Urine analysis about physical examination of urine

1. Chapter Three
Physical Examination of Urine

2. Objective
At the end of this chapter, the student will be able to:
Carry out physical examination of urine such as
odor, volume, color, transparency, foam, specific
gravity of urine and interpretation of the test result.
Explain each interfering factors at the moment of
doing the test
Relate abnormal macroscopic appearance of urine
with pathologic states.

3. Physical Examination of urine
o Volume
o Color
o Transparency
o Odor
o Foam
o Specific gravity

4. Introduction
 Physical examination of urine is macroscopic
examination of urine
 The first part of routine urinalysis.
 It is simplest procedure of all urine examination
 But this simplicity doesn’t mean that any one can do it
without any background knowledge and experiences.
 Despite its simplicity, it provides hint for the subsequent
chemical and microscopic urinalysis
 It includes measurement of the volume of urine,
examination of color and appearance, detecting the foam,
odor, and measuring the specific gravity.

5. Volume
 Not measured as part of a routine urinalysis
 But volume of urine excreted in 24 hours aids for
clinical diagnosis.
 The 24-hour urine voided by a healthy
Adult range 600-2000ml
 Children (6 to 12 years) about 1000ml
Infants about 600ml.

6. Volume Cont’d…
 Factors that affect the urine output
 Fluid intake
 Diet
 Physiological and environmental factors of the
body

7. Volume Cont’d…
 Procedures for measurement of urine volume
 Collect 24-hour urine specimen in a container of clean and
dry, brown colored.
 Add appropriate preservative for the desired urine chemical
test
 Label on the container that indicates name of patient,
collection time and date, type of chemical test ordered and
preservative used.
 Pour the collected urine into a graduated cylinder of
suitable size (500ml or 2000ml)
 Measure the volume and report in terms of ml in 24hrs

8. Volume Cont’d…
 Clinical Significance
 Abnormal urine volume
 Suggests several renal diseases but it is confirmed by
confirmatory tests
 Helps for determination of protein
 Indicates some clinical features like abnormal execration of
urine/ day

9. Volume Cont’d…
 Measurement of urine volume used for:
 Quantitative tests
 GFR
 Clearance tests
 Evaluation of fluid balance and kidney function

10. Abnormal urine Volume

11. Volume Cont’d…
 Oliguria :urine volume is less normal <400ml per 24 hours for
prolonged period
 Dehydration or poor blood supply to the kidneys
 Mechanical obstruction of the urinary system [e.g. due to
renal calculi or tumors]
 Excessive salt intake.
 Diuresis: temporal increment of urine due to excessive fluid
intake

12. Color
 Normal urine has pale yellow, yellow, and dark yellow
 Urochrome, uroerythrin and urobilin give the urine its
pale yellow color
 Urine color is recorded within 30 minute after collection
 Pale to colorless urine may indicate
 Large fluid intake
 Diabetic mellitus
 Alcohol consumption

13. Color cont’d…
 Dark yellow or brown red urine may indicate
 Concentrated urine
 Decreased fluid intake
 Fever

Dehydration
 Yellow brown or beer brown (amber) color may indicate
the presence of bilirubin.
 Clear red color may indicate presence of
hemoglobin/myoglobin
 Cloudy red or smoky red color indicates hematuria.
 Brown /Black due to methemoglobin
 Distinguishing between hemoglobinuria and myoglobinuria may be possible by examining the
patient’s plasma. HOW?

14. Odour
 Normally freshly voided urine from healthy individuals has
faint aromatic odor
 The test is conducted by smelling of urine and the result is not
used for reporting but for the purpose of comparison with the
subsequent chemical test result.
 If the urine specimen is old, it will have ammonical or pungent
odor, which results from the break down and conversion of urea
in the urine into ammonia by the action of bacteria.
 Sweet fruity odor of urine results from the presence of ketone
bodies due to diabetes mellitus, prolonged vomiting, starvation
or strenuous exercise.

15. Foam
 Normally fresh urine produces small amount of white foam, but
during certain abnormal conditions, it may be changed.
 Yellowish foam indicates the presence of bilirubin in the urine
o must be confirmed by chemical test
 When high concentrations of protein are present in the urine, a
large amount of white foam may be seen (for prolonged period
of time)

16. high bilirubin concentration high concentration of protein

17. Transparency/clarity
 Freshly voided urine specimen is normally clear and
transparent
 Excretion of turbid urine is not always abnormal
 Refrigeration of urine results in the turbidity of the
urine.
 Occasionally turbidity of urine may result from
 White blood cells [pus cells]
 Kidney stones
 Yeast cells
 High number of bacteria cells
 High number of mucus treads
N.B All the above physical findings must be confirmed by
chemical and/or microscopic examination

18. Degree of Urine transparency
 Clear: no visible particulate mater present
 Hazy: some visible particulate mater present;
newsprint is not distorted or obscured when viewed
through the urine
 Cloudy: Newsprint can be seen through the urine but
letters are distorted or blurry
 Turbid: Newsprint cannot be seen through the urine

19.  Note:
If the urine is so cloudy, microscopical
examinations should be done for the suspended
solutes in the sample.
All urine specimens should be assessed for color
and transparency in similar containers to ensure
consistent results.

