Chemical Examination of Urine | from Strasinger (6th ed.) Flashcards
In UA, rgnt strips currently provide what?
It provide a simple, rapid means for performing medically significant chemical analysis of urine
What are the components that are included in the rgnt strips (in the chemical analysis of urine)?
1) pH
2) Protein
3) Glucose
4) Ketones
5) Blood
6) Bilirubin
7) Urobilinogen
8) Nitrite
9) Leukocytes
10) SG
What are the 2 major types of rgnt strips?
Trade names:
1) Multistix
2) Chemstrip
True or False
Both Multistix and Chemstrip are available w/ single-or multiple-testing areas
True
True or False
The brand and # of tests used (for the rgnt strip) are a matter of lab preference
True
True or False
Rgnt strip brands are also specified by instrumentation manufacturers
True
What are the components of rgnt strips?
Chemical-impregnated absorbent pads (w/c are attached to a plastic strip)
What is the action that takes place when the absorbent pad (present in the rgnt strip) comes in contact w/ urine?
A color-producing chemical rxn takes place
How are the rxns (in the rgnt strip) interpreted?
The rxns are interpreted by comparing the color produced on the pad within the required time frame w/ a chart supplied by the manufacturer (whereas several colors or intensities of a color for each substance being tested appear on the chart)
What is the manner of reporting results (after careful comparison of the colors on the chart and the rgnt strip)?
Semiquantitative value
What are the reports / interpretations that can be reported (via the use of the chart where the rgnt strip was compared)?
1) Trace
2) 1+
3) 2+
4) 3+
5) 4+
True or False
An estimate of the milligrams per deciliter is present in appropriate testing areas (in the rgnt strip)
True
True or False
Automated rgnt strip readers does not provide Système International units
False, because automated rgnt strip readers also provide Système International units
What is the procedure of rgnt strip technique (w/c is a part of the chemical examination in UA)?
1) Dip the rgnt strip completely, but briefly, into a well-mixed sx
2) Remove excess urine from the strip (via running the edge of the strip on the container when withdrawing it from the sx)
3) Blot the strip horizontally on an absorbent medium (waiting for the specified length of time for rxns to take place)
4) Compare the colored rxns against the manufacturer’s chart (using a good light source)
What are the errors caused by improper technique (in rgnt strip technique)?
1) Formed elements (such as RBCs and WBCs) sink to the bottom of the sx and will be undetected in an unmixed sx
2) Allowing the strip to remain in the urine for an extended period may cause leaching of rgnts from the pads
3) Excess urine remaining on the strip after its removal from the sx can produce a run-over between chemicals on adjacent pads, producing distortion of the colors
4) The timing for rxns to take place varies between tests and manufacturers, and ranges from an immediate rxn for pH to 120 secs for leukocyte esterase (LE)
5) A good light source is essential for accurate interpretation of color rxns
What is the resolution that should be done against run-over (between chemicals on adjacent pads in the rgnt strip)?
To ensure against run-over, blotting the edge of the strip on absorbent paper and holding the strip horizontally while comparing it w/ the color chart is recommended
What is the resolution that should be done when it comes to timing for rxns to take place (in the rgnt strip)?
For the best semi-quantitative results, the manufacturer’s stated time should be followed; however, when precise timing cannot be achieved, manufacturers recommend that rxns be read between 60 and 120 secs, w/ the LE rxn read at 120 secs
What is the detailed procedure of rgnt strip technique?
1) Dip the rgnt strip briefly into a well-mixed uncentrifuged urine sx at room temp
2) Remove excess urine by touching the edge of the strip to the container as the strip is withdrawn
3) Blot the edge of the strip on a disposable absorbent pad
4) Wait the specified amt of time for the rxn to occur
5) Compare the color rxn of the strip pads to the manufacturer’s color chart in good lighting
6) The strip must be held close to the color chart w/out actually being placed on the chart. Automated rgnt strip instruments standardized the color interpretation and timing of the rxn and are not subject to room lighting deficiencies or inconsistency among lab personnel
7) Rgnt strips and color charts from different manufacturers are not interchangeable
8) Sxs that have been refrigerated must be allowed to return to room temp prior to rgnt strip testing, as the enzymatic rxns on the strips are temp dependent
What are the ways to properly handle and store rgnt strips?
