Brief Answer:
Age wise predisposition to prostate enlargement.other causes in detail belo

Detailed Answer:
Hi,

Blood in urine is evident in following conditions.
- Heavy weight lifting, excessive exercise. or kidney injury
- Family history of bleeding by sickle cell disease or kidney or bladder stone (specially oxilate stones)
- Certain drugs like diuretics, anti cancer medicines, blood thinners like aspirin can cause it
- Infection / inflammation of bladder or kidney following bacterial or viral infection.
- Infection of kidneys, glomerulonephitis / pyelonephritis
- Infection / age wise enlargement of prostate.
- Malignancy

* Though each cause needs to be excluded by physical examination and needful investigations. In absence of stress to the part, urinary symptoms, Family history, considering your age...enlarged prostate, seems to be possible cause (cancer needs to be excluded) in your case. Please consult a urologist.

I hope that answers your query. Any follow up query is welcome.
Thanks.

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