk factors such as smoking, obesity, hypertension and a family history of the disease. Regular check-ups with urine tests and imaging can detect issues early, when they're the most treatable. 

If haematuria is detected, a cystoscopy procedure within three months could substantially reduce your risks. This minimally invasive procedure allows doctors to inspect the urinary tract directly, identifying abnormalities before they progress. Combine it with routine blood work, ultrasounds, or CT scans, RCC can be detected in its localized stage, boosting 5-year survival rates above 90%. 

What Should You Do If You Notice Blood in Your Urine? 

If you spot red or pink urine, don't panic—but don't ignore it either. Schedule a visit with your doctor or a urologist right away. Early action is the key to safeguarding your personal health, better safe than sorry! 

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References

1. Harrison, H., Usher-Smith, J. A., Li, L., Roberts, L., Lin, Z., Thompson, R. E., Rossi, S. H., Stewart, G. D., Walter, F. M., Griffin, S., & Zhou, Y. (2022). Risk prediction models for symptomatic patients with bladder and kidney cancer: A systematic review. British Journal of General Practice, 72(714), e11-e18. [https://doi.org/10.3399/BJGP.2021.0319]

2. Nørgaard, M., Veres, K., Ording, A. G., Djurhuus, J. C., Jensen, J. B., & Sørensen, H. T. (2018). Evaluation of hospital-based hematuria diagnosis and subsequent cancer risk among adults in Denmark. JAMA Network Open, 1(7), e184909. [https://doi.org/10.1001/jamanetworkopen.2018.4909]

3. Bukhari, S., Amodu, A., Akinyemi, M., & Wallach, S. (2017). Persistent hematuria caused by renal cell carcinoma after aortic valve replacement and warfarin therapy. Bayl Univ Med Cent Proc, 30(3), 327-329. [https://doi.org/10.1080/08998280.2017.11929635]

4. Nørgaard, M., Veres, K., Ording, A. G., Djurhuus, J. C., Jensen, J. B., & Sørensen, H. T. (2018). Evaluation of hospital-based hematuria diagnosis and subsequent cancer risk among adults in Denmark. PMC. PMCID: PMC6323488. [https://doi.org/10.1001/jamanetworkopen.2018.4909]