These must be protected from deterioration caused by:
1) Moisture
2) Volatile chemicals
3) Heat
4) Light
What is that 1 component of rgnts strips in its packaging?
Desiccant
Where are rgnt strips packaged?
In opaque containers
What is the purpose of desiccant present in the container of rgnt strips?
To protect the rgnt strips from light and moisture
When should the rgnt strips be removed from their respective containers?
These should be removed just prior to testing
What should be done to the bottle (of the rgnt strips) after obtaining rgnt strips for testing?
The bottle should be tightly resealed immediately
True or False
The bottles (of rgnt strips) can be opened in the presence of volatile fumes
False, because the bottles (of rgnt strips) should not be opened in the presence of volatile fumes
At what temp should the rgnt strips be stored (based on the recommendation of the manufacturers)?
Room temp below 30 DC (but never refrigerated)
What is the component of the bottles (of rgnt strips) w/c is important?
Expiration date (w/c is stamped in all bottles)
What is the importance of the stamped expiration date (in all bottles)?
It represents the fxnal life expectancy of the chemical pads
Can the rgnt strips be used even though that these are already past the expiration date?
No
Is it okay to touch the chemical pads when removing the strips?
No
What should be done to each strip each time it is used?
Visual inspection
What is the purpose of performing a visual inspection to the strip each time a strip is used?
To detect deterioration
Should visual inspection be done even though the strips may still be within the expiration date?
Yes
What must be done to rgnt strips (in terms of quality control [QC])?
These must be checked w/ both (+) and (-) controls
When must rgnt strips be checked w/ both (+) and (-) controls (in terms of QC)?
A minimum of once every 24 hrs
When is the sp time that many labs perform the check (/ QC) of rgnt strips?
At the beginning of each shift
Aside from performing testing (/ QC) a minimum of once every 24 hrs (specifically at the beginning of each shift), when are the other times that testing (/ QC | of rgnt strips) is also performed?
1) When a new bottle of rgnt strips is opened
2) When questionable results are obtained
3) When there is concern about the integrity of strips
What must be done to all QC results (of rgnt strips)?
All QC results must be recorded (following lab protocol)
True or False
Several companies manufacture both (+) and (-) controls
True
Is distilled H2O recommended as a (-) control (in terms of QC)?
No
Why is distilled H2O not recommended as (-) control (in terms of QC)?
Because rgnt strip chemical rxns are designed to perform at ionic concs similar to urine
True or False
In terms of QC, all readings of the (-) control must be (-), and (+) control readings should agree w/ the published value
True
What must be done to results that do not agree w/ the published values (in terms of QC)?
This must be resolved through the testing of the additional strips and controls
True or False
Demonstration of chemically acceptable rgnt strips does entirely rule out the possibility of inaccurate results
False, because demonstration of chemically acceptable rgnt strips does not entirely rule out the possibility of inaccurate results
What are the other aspects that can also produce errors?
1) Interfering substances in the urine
2) Technical carelessness
3) Color blindness
True or False
Rgnt strip manufacturers have published info concerning the limitations (e.g. interfering substances, sensitivities) of their chemical rxns, and lab personnel should be aware of these conditions
True
Provide a primary ex of rgnt strip interference
The masking of color rxns by the orange pigment present in the urine or persons taking phenazopyridine compounds
What will be the result if lab personnel do not recognize the presence of orange pigment / other pigments present in the pt’s urine?
They will report many erroneous results
What are confirmatory tests?
These are defined as test using different rgnts or methodologies to detect the same substances as detected by rgnt strips w/ the same or greater sensitivity / specificity
When is nonreagent strip testing procedures (via the use of tablets and liquid chemicals) available?
