You may be aware of reflux or regurgitation or of the acid burn we refer to as heartburn and this book may make you aware of other possible symptoms you may not have previously considered pertinent. (N.B. Not everyone with acid reflux experiences heartburn.)
It is claimed you can test your stomach acidity by ingesting baking soda and determining how long it is before you belch. Whereas the science behind this has some credibility (baking soda + stomach acid = carbon dioxide = burp), there are so many variables as to make results calculated this way too unreliable for accurate diagnosis.
Other tests of acidity of saliva, urine or blood have no correlation to the acidity of the stomach.
The February 2015 Be Clear On Cancer eosophago-gastric cancers campaign claimed persistent heartburn could be a sign of cancer and to "Tell your doctor"
Action Against Heartburn says, consult your GP if you have any of these symptoms:
There are many tests that may be undertaken to determine whether problems are from excess or too little acid (24 hr pH manometry or Bravo 48 hr ambulatory pH monitoring), swallowing difficulties (barium meal), reflux caused by a weak Lower Oesophageal Sphincter (manometry), Peptest and others but the usual first diagnostic tool is endoscopy when a camera is used to look down your throat and oesophagus for signs of damage or a pill with a camera in may need to be swallowed. It is hoped a newer, less invasive technique (cytosponge) will be available soon.
Other tests that may be performed include ultrasound, various x-rays and a CT scan.
Results of these tests are analysed to determine exactly what the problems may be so a treatment regimen may be prepared.