Lecture 3 : Physical Examination of Urine

Urinalysis

is the physical, chemical, and microscopic examination of urine.

• Physical Examination

• Chemical Examination

• Microscopic Examination

Three phases or examinations to complete urinalysis

• Urine color

• Clarity

• Specific gravity

• Odor

Physical examination of urine includes the determination of ?

Urine color

It is the reflection of urine concentration

Diabetes Mellitus

Pale yellow colored urine but increased specific gravity. 

Mainly attributed to the presence of the glucose in the urine

Polyphagia

Excessive hunger

Polydipsia

Excessive thist

Polyuria

Excessive urination

Urochrome

pigment that causes yellow color

Pale yellow

color of Dilute urine

Dark yellow

Color of Conentrated urineconcentrated

• Thyroid

• Fasting state

Urochrome is increased in what conditions?

Chronic Renal Failure

A condition that have decreased excretion of the urochrome

Uroerythrin

pink pigment, most evident in specimens that have been refrigerated, resulting in the precipitation of amorpous urates.

Urobilin

Oxidation product of the normal urinary constituent urobilinogen, imparts an orange-brown color to urine that is not fresh

Examine under a good light source, looking down through the container against a white background.

How to correctly examine the color of the urine sample?

Colorless to deep yellow

Normal color of urine

Recent fluid consumption

what does a colorless urine indicate?

sign of Diabetes mellitus or diabetes insipidus

What does a pale yellow urine indicate?

insulin resistance

Diabetes mellitus is due to what?

Diabetes Insipidus

decreased production of ADH, less water absorption, increased excretion of urine

Dark yellow/Amber/Orange

Color of urine first considered as abnormal

(presence of bilirubin)

Shake the sample - yellow foam

How can you test for bilirubin in urine?

High protein concentration

What causes large white foam in urine?

Phenazopyridine (Pyridium) or azogantrisin (used for UTI)

What medication causes orange urine?

Bilirubin turns into biliverdin, giving a yellow-green color.

What happens when urine with bilirubin is photooxidized?

Presence of blood

What is the most common cause of red urine?

RBCs oxidize hemoglobin to methemoglobin

Why does acidic urine turn brown after standing?

Gomerular bleeding

What does fresh brown urine with blood indicate?

Hemoglobin and Myoglobin

What substances besides RBCs can cause red urine?

Cloudy red urine

color of urine when RBCs are present

Clear red urine

color of urine when Hemoglobin and Myoglobin are present

Examine the plasma of the patient from the extracted blood

How to differentiate Hemoglobinuria and Myoglobinuria

Plasma becomes red due to RBC breakdown in vivo

What happens to plasma in hemoglobinuria?

Reddish-brown

What color is urine with myoglobin ?

Porphyrins, from oxidation of porphobilinogen

What causes “port wine” colored urine?

• Menstrual contamination

• Foods

• Medication

What are the non-pathologic causes of red urine?

Rifampin

What drug turns urine red/orange?

Test for melanin or homogentisic acid

What should you do if urine turns brown/black but tests negative for blood ?

Melanin

What pigment causes black urine after standing or air exposure

Homogentisic acid

What metabolic causes black urine when alkaline?

Black urine disease

What is another name for alkaptonuria?

Failure to break down tyrosine and phenylalanine

What causes alkaptonuria?

Homogentisic acid

What chemical builds up in alkaptonuria?

• Levodopa

• Methyldopa

• Phenol derivatives

• Metronidazole

Medications producing Brown / Black urines

Blue/Green

Color of urine that are limited to bacterial infections, including UTI by Pseudomonas species and intestinal tract infections resulting in increased urinary indican.

Purple

This color of urine may occur in catheter bags and is caused by indican in the urine or a bacterial infection

Clarity

The transparency or the turbidity of a urine specimen

In front of a light source and viewing it through a newspaper print

How is clarity examined?

