Addison's disease, a chronic disorder of the endocrine system, is caused by an inability of the adrenal glands to produce sufficient steroid hormones (specifically, two types of necessary natural corticosteroids). In addition to causing renal insufficiency and muscle weakness, Addison's has been known to idiopathically—through an unknown mechanism—hyper-sensitize one or more senses in the body, most commonly taste.

The receptors for salty and sour are believed to be ion sensors. MSG stimulates receptors corresponding to unami. PROP causes an intense bitter sensation in "supertasters." Sweet and bitter receptors are believed to be similar to odorant receptors because molecules dock on transmembrane receptors in order to initiate an action potential.