3 doctors weighed in:

What can cause diarrhea and abdominal discomfort? Is there a blood test for irritable bowel syndrome?

3 doctors weighed in
1 doctor agrees

In brief: Many causes/ No

There is no blood test for irritable bowel syndrome.
It is a diagnosis made by excluding other serious causes of intestinal disease. You should have a colonoscopy, ct scanning of the abdomen, endoscopy to rule out celiac disease, and certain blood tests to look for autoimmune disorders. In many cases all of these studies will be negative, and irritable bowel syndrome will be the diagnosis. Goo.

In brief: Many causes/ No

There is no blood test for irritable bowel syndrome.
It is a diagnosis made by excluding other serious causes of intestinal disease. You should have a colonoscopy, ct scanning of the abdomen, endoscopy to rule out celiac disease, and certain blood tests to look for autoimmune disorders. In many cases all of these studies will be negative, and irritable bowel syndrome will be the diagnosis. Goo.
Dr. Crystal Twynham
Dr. Crystal Twynham
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Dr. Laurence Badgley
Irritable bowel syndrome is a functional disorder without a known cause.  Empirically it is known that useful medications modify autonomic neural function.  My clinical research has discovered a group (N=20) of male extreme sport enthusiasts who suffer from IBS.  The unifying clinical finding was that they all had sacroiliac joint (SIJ) injury and hypermobility (subluxation) disorder (diagnosed via criteria published in the Occupational Disabilities Guidelines).  I speculate that SIJ hypermobility stimulates the pelvic presacral plexus & contained parasympathetic nerves that innervate the colon, inducing colon spasm and evacuation.  IBS highly correlates with fibromyalgia, which is likewise common in persons with SIJ subluxation disorder. The reason for a "spectrum of disorder" for fibromyalgia is that the cause, pelvic girdle instability due to pelvic ligament laxity, manifests differently in individuals & genders.  The body musculoskeletal tower is constantly stressed by gravity & a body tilted above an unstable pelvis incurs widely ranging chronic muscle spasm leading to varying densities of painful trigger points. The delicate female pelvis is more easily injured & women have an higher incidence of Joint Hypermobility Syndrome (inherited trait) that contributes to pelvis instability.  Female pelvices are subject to varying intensities of permanent injury related to frequency of childbirth.  In both sexes, severity of fibromyalgia symptoms is a function of musculoskeletal deconditioning & upper body mass borne by an unstable pelvis.  On a Pain Board at Quora.com I discusses these dynamics, which are the true cause of fibromyalgia.  I also discuss my study of male extreme sport enthusiasts who have IBS. 
Dr. Laurence Badgley
General Practice

In brief: Parasympathetic

Parasympathetic nervous system over activity evokes colon spasm & evacuation; imo a possible cause of ibs, which is a functional disorder for which there are no demonstrable tissue pathological features, blood tests, laboratory finding, or imaging studies.
Pain arises from involuntary spasm of colon smooth muscle. Imo a disordered pelvic girdle explains ibs & fibromyalgia (often concommitant).

In brief: Parasympathetic

Parasympathetic nervous system over activity evokes colon spasm & evacuation; imo a possible cause of ibs, which is a functional disorder for which there are no demonstrable tissue pathological features, blood tests, laboratory finding, or imaging studies.
Pain arises from involuntary spasm of colon smooth muscle. Imo a disordered pelvic girdle explains ibs & fibromyalgia (often concommitant).
Dr. Laurence Badgley
Dr. Laurence Badgley
Thank
1 comment
Dr. Laurence Badgley
Irritable bowel syndrome is a functional disorder without a known cause.  Empirically it is known that useful medications modify autonomic neural function.  My clinical research has discovered a group (N=20) of male extreme sport enthusiasts who suffer from IBS.  The unifying clinical finding was that they all had sacroiliac joint (SIJ) injury and hypermobility (subluxation) disorder (diagnosed via criteria published in the Occupational Disabilities Guidelines).  I speculate that SIJ hypermobility stimulates the pelvic presacral plexus & contained parasympathetic nerves that innervate the colon, inducing colon spasm and evacuation.  IBS highly correlates with fibromyalgia, which is likewise common in persons with SIJ subluxation disorder. The reason for a "spectrum of disorder" for fibromyalgia is that the cause, pelvic girdle instability due to pelvic ligament laxity, manifests differently in individuals & genders.  The body musculoskeletal tower is constantly stressed by gravity & a body tilted above an unstable pelvis incurs widely ranging chronic muscle spasm leading to varying densities of painful trigger points. The delicate female pelvis is more easily injured & women have an higher incidence of Joint Hypermobility Syndrome (inherited trait) that contributes to pelvis instability.  Female pelvices are subject to varying intensities of permanent injury related to frequency of childbirth.  In both sexes, severity of fibromyalgia symptoms is a function of musculoskeletal deconditioning & upper body mass borne by an unstable pelvis.  On a Pain Board at Quora.com I discusses these dynamics, which are the true cause of fibromyalgia.  I also discuss my study of male extreme sport enthusiasts who have IBS. 
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