Clarice,
The Heidelberg Gastric Acid Analysis test is the most accurate, but it is expensive. I have never done it, but it is indicated for individuals with poor digestion who are not responding to general supplement administration.
In some patients where infection induced reflux problems have been ruled out, i.e. H. pylori, SIBO administering HCL supplementation seems to work fine. For example, the Support Digestion product from BioMatrix One – http://www.biomatrixone.com – calls for 2 capsules with meals. I have used higher dosages is a few individuals and if burning or irritation occurs I back off on the dose.
Dr. Woeller