Polydipsia: symptoms of diabetes mellitus

Polydipsia is the exaggerated ingestion of water; the thirst is due to the excessive water loss in the urine. Excessive thirst is best analyzed by the application of physiology. Thirst is cause by: intracellular dehydration and extracellular dehydration.

Increased desire for water may be due to a decreased intake, as in prolonged abstinence, vomiting of pyloric stenosis and intestinal obstruction, and diarrhea.

Diabetes mellitus is the single most common cause of polydipsia. Other common causes of polydipsia include sickle cell anemia and diabetes insipidus.

Urine production and water consumption (thirst) are controlled by interactions between the kidneys, pituitary gland and hypothalamus.

Usually, polydipsia occurs as a compensatory response to polyuria to maintain hydration. The patient’s plasma becomes relatively hypertonic and activates thirst mechanism.
Polydipsia: symptoms of diabetes mellitus