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Urine Specific Gravity by Refractometer (1595.P038)

Urine Specific Gravity by Refractometer (1595.P038) - Policies, Clinical, UWHC Clinical, Department Specific, Point of Care, Urinalysis Specific Gravity

1595.P038

UWHC Clinical Laboratories Original Date: 5/1/2013
Point of Care Current Version Date: 5/1/2013
Document Title: Urine Specific Gravity by Refractometer
Document ID: 1595.P38 Page 1 of 5



Medical Director and Date: Diane Norback, MD 5/6/2013
Diane Norback 3/17/17



Effective Date: 5/1/2013
Faculty Director Date Manager Date Technical Reviewer Date
Teresa Darcy, MD 5/3/13 Chris Reuter 5/22/13 Beth Urban 4/29/13
Teresa Darcy, MD 3/26/15 Cheryl Jordan 4/1/15 Sarah Emond 3/23/15
David Yang, MD 3/16/17 Cheryl Jordan 3/16/17 Lisa Wilson 3/16/17




I. Purpose
To accurately determine urine specific gravity using a refractometer

II. Policy
In order to ensure quality and accurate patient results, the clinics will participate in the
following:
A. This test may only be performed on units that have been approved to perform this test,
perform the required quality control checks and maintain the necessary training and
competency assessments.
B. If a unit is not approved unit to perform this test, the unit should collect and label the
specimen and sent to the Lab for testing.
C. The list of units approved to perform this point of care test will be maintained by the
Point of Care Testing Coordinators in the Clinical Laboratory.

III. Specimen
A. Identify the patient using 2 patient identifiers. Acceptable identifiers are the patient’s full
name, medical record number and birthdate. Room or bed numbers are not acceptable
identifiers.
B. A random urine specimen should be collected in a sterile container. If testing is not
performed at the patient’s bedside or treatment room where the specimen was collected,
the specimen container (not the lid) must be labeled with 2 patient identifiers in the
presence of the patient.
C. Testing should be complete within 1 hour of collecting the sample.

IV. Reagents (or Media), Standards, Supplies and Equipment
A. Reagents and Standards
1. Alta Diagnostics® Urine Dipstick Control Solutions Storage and Handling
a. Bring to room temperature before use. Good until expiration date listed on bottle
when kept refrigerated at 2-8ºC.
b. When stored at room temperature, controls are stable for up to 8 weeks. Store
away from ultraviolet light. Write 8 week expiration date on bottle when removed
from refrigerator.
c. May be harmful by inhalation, ingesting or skin absorption. If reagent is inhaled,
ingested or absorbed into skin, flush with copious amounts of water.

UWHC Clinical Laboratories Original Date: 5/1/2013
Point of Care Current Version Date: 5/1/2013
Document Title: Urine Specific Gravity by Refractometer
Document ID: 1595.P38 Page 2 of 5



B. Wear gloves when handling patient samples or liquid QC materials
C. Urine specific gravity refractometer
D. Sterile water

V. Calibration and Calibration Verification
Instrument calibration must be performed before testing patient samples. Calibrate
refractometer every 24 hours when patient samples are tested during those 24 hours

A. Calibration Procedure
1. Raise the daylight plate and place a few drops of sterile water on the face of the
prism. Close the cover plate gently.
2. Bring scale into focus by turning the eyepiece. If the boundary line does not coincide
with the 1.000 line, make an adjustment by turning the scale adjusting screw found
on the underside of the instrument opposite the prism surface until the boundary line
coincides with the 1.000 line (See Figure2)
3. Record the performance of calibration in the log (see related resources) on the Urine
Specific Gravity Quality Control


VI. Procedure
A. Open the daylight plate of the refractometer Figure 1) and place 1 or 2 drops of urine
sample on the prism surface. Close the daylight plate gently so that the plate comes into
contact with the prism.
B. Point the end of the refractometer in the direction of a bright light, rotate the eyepiece
while looking through it until the image is correctly adjusted and the scale becomes
clearly visible.
C. When the sample is severely turbid or colored, the field of vision darkens and the
boundary line may become unclear or completely disappear. In such a case, use direct
sunlight or more intense light.
D. A boundary line which separates the brighter and darker sides at the upper and lower
portions respectively appears in the field of vision. Read specific gravity by noting the
point at which the boundary in the field of vision. Read specific gravity by noting the
point at which the boundary line intersects the scale at the left of the field.
E. Record the results in patient’s clinic record, either on an approved form with reference
ranges or by using the electronic POC result entry program.
F. Rinse prism and plate with water to remove residual urine. Place clean gauze square
between prism face and daylight plate between readings.


UWHC Clinical Laboratories Original Date: 5/1/2013
Point of Care Current Version Date: 5/1/2013
Document Title: Urine Specific Gravity by Refractometer
Document ID: 1595.P38 Page 3 of 5





VII. Method Specification
A. Reference range is 1.005 – 1.035.
B. Limitations and/or Exceptions
1. Moderate amounts of protein (100-750 mg/dL) may cause elevated readings.
2. Highly buffered alkaline urine may cause falsely low readings.
3. Radiopaque x-ray contrast media may cause elevated readings.

