A reference laboratory is a large central laboratory that receives samples from many clinics, hospitals and collection centres, and runs tests on them in very large numbers. The company that runs it is called a laboratory company, or in India, a diagnostic chain. The two largest laboratory companies in the United States each run hundreds of millions of tests a year.
Why send a sample to a central lab instead of testing it nearby? A small lab can run the common tests, such as a blood count. But many tests need an expensive machine, a rare reagent or a specialist doctor, and a small lab receives only a few such samples a month. A central lab receives the same test from hundreds of places, so it can run that test every day, on the best machines, at a lower cost per test. These rarer tests are often called specialised or esoteric tests.
The network is built like a wheel, with a hub and spokes. The spokes are the collection centres, clinics and hospitals where samples are drawn. Couriers carry the samples to regional labs, and the rarer tests travel on to the central lab, often by air. Many samples must be kept cool or frozen on the way, so the boxes carry temperature loggers. This is a cold chain for samples. More samples now come from home sample collection, in which a technician draws blood at the patient's home.
Here is a typical case. A nursing home in Satara, Maharashtra, needs a test for antibodies that point to an autoimmune disease, an illness in which the body attacks its own tissue. Its own small lab does not run this test. At 4 p.m., the nursing home hands the tube to the courier of a diagnostic chain. That night, the tube reaches the chain's central lab in Mumbai, kept at 2–8 °C all the way. The lab's laboratory information system reads its barcode and records its temperature. The next morning, the test runs on an immunoassay clinical lab analyser, and a pathologist approves the report by 2 p.m. The nursing home's doctor reads it on the chain's website less than 24 hours after the sample was drawn.
A reference lab is also a business that bills for every test. In the United States, it sends a claim to the patient's insurer through revenue cycle management (RCM) software. In India, most patients pay the lab directly, and some tests are paid for by insurers or by government schemes. Doctors order the tests and read the results through a lab ordering and results portal.