Eastern Health CEO Vickie Kaminski spoke with reporters in St. John's Friday. (CBC)

The head of Newfoundland and Labrador's largest health authority said Friday she should have been told sooner about a problem with the way the Health Sciences Centre in St. John's was administering the drug cyclosporine.

Eastern Health CEO Vickie Kaminski said she only learned that some of the hospital's patients might have gotten the wrong dose of the drug 11 days after a nurse warned staff about the problem.

"I think we should have known sooner," Kaminski said. "And certainly, that's what we will look at. Was it reasonable for us to know that sooner? And if so, why not? Why weren't we [told]?"

Cyclosporine suppresses the immune system and is used to prevent organ rejection in transplant patients and to treat symptoms of autoimmune diseases like lupus and rheumatoid arthritis.

In early February, a nurse told hospital staff in St. John's that she was concerned about the doses of cyclosporine some patients were receiving.

In mid-February, doctors realized a seriously ill 14-year-old patient might have been given too much of the immunosuppressant, which can cause kidney damage.

Kaminski said she found out about the problem on Feb. 19 after the teenager became sicker and had to be admitted to intensive care.

Although Kaminski had told media earlier Friday that the teen was out of intensive care, Eastern Health corrected that detail Friday evening and said the 14-year-old was still in intensive care.

A patient review that began before Kaminski was told about the problem found that 234 patients had received cyclosporine in the nine months since the hospital began using a new machine for testing levels of the drug in a patient's blood. The bloodwork of those patients is now being retested in Halifax.

Kaminski said 13 of the patients died during the nine-month period, but there is no reason to believe any of their deaths were related to the amount of cyclosporine they received.

She said it's believed that the dosing problem began when an employee of the hospital's biochemistry lab incorrectly calibrated the new machine.

An Eastern Health quality-control team is looking into what went wrong in the lab. It is expected to report its findings, which Kaminiski said will be made public, next week.

A group from the University Health Network in Toronto is to begin a review next week of Eastern Health's laboratory services.