Polyphagia

Polyphagia or hyperphagia is an abnormally strong sensation of hunger or desire to eat often leading to or accompanied by overeating. In contrast to an increase in appetite following exercise, polyphagia does not subside after eating and often leads to rapid intake of excessive quantities of food. Polyphagia is not a disorder by itself, rather it is a symptom indicating an underlying medical condition. It is frequently a result of abnormal blood glucose levels (both hyperglycemia and hypoglycemia), and, along with polydipsia and polyuria, it is one of the "3 Ps" commonly associated with diabetes mellitus.

Etymology and pronunciation

The word polyphagia (/ˌpɒliˈfeɪdʒiə/) uses combining forms of poly- + -phagia, from the Greek words πολύς (polys), "very much" or "many", and φαγῶ (phago), "eating" or "devouring".

Underlying conditions and possible causes

Polyphagia is one of the most common symptoms of diabetes mellitus. It is associated with hyperthyroidism and endocrine diseases, e.g., Graves' disease, and it has also been noted in Prader-Willi syndrome and other genetic conditions caused by chromosomal anomalies. It is only one of several diagnostic criteria for bulimia and is not by itself classified as an eating disorder. As a symptom of Kleine–Levin syndrome, it is sometimes termed megaphagia.

Knocking out vagal nerve receptors has been shown to cause hyperphagia.

According to the National Center for Biomedical Information, polyphagia is found in the following conditions:

• Chromosome 22q13 duplication syndrome
• Chromosome Xq26.3 duplication syndrome
• Congenital generalized lipodystrophy type 1
• Congenital generalized lipodystrophy type 2
• Diabetes mellitus type 1
• Familial renal glucosuria
• Frontotemporal dementia
• Frontotemporal dementia, ubiquitin-positive
• Graves' disease
• Hypotonia-cystinuria syndrome
• Kleine-Levin syndrome
• Leptin deficiency or dysfunction
• Leptin receptor deficiency
• Luscan-lumish syndrome
• Macrosomia adiposa congenita
• Mental retardation, autosomal dominant 1
• Obesity, hyperphagia, and developmental delay (OBHD)
• Pick's disease
• Prader-Willi syndrome
• Proopiomelanocortin deficiency
• Schaaf-yang syndrome

Polyphagia in diabetes

Diabetes mellitus causes a disruption in the body's ability to transfer glucose from food into energy. Intake of food causes glucose levels to rise without a corresponding increase in energy, which leads to a persistent sensation of hunger. Polyphagia usually occurs early in the course of diabetic ketoacidosis. However, once insulin deficiency becomes more severe and ketoacidosis develops, appetite is suppressed.

See also