The Health Service Executive is reviewing the results of prostate cancer tests on 145 patients who used a diagnostic kit that has since been recalled.
The Siemens-made testing kit was used at Dublin's Connolly Hospital to detect the risk of prostate cancer.
The Irish Examiner first revealed the kit has been recalled after doubts over the reliability of test results.
The HSE told RTÉ that the kits were used at Connolly Hospital between February 2013 and June 2013, and during those dates, 2,186 patients were tested.
Of these patients, 145 received a result that may have indicated a need for further investigation.
So far, five went on to have biopsies and three were found to have prostate cancer of varying degrees.
Professor Bill Tormey, chemical pathologist at Beaumont Hospital, where the prostate cancer tests are now being referred by Connolly Hospital, cautioned that laboratory tests are not as precise as some would claim.
He said repeat testing was vital for anything in doubt and this included physical examination.
The kits are used to measure PSA, a protein found in blood.
A high level of PSA may indicate the presence of prostate cancer, among other things.
There are recognised norms for these tests.
In June of this year one of the diagnostic kits manufactured by Siemens, the IMMULITE PSA range, was recalled, after it returned average readings of around 20-23% higher than normally expected.
In a statement to RTÉ Siemens said the higher than normal results may impact on the clinical interpretation of test results.
Mayo General Hospital in Castlebar says it will review 12,866 prostate cancer tests conducted between 6 July, 2012 and 25 June of this year linked to a faulty test kit.
The hospital says it wants to determine how many had elevated levels and if any further action is needed.
The hospital says the incident is considered to be of low clinical risk and it is currently contacting all doctors who ordered the PSA tests.