Test may underestimate lead levels in children’s blood

Certain tests used to measure blood lead levels in children and pregnant women are inaccurate and may underestimate true concentrations, the Food & Drug Administration and the Centers for Disease Control & Prevention warned on May 17. Complaints about the tests, which are produced by Magellan Diagnostics, date back to 2014, the agencies said.

The government’s warning “is based on currently available data that indicate Magellan lead tests, when performed on blood drawn from a vein, may provide results that are lower than the actual level of lead in the blood,” FDA said. The agency believes the tests are accurate, however, when used with blood from a finger or heel stick. FDA also believes other blood lead testing methods, such as atomic absorption spectroscopy, are accurate.

It is unclear why Magellan lead tests perform differently with venous blood than with capillary blood from a finger or heel stick, FDA said. “FDA is deeply concerned by this situation and is warning laboratories and health care professionals that they should not use any Magellan Diagnostics lead tests with blood drawn from a vein,” said Jeffrey Shuren, director of the FDA’s Center for Devices & Radiological Health. “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.”

FDA estimates that about 8 million blood lead tests have been performed using the Magellan systems since the beginning of 2014. Although the majority of children tested were subject to a finger prick or a heel stick, a small percentage had blood drawn from a vein. CDC recommends retesting all children under six who had their blood drawn from a vein and had a blood lead result of less than 10 µg/deciliter with a Magellan Diagnostics lead test.

“While most children likely received an accurate test result, it is important to identify those whose exposure was missed, or underestimated, so that they can receive proper care,” said Patrick Breysse, director of CDC’s National Center for Environmental Health.

Children and infants are particularly vulnerable to the neurotoxic effects of lead poisoning.