For a growing number of medical startups, the holy grail is to develop technology that can diagnose hundreds of diseases with a single drop of blood. 
 
 Many people are squeamish about getting their blood drawn by traditional methods, such as inserting a long needle into a vein. And in developing countries, health clinics are eager for "lab on a chip" diagnostics that can be done without piercing a vein. 
 
 But researchers are finding myriad challenges with relying on a single blood drop. In a recent experiment, scientists at Rice 360° Institute for Global Health took seven drops of blood from 10 individuals. They tested each blood drop for basic health measures, such as hemoglobin and platelet counts, and found a wide range of results between drops that came from the same person. 
 
 "These data suggest caution when using measurements from a single drop of fingerprick blood," researchers Meaghan M. Bond and Rebecca R. Richards-Kortum concluded in The American Journal of Clinical Pathology. 
 
 Bond and Richards-Kortum told the New York Times that in order to achieve results as accurate as conventional methods—the venous blood draw—they had to average six to nine drops of blood from each individual. 
 
 In recent months, Theranos, a company that hoped to revolutionize the blood-testing industry, has come under fire from federal regulators. Theranos's CEO Elizabeth Holmes once promised to detect dozens of medical conditions, from high cholesterol to cancer, based on a few drops of blood. 
 
 San Diego-based Genalyte is also working on a diagnostics system to produce test results from a single blood drop. But unlike Theranos, Genalyte has generated a number of peer-reviewed studies to validate its approach. The company is focusing initially on autoimmune diseases, such as lupus and rheumatoid arthritis. ||||| , cost as little as $3.40 
 
 Some tests, such as 
 
 At 19-years-old, Elizabeth Holmes dropped out of her chemical engineering degree at Stanford University and used her tuition money to pursue a business idea she hoped would change the landscape of healthcare. 
 
 With a major fear of needles, she decided the current system for testing blood - implemented in the 1960s - was archaic, expensive, painful and slow. 
 
 Holmes, 30, endeavored to change that method and develop a way that would eradicate the need for vials of blood to be taken and for blood tests to have to take place at the doctors or a lab. 
 
 Working mostly in secret for the last 11 years, her company, Theranos, is now valued at $9 billion and, according to Holmes, is changing people's lives. 
 
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 Revolutionary: The CEO of diagnostic center Theranos, Elizabeth Holmes, 30, is the brains behind a $9 billion company that has changed the medical landscape by developing a new method to run blood tests 
 
 Theranos' technology requires only a finger prick of blood to be drawn from a patient in order to get fast, effective results. 
 
 One drop can run 30 lab tests, the company claims. 
 
 Holmes told Wired they can get results in less than four hours. 
 
 She said that her fear of needles allowed her to realize that people avoid blood tests for that reason. 
 
 Partnered with Walgreens, the flagship Theranos Wellness Center is based in Palo Alto, California. 
 
 There are also 20 others that have opened inside Walgreens around Phoenix. 
 
 Patients are able to walk into the stores, have their finger pricked, and get blood results within hours. 
 
 The cost, depending on the extent of the tests, averages around $30. 
 
 Holmes' goal is to launch Theranos in all 8,200 Walgreens across the country. 
 
 'Our work is enabling everyone, no matter how much money they have, or where they live, or what kind of insurance they have, to be able to have access to the kind of testing information that could change their lives,' she told USA Today. 
 
 'Theranos is a company dedicated to the belief that access to actionable health information at the time it matters most is a basic human right.' 
 
 Leader: Theranos Chairman, CEO and Founder Elizabeth Holmes and TechCrunch Writer and Moderator Jonathan Shieber speak onstage at TechCrunch Disrupt at Pier 48 on September 8, 2014 in San Francisco 
 
 'Archaic': Holmes decided the current method for testing blood, requiring one or multiple vials of blood and first introduced in the 1960s, was out-of-date and needed to be streamlined 
 
 New system: Theranos developed software that allowed blood tests to be performed using a 'micro-sample', needing just a drop of blood taken from a person with a finger prick 
 
 Menu: Now in 21 locations - a flagship in California and 20 smaller clinics in Phoenix - Theranos charges different amounts for their blood tests, depending on what is being tested 
 
 Now 30, Holmes was the youngest self-made woman on this years Forbes 400 rich list. 
 
 Shes owns 50 percent of Theranos, and has a net worth of about $4.5 billion. 
 
 'She could totally overturn an entire industry if Theranos is as successful as it seems to be,' Abram Brown, associate editor at Forbes, told Yahoo. 
 
 Holmes has a team of influential backers behind her company. 
 
 The Theranos board of directors includes former secretaries of State Henry Kissinger and George Shultz, former Defense Secretary William Perry, and former senators Sam Nunn and Bill Frist. 
 
 Holmes is getting great responses from patients using the Theranos diagnostic centers. 
 
 Dropout: Holmes left her chemical engineering degree at Stanford to develop a way to take the pain and cost out of getting blood tested. She is now worth $4.5 billion 
 
 She told USA Today of a diabetic woman who wrote to her that had three fingers picks for a wide-range of blood tests. 
 
 She paid $34. 
 
 The woman said she had undergone the same tests earlier this year and that it cost her insurance $876. 
 
 'When I realized this is what I wanted to do with my life, things got easy,' Holmes told USA Today.
– As doctors shift away from drawing vials of blood from patients and rely on lab-on-a-chip diagnostics that identify a myriad of conditions using a single drop of blood, there's now concern that not all of your blood is equal. A new study in the American Journal of Clinical Pathology suggests "caution when using measurements from a single drop of fingerprick blood," write researchers at Rice 360° Institute for Global Health: Our blood can change rather dramatically from one drop to the next. Researchers tested seven drops of blood from each of 10 participants and analyzed them for basic health metrics such as platelet counts and hemoglobin, and found a pretty wide range of results—so much so that they had to average the results from six to nine drops to rival the accuracy of a larger blood draw from a vein, reports the New York Times. "If you’re going to take a fingerprick stick to get your measures, you need to be aware that you’re sacrificing some accuracy," one of the researchers warns. The results have implications for startups like Theranos and Genalyte, which hope to diagnose diseases using only one drop. Unlike Theranos, however, Genalyte has produced results via peer-reviewed studies on tests to find autoimmune diseases such as lupus, reports Fast Company. (The Theranos founder dropped out of college at 19 to start the company.)