Thanks to Ashley Stein-Merlob for presenting an yet to be solved case of a 63 yo female with worsening cognitive impairment, chronic diarrhea and weight loss undergoing a work-up for malabsorption.
The dirty scoop on STOOL STUDIES
- Fecal fat
- Sudan Ill Stain: Qualitative assessment, less sensitive, often used as a first pass test
- Quantitative 72-96 hour collection. Gold standard. More sensitive but difficult to get.
- Bacterial culture
- Not necessary in chronic diarrhea
- Indications in acute diarrhea: severe illness, inflammatory diarrhea, high risk hosts, symptoms lasting > 7d days, public health concerns
- Osms and Electrolytes
- Order if suspect surreptitious diarrhea from laxative abuse
- Biofire PCR
- Available at the VA, tests for 22 pathogens including C. dif, e. coli, shigella, giardia, and more. May be helpful for acute diarrhea but more costly than targeted testing
Approach to UNEXPLAINED WEIGHT LOSS in Older Adults
- The differential is broad and includes almost every organ system.
- Most common categories: malignancy, psychiatric, gastrointestinal disease, endocrine.
- In the elderly consider the 9 D’s of weight loss: Dementia, Dentition, Depression, Diarrhea, Disease (acute and chronic), Drugs, Dysfunction, Dysgeusia, and D
- First pass work-up
- Basic labs: CBC, BMP, LFTs, TSH
- CRP, ESR
- ** Pearl from Meg Pearson – Although non-specific an elevated test result may prompt you to do a more thorough work-up.***
- LDH, UA, CXR, FOBT
- Consider: Abdominal ultrasound
- A prospective study demonstrated that if this baseline work-up is normal none of the patients went on to have malignancy demonstrated on additional testing. Therefore if the baseline work-up is normal, no further testing is necessary but continue with close follow-up.
- When to get colonoscopy?
- Primarily to look for microscopic colitis, IBD, malignancy
- Should be considered if there are persistent symptoms, inconclusive diagnosis, or failure to respond to therapy.
- Probably best to refer to GI prior to colo to ensure biopsies are taken
- Resource: AAFP Practice guidelines for Unexplained Weight Loss in Older Adults