June 1988

Interpretation of Specific Gravity by Dipstick

Author Affiliations

Department of Pediatrics State University of New York Health Science Center at Brooklyn 450 Clarkson Ave Box 49 Brooklyn, NY 11203

Am J Dis Child. 1988;142(6):592. doi:10.1001/archpedi.1988.02150060026016

Sir.—The widespread use of dipsticks such as the Ames N-Multistix-SG strip (Miles Laboratories, Elkhart, Ind) has some built-in problems as well as a form of medical laboratory absurdity. Comments have been made in the more general literature, but to date we have not read a comment in a pediatric journal.

I refer specifically to the use of the term specific gravity that one reads from these strips. The measurement of specific gravity in urine has been used in clinical medicine for a number of years with known advantages and disadvantages. One advantage is that in the absence of albumin and glucose, the specific gravity has a nearly linear correspondence to osmolality over the range of interest to the clinician. This correlation enables one to detect the ability of the kidney to concentrate and dilute, which is a sensitive measure of renal function. This usefulness is lost if there is

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