CAUSES OF CHRONIC DIARRHEA
Suspect / Diagnose in 1° Care
Let G-I Figure Out
KEY CLUES / RED FLAGS
Consider– Any Organic Etiology – IBD, Colon Cancer, Ameba – Colon Cancer – Malabsorption – Parasites – Parasites; HIV; AIDS infections – IBD – Needs extensive work-up
- CBC — Normocytic Anemia suggests IBD; Microcytic suggests iron deficiency from Cancer, IBD, Celiac Disease
- ESR / CRP — significant elevation suggests IBD, maybe cancer metastases
- Total Protein & Albumin – serum globulin >4 g/dL suggests systemic inflammation (how to calculate); low albumin suggests nutritional deficiency)
- Tissue-Transglutaminase Antibody (TTG), IgA fraction (for Celiac Disease)
- Stool for Giardia Antigen
- TSH (hyperthyroidism is unlikely, but a one-time cheap test rules it out)
- Ova & Parasites (O&P) [need to order at least 3 separate specimens]
- Stool for C. difficile (if antibiotic use preceded onset of Sx; also in immunocompromised patients)
- Stool C&S (esp. in immunocompromised persons)
- Fecal Fat for malabsorption, esp. if greasy stools. Ask you lab about single-stool options, before ordering a 72-hour stool collection. You could let G-I deal with this, since they’d be the ones to work-up positive results anyway.
NEVER an Occult Blood test for Diarrhea (terrible specificity, ? sensitivity).