Nonrgnt strip testing procedures may be available when:
1) Questionable results are obtained
2) Highly pigmented sxs are encountered
True or False
In the past, many of the nonrgnt strip testing procedures (via the use of tablets and liquid chemicals) were used routinely to confirm (-) results
False, because in the past, many of the nonrgnt strip testing procedures (via the use of tablets and liquid chemicals) were used routinely to confirm (+) results
What is the aid of increased specificity and sensitivity of rgnt strips and the use of automated strip readers?
These have reduced the need for routine use of these procedures
How to check the chemical reliability of nonrgnt strip testing procedures?
Via the use of (+) and (-) controls
What are the major regulators (/ organs) of the acid-base content in the body?
1) Lungs
2) Kidneys
What is the mechanism of the lungs and kidneys in terms of regulating the acid-base content in the body?
They secrete hydrogen (in the form of ammonium ions), hydrogen phosphate, and weak organic acids, and by the reabsorption of bicarbonate from the filtrate in the convoluted tubules
What is the usual pH of the pt’s first morning sx from a healthy individual?
Slightly acidic pH (5.0 - 6.0)
What is the pH found following meals (done by the pt)?
Alkaline pH (alkaline tide)
What is the range of the pH of normal random sxs?
4.5 - 8.0
Are there normal values assigned to urinary pH?
None
The urinary pH must be considered in conjunction w/ what?
In conjunction w/:
1) Other pt info
a. Acid-base content of the blood
b. Pt’s renal fxn
c. Presence of a UTI
d. Pt’s dietary intake
e. Age of the sx
What are the causes of acid urine?
1) Emphysema
2) Diabetes mellitus (DM)
3) Starvation
4) Dehydration
5) Diarrhea
6) Presence of acid-producing bacteria (Escherichia coli)
7) High-protein diet
8) Cranberry juice
9) Medications
a. Methenamine
b. Mandelate (Mandelamine)
c. Fosfomycin tromethamine (Monurol)
What are the causes of alkaline urine?
1) Hyperventilation
2) Vomiting
3) Renal tubular acidosis
4) Presence of urease-producing bacteria
5) Vegetarian diet
6) Old sxs
What are the importance of urinary pH?
1) It is the primary aid in determining the existence of systemic acid-base disorders of metabolic / respiratory origin
2) It also aids in the management of urinary conditions that require the urine to be maintained at a sp pH
What is the pH of urine in pts w/ respiratory / metabolic acidosis w/c are not related to renal fxn disorders?
Acidic
What is the pH of urine in pt’s w/ respiratory / metabolic alkalosis?
Alkaline
How to rule out the presence of suspected conditions (such as respiratory / metabolic acidosis and respiratory / metabolic alkalosis)?
If the urinary pH does not conform to the pattern (in relation to such disorders)
Patterns:
1) For pt’s w/ respiratory / metabolic acidosis -> pt have acidic urine
2) For pt’s w/ respiratory / metabolic alkalosis -> pt have alkaline urine
What is the indication if the urinary pH of the pt does not conform to the said patterns (in relation to such conditions)?
It may indicate a disorder resulting from kidneys’ inability to secrete or to reabsorb acid / base
How are urinary crystals / renal calculi formed?
These are formed via the precipitation of inorganic chemicals dissolved in the urine
The precipitation of inorganic chemicals (w/c are dissolved in the urine) depends on what?
Urinary pH
How can the precipitation of inorganic chemicals (w/c are dissolved in the urine) be controlled?
It can be controlled via maintaining the urine at a pH that is incompatible w/ the precipitation of the particular chemicals causing calculi formation
What is the frequent constituent of renal calculi?
Calcium oxalate
At what urinary pH does Ca oxalate primarily precipitate?
In acidic urine (not in alkaline urine)
*What should be done to discourage the formation of calculi?
