Saul Marcus, ND - Naturopathic Doctor

257 West 39th street, 10th floor - New York, NY 10001

Phone:(646)330-0388 | Email:

Contact Office For Appointment

Introduction To Functional Lab Tests

What is a functional lab test?

In conventional lab tests are designed to diagnose disease. This is important and conventional labs do have their place. Nonetheless, diagnosing a disease does not necessarily tell you why someone has the disease.

For example testing for elevated RA factor in blood is helpful in diagnosing rheumatoid arthritis. But this doesn't say why RA factor is elevated.

In natural health we want to go further than diagnosing disease. We want to diagnose the cause of disease. For example, a positive RA factor blood test is important for diagnosing rheumatoid arthritis. However from a "functional medicine" perspective a comprehensive stool test may be more important in uncovering the causes inflammation which leads to rheumatoid arthritis.

Additionally it may take years for the underlining functional issues to cause a disease. Functional labs tests may give us the chance to address the causes of disease far before the problem ever progresses to that point. This is truly preventative medicine.

functional problem gradually becomes a pathological disease

Functional labs typically may test the following compartments:

Since many of these labs do not test blood, often sample collection is done by patients at home and then shipped to the lab.

Some of the labs more commonly used by practitioners include:

The following pages cover a few specific functional labs in more detail:

Porphyrin testing

Hair analysis

Saliva cortisol

Functional stool test

Limits of lab tests

It should be kept in mind that lab tests are only one part of assessment. Taking a good history, in office evaluation and conventional lab test all have their place as well. Lab tests results need to be understood in context of the individual. It's important to treat the person with lab tests just another tool. The goal is not to treat markers on a lab tests outside of any other individualized assessment.