The kidneys are bean-shaped excretory organs in vertebrates. Part of the urinary system, the kidneys filter wastes (especially urea) from the blood and excrete them, along with water, as urine. The medical field that studies the kidneys and diseases affecting the kidney is called nephrology, from the Greek name for the kidney; the adjective meaning "kidney-related" is renal, from the Latin.
In humans, the kidneys are located in the posterior part of the abdomen. There is one on each side of the spine; the right kidney sits just below the liver, the left below the diaphragm and adjacent to the spleen. Above each kidney is an adrenal gland (also called the suprarenal gland). The asymmetry within the abdominal cavity caused by the liver results in the right kidney to be slightly lower than the left one.
The kidneys are retroperitoneal, which means they lie behind the peritoneum, the lining of the abdominal cavity. They are approximately at the vertebral level T12 to L3, and the right kidney usually lies slightly lower than the left in order to accommodate the liver. The upper parts of the kidneys are partially protected by the eleventh and twelfth ribs, and each whole kidney is surrounded by two layers of fat (the perirenal fat and the pararenal fat) which help to cushion it. In very rare cases, it is possible to have developed three kidneys.
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Best Practice of Medicine - A medical reference that covers management highlights, background, diagnosis, treatment, complications, special circumstances, when to consult or refer, prognosis, patient education, follow-up, prevention and screening, and charts.
Cecilia Maida's Page - Working to increase public awareness of polysystic kidney disease. Contact information and related links.
General Practice Notebook - Adult polycystic kidney disease - Information with emphasis on clinical aspects.
Mayo Clinic: Polycystic Kidney Disease - A description of the disease, and its detection and treatment.
Meta Description: [ Polycystic kidney disease — Comprehensive overview covers symptoms, treatment, prevention of this kidney condition. ]
Melanie's PKD Page - The personal story of experiences with polycystic kidney disease and resources.
National Kidney and Urologic Diseases Information Clearinghouse (NKUDIC) - Provides information about the inheritance, diagnosis and pathological course of the several forms of polycystic kidney diseases, as well as the molecular basis of the adult form.
Meta Description: [ Defines three types of polycystic kidney disease and describes its genetic origins, symptoms, diagnosis, and treatment, as well as ongoing research. ]
Nephrology Channel - An overview of polycystic kidney disease, including a description, types, causes, diagnosis and treatment.
Meta Description: [ Cystic kidney disease describes several conditions in which fluid-filled cysts form in the kidneys. PKD, which causes kidney cysts, is the most common inherited disease in the United States. ]
PKD Access Center - Information about polycystic kidney disease, its symptoms, causes and progression. Research and support group.
PKD Foundation - A site for patients, medical professionals and researchers of polycystic kidney disease.
Pkdiet - Personal accounts of dietary, herbal and topical means of coping with some aspects of kidney and liver disease.
Polycystic Kidney Disease (PKD) - Describes symptoms, organs affected, treatment and diagnosis.
Meta Description: [ Information about polycystic kidney disease from the American Academy of Family Physicians. ]
Polycystic Kidney Disease Message Board - Provides a forum for exchanges between individuals who suffer from polycystic kidney disease.
Meta Description: [ message board for people with Polycystic Kidney Disease to share information, talk about their problem and give support to one another. ]
The New England Journal of Medicine: Kidney Disease - The Kidney Disease collection covers topics such as renal failure, dialysis, and pathogenesis of nephropathy. Articles may be downloaded for a fee.
Meta Description: [ The Kidney Disease collection covers topics such as renal failure, dialysis, and pathogenesis of nephropathy and includes research articles, case reports, reviews, and editorial commentary. ]