Clear

No visible particulates, transparent

Hazy/Slightly Cloudy

Few particulates, print easily seen through urine

Cloudy

Many particulates, print blurred through urine

Turbid

Print cannot be seen through urine

Milky

May precipitate or be clotted

Nubecula

Faint clouds in urine after standing, due to white blood cells, epithelial cells and mucus

• RBCs

• WBCs

• Bacteria

• Yeast

• Non squamous epithelial cells

• Abnormal crystals

• Lymph fluid

• Lipids

Pathological causes of turbidity

• Squamous epithelial cells

• Mucus

• Amorphous crystals

• Semen, Spermatozoa

• Fecal contamination

• Radiographic contrast media

• Talcum powder

• Vaginal cream

Non-pathologic causes of turbidity

• RBCs

• WBCs

• Bacteria

Most commonly encountered pathologic causes of turbidity in a fresh specimen

• Squamous epithelial cells

• Mucus

Urine Sediments that can be seen in women samples

Acidic urine

• Amorphous urates

• radiographic contrast media

Alkaline urine

• Amorphous phosphate

• Carbonate

Soluble with heat

• Amorphous urates

• Uric acid crystals

Soluble in dilute acetic acid

• RBCs

• Amorphous phosphates

• Carbonates

Insoluble in dilute acetic acid

• WBCs

• Bacteria

• Yeast

• Spermatozoa

Soluble in ether

• Lipids

• Lymphatic fluid

• Chyle

Amorphous phosphates and carbonates

Produce white precipitate in urine with an alkaline pH

Amorphous urates

Produce a precipitate in acidic urine that resembles pink brick dust due to the presence of uroerythrin

Specific Gravity

Defined as the density of a solution compared with the density of a similar volume of distilled water (SG 1.000) at a similar temperature

Reagent strip

Influenced by the number of particles

Specific gravity per se

Influenced by the number and size of particles

1.002 - 1.035

Normal urine specimen Specific Gravity range

1.010

Specific Gravity of plasma filtrate entering the glomerulus

Isosthenuric

1.010 SG

Hyposthenuric

< 1.010 SG

Hypersthenuric

> 1.010 SG

• Refractometer

• Urinometer

• Harmonic Oscillation Densitometry

• Reagent Strip Method

Methods in measuring Specific Gravity

Refractometer / Total solid meter

Determines the concentration of dissolved particles in a specimen by measuring refractive index

Refractive index

Principle of Refractometer

• Using small volume of specimen (1-2 drops)

• Temperature corrections are not necessary

Advantages of Refractometer

Corrections for glucose and protein must be calculated by subtracting 0.003 (protein) and 0.004 (glucose)

Disadvantages of Refractometer

1.000

Specific Gravity of Distilled water in Refractometer

1.022 +_ 0.001

Specific Gravity of 5% NaCl in Refractometer

1.034 +_ 0.001

Specific Gravity of 9% Sucrose in Refractometer

1.015 +_ 0.001

Specific Gravity of 3% NaCl in Refractometer

• 0.003 × 2 = 0.006

• 1.030 - 0.006 = 1.024

• SG = 1.024

Solve for SG:

• Initial SG using Refractometer: 1.030

• 2 g/dL of protein

• What is the corrected SG?

• 0.003 + 0.004 = 0.007

• 1.030 - 0.007 = 1.023 (SG)

A specimen containing 1g/dL protein and 1g/dL glucose has a specific gravity reading of 1.030. Calculate the corrected reading.

Intravenous Pyelogram (IVP)

A tool in the assessment of flank and lower back pain and hematuria

Urinometer / Hydrometer

Consists of a weighted float attached to a scale that has been calibrated in terms of urine specific gravity.

Not recommended due to its disadvantage

Requires temperature correction

Disadvantage of Urinometer

Distilled water

Urinometer is calibrated by using?

• 20-26 = 6

• 6/3 = 2

• 0.001 × 2 = 0.002

• 1.030 + 0.002 = 1.032

• Initial SG using Refractometer: 1.030

• Urinometer Calibrated at 20 degree Celsius

• Specimen Temperature is 26 degree Celsius

• What is the corrected SG?

Specimen dilution

Specimen with specific gravity readings greater than the Refractometer or urinometer scale can be diluted and retested.

1.025 × 2 = 1.050

A specimen diluted 1:2 with a reading of 1.025 would have an actual SG of a 1.050.

What is the final Specific Gravity?

Harmonic Oscillation Densitometry

The frequency of the sound wave entering a solution changes in proportion to the density of the solution.

Reagent Strip Method

Reagent sensitive to number of ions in the urine specimen; indicator changes color in relation to ionic concentration.

pKa change of polyelectrolyte

Reagent Strip Method Principle

Poly (methyl vinyl ether/maleic anhydride ) bromthymol blue

Multistix

Ethyleneglycol-Bis(aminoethylether) bromthymol blue

Chemstrip

1.000 - 1.030

Sensitivity of Reagent strip method

False Positive

High concentration of protein