Bilirubin is a breakdown product of hemoglobin. Red blood cells contain hemoglobin, which is broken down into the components "heme" and "globin." Heme is converted into bilirubin. Albumin carries bilirubin to the liver, where most of it is conjugated with a glucuronide before it is excreted in the bile. Conjugated bilirubin is called "direct bilirubin;" unconjugated bilirubin is called "indirect bilirubin." Total bilirubin equals direct bilirubin plus indirect bilirubin.
A recent case of a 51 year old male with an interest in testosterone replacement illustrates the benefits of the multi-parametric prostate MRI scan. Noting a PSA value of only ng/ml; the digital rectal exam (DRE) identified an area of interest on the left side, albeit, it was not definitive for prostate cancer. Neither the gray scale ultrasound nor Color Flow Doppler ultrasound evaluation suggested any specific abnormality consistent with the area of interest previously identified on DRE. An MRI scan was suggested as the next best step in the evaluation. The scan isolated a region of interest on the left side at the Apex to Middle portion of the prostate gland concordant with the findings on the DRE. Based upon the findings of the MRI scan, a targeted biopsy with 6 needle cores was recommended and implemented. An Antiandrogen was initiated pre-biopsy to mitigate against “needle tracking”. Specifically, an Antiandrogen selectively blocks the receptor on the prostate cell from attracting testosterone as it exits the capsule, thereby, disabling the cells in preparation for cell death or apoptosis. The Pathology evaluation revealed a grade of cancer that was amenable to being treated conservatively or focally. In this case, the failure to use a MRI scan would have exposed this patient to the possibility of missing the cancer altogether; associated with sampling bias, a very real possibility for needle tracking (assuming cancer was found), or worse yet, the go ahead to supplement with testosterone, when in fact, the cancer was missed. Using testosterone in this scenario would have stimulated cancer cells to grow wildly, while causing the PSA to spike abnormally, thereby, making the diagnosis of prostate cancer – a potentially uncontrollable clinical event, albeit, avoidable. Given the expertise of a Urolologic consultation, this case turned out well. The patient is now contemplating a focal treatment with high intensity focused ultrasound with a plan to supplement with testosterone once his cancer has been cured. An inability to document the resolution of prostate cancer by a repeat MRI scan and/or a stable PSA post-operatively will preclude this patient from using testosterone replacement therapy.