PMID- 21089176
OWN - NLM
STAT- MEDLINE
DCOM- 20110315
LR  - 20211020
IS  - 1098-2825 (Electronic)
IS  - 0887-8013 (Print)
IS  - 0887-8013 (Linking)
VI  - 24
IP  - 6
DP  - 2010
TI  - Is specific gravity a good estimate of urine osmolality?
PG  - 426-30
LID - 10.1002/jcla.20424 [doi]
AB  - CONTEXT: Urine specific gravity (USG) is often used by clinicians to estimate 
      urine osmolality. USG is measured either by refractometry or by reagent strip. 
      OBJECTIVE: We studied the correlation of USG obtained by either method with a 
      concurrently obtained osmolality. DESIGN: Using our laboratory's records, we 
      retrospectively gathered data on 504 urine specimens on patients on whom a 
      simultaneously drawn USG and an osmolality were available. Out of these, 253 
      USG's were measured by automated refractometry and 251 USG's were measured by 
      reagent strip. Urinalysis data on these subjects were used to determine the 
      correlation between USG and osmolality, adjusting for other variables that may 
      impact the relationship. The other variables considered were pH, protein, 
      glucose, ketones, nitrates, bilirubin, urobilinogen, hemoglobin, and leukocyte 
      esterase. The relationships were analyzed by linear regression. RESULTS: This 
      study demonstrated that USG obtained by both reagent strip and refractometry had 
      a correlation of approximately 0.75 with urine osmolality. The variables 
      affecting the correlation included pH, ketones, bilirubin, urobilinogen, glucose, 
      and protein for the reagent strip and ketones, bilirubin, and hemoglobin for the 
      refractometry method. At a pH of 7 and with an USG of 1.010 predicted osmolality 
      is approximately 300  mosm/kg/H(2)O for either method. For an increase in SG of 
      0.010, predicted osmolality increases by 182  mosm/kg/H(2) O for the reagent 
      strip and 203  mosm/kg/H(2)O for refractometry. Pathological urines had 
      significantly poorer correlation between USG and osmolality than "clean" urines. 
      CONCLUSION: In pathological urines, direct measurement of urine osmolality should 
      be used.
CI  - (c) 2010 Wiley-Liss, Inc.
FAU - Imran, Sethi
AU  - Imran S
AD  - Berkshire Medical Center, Internal Medicine, Pittsfield, Massachusetts, USA. 
      imransethi79@yahoo.co.in
FAU - Eva, Goldwater
AU  - Eva G
FAU - Christopher, Shutty
AU  - Christopher S
FAU - Flynn, Ethan
AU  - Flynn E
FAU - Henner, David
AU  - Henner D
LA  - eng
PT  - Comparative Study
PT  - Journal Article
PL  - United States
TA  - J Clin Lab Anal
JT  - Journal of clinical laboratory analysis
JID - 8801384
RN  - 0 (Reagent Strips)
SB  - IM
MH  - Humans
MH  - Hydrogen-Ion Concentration
MH  - Linear Models
MH  - Osmolar Concentration
MH  - Reagent Strips
MH  - Refractometry
MH  - Retrospective Studies
MH  - Specific Gravity
MH  - Urinalysis/*methods
MH  - Urine/*chemistry
PMC - PMC6647580
EDAT- 2010/11/23 06:00
MHDA- 2011/03/16 06:00
PMCR- 2010/11/18
CRDT- 2010/11/20 06:00
PHST- 2010/11/20 06:00 [entrez]
PHST- 2010/11/23 06:00 [pubmed]
PHST- 2011/03/16 06:00 [medline]
PHST- 2010/11/18 00:00 [pmc-release]
AID - JCLA20424 [pii]
AID - 10.1002/jcla.20424 [doi]
PST - ppublish
SO  - J Clin Lab Anal. 2010;24(6):426-30. doi: 10.1002/jcla.20424.