Secretin is a peptide hormone most people have never heard of, even though it played a foundational role in the history of endocrinology — it was one of the first hormones ever identified, over a century ago. Today, a synthetic version is an FDA-approved diagnostic tool, not a treatment, which makes it one of the more unusual peptide drugs covered on this site.

What It Is and How It Works

Naturally, secretin is released by the upper small intestine in response to acidic stomach contents entering it after a meal. It signals the pancreas to release a bicarbonate-rich fluid that neutralizes that acid, and it has related effects on stomach and bile-duct function. The FDA-approved drug ChiRhoStim is a synthetic human secretin formulation given by intravenous injection to trigger this same response under controlled conditions, so clinicians can measure how well the pancreas and related organs are working.

What It's Approved For

ChiRhoStim has two main approved uses. The first is as a diagnostic stimulant to test pancreatic exocrine function, including as part of the workup for suspected gastrinoma (a rare tumor that oversecretes the hormone gastrin) by measuring how gastrin levels respond after a secretin injection. The second is to help identify the ampulla of Vater and accessory papilla — small anatomical landmarks in the small intestine — during endoscopic retrograde cholangiopancreatography (ERCP), a procedure used to examine and treat problems in the bile and pancreatic ducts.

A Diagnostic Tool, Not a Home-Use Drug

Unlike most peptides discussed on this site, secretin isn't something a patient decides to try or avoid on their own. It's ordered by a physician for a specific diagnostic workup and administered by a clinician during a procedure, typically in a hospital or endoscopy setting. There's no outpatient self-administration version and no reason for one, since its entire purpose is to produce a measurable physiological response in a monitored clinical setting.

The Autism Research Chapter

Secretin has a notable chapter in research history worth knowing about if you encounter claims about it online. In the late 1990s, anecdotal reports suggested that children with autism who received secretin during gastrointestinal workups showed improved behavior and communication afterward, which led to a wave of public interest and off-label use as a purported autism treatment. That prompted a series of randomized, placebo-controlled trials specifically designed to test the claim. Those controlled trials, including a multi-site study and later systematic reviews summarizing the broader body of research, consistently found that secretin performed no better than placebo for autism symptoms. The National Institutes of Health and subsequent systematic reviews concluded there was no evidence to support secretin as an autism treatment, and it is not FDA-approved or clinically recommended for that purpose. The episode is frequently cited in medical and research-methods literature as a clear example of how early anecdotal enthusiasm for a treatment can fail to hold up once it's tested in properly controlled trials — the same animal-evidence-versus-human-evidence, anecdote-versus-RCT theme that comes up repeatedly with other peptides covered on this site.

Safety Considerations

As a diagnostic agent given in a single clinical dose under direct medical supervision, secretin is generally well tolerated, with occasional mild and transient effects such as flushing, nausea, or abdominal discomfort reported during testing. Because it's administered by a clinician as part of a defined procedure, safety monitoring is built into how it's used rather than something a patient needs to manage independently.

Regulatory Status

ChiRhoStim is an FDA-approved prescription diagnostic drug, used exclusively in clinical settings. It is not sold for self-administration, and it is not an approved or recommended treatment for autism or any condition other than its labeled diagnostic uses.