Polydipsia

Polydipsia is excessive thirst or excess drinking. The word derives from the Greek πολυδίψιος ("poludípsios") "very thirsty", which is gotten from πολύς ("polús", "much, many") + δίψα ("dípsa", "thirst"). Polydipsia is a symptom in many diseases. It also occurs as a weird behaviour in some animals, such as in birds.
Causes.
Diabetes.
Polydipsia can be a symptom of diabetes mellitus. It is seen in cases of poorly controlled diabetes. Diabetes insipidus can also cause polydipsia.
Other physiological causes.
It can also be caused by a change in the osmolality of the extracellular fluids of the body, hypokalemia, decreased blood volume, and other conditions that create water deficiency.
Diagnosis.
Polydipsia is a symptom and not a disease in itself. Polydipsia investigations at diagnosing diabetes insipidus and diabetes mellitus can be useful.