E-Case #5

Week of  2/3 -2/7/03

Kathryn Kovacs. MD

CC/ID:

41 yo female, new to your clinic, presents with 1 month history of intermittent diarrhea and abdominal pain.

HPI:

Describes gradual onset of watery diarrhea 1 mos ago with associated diffuse abdominal cramping, intermittent and somewhat relieved by defecation.  Episodes initially 2-3 days/wk but over last week occur daily, 5-6 loose stools/day. Occasional flatus. Denies fecal incontinence.  Denies any blood with stools.  No F/C.  Intermittent nausea with only 1 episode of emesis about 2 wks ago.  Symptoms worse with eating.   Currently only tolerating 7-UP and crackers.  No prior episodes and no recent antibiotic use, raw food ingestion or travel. No well water consumption. No sick contacts. Loperimide of benefit.

ROS:

No wt loss. No dysphagia or odynophagia.  Occasional dyspepsia, ~ 1 episode /2 wks.  No prior hx of constipation, diarrhea, fecal incontinence, hematochezia, melena.  No CP, SOB/DOE, cough. No irritative voiding sxs or urinary incontinence. No rashes or lesions.  LMP completed 4 days ago and last pelvic exam with pap smear 2 mos prior, all normal.

Medications:

No prescription meds or herbal remedies.  Loperimide on a prn basis over the last month.

Allergies:

• NKDA

• PMHx/PSHx:

• Hx of atypical CP in 11/01 but had negative ischemic/CAD w/u with stress echocardiogram.  No chronic illness, no hospitalizations or surgeries.

Social  History/Habits:

No tobacco or alcohol ever. No IVDU or illicit drug use ever.  Married, mutually monogamous over last 15 yrs.

Family History:

Negative for IBD, or colon cancer.

Focused PE:

Normal VS. Moderately overweight.  Appears euvolemic.  and exam essentially unremarkable with exception of bilateral lower quadrant tenderness elicited with deep palpation, but no masses, or HSM and BS normoactive.  DRE also elicited some tenderness, but no palpable mass and hemoccult negative.

What is your differential dx?

Watery, stools suggests secretory or osmotic diarrhea.

• Osmotic diarrhea generally from carbohydrate malabsorption or magnesium, phosphorus excess.
• Secretory diarrhea broad diff dx and includes laxative abuse, infectious etiologies, IBD, bile acid malabsorption, vasculitis, drug side effect, disordered motility syndromes, neuroendocrine tumors, neoplasia and idiopathic.

What tests do you order to narrow your differential dx?

Labs:

• CBC to look for leukocytosis, i.e. infection, and anemia.  The latter would be a red flag in w/u of this patient's diarrhea.
• BMP to assess for dehydration, alkalosis, hypokalemia, if diarrhea severe.
• TSH (since diarrhea predominant symptom)
• Stool sample
  • examine for O and P, fecal leukocytes, +/- enteric pathogens, +/-giardia antigen based on clinical suspicion.
  • three separate and fresh stools are actually recommended to enhance sensitivity.
  • Ancillary stool tests:
  • pH to assist in diagnosing carbohydrate malabsorption (low pH)
  • quantitate fat output (not done here as no hx suggesting fat malabsorption).

All above labs except ancillary stool tests completed and are normal, and patient denies magnesium-containing antacid use, lactose intolerance or consumption of sorbitol-containing foods.

There are no red flags, i.e., fever, heme-positive stools, weight loss, nocturnal symptoms, abdominal or rectal mass, family hx of colon cancer or IBD or age >50.  This patient has a typical presentation (history and PE findings) for Irritable Bowel Syndrome,(IBS) as the etiology of her diarrhea and abdominal pain.  What should you do to confirm your diagnosis and what are the treatment options?

