Polydipsia is possible to rule out psychogenic polydipsia or habit polydipsia. Polydipsia is a symptom (evidence of a disease state), not a disease in itself. As it is often accompanied by polyuria, investigations directed at diagnosing diabetes insipidus and diabetes mellitus can be useful. Blood serum tests can also provide useful information about the osmolality of the body's extracellular fluids. A decrease in osmolality caused by excess water intake will decrease the serum concentration of red blood cells, blood urea nitrogen (BUN), and sodium. Polydipsia Polydipsia is excessive thirst or excess drinking. The word derives from the Greek () "very thirsty",
Medical sign Medical sign A medical sign is an objective indication of some medical fact or characteristic that may be detected by a patient or anyone, especially a physician, before or during a physical examination of a patient. For example, whereas a tingling paresthesia is a symptom (only the person experiencing it can directly observe their own tingling feeling), erythema is a sign (anyone can confirm that the skin is redder than usual). Symptoms and signs are often nonspecific, but often combinations of them are at least suggestive of certain diagnoses, helping to narrow down what may be wrong. In other cases