Prometheus Receives New York State Approval for Prometheus® IBS Diagnostic, First Blood Test for Irritable Bowel Syndrome

San Diego, March 16, 2009 – Prometheus Laboratories Inc., a specialty pharmaceutical and diagnostic company, announced today that it has received New York State approval for PROMETHEUS® IBS Diagnostic, the first and only blood test for irritable bowel syndrome (IBS). This novel test incorporates 10 biomarkers, two of which are proprietary, along with a proprietary algorithm to help physicians diagnose patients with IBS.

"One out of five Americans has symptoms of IBS, however the majority go untreated due in part to current limitations in diagnostics," said Henry Pan, M.D., Ph.D., Chief Scientific and Medical Officer of Prometheus. "PROMETHEUS IBS Diagnostic is a valuable tool that can help accelerate the diagnosis and treatment of IBS. We have worked diligently with the New York State Department of Health to ensure that this innovative test is broadly available to patients in need. In addition, we are pleased to report that a manuscript describing PROMETHEUS IBS Diagnostic has recently been accepted for publication in Alimentary Pharmacology & Therapeutics."

IBS can be challenging to diagnose because it is a functional disease that is not associated with any visible abnormality and symptoms often overlap with other gastrointestinal conditions, such as inflammatory bowel disease, celiac disease and chronic functional constipation/diarrhea. Without a blood-based biomarker, the diagnosis of IBS is typically made through a process of elimination, by determining the patient does not have other gastrointestinal diseases with similar symptoms, together with the use of the standard Rome diagnostic criteria.

As with Prometheus’ entire portfolio of proprietary diagnostics, PROMETHEUS IBS Diagnostic testing is performed at the Company’s CLIA-certified laboratory in San Diego, California. Blood samples are collected and shipped overnight to Prometheus, after which test results are generally reported back to physicians within two to three days. Subscribing physicians may also view their test results over the Internet. For more information, please visit www.ibsbloodtest.com.

About IBS
According to the National Institute of Diabetes and Digestive and Kidney Diseases, in 2007, almost 60 million, or 20%, of the U.S. population had symptoms of IBS, making it one of the most common disorders diagnosed by physicians. At least twice as many women as men are affected by IBS, a disorder characterized most commonly by cramping, abdominal pain, bloating, constipation and diarrhea. Although it significantly impairs health-related quality of life, many people suffer from IBS for years before being properly diagnosed and treated. It is believed that up to 75% of people suffering from IBS are not receiving medical care for their symptoms, due in part to the current difficulties of diagnosing IBS.

About Prometheus
Prometheus Laboratories Inc. is a specialty pharmaceutical and diagnostic company committed to developing and commercializing novel pharmaceutical and diagnostic products to help physicians individualize patient care. Prometheus is currently focused on the detection, diagnosis and treatment of gastrointestinal diseases and disorders in the United States. Its strategy includes the marketing and delivery of pharmaceutical products complemented by proprietary, high-value diagnostic testing services. By integrating pharmaceutical products and diagnostic testing services, Prometheus believes it can address the full continuum of care, thereby providing physicians with a comprehensive solution to treat chronic diseases. Prometheus’ corporate offices are located in San Diego, California.

Contact
Pete De Spain
Director, Investor Relations
& Corporate Communications
Prometheus Laboratories Inc.
(858) 587-4117
pdespain @prometheuslabs.com