Hospital officials in Hamilton are trying to determine whether thousands of possibly faulty blood and urine tests done at the city's major laboratories have led to patients receiving improper diagnosis or treatment.

The Hamilton Regional Laboratory Medicine Program has contacted all physicians in the region, warning them of potentially flawed lab chemistry tests and higher-than-usual error rates in their testing division.

"Recently, it has come to our attention that some of the results from chemistry tests conducted in our labs at Hamilton Health Sciences and St. Joseph's Healthcare Hamilton were incorrect …," the program said in a Sept. 20 letter to doctors.

"We are concerned that our rate [of errors] may be higher than expected. If you are aware of a test result that has impacted a patient's care in a negative way, we encourage you to contact the office of the Chief of Laboratory Medicine."

Hospital officials played down concerns about risk to patients, saying they first became aware of potential problems this past summer.

2 separate cases

Hamilton Health Sciences and St. Joseph's Health Care — the two corporations that govern Hamilton's area hospitals — say that to date they have found no evidence any patient has suffered any harm due to the lab problems, Rebecca Repa, integrated vice-president for lab and diagnostics, told CBC News.

Concerns about test results surfaced in two separate cases: first when an employee was dismissed for sloppy recording of test results, and second in late August, when two physicians contacted the lab to report suspicious lab results, which officials have since traced to faulty equipment.

"We went back to a look at all the testing that had been done," Repa said. "We looked it at both ways — from 'what possible tests could be affected?' And we looked at it from 'where could be some of the high concern areas?'"

In both cases, she said, the hospitals were able to determine there was no patient harm and "no pending legal issues that would be a result."

Repa said the lab system in Hamilton conducts 13 million tests a year, and that only the chemistry lab testing is under review, not other kinds of screening including pathology, genetics and hematology.

Worker's dismissal

Officials first detected a problem earlier this spring after discovering a laboratory worker based at the Hamilton General Hospital was routinely making errors in recording the lab results being generated on lab equipment.

"A laboratory technologist had an error with the transcription of the laboratory results," said Dr. Tony Chetty head of clinical chemistry overseeing the labs. "We investigated, reviewed all the charts and found no harm to patients."

But Chetty and Repa acknowledge the errors presented a major conundrum for the lab. They were unable to re-test samples which were discarded after two weeks.

And given known problems with the employee's work, it cast thousands upon thousands of lab results into question, raising the potential that patients might have been misdiagnosed or mistreated.

In addition, there was concern erroneous lab tests may have been sent to and relied on by police, Crown prosecutors and the coroner's office.

After investigation, Repa insists they've ruled out any problems with those specific test results.

Complaints from 2 physicians

In August, two separate physicians called the HRLMP to complain of erratic and erroneous results, prompting officials to again launch a review of thousands of tests, this time exclusively in the chemistry testing lab.

"We still don't have all the answers," said Repa, who says HRLMP sent a memo to area physicians cautioning there was a slim chance that all 80 chemistry tests conducted by the lab (from potassium, to toxicology screening, to urine tests) could be compromised.

However, she says, so far, the problems appear to relate to errors with two specific tests which are not on the top of the "high concern" list in terms of their potential to affect a patient's health.

To date, officials say they have received six calls, five of which were simple inquiries, while the sixth identified a faulty test results which Repa said did not result in any misdiagnosis nor mistreatment.

"We just wanted to be as transparent as possible," Dr. Chetty said. "Make physicians aware that if they notice a result that does not match with a patients clinical condition they need to contact us to repeat that result."