Maintaining urine at an alkaline pH
True or False
Knowledge of urinary pH is not impt in the identification of crystals observed during microscopic examination of the urine sediment
False, because knowledge of urinary pH is impt in the identification of crystals observed during microscopic examination of the urine sediment
In connection of urinary pH, what is the action that is valuable in terms of treating UTIs caused by urea-splitting organisms?
Maintaining an acidic urine
Why is maintaining an acidic urine valuable in treating UTIs caused by urea-splitting organisms?
Because they do not multiply as readily in an acidic medium
What organisms are responsible for highly alkaline pH found in sxs that have been allowed to sit unpreserved for extended periods?
Urea-splitting organisms
What is the aspect that primarily controls urinary pH?
Dietary regulation
Can medications be also used to control the urinary pH?
Yes
What is the pH of urine of pts who are on high-protein and high-meat diets?
Acidic urine
What is the pH of the urine of pts who are vegetarians?
More alkaline (compared to pts who have high-protein and high-meat diets | / alkaline)
Why is the pH alkaline of pts who are vegetarians?
Due to the formation of bicarbonate following digestion of many fruits and vegetables
What is the urinary pH of pts who drinks cranberry juice?
Acidic (w/c is the exemption to the rule whereas pts who are vegetarians [/ pts who eat many fruits and vegetables] have alkaline urinary pH)
What is the use of cranberry juice?
It has long been used as a home remedy for minor bladder infections
Why do cranberry juice long been used as a home remedy for minor bladder infections?
Because it inhibits the colonization of certain urinary pathogens
What is advised to people who are prone to frequent UTIs?
They are often advised to drink cranberry juice or take over-the-counter cranberry pills
What are the medications prescribed for UTIs?
1) Methenamine mandelate (Mandelamine)
2) Fosfomycin tromethamine (Monurol)
What is the action done to methenamine mandelate and fosfomycin tromethamine?
These are metabolized to produce acidic urine
What is the pH of freshly excreted urine?
Its pH does not reach above 8.5 (in normal or abnormal conditions)
What is the pH of an improperly preserved sx?
Above 8.5
What is the indication if the pH of urine is above 8.5?
It indicates that a fresh sx should be obtained to ensure the validity of the analysis
What is the effect to the urinary pH if sxs are collected in containers (w/ remaining alkaline detergent) other than single-use laboratory-supplied containers?
It can produce pH above 8.5
What are the things that can be done for care of rgnt strips?
1) Store w/ desiccant in an opaque, tightly closed container
2) Store below 30 DC; do not freeze
3) Do not expose to volatile fumes
4) Do not use past the expiration date
5) Do not use if chemical pads become discolored
6) Remove strips immediately prior to use
What is the technique (/ procedure) for rgnt strip testing?
1) Mix sx well
2) Let refrigerated sxs warm to room temp before testing
3) Dip the strip completely, but briefly, into sx
4) Remove excess urine by withdrawing the strip against the rim of the container and by blotting the edge of the strip
5) Compare rxn colors w/ the manufacturer’s chart under good light source at the specified time
6) Perform backup tests when indicated
7) Be alert for the presence of interfering substances
8) Understand the principles and significance of the test; read package inserts
9) Relate chemical findings to each other and to the physical and microscopic UA results
What is the procedure of QC for rgnt strip testing?
1) Test open bottles of rgnt strips w/ known (+) and (-) controls every 24 hrs
2) Resolve control results that are out of range by further testing
3) Test rgnts used in backup tests w/ (+) and (-) controls
4) Perform (+) and (-) controls on new rgnts and newly opened bottles of rgnt strips
5) Record all control results and rgnt lot numbers
What are the brands of rgnt strips?
1) Multistix
2) Chemstrip
How many increments are used when measuring the urinary pH via the use of either Multistix or Chemstrip?
0.5- or 1-unit increments between pH 5 and 9
How to differentiate pH units throughout the wide range (of pH when either Multistix or Chemstrip is used in terms of measuring the pH of urine)?
