Shift of the f/t-PSA quotient in relation to renal insufficiency: consequences for the early detection of prostate carcinoma in patients with terminal renal failure.

BACKGROUND Whether the quotient of free to total PSA (f/t-PSA) can be used to increase the specificity in the early detection of prostate carcinoma is a matter of discussion in cases of renal failure. We therefore compared f/t-PSA values of patients with kidney failure and patients after successful kidney transplantation. PATIENTS AND METHODS The serum levels of total PSA (t-PSA) and free PSA (f-PSA) were determined in 57 patients. For those where t-PSA was between 2 and 10 ng/ml the f/t-PSA quotient was calculated. Out of the 57 patients, 32 suffered from renal failure (15 cases with prostate carcinoma, 17 with benign prostate disorder), the other 25 had successfully undergone kidney transplantation with a working transplant (10 with prostate carcinoma, 15 with benign prostate disorder). RESULTS There were no statistically significant differences between the t-PSA levels of the various groups of patients. The f/t-PSA quotients, however, were consistently higher for the patients with kidney failure than for those with a kidney transplant or with a normal kidney function. There were no differences in the f/t-PSA quotients between transplant recipients and men with normal kidney function. CONCLUSION For the use of the f/t-PSA quotient as a tool to support the decision for or against a prostate biopsy, it should be borne in mind that the cut-off criteria determined for men with a normal kidney function cannot be applied to patients who suffer from kidney failure. The f/t-PSA quotient of patients with terminal renal failure is often shifted towards higher values. On the other hand, there is no statistically significant difference between the f/t-PSA quotients of kidney transplant recipients and patients with normal kidney function, therefore the same diagnostic criteria apply in this case.