to determine whether it is too high. Others, like the syphilis test, provide a yes-or-no answer about whether a patient has a particular disease or not. The accuracy of those tests is gauged by their sensitivity—the measure of how often they correctly label someone with the disease as positive. Over a period of several days, Tyler and several colleagues tested 247 blood samples on Edisons, 66 of which were known to be positive for the disease. During the first run, the devices correctly detected only 65 percent of the positive samples. During the second run, they correctly detected 80 percent of them. Yet, in its validation report, Theranos stated that its syphilis test had a sensitivity of 95 percent.
Erika and Tyler thought Theranos was also being misleading about the accuracy of other Edison tests, such as a test to measure vitamin D. When a blood sample would be tested on an analyzer made by the Italian company DiaSorin, it might show a vitamin D concentration of 20 nanograms per milliliter, which was considered adequate for a healthy patient. But when Erika tested the same sample on the Edison, the result would be 10 or 12 nanograms per milliliter—a value that signified a vitamin D deficiency. The Edison’s vitamin D test was nonetheless cleared for use in the clinical lab on live patient samples, as were two Edison thyroid hormone tests and a test to measure PSA, the prostate cancer marker.
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IN NOVEMBER 2013, Erika was moved from the immunoassay group to the clinical lab and assigned to Normandy, the room downstairs with the lab’s Edison machines. During the Thanksgiving holiday, a patient order came in from the Walgreens store in Palo Alto for a vitamin D test. As she had been trained to do, Erika ran a quality-control check on the Edison devices before testing the patient sample.
Quality-control checks are a basic safeguard against inaccurate results and are at the heart of the way laboratories operate. They involve testing a sample of preserved blood plasma that has an already-known concentration of an analyte and seeing if the lab’s test for that analyte matches the known value. If the result obtained is two standard deviations higher or lower than the known value, the quality-control check is usually deemed to have failed.
The first quality-control check Erika ran failed, so she ran a second one. That one failed too. Erika was unsure what to do. The lab’s higher-ups were on vacation, so she emailed an emergency help line the company had set up. Sam Anekal, Suraj Saksena, and Daniel Young responded to her email with various suggestions, but nothing they proposed worked. After a while, an employee named Uyen Do from the research-and-development side came down and took a look at the quality-control readings.
Under the protocol Sunny and Daniel had established, the way Theranos generated a result from the Edisons was unorthodox to say the least. First, the little finger-stick samples were diluted with the Tecan liquid handler and split into three parts. Then the three diluted parts were tested on three different Edisons. Each device had two pipette tips that dropped down into the diluted blood, generating two values. So together, the three devices produced six values. The final result was obtained by taking the median of those six values.
Following this protocol, Erika had tested two quality-control samples across three devices, generating six values during each run for a total of twelve values. Without bothering to explain her rationale to Erika, Do deleted two of those twelve values, declaring them outliers. She then went ahead and tested the patient sample and sent out a result.
This wasn’t how you were supposed to handle repeat quality-control failures. Normally, two such failures in a row would have been cause to take the devices off-line and recalibrate them. Moreover, Do wasn’t even authorized to be in the clinical lab. Unlike Erika, she didn’t have a CLS license and had no standing to process patient samples. The episode left Erika shaken.
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LESS THAN a week later, Alan Beam was chatting nervously in Jurassic Park, the upstairs lab, with a female inspector from the Laboratory Field Services division of the California Department of Public Health. The Theranos lab’s CLIA certificate was nearly two years old and up for renewal, which required the lab to pass an inspection. The federal Medicare agency outsourced these types of routine inspections to state inspectors.
Sunny had let it be known that no employee was to enter or exit Normandy