Polydipsia

Polydipsia is excessive thirst. The word derives from the Greek πολυδιψία, which is derived from πολύς (polys, "much, many") + δίψα (dipsa, "thirst"). Polydipsia is a nonspecific symptom in various medical disorders. It also occurs as an abnormal behaviour in animals.

Causes

This symptom is characteristically found in diabetics, often as one of the initial symptoms, and in those who fail to take their anti-diabetic medications or whose condition is poorly controlled. It can also be caused by a change in the osmolality of the extracellular fluids of the body, hypokalemia, decreased blood volume (as occurs during major hemorrhage), and other conditions that create a water deficit. This is usually a result of osmotic diuresis. Diabetes insipidus ("tasteless" diabetes, as opposed to diabetes mellitus) can also cause polydipsia. Polydipsia is also a symptom of anticholinergic poisoning. Zinc is also known to reduce symptoms of polydipsia by causing the body to absorb fluids more efficiently (reduction of diarrhea, induces constipation) and it causes the body to retain more sodium; thus a zinc deficiency can be a possible cause. The combination of polydipsia and (nocturnal) polyuria is also seen in (primary) hyperaldosteronism (which often goes with hypokalemia). Antipsychotics can have side effects such as dry mouth that may make the patient feel thirsty.

Polydipsia in birds

Polydipsia is an excessively large water intake. Its occurrence in captive birds has been recorded, although it is a relatively rare abnormal behaviour.

Causes

Toxins

Polydipsia can be the result of a bird having ingested a toxin, or overconsumption of natural substances. For example, in pet birds, crackers, snack items, chips, fast foods, and canned vegetables (unrinsed) if eaten in sufficient quantities may cause a mild salt toxicity (5-10 times requirement) and subsequent polydipsia. Polydipsia can result from zinc poisoning to which caged birds may be particularly susceptible because of the zinc coating often used on birdcage bars.

Polydipsia has been experimentally induced in pigeons, budgerigars and ducks, by the administration of lithium chloride (LiCl). The polydipsic effect was greatest in budgerigars, a desert-dwelling species with a well-developed fluid retention system, and least in ducks, a species with an efficient sodium-secretion system.

Symptom of disease