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Research article2014Peer reviewed

Comparison of a Schmidt and Haensch refractometer and Atago PAL-USG Cat refractometer for determination of urine specific gravity in dogs and cats

Tvedten, Harold; Norén, Åsa


Background: A digital Atago PAL-USG Cat refractometer (Atago) was compared to a Schmidt and Haensch, Goldberg type refractometer (S+H). Materials and Methods: Specific gravity of 47 canine and feline patient urine samples was determined with both refractometers. Specific gravity of dilutions of 10 % glucose, 10 %Na Cl and 3 % albumin solutions was determined and compared to expected values. Results: Both refractometers reported 1.000 with distilled water. Correlation between instruments with 47 urine samples was excellent, r = 0.99, but Atago had a significant, proportional, negative error. Ten urine samples had an S+H result of > 1.030 but Atago results for the same samples were 1.023-1.028. S+H results of various glucose solutions matched exactly expected values but Atago results were lower. S+H results with diluted NaCl solutions were closer to expected results than Atago results. Atago results with dilutions of 3 % albumin were closer to expected results than S+H results. Discussion: An Atago refractometer reported lower specific gravity results which could adversely affect determination of a canine urine sample considered concentrated enough (> 1.030) to indicate normal renal function.

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Veterinary Clinical Pathology
2014, Volume: 43, number: 1, pages: 63-66

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