What cause gross hematuria every bowel movement? mri says i have prostate calcification with suspicious hypodense within?

Do you have gross hematuria with bowel movement only, not with regular voiding? If prostate problem is the cause, hematuria (gross or microscopic) should be present without bowel movement as well. If PSA level is high prostate biopsy is indicated.

At your age probably from prostatic inflammation and should be treated for it first under care of a good Urologist.