A 56-year-old white woman with a history of fibromyalgia and anxiety presents to her primary care physician (PCP) for follow-up to review abnormal laboratory findings. During her visit she mentions worsening digestive problems including bloating and frequent diarrhea. The patient denies abdominal pain, nausea, and vomiting. Her digestive symptoms began approximately 3 years ago and have waxed and waned in severity. She believes certain foods intensify her symptoms but cannot pinpoint exactly which foods are the triggers.
The patient is not on any long-term prescription medications but occasionally takes an antacid. She recently finished courses of trimethoprim and sulfamethoxazole for a urinary tract infection.
Upon physical examination, the patient’s abdomen is extremely distended with hyperactive bowel sounds and hyper-resonance with percussion in all 4 quadrants. The abdomen is non-tender to palpation and the spleen and kidneys are non-palpable. Neither pulsatile mass nor ascites are present.
Laboratory tests are ordered: white blood cell count is 4.3 K/µL and lymphocytes are 1.2 K/µL. The patient’s calcium level is 10.3 mg/dL, but was reduced to 9.7 mg/dL following correction of albumin of 4.8 g/dL. Vitamin D 25-hydroxy is 20.9 ng/mL. Additional tests were within normal limits.
Differential diagnoses include antibiotic-induced Clostridium difficile colitis, food intolerance, irritable bowel syndrome (IBS), diverticulitis, and inflammatory bowel disease.
Additional tests are ordered, including thyroid-stimulating hormone, antinuclear antibody, erythrocyte sedimentation rate, and C-reactive protein, which are all within normal range. Stool guaiac and culture are also negative, ruling out C difficile infection.
The patient is referred to gastroenterology for further testing. Gallbladder ultrasound was normal with no stones or sludge identified in the gallbladder lumen. Endoscopy and colonoscopy images and biopsies were unremarkable.
The patient is then referred to an allergist. Food allergy testing was negative. The patient was instructed to try a dairy-free diet for 1 month and subsequently a gluten-free diet for 1 month. The patient did not experience relief from either elimination phase diets.
The patient returned to her PCP and was told she likely suffered from diarrhea-predominant irritable bowel syndrome (IBS-D); her demographics as a woman with fibromyalgia and anxiety and recent antibiotic use made the diagnosis even more likely. However, no specific test was performed to confirm the diagnosis.