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Urine volume

Educational resources for renal medicine

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Urine volume

Urine volume is a poor guide to renal function as it is physiologically variable and 24-hour collections are often erroneous. However severe oliguria or polyuria imply pathology and require further investigation.

Too much

Difficult to set an upper limit of normal, but 4 litres is a lot.  Causes:

•    Osmotic diuresis – diabetes mellitus
•    Loss of antidiuretic hormone (ADH) – cranial diabetes insipidus (head injury, etc)
•    Failure to respond to ADH – nephrogenic diabetes insipidus
•    Excessive intake – psychogenic polydipsia

Too little

300-500 mls of urine is needed to excrete adequate amounts of solute each day.  Less than this is therefore oliguria.
•    Physiological response to severe dehydration
•    Hypoperfusion of the kidneys – hypotension or damage/occlusion to renal artery/aorta
•    Acute Renal Failure (see Approach to the patient with oliguria)


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Page last modified 01.12.2016, 22:47 by Administrator. edrep and edren are produced by the Renal Unit at the Royal Infirmary of Edinburgh and Univ. Edinburgh. CAUTIONS and Contact us. Note that the information published here is primarily intended for education, not for clinical care.