Both manufacturers (of Multistix and Chemstrip) use a double-indicator system of methyl red and bromthymol blue
What is the color change produced by methyl red (w/c is present in the double-indicator system of both Multistix and Chemstrip)?
From red to yellow (in the pH range 4 - 6)
Red -> yellow (at pH 4 - 6)
What is the color change produced by bromthymol blue (as a component of the double-indicator system used by both Multistix and Chemstrip)?
From yellow to blue (in the pH range of 6 - 9)
Yellow -> blue (at pH 6 - 9)
What is the summary of the principle of double-indicator system used by both Multistix and Chemstrip?
In the pH range 5 - 9 measured by the rgnt strips (Multistix and Chemstrip), 1 sees colors progressing from orange at pH 5 through yellow and green to a final deep blue at pH 9
At pH 5 (orange -> yellow); at pH 9 (green -> deep blue)
What is the rgnt strip rxns (for both Multistix and Chemstrip)?
Methyl red + H^+ -> bromthymol blue - H^+
red-orange -> yellow) (green -> blue
True or False
There are certain known substances that interfere w/ urinary pH measurements performed by rgnt strips
False, because there are no known substances that interfere w/ urinary pH measurements performed by rgnt strips
True or False
If Multistix is used, care must be taken to prevent run-over between the pH testing area and the adjacent, highly acidic protein testing area, as this may produce a falsely acidic reading in an alkaline urine
True
What are the clinical significance of urine pH?
1) Respiratory or metabolic acidosis / ketosis
2) Respiratory or metabolic alkalosis
3) Defects in renal tubular secretion and reabsorption of acids and bases- renal tubular acidosis
4) Renal calculi formation and prevention
5) Treatment of UTIs
6) Precipitation / identification of crystals
7) Determination of unsatisfactory sxs
Answer the ff questions w/ regards to the given pH rgnt strip:
1) What is/are the rgnt/s?
2) What is the sensitivity?
3) What is/are the sources of error / interference?
4) On what other test/s can pH (via rgnt strip) be correlated?
Given rgnt strip: Multistix
1) Methyl red and bromthymol blue
2) 5.0 - 8.5 in 0.5 increments
3) No known interfering substances, run-over from adjacent pads, and old sxs
4) Nitrite, leukocytes, and microscopic
Answer the ff questions w/ regards to the given pH rgnt strip:
1) What is/are the rgnt/s?
2) What is the sensitivity?
3) What is/are the sources of error / interference?
4) On what other test/s can pH (via rgnt strip) be correlated?
Given rgnt strip: Chemstrip
1) Methyl red and bromthymol blue
2) 5.0 - 9.0 in 1.0 increments
3) No known interfering substances, run-over from adjacent pads, and old sxs
4) Nitrite, leukocytes, and microscopic
Of the routine chemical tests performed on urine, what is the most indicative of renal disease?
Protein determination
What is proteinuria (/ where is it often associated)?
It is often associated w/ early renal disease
True or False
Since proteinuria is often associated w/ early renal disease, it makes the urinary protein test an impt part of any physical examination
True
True or False
Normal urine contains little protein
False, because normal urine contains very little protein
What is the usual quantity of protein contained by normal urine?
Usually < 10 mg/dL or 100 mg per 24 hrs is excreted
As stated earlier, normal urine contains very little protein, what type of proteins are present in this normal urine?
This consists primarily of:
1) Low-molecular-weight serum proteins (w/c have been filtered by the glomerulus)
2) Proteins produced in the genitourinary tract (GUT)
Since 1 of the protein present in the protein component (very little protein) in normal urine is low MW, what is the major serum protein found in normal urine?
Albumin
What is the conc of albumin in normal urine?
Low conc
Why is albumin present in low conc. in normal urine?
Because majority of the albumin presented to the glomerulus is not filtered, and much of the filtered albumin is reabsorbed by the tubules (even though that albumin is present in high concs in the plasma)
What are the other proteins w/c are present in small amts?
1) Serum microglobulins
2) Tubular microglobulins
What is the more recent name for Tamm-Horsfall protein?
