The Urinary Concentrating Mechanism

Disorders of the urinary concentrating mechanism vary widely in their clinical importance. At one extreme, they may simply represent an inconvenience to the patient who has to arise several times each night to urinate. At the other extreme, they cause life-threatening fluid losses: in one memorable instance, a patient with diabetes insipidus was reported to excrete 47 liters in one day. Between these extremes, impaired urinary concentration may be the first clue to the presence of a systemic disturbance, such as hypercalcemia, Sjögren's syndrome or amyloidosis.The factors responsible for the kidney's remarkable ability to regulate daily water output from . . .