Just take very good care of the one you have left. Maybe do some reading about "adrenal fatigue" and its causes and prevention. There's lots of info. out there on the subject but in short you want to avoid prolonged stress on your adrenal gland such as from lack of sleep, too much stress, caffeine or other stimulants, fasting, and chronically elevated catecholamines that are caused by unrelenting VLC dieting. One author that has written a fair amount about adrenal fatigue and the lifestyle eating style to prevent that, is Diana Schwarzbein, endocriniologist. Aka "The Schwarzbein Principle."
It is possible to test the functioning of your adrenal glands via a saliva test that is taken at muliple times during the day, then those samples frozen and sent to a lab. Not sure how this test would work in your situation though. I did mine through a naturopath.