From the Guidelines
It is not uncommon to have minor hematuria on a urinalysis while taking Aspirin (acetylsalicylic acid), but significant hematuria should be evaluated by a healthcare provider. While aspirin does have blood-thinning properties that can increase bleeding risk, it typically doesn't cause significant hematuria at standard doses, as shown in a study published in The Journal of Urology 1. If you're taking aspirin and notice red blood cells in your urinalysis, this could indicate several possibilities:
- the aspirin might be causing irritation to your urinary tract
- you could have developed a bleeding disorder
- there might be an unrelated urinary tract condition such as infection, kidney stones, or potentially more serious conditions like tumors. The timing matters - if hematuria developed after starting aspirin, there may be a connection, but this doesn't rule out other causes. You should not stop your aspirin without medical advice, especially if prescribed for heart conditions, but should promptly report this finding to your doctor. They will likely recommend additional tests to determine the cause of the blood cells in your urine and may adjust your medication if necessary. Some key points to consider include:
- Minor hematuria was statistically more frequent among patients taking aspirin than in the control group (p = 0.001, OR 1.36,95% CI 1.13e1.64) 1
- Uninterrupted use of aspirin does not increase the risk of moderate/severe hematuria, hemospermia or rectal bleeding after TRUSBx 1
- Aspirin use is associated with an increased risk of major bleeding events, including gastrointestinal bleeding and hemorrhagic strokes 1. However, the most recent and highest quality study on this topic is 1, which suggests that the risk of significant hematuria associated with aspirin use is low. Therefore, if you are taking aspirin and experience hematuria, you should consult your healthcare provider to determine the cause and appropriate course of action.
From the Research
Hematuria and Aspirin (Acetylsalicylic Acid)
- Hematuria, the presence of an increased number of red blood cells in the urine, may be a sign of a serious underlying genitourinary disease 2.
- The causes of hematuria can be classified as systemic disorders, those involving the renal parenchyma, or those involving the urinary collecting system 2.
- Aspirin (acetylsalicylic acid) is known to affect platelet aggregation and may increase the risk of bleeding, including bleeding in the urinary tract 3.
- A study on the effects of very low dose and enteric-coated acetylsalicylic acid on prostacyclin and thromboxane formation and on bleeding time in healthy subjects found that low dose acetylsalicylic acid can inhibit platelet aggregation and increase bleeding time 3.
Aspirin and Urinalysis Results
- There is no direct evidence in the provided studies that links Aspirin (acetylsalicylic acid) to hematuria on a urinalysis.
- However, it is possible that Aspirin may increase the risk of bleeding in the urinary tract, which could lead to hematuria 3.
- A positive dipstick heme test should always be confirmed by microscopic urinalysis before urological referral or evaluation, as false-positive results can occur 4.
- Pre-analytical issues, such as the use of vacuum tubes or urine tubes containing preservatives, can affect test results and lead to incorrect diagnosis 5.
Diagnosis and Evaluation of Hematuria
- The history, physical examination, and microscopic urinalysis are the key elements in reaching a diagnosis of hematuria 2.
- Further testing is based on these results, and the primary care provider's role in hematuria evaluation involves detection, confirmation, and initiation of the evaluation process, including appropriate laboratory studies and referral as necessary 2.
- The American Urological Association guidelines recommend urological evaluation for asymptomatic patients only for at least 3 red blood cells per high power field in 2 of 3 microscopic urinalyses 4.