Uromodulin
What are responsible for producing uromodulin?
1) Renal tubular epithelial cells
2) Proteins
a. From prostatic secretions
b. From seminal secretions
c. From vaginal secretions
Where is uromodulin routinely produced?
In the distal convoluted tubule (DCT)
True or False
Demonstration of proteinuria in a routine analysis does always signify a renal disease
False, because demonstration of proteinuria in a routine analysis does not always signify a renal disease
What should be done if proteinuria is present in the pt’s sx?
It is required to do additional testing
Why is additional testing required to be done if proteinuria is present in the pt’s sx?
To determine whether the protein represents a normal / pathologic condition
Where is clinical proteinuria indicated (/ what is the value of clinical proteinuria)?
30 mg/dL or greater (300 mg/L)
What are the 3 major categories (based on the origin of protein) / causes of proteinuria?
1) Prerenal
2) Renal
3) Postrenal
What is the principle of the cause of prerenal proteinuria?
As it name implies, it is caused by conditions affecting the plasma prior to its reaching the kidney, and, therefore, is not indicative of actual renal disease
What is the characteristic of prerenal proteinuria?
It is frequently transient
What is the cause of prerenal proteinuria?
Increased lvls of low-molecular-weight plasma proteins (such as hgb, myoglobin, and acute phase reactants) w/c is associated w/ infection and inflammation
Increased lvls of low MW plasma protein (hgb, myoglobin, and acute phase reactants) + infection and inflammation
What is the principle (/ action) done to low MW plasma proteins in association w/ prerenal proteinuria?
There is an increased filtration of these proteins (hgb, myoglobin, and acute phase reactants) w/c exceeds the normal reabsorptive capacity of the renal tubules, resulting in an overflow of the proteins into the urine
Is prerenal proteinuria usually discovered in a routine UA? Why or why not?
No, because rgnt strips detect primarily albumin, hence prerenal proteinuria is usually not discovered in a routine UA
What is the primary example of proteinuria due to increased serum protein lvls?
Excretion of Bence Jones protein
Who are the pts who excretes Bence Jones protein?
Pts w/ multiple myeloma
What is multiple myeloma?
It is a proliferative disorder of the immunoglobulin-producing plasma cells
What is the component of the serum of pts w/ multiple myeloma?
Their serum contains markedly elevated lvls of monoclonal immunoglobulin light chains (Bence Jones protein)
What is the characteristic of Bence Jones protein?
It is a low MW protein
Why is Bence Jones protein present in the urine (as a primary example of proteinuria due to increased serum protein lvls)?
Bence Jones protein is filtered in quantities exceeding the tubular reabsorption capacity and is excreted in the urine
What are the methods that can be used to diagnose suspected cases of multiple myeloma?
1) Serum electrophoresis
2) Immunoelectrophoresis
Is the screening test for Bence Jones protein routinely performed? Why or why not?
No, because cases of multiple myeloma are easily detected by chemical methods
What is renal proteinuria?
It is the proteinuria associated w/ true renal disease (w/c may be the result of either glomerular or tubular damage)
What is the principle of glomerular proteinuria?
When the glomerular membrane is damaged, selective filtration is impaired, and increased amts of serum protein and eventually RBCs and WBCs pass through the membrane and are excreted in the urine
Damaged glomerular membrane (resulting to selective filtration being impaired) -> presence of increased amts of serum protein and eventually, presence of RBCs and WBCs -> these pass through the membrane -> these are excreted in the urine
What are the major causes of proteinuria due to glomerular damage?
Conditions that present the glomerular membrane w/ abnormal substances such as:
1) Amyloid material
2) Toxic substances
3) Immune complexes
a. Found in lupus erythematosus
b. Found in streptococcal glomerulonephritis
What is the effect of increased pressure from the blood entering the glomerulus?