VIII. Result Reporting and Interpretation
A. Result Review and Data Entry - Record the results in patient’s clinic record, either on an
approved form with reference ranges or by using the POC result entry program.

IX. Safety
A. All reagents have been reviewed for risk including reproductive toxicity, acute toxicity,
and carcinogenic potential. None were found.

X. Quality Assurance
A. Quality Control
Accuracy of the tester(S) and instrument(S) must be confirmed through quality control
testing. This testing is consistent with current acceptable guidelines. Control samples
with known ranges are tested by the same persons who routinely perform the test on
patient samples to ensure that patient results are accurate and reliable. Quality control
must be performed once each 24 hours if any patient samples have been tested within
the same 24 hours period. The Nurse Manager or designee must review and sign off on
the Quality Control Log at least monthly.

Note: Since Quality control solutions contain human source materials, they should be
handled in accordance with Standard Precautions.

B. Control Procedure – Low Specific Gravity
1. Raise the daylight plate of the refractometer and place a few drops of Alta
Diagnostics® positive control solution on the face of the prism. Close the cover plate
gently.
2. Read specific gravity as outlined in section V.
3. Record results in the “Control” column on the “POS” line on Quality Control Log.
Compare results with acceptable control value ranges for the lot number of positive
control used. Repeat test if results fall outside of acceptable ranges.
4. If repeat test fails, do not use refractometer or record patient results obtained with
that instrument. Call the Point of Care Testing Coordinators in the Clinical
Laboratories.

UWHC Clinical Laboratories Original Date: 5/1/2013
Point of Care Current Version Date: 5/1/2013
Document Title: Urine Specific Gravity by Refractometer
Document ID: 1595.P38 Page 4 of 5



5. Record any corrective actions(S) taken on Quality Control Log along with date and
initials of tester.

C. Control Procedure – High Specific Gravity
1. Using Alta Diagnostics® negative control solution, follow procedure outlined in
section IX.A
2. Read specific gravity as outlined in section V.
3. Record results in the “Control” column on the “NEG” line on the Quality Control Log.
Compare results with acceptable control value ranges for the lot number of negative
control used. Repeat test if results fall outside of acceptable ranges.
4. If repeat test also fails, do not use the refractometer or record patient results
obtained with that instrument. Call the Point of Care Testing Coordinators in the
Clinical Laboratories.
5. Document corrective action taken in the Quality Control log, along with date an
initials of tester.
6. Quality control records and the manufacturer’s documentation of quality control
ranges are maintained for 2 years.
7. Quality Control Log – Urine Specific Gravity by Refractometer.

D. Proficiency Testing
The UWHC inpatient nursing units/procedure areas performing urine specific gravity by
refractometer will enroll in an approved Proficiency Testing (PT) program on an annual
basis. At least 2 times per year, the PT Provider sends specimens to the Point of Care
Testing division of the main Clinical Laboratory. The Point of Care Testing Coordinators
is responsible for preparing the specimens and delivering them, on a rotating basis, to
the designated nursing units/procedure areas.
1. The testing sites will:
a. Prepare for that day’s testing by performing calibration (if required) and quality
control.
b. Test the PT specimens in the same manner as patient samples.
c. Record the refractometer specific gravity results on the sheet provided, sign the
attestation form, and return the sheet and the specimens to the Point of Care
Testing Coordinator from the Clinical laboratories.
2. The Point of Care Testing Coordinator will:
a. Obtain the director’s or designee’s signature on the answer sheet.
b. Fax the answer sheet to the PT provider or enter the results electronically.
c. Follow up with corrective action for any incorrect result(s).
d. Maintain records of all testing.

E. Training and Competency Assessment
1. All staff is trained and competent before performing patient testing. Initial training is
documented and records are retained.
2. In their first year of testing, all staff is required to complete two competency
assessments (at around 6 months after start of employment and at one year).
3. After their first year of testing, all staff is required to complete an annual competency
assessment.

UWHC Clinical Laboratories Original Date: 5/1/2013
Point of Care Current Version Date: 5/1/2013
Document Title: Urine Specific Gravity by Refractometer
Document ID: 1595.P38 Page 5 of 5



4. Any unsatisfactory competency assessment will be followed up with retraining. The
staff member will not perform any patient testing until acceptable competence is
achieved.
5. Copies of these competency records will be kept in nursing education or at the
testing site.

XI. Maintenance (Not Applicable)

XII. Alternate Testing and/or Down Time Procedures
A. Send specimen to the main lab

XIII. References
A. Alta Diagnostics® Urine Dipstick Control product insert,10/25/11
B. Material Safety Data Sheet (MSDS), Alta Diagnostics Liquid Urine Control, 10/25/11
C. Product insert form Reichert® Urine Specific Gravity Refractometer

XIV. Appendices and Forms
A. 1595.P038.F1 Urine Specific Gravity by Refractometer Training and Competency Form
(pdf), February 2013
B. 1595.P038.F2 Quality Control log – Urine Specific Gravity by Refractometer (pdf),
February 2013

XV. Author and/or Revised By
Elizabeth Urban, MT (ASCP) Point of Care Testing Coordinator

XVI. Coordination and/or Review
Point of Care Testing Faculty Director
CLIA Laboratory Director UWHC Point of Care Testing
Nursing Patient Care Policy and Procedure Committee