Cats, like all other mammals, need proper electrolyte balance for their bodies to function properly. Electrolyte imbalances are often the result of a kidney dysfunction, a sign that the organs aren't functioning properly.
The kidney is full of small structures called nephrons. The nephrons filter waste out of the body and help regulate the levels of electrolytes. If a cat has a disease like Chronic Renal Insufficiency, the nephrons die and electrolytes become imbalanced.
Cats with electrolyte imbalances will exhibit symptoms like a marked increase in thirst and excessive urination. Other symptoms include weight loss, vomiting and lack of appetite.
Chronic Renal Insufficiency is a terminal disease. You can, however, maintain quality of life through proper diet and medication. Other conditions like urethral obstruction or interstitial cystitis can also cause electrolyte imbalances.