The 4Kscore test is a simple blood test that detects high risk, aggressive prostate cancer. It measures four prostate protein (prostate-specific kallikreins) levels in your blood including total PSA, free PSA, intact PSA, and human kallikrein 2 (hK2). The results are combined in an algorithm with patient age, digital rectal exam and prior negative biopsy to give physicians a personal score for each patient.