Objective: To investigate the reliability and validity of refractometry, hydrometry, and reagent strips in assessing urine specific gravity in collegiate wrestlers.
Design and Setting: We assessed the reliability of refractometry, hydrometry, and reagent strips between 2 trials and among 4 testers. The validity of hydrometry and reagent strips was assessed by comparison with refractometry, the criterion measure for urine specific gravity.
Subjects: Twenty-one National Collegiate Athletic Association Division III collegiate wrestlers provided fresh urine samples.
Measurements: Four testers measured the specific gravity of each urine sample 6 times: twice by refractometry, twice by hydrometry, and twice by reagent strips.
Results: Refractometer measurements were consistent between trials (R 5 .998) and among testers; hydrometer measurements were consistent between trials (R 5 .987) but not among testers; and reagent-strip measurements were not consistent between trials or among testers. Hydrometer (1.018 6 0.006) and reagent-strip (1.017 6 0.007) measurements were significantly higher than refractometer (1.015 6 0.006) measurements. Intraclass correlation coefficients were moderate between refractometry and hydrometry (R 5 .869) and low between refractometry and reagent strips (R 5 .573). The hydrometer produced 28% false positives and 2% false negatives, and reagent strips produced 15% false positives and 9% false negatives.
Conclusions: Only the refractometer should be used to determine urine specific gravity in collegiate wrestlers during the weight-certification process.
This is the publisher's version of the work. This publication appears in Gettysburg College's institutional repository by permission of the copyright owner for personal use, not for redistribution.
Stuempfle, K., and D. Drury. Comparison of 3 Methods to Assess Urine Specific Gravity in Collegiate Wrestlers. Journal of Athletic Training (December 2003) 38(4):315-319.