(This version of the May 17 story corrects paragraph 12 to show FDA reviewed application for label change to a test, not a new test)
By Toni Clarke
WASHINGTON (Reuters) - U.S. health officials on Wednesday warned that tests made by Meridian Bioscience Inc may underestimate lead levels in blood drawn from veins, sending the manufacturer's stock down 9 percent.
The Food and Drug Administration warned laboratories and healthcare professionals not to use any lead testing device made by Magellan Diagnostics, a company acquired by Meridian in 2016 for $66 million, to test blood drawn from veins. The devices are the only lead testing products cleared by the FDA and account for about half of all lead tests in the United States.
The tests are designed to detect lead poisoning that can stunt children's growth and reduce their IQs, according to the Centers for Disease Control and Prevention.
Awareness of lead poisoning escalated following widespread exposure in Flint, Michigan. Reuters has identified more than 3,300 areas with childhood lead poisoning rates at least double those found in the Michigan city.
The CDC recommended healthcare professionals retest children under the age of 6 who were tested using blood drawn from a vein who received a result of less than 10 micrograms per deciliter. It also recommended that pregnant women and nursing mothers who have been tested for lead exposure ask their doctor whether they should be retested.
"The FDA is deeply concerned by this situation," Dr. Jeffrey Shuren, head of the FDA's medical device division, said in a statement. "The agency is aggressively investigating this complicated issue to determine the cause of the inaccurate results and working with the CDC and other public health partners to address the problem as quickly as possible."
It is unclear how many people may need to be retested, Shuren said on a conference call with reporters. About 8 million tests were conducted using Magellan devices since 2014. Most people were tested using capillary blood drawn with a heel stick or finger stick and so far data suggests there is no problem with those tests.
"At this time we believe most people will not be affected by this issue," Shuren said on a conference call with reporters.
Neither are there problems with other blood tests used to detect lead, which account for about half the total, he said.
Magellan CEO Amy Winslow said the company does not expect a big demand for retesting because the warning does not cover capillary results. She said the company's Ultra and Plus systems, launched in 2013 and 2015 respectively, are typically used to analyze venous blood, though they can analyze capillary blood as well.
The problem with the venous blood testing appears to date back to August 2014 when Magellan received a number of complaints from customers about its LeadCare Ultra device, the FDA said. On Nov. 24, the company instructed its customers to implement a 24-hour incubation period with the blood sample before running the test. It subsequently issued instructions to mitigate problems with its LeadCare II testing system.
The FDA learned about the problem earlier this year when it began to review an application requesting changes to a device's label. It discovered deficiencies in the company's previous mitigation strategy and categorization of the problem as minor.
The agency "did not feel that the data was either adequate regarding what they thought may have been the cause of the problem, the extent of the problem or the effectiveness of the mitigation they put in place," the FDA's Shuren said.
The company declined to comment on the FDA's statement that it had minimized problems with its tests, citing the ongoing inquiry.
So far the cause of the problem is unclear.
"It may not be something specific to the test itself. It may have to do with other aspects, including the tubes in which the blood is collected. It may have to do with reactions with the chemicals involved," he said.
Reporting by Toni Clarke. Additional reporting by Natalie Grover in Bengaluru, Michael Pell and Joshua Schneyer in New York; Editing by Andrew Hay and Lisa Shumaker