digital pdf guide

Stool Testing – A Guide for Practitioners

You ordered the GI 360. Now what does it actually mean?

A 16-section reference for reading stool panels — GI 360, CSA+P, CSA, and Microbiology Only — marker by marker. Built from how Dr. Lundell reads these reports in his own practice, so you know which test to order, what each value is telling you, and where the common interpretation traps are.
Stool testing is foundational to functional medicine, but the reports are dense and easy to misread. A "normal" Dysbiosis Index can sit right next to a 3+ Klebsiella growth. A clean microbiome score can be a false negative. This guide walks you through how to read the whole picture — culture, PCR, microscopy, and chemistries together — rather than chasing single markers.

You'll learn how to match the right test to the clinical scenario, interpret every section of the report, and build a progressive testing strategy that controls patient cost without losing precision.

What's Inside

Test selection — When to order GI 360 vs. CSA+P vs. CSA vs. Microbiology Only, and a step-by-step progressive testing strategy from baseline through monitoring.

Microbiome & the Dysbiosis Index — How to read the hexagonal phyla chart, why the DI alone misleads, and how to integrate it with culture and parasitology.

Microbiology culture — The three bacterial categories, the four dysbiotic organisms that warrant treatment at any growth level, and how to read yeast on culture vs. microscopy.

Parasitology — PCR and microscopy together, why 3-sample collection raises sensitivity from 80% to 96–98%, and which organisms to treat regardless of symptoms.
Stool chemistry markers — A complete reference for elastase, calprotectin, lactoferrin, sIgA, SCFAs, beta-glucuronidase, zonulin, and more — with reference ranges and what each one means clinically.

Susceptibility testing — Prescriptive and natural agents, biofilm disruptors, and why a high-sensitivity result can still fail clinically.

HCl assessment protocol — A step-by-step betaine HCl titration, including the gastritis screen that comes first.

Follow-up & monitoring — Testing sequence, what should change with effective treatment, and when to repeat a full panel.

Who This Is For

Licensed practitioners — chiropractors, MDs, NDs, NPs, and others — who order functional stool panels and want to read them with more confidence. Whether you're new to GI testing or sharpening interpretation you already do, this is a working reference you'll keep open next to the report.
This guide pairs with the GI Restoration Protocol, which covers the treatment side — antimicrobial protocols, the 4R framework, and the GI Repair Shake. Together they take you from testing through treatment.
Meet Your Instructor

Dr. Brandon Lundell, DC

Dr. Brandon Lundell, DC, DABCI, IFMCP has been in clinical practice for over 20 years and has trained more than 1,000 practitioners in functional medicine nationwide. He maintains an active waiting-list practice at Harmony Healing Center in Longmont, Colorado. The protocols in these guides reflect what's being applied in practice, not theoretical frameworks.

View Dr. Lundell's CV
Patrick Jones - Course author

Get the Practitioner's Guide to Interpreting Stool Tests

16 sections · complete marker reference · written by a clinician still in practice
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