Section 11. Kidney and Urinary Tract Disorders

Chapter 146. Tubular and Cystic Kidney Disorders

Topics: Introduction | Renal Tubular Acidosis | Renal Glucosuria | Nephrogenic Diabetes Insipidus | Cystinuria | Fanconi's Syndrome | Hypophosphatemic Rickets | Hartnup Disease | Bartter's Syndrome | Liddle's Syndrome | Polycystic Kidney Disease | Medullary Cystic Disease | Medullary Sponge Kidney | Alport's Syndrome | Nail-Patella Syndrome

Introduction

The primary function of the kidneys is to filter and cleanse the blood. They also maintain the body's balance of water, dissolved salts (electrolytes), and nutrients in the blood. The kidneys begin these tasks by filtering the blood as it flows through tiny blood vessels (glomeruli). This process moves a large amount of water and electrolytes and other substances into small tubules. The cells lining these tubules reabsorb and return needed water, electrolytes (sodium, potassium, calcium), and nutrients (glucose, amino acids) to the blood. The cells also move waste products and drugs from the blood into the fluid (which becomes urine) as it flows through the tubules.

Disorders that interfere with the function of the cells lining the tubules are called tubular disorders. Some conditions, called cystic disorders, interfere with these tubular cell functions by causing fluid-filled sacs (cysts) to form and in doing so compress normal tubules. Many of these tubular and cystic disorders are hereditary; of these hereditary disorders, some are present at birth. The effects of other hereditary disorders are not obvious until years later.