20. Specific gravity (Sp.g)
Specific gravity
Is ratio of the weight of a fixed volume of solution to that of the
same volume of distilled water at a specified similar temperature
Indicator of the kidneys ability to concentrate or dilute urine.
Loss of concentrating or diluting capacity is an indication of
renal dysfunction.
Reflects degree of hydration or dehydration.
A concentrated urine may have a specific gravity of 1.025 –1.030
A diluted urine can have a specific gravity of 1.001-1.010.
Used to assess the kidney’s ability to reabsorb a necessary
component

21. Measurement of Specific Gravity
 There are different methods to measure the urine
specific gravity
 Direct method using Urinometer (hydrometer)
 Indirect method using
Refractometer
Reagent strip
 Falling drop method
 Weighing technique

22. A) Urinometer method
 Urinometer : a glass float weighted with mercury, with an air bulb
above the weight and a graduated stem on the top.
 Weighted to float at the 1.000 graduations in pure water when
placed in a glass Urinometer cylinder or appropriate sized test tube.
 It is important that the cylinder, or test tube of the correct size so
that the Urinometer can float freely.
 The specific gravity of the urine is read directly from the graduated
scale in the Urinometer stem at the lower meniscus.
 The scale of the Urinometer is calibrated from 1.000 – 1.060 with
each division being equal to 0.001.
 It is not longer considered an accurate device for determination of
urine specific gravity

23. A urinometer (hydrometer)

24. Reading the Urinometer scale
1000
1010
1020
1030

25. Calibration of urinometer
 The urinometer must be calibrated everyday.
 Distilled water should read 1.000.
 Following two standards may also be used for calibrating the
urinometer at different specific gravities
 a. Specific gravity 1.011 (750 mOsm/kg): This is prepared by
weighing 24.03 g of oven-dried sodium chloride and adding it
to 1000mL of distilled water .
 b. Specific gravity 1.023 (1600 mOsm/kg): Weigh 51.37 g of
oven-dried sodium chloride and add it to 1000 mL of distilled
water

26. Correction or urinometer reading
 Temperature Correction
 Most urinometer are calibrated at 20 o
C( sometimes at 15
o
C ) .
 For each 3o
C difference 0.001 must be added if above
 Subtracted if lower than the calibration temperature.
 For example, if the specific gravity of the urine is 1.022 at
23o
C, and the urinometer has been calibrated at 20 o
C, the
correct reading is 1.022+0.001= 1.023.

27. Correction or urinometer reading
 Correction for abnormal Dissolved Substances
 The specific gravity increases by
 0.004 for every 1% glucose (g/dL) in urine
 0.003 for every 1% protein (g/dL) in urine.
 Therefore subtract 0.004 from the specific gravity reading for
every 1% glucose in urine.
 And subtract 0.003 from the specific gravity reading for every
1% protein in the urine.

28. Sources of Errors

29. A refractometer
with the pathway
of light
superimposed

30. Refractometer method
 Refractometer is an instrument, which indirectly measures the
specific gravity by measuring the refractive index
 The ratio of the velocity of light in air to the velocity of light
in solution.
 This ratio varies directly with the number of dissolved
particles in solution.
 The concentration of the specimen determines the angle at
which the light beam enters the prism.
 specific gravity scale is calibrated in terms of the angles at
which light passes through the specimen

31. Factors affect refractive index
 Wavelength of light used
 Temperature of the solution
 The concentration of the solution

32. Principle:
 Refractometer is based on the principle of light
refraction.
 When a ray of light passes through the optical
system of the refractometer, the path of light going
through air and glass deviates when it meets the fluid
or the urine specimen.
 The degree of refraction is proportional to the amount
of solute concentration or the specific gravity of the
fluid.

33. procedure
 Put one or two drops of sample on the prism
 Close the daylight plate gently
 The sample must spread all over the prism
surface.
 Look at the scale through the eyepiece.
 Read the scale where the boundary line
intercepts it.

35. Refractometer cont’d…
 Advantage
 Temperature corrections are not necessary
 compensated between 15C and 38 C
Limitation:
 It require pure test tube transparent to light
 Needs skilled professional about handling of the test tube
 Corrections for glucose and protein are still calculated
Clinical significance:
 the same as urine sp.gv. measurment using urinometer

36. Reagent Strip Test
 Reagent strips have been developed as an indirect method of
measuring specific gravity of urine.
 These strips actually measure ionic concentration, which is
related to specific gravity.

37. Principle

38. Weighing technique
o This technique requires the use of an analytical balance
o As urinometer method, adjustments to the value are necessary
if the urine contains large amount of protein or glucose. :
o Assume that 10 ml of urine weighs 10.15gm
o Assume that 10ml of distilled water is10gm.
o specific gravity urine should be:
10.15gm =1.015
10gm

39. Clinical Significance
 used to obtain information about two general functions:
 the state of the renal epithelium, and
 the state of hydration of the patient.
 If the kidney is performing adequately, it is capable of
producing urine with a specific gravity ranging from 1.003-
1.030 or higher.

40. Exercise
1. Define the following term
 Specific gravity
 Oliguria
 Refractive index
2. Describe abnormal color and transparency of urine
specimen and the significance of each.
3. Describe normal and abnormal odour and foam of
urine specimen and the significant of each.
4. How can you correct specific gravity value measured
by urinometer for temperature glucose and protein?
5. Describe the terminologies that indicates abnormal
urine volume and the significance of each.
6. List the method used for determining the specific
gravity of urine and write the principle of each method.