How Accurate Is Stool Testing?

The popularity of stool testing is on the rise. With companies claiming to be able to diagnose a possible treatable cause of your digestive symptoms, it only seems fair that you may be tempted.

But, are these stool tests actually accurate? And, are the results actually useful?

Table of Contents

What CAN a Stool Test Show?

Parasites

Hook, Round or Tape Worms: these parasites can be easily transferred to humans from infested foods or surfaces. A stool test can be used to diagnose a hook worm infestation by looking for eggs in the stool.
Blastocystis Hominis: these parasites are commonly found in those with an IBS diagnosis (1). Often this issue clears itself up over time but in some circumstances of continued symptoms, treatment is required (2).
Dientamoeba Fragilis: this parasite is less common, with around 2% of IBS patients being shown to have it present (3). Medical treatment is required (4).
Endolimax Nana: this parasite is thought to infect around 13% of the healthy population. It is not clear whether this parasite actually causes any symptoms or not and so may actually live in the gut without any problem (like many other microbes) (5).
Entamoeba Coli: another microbe which causes no symptoms or problems in the gut.
Pentatrichomonas Hominis: this parasite is found in many animals, including humans where it can colonise the large bowel. However, it has only been shown affect 6% of children and 0% of adults (6).

Fungi / Yeast

Geotrichum spp: a fungi found commonly in soil, water and air which can spread and cause disease in those who are immunocompromised e.g. those undergoing chemotherapy with a low white blood cell count (7).
Microsporidium spp: a fungi which can cause a disease know as Microsporidiosis in those with an extremely weak immune system e.g. HIV positive. It is rarely seen in those with a healthy immune system (8).
Trichosporon spp: a fungi which is usually only seen in individuals with a weakened immune system such as those with cancer (9)

Enzyme Deficiency

Elastase-1: otherwise known as faecal elastase, this test determines whether your body is producing enough pancreatic enzymes. A deficiency of pancreatic enzymes is both a symptom of pancreatitis and pancreatic cancer.
Steatocrit: a measure used to look for steatorrhoea (fat the stool). This can occur in liver disease, pancreatic disease and bile salt malabsorption.

Inflammatory Markers

Calprotectin: commonly used to identify a potential inflammatory bowel disease diagnosis. However, further testing under a gastroenterologist is required to make this diagnosis.

Bacteria

Shigella and C.Difficile: Stool tests are commonly used to diagnose a number of bacterial infections.

What Does Stool Testing NOT Show?

Bacterial Overgrowth:

small bowel bacterial overgrowth is common and often mis-diagnosed as IBS. However, the only test we currently have is hydrogen breath testing alongside a clinical history from a gastroenterologist. Stool tests only show types of bacteria, not if these are in a state of overgrowth or not.

Candida Overgrowth:

candida overgrowth is rare condition and is usually only seen in those with a weekend immune system e.g. those going through chemotherapy or who have HIV. The only way to diagnose this is via a gastroscopy (camera down the throat).

Candida, as with many microbes, is actually commonly seen growing in many people people and causes no issues. The problem comes when there is an overgrowth, so detecting candida is there in a stool test is irrelevant.

Dysbiosis:

this terminology refers to an ‘imbalance’ in gut bacteria. Whilst we have a lot of research on gut bacteria, we actually don’t know what a ‘normal’ level is. This is why dysbiosis technically doesn’t exist – because, what is abnormal?

Autoimmunity:

there is nothing within a stool test to diagnose an autoimmune condition. This is done via blood tests and histological examinations e.g. a camera and biopsy to look for damage in the small bowel during a coeliac disease diagnosis.

Treatments

If testing positive for any of the issues mentioned above, treatment will need to be provided by your doctor.

Treatments will vary greatly depending on your symptoms, the test results and your current medical status.

Due to many of the tests being done privately, your doctor may wish to do further stool testing which then can guarantee the accuracy of.

Please note that herbal remedies are not recommended as they have limited scientific backing, which will only delay your treatment. Shop bought enzymes are also not recommended, if you do have an enzyme deficiency, then you will need prescription level enzymes and further investigations.

Summary

Many of the parasites / bacteria which stool tests show are naturally occurring in most individual’s digestive systems as part of a healthy gut microbiome. They only become an issue in large numbers which usually occur in rare cases where an individual’s immune system is extremely weak.

As part of ‘first line’ treatment, GP’s will test your stools when you report your digestive symptoms to them. They will use this, alongside a clinical history and blood tests to help diagnose you accurately.

Privately purchased stools tests, may be accurate in some cases, but without the clinical assessment and management of a doctor, their results are pretty useless. So save your money and head to your GP.

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Kirsten Jackson Consultant Dietitian BSc Hons, RD, PG Cert

Kirsten Jackson is a UK registered Consultant Gastroenterology Dietitian and founder of The Food Treatment Clinic. She has undergone many qualifications to get where she is today, including a UK BSc Honours Degree in Dietetics and Post-Graduate Certificate in Advanced Dietetics. In addition to this, she has FODMAP Training from Kings College London University. Kirsten set up The Food Treatment Clinic in 2015 after first experiencing digestive problems herself. She felt that the NHS was unable to provide the support individuals needed and went on to specialise in this area before opening a bespoke IBS service. Kirsten also participates in charity work as an Expert Advisor for the IBS Network. In addition, she can be seen in publications such as Cosmopolitan and The Telegraph discussing IBS as an Official Media Spokesperson to the IBS Network.