It may override the selective filtration of the glomerulus, causing increased albumin to enter the filtrate
Increased pressure from the blood entering the glomerulus may override the selective filtration of the glomerulus, causing increased albumin to enter the filtrate, is this condition reversible? When does this condition occur?
Yes, this occurs during strenuous exercise and dehydration or is associated w/ hypertension
Proteinuria that occurs during the latter months of pregnancy may indicate what?
Pre-eclamptic state
Should proteinuria that occurs during the latter months of pregnancy be considered by the physician in conjunction w/ other clinical symptoms (such as hypertension)?
Yes
Why should proteinuria that occurs during the latter months of pregnancy (w/c may indicate a pre-eclamptic state) be considered by the physician in conjunction w/ other clinical symptoms (such as hypertension)?
To determine if this condition exists
True or False
The discovery of protein, particularly in a random sx, is always of pathologic significance
No, because the discovery of protein, particularly in a random sx, is not always of pathologic significance
Why is the discovery of protein (in a random sx) not always of pathologic significance?
Because several benign causes of renal proteinuria exist
What is the characteristic of benign proteinuria?
It is usually transient
What are the conditions that can produce benign proteinuria?
1) Strenuous exercise
2) High fever
3) Dehydration
4) Exposure to cold
What is a common occurrence that happens in pts w/ both type 1 and type 2 DM?
The development of diabetic nephropathy leading to reduced glomerular filtration and eventual renal failure
How to 1st predict the onset of renal complications (for pts w/ both type 1 and type 2 DM)?
By detection of microalbuminuria
How to prevent the progression of renal disease in pts w/ both type 1 and type 2 DM?
Through better stabilization of blood glucose lvls and control of hypertension
The presence of microalbuminuria is also associated w/ what?
W/ an increased risk of cardiovascular disease
What is orthostatic proteinuria?
It is a persistent benign proteinuria w/c occurs frequently in young adults
What is the other term for orthostatic proteinuria?
Postural proteinuria
When does orthostatic proteinuria occur and when does it disappear?
It occurs following periods spent in a vertical posture and disappears when a horizontal position is assumed
What is the cause of orthostatic proteinuria?
Increased pressure on the renal vein when in vertical position
What are requested for the pts to do if they are suspected of having orthostatic proteinuria?
They are requested to:
1) Empty the bladder before going to bed
2) Collect a sx immediately upon arising in the morning
3) Collect a 2nd sx after remaining in a vertical position for several hrs
What is done to both sxs (1st sx: collected immediately upon arising in the morning | 2nd sx: sx collected after remaining in a vertical postiion for several hrs) collected by the pt?
Both sxs are tested for protein, if orthostatic proteinuria is present, a (-) reading will be seen on the 1st morning sx, and a (+) result will be found on the 2nd sx
Both sxs are tested for protein -> if orthostatic proteinuria is present -> 1st morning sx: (-) reading | 2nd sx: (+) reading / result
True or False
Increased albumin is also present in disorders affecting tubular reabsorption
True
Why is increased albumin also present in disorders affecting tubular reabsorption (tubular proteinuria)?
Because the normally filtered albumin can no longer be reabsorbed
Are other low MW proteins (w/c are usually reabsorbed) also present in disorders affecting tubular reabsorption?
Yes
What are the causes of tubular dysfxn?
1) Exposure to toxic substances
2) Exposure to heavy metals
3) Severe viral infections
4) Fanconi syndrome
What is the range of amt of protein that appears in the urine following glomerular damage?
From slightly above normal - 4 g/day
True or False
Markedly elevated protein lvls are always seen in tubular disorders
False, because markedly elevated protein lvls are seldom seen in tubular disorders
Can protein be added to a urine sx? If yes, how? If not, why?
Yes, as it passes through the structures of lower urinary tract
What are the components of the lower urinary tract (where protein passes through as it was added to the urine sx)?
1) Ureters
2) Bladder
3) Urethra
4) Prostate
5) Vagina
What does bacterial and fungal infections and inflammations produce?
These produce exudates containing protein from the interstitial fluid
What are the causes of presence of blood?