Diagnosing IBS:

• IBS is chronic or recurrent GI symptoms of abdominal pain and altered bowel habits, not explained by structural or biochemical abnormalities.
• Diagnosis should not be made only by excluding organic disorders. Latter approach would be costly and involve unnecessary testing since a limited diagnostic approach rules out organic disease in over 95 percent. ^{1, 4}
  • This includes CBC, chemistry panel in all patients and TSH and stool studies if diarrhea is the predominant symptom. Some advocate ESR.
  • Other initial diagnostic studies recommended for pts > 50 include flexible sigmoidoscopy or colonoscopy.
• Emphasis placed on identifying a symptom complex based on patient's history with careful assessment for the presence of red flags or possible dietary or medication precipitants of diarrhea.²
• Consensus definition published in 1992 known as the Rome I criteria, with a revision (Rome II criteria) put forth in 1999 and currently in use.²

• Reasonable to consider additional diagnostic studies and/or gastroenterolgist referral in patients who do not respond to recommended treatment measures  (see below).^{1, 2}
• Further diagnostic evaluation, like recommended treatment options, is based upon the predominant symptom(s) of diarrhea, constipation and/or abdominal pain.²
• Treatment
• For all patients, the physician should establish an effective, therapeutic relationship educating and reassuring patients on the benign nature of the disease.

Basic treatment options based on the nature and severity of the symptoms:

Milder symptoms relate primarily to visceral hyperactivity and/or hypersensitivity.¹

More severe symptoms associated with psychosocial difficulties.

Predominant symptom(s), i.e. constipation, diarrhea and/or abdominal pain also guide basic therapy.^1,3

Newer treatment modalities target possible but unproven etiologies, e.g. abnormal GI motility, visceral hypersensitivity/hyperalgesia, altered GI immune function, GI autonomic dysfunction.^{1, 3}

Dietary modification may be necessary as certain foods, e.g. fatty foods, beans, lactose, alcohol and caffeine can exacerbate symptoms.

Table 2:  Drugs currently used for IBS and their efficacy*³

• For pain and bloating, antispasmodics/anticholinergics are used; best on prn basis.
• For constipation, recommendations include increasing dietary fiber at low doses initially as it may worsen abdominal distension and bloating if present.
• For diarrhea, loperamide and cholestyramine are commonly prescribed.

Table 3:  Newer agents under investigation for IBS³

• 5-hydroxytrptamine (serotonin) 4 receptor agonists stimulate the release of neurotransmitters and increase colonic motility.
• 5-hydroxytryptamine (serotonin) 3 receptor antagonists modulate visceral afferent activity and may improve abdominal pain, reduces colonic transit and small intestinal secretion.^1,4
  • Alosetron was withdrawn form the marked in November 2000 secondary to significant adverse event of severe constipation and ischemic colitis in some individuals taking the drug, despite no established causal relationship. It is now back on the market since spring of 2002 but has restricted guidelines for its use.
• Kappa agonists inhibit somatic pain and may improve abdominal pain.
• Whatever the treatment regimen:
• Patients should be reevaluated in 3-6 wks after trial of therapy to assess response, but persistent symptoms do not mean the diagnosis of IBS is incorrect.
• Patients with refractory or severe IBS should be questioned about physical and sexual abuse due to the role psychosocial stress has in modifying the illness experience and the outcome.  Psychiatric referral/medications may be necessary.

References

1. AGA Technical Review on Irritable Bowel Syndrome. AGA Clinical Practice Committee. Gastroenterology 2002; 123: 2108-31.

2. Fass R et al, Evidence-and Consensus-Based Practice Guidelines for the Diagnosis of Irritable Bowel Syndrome. Arch. Intern. Med 2001; 161: 2081-88.

3. Talley, NJ and Spiller, R. Irritable bowel syndrome: a little understood organic bowel disease?  The Lancet, 2002;360: 555-64.

4. Chun AB et al. Clinical manifestations and diagnosis of irritable bowel syndrome. UpToDate®,  www.uptodate.com, 2003