Further links between Fibromyalgia and Irritable Bowel Syndrome (IBS)

Researchers have long known of a link between irritable bowel syndrome (IBS) & fibromyalgia. In some studies, as many as one third of fibromyalgia patients were also diagnosed with IBS. Fibromyalgia and IBS are both common conditions that account for 30% or more of referrals to rheumatology and gastroenterology clinics. A study at Cedars-Sinai Medical Center has zeroed in on a test that might identify this link.

Irritable Bowel Syndrome is the most common gastrointestinal diagnosis, where prevalence in some populations reported as high as 30%. IBS is significantly more common in woman than in men and affects an estimated 13% to 20% of Canadians. Symptoms of IBS include abdominal pain, bloating, and altered bowel habits such as constipation and diarrhea, or alternating between the two stool consistency extremes.

Fibromyalgia is widespread pain in the muscles, ligaments, and tendons that often leaves people with fatigue and trouble sleeping. It may also include other symptoms. It is not associated with tissue inflammation and the cause of the pain is unknown. Fibromyalgia seems to increase with age, where 2% of the population at age 20 has this disorder, and 8% have it at age 70. It is about ten times more common in females than in males. In approximately one-half of fibromyalgia cases, the symptoms appeared to begin after a specific event, most often some form of physical or emotional trauma or a flu-like illness.

In an older study from Ireland, researchers compared groups of patients with fibromyalgia and IBS to normal and disease control populations. They studied four patient groups, 20 patients in each group, with fibromyalgia, IBS, inflammatory arthritis, inflammatory bowel disease, and 20 normal controls. Using strict diagnostic criteria, two investigators assessed each group for symptoms and signs of fibromyalgia and IBS. Sigmoidoscopy was performed when indicated. Results indicate that 70% of fibromyalgia patients had IBS and 65% of IBS patients had fibromyalgia. This compared with the control groups where 12% had fibromyalgia and 10% IBS. In conclusion, these findings indicate that fibromyalgia and IBS frequently coexist.1

Researchers at the Cedars-Sinai Medical Center concluded from a small study that subjects with IBS appear to have a high prevalence of small intestinal bacterial overgrowth (SIBO), as reported in The Inside Tract, Issue #129 January/February 2002. There are mechanisms in the body to help prevent naturally occurring colon bacteria from backing-up into the small intestine (which should be bacteria-free). A specialized breath test to assess this overgrowth, called a lactulose hydrogen breath test, or LHBT for short, has been helpful in identifying IBS patients with SIBO. When treated with antibiotics, 48% of patients with SIBO experienced successful resolution of their IBS symptoms.2

Now researchers at the same US centre are using this LHBT to check for microbes in the intestine, which might provide a stronger link between fibromyalgia and irritable bowel syndrome. Their hypothesis was that the LHBT would be abnormal in both IBS and fibromyalgia subjects. They tested this hypothesis by performing the test in 42 fibromyalgia patients, 111 IBS patients, and 15 healthy subjects. All 42 patients with fibromyalgia had an abnormal LHBT result, as did 93 (84%) of IBS patients, but only three (20%) of the controls had abnormal LHBT results. Interestingly, the amount of hydrogen gas produced during the LHBT seemed to correlate directly with the degree of pain in fibromyalgia patients, in that the greater the amount of hydrogen gas produced, the greater the somatic (pertaining to the body not the mind) pain.3

In conclusion, the researchers found that an abnormal LHBT might be a shared characteristic among individuals with fibromyalgia and irritable bowel syndrome. They note that, “Further study is needed to determine if treatment and normalization of the breath test with antibiotic treatment can produce an improvement in fibromyalgia in addition to bowel complaints.”

First published in the Inside Tract® newsletter issue 142 – March/April 2004
1. Veale D, Kavanagh G, Fielding JF, Fitzgerald O. Primary fibromyalgia and the irritable bowel syndrome: different expressions of a common pathogenetic process. British Journal of Rheumatology 1991; Jun; 30(3): 220-2
2. Pimentel M, Chow E, Lin HC. Eradication of small intestinal bacterial overgrowth reduces symptoms of irritable bowel syndrome. American Journal of Gastroenterology 2000; 95: 3503-3506
3. Pimentel M, Wallace D, Hallegua D, Chow E, Kong Y, Park S. Lin HC. A link between irritable bowel syndrome and fibromyalgia may be related to findings on lactulose breath testing. Annals of Rheumatic Diseases 2004; 63: 450-452
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