1) Injury
2) Menstrual contamination
Does the presence of blood (as a result of injury or menstrual contamination) contribute protein?
Yes
What are the other components that contributes protein (aside from injury and menstrual contamination)?
1) Presence of prostatic fluid
2) Large amts of spermatozoa
What is the principle used by the traditional rgnt strip testing (for protein)?
Protein error of indicators
What is the result of the principle used by traditional rgnt strip testing?
Production of a visible colorimetric rxn
True or False
Contrary to the general belief that indicators produce sp colors in response to particular pH lvls, certain indicators change color in the presence of protein even though pH of the medium remains constant
True
Why do certain indicators (in the rgnt strip) change color in the presence of protein even though the pH of the medium remains constant?
Because protein (primarily albumin) accepts hydrogen ions from the indicator
Is the test (for rgnt strip rxns for protein) more sensitive to albumin? Why or why not?
Yes, because albumin contains more amino grps to accept the hydrogen ions than other proteins
True or False
The component present in the protein area of the strip is constant w/ every manufacturer of rgnt strips
False, because the component present in the protein area of the strip varies depending on the manufacturer of the rgnt strips
What is the component present in the protein area of the strip (Multistix)?
Tetrabromophenol blue
What are the components present in the protein area of the strip (Chemstrip)?
1) 3’, 3”, 5’, 5”-tetrachlorophenol, 3, 4, 5, 6-tetrabromosulfonphthalein
2) Acid buffer
What is the purpose of the acid buffer (w/c is present in the protein are of the strip [Chemstrip])?
To maintain the pH at a constant lvl
What happens to both indicators (w/c are present in the protein area of the strip | in Multistix and Chemstrip) in the absence of protein at a pH lvl of 3?
Both indicators appear yellow
What happens to both indicators (w/c are both present in the protein area of the strips | in Multistix and Chemstrip) as the protein conc increases?
The color progresses through various shades of green and finally to blue
How are readings reported (in rgnt strip rxns for protein)?
1) (-)
2) Trace (< 30 mg/dL)
3) 1+
4) 2+
5) 3+
6) 4+
Or via semiquantitative values (in mg/dL | corresponding each color change):
1) 30
2) 100
3) 300
4) 2000
True or False
Interpretation of trace readings is not difficult
No, because interpretation of trace readings can be difficult
True or False
Reporting of trace values may be not a lab option
False, reporting of trace values may be a lab option
What is the rgnt strip rxn for protein?
pH 3.0
Indicator + protein ——–> protein + H^+
(yellow) indicator - H^+
(blue-green)
What is the clinical significance of urine protein?
Prerenal:
1) Intravascular hemolysis
2) Muscle injury
3) Acute phase reactants
4) Multiple myeloma
Renal:
1) Glomerular disorders
2) Immune complex disorders
3) Amyloidosis
4) Toxic agents
5) Diabetic nephropathy
6) Strenuous exercise
7) Dehydration
8) Hypertension
9) Pre-eclampsia
10) Orthostatic or postural proteinuria
Tubular Disorders:
1) Fanconi syndrome
2) Toxic agents / heavy metals
3) Severe viral infections
Postrenal:
1) Lower UTIs / inflammation
2) Injury / trauma
3) Menstrual contamination
4) Prostatic fluid / spermatozoa
5) Vaginal secretions
At what type of urine is the major source of error w/ rgnt strips occur?
At highly alkaline urine that overrides the acid buffer system, producing a rise in pH and a color change unrelated to protein conc
What is the result of a technical error whereas the rgnt pad is allowed to remain in contact w/ the urine for a prolonged period?
This technical error may remove the buffer
When are false-(+) readings obtained (in rgnt strip rxn for protein)?
When the rxn does not take place under acidic conditions
What are the other causes of false-(+) readings (aside from when the rxn does not take place under acidic conditions)?
1) Highly pigmented urine
2) Contamination of the container
a. W/ quaternary ammonium compounds
b. W/