For hormones, why saliva testing?

Saliva is really lymph fluid and lymph is what has come in contact with the your cells. What is in your blood may never get outside your blood vessels and impact the function of your cellular metabolism, especially your endocrine metabolism. Here's a lot more information from one of the labs we use at the Institute.
https://www.labrix.com/reporting-spring/staticContent.do?page=testing.saliva.whySaliva

Holistic medicine’s philosophy is to correct the problem through the use of substances that address the cause.  This can be done through supplying the body with the nutrients it is lacking, by balancing and optimizing the hormones produced by the endocrine system, through cleansing the tissues of irritating toxins, by clearing away bacteria or fungus that can be the source of inflammation, by improving immunological resistance, and by offering advice about correcting a lifestyle that’s contributing to their illness.

Both systems, whether it’s allopathic or holistic, should utilize the same diagnostic tools such as the physical exam and lab testing.  Holistic practitioners often incorporate other less orthodox tools for this investigation.  Some of the tools we use at our institute are dark field microscopy, electro-dermal screening, heart rate variability and the BIA screening for metabolic rater adn fat muscle ratio.

To clarify, there are many MDs practicing holistic medicine and there are many supposedly holistic practitioners who are not using all the tools necessary to properly and ethically diagnose.  Nor are these practitioners trained or equipped to determine and address the full range of causes or etiologies of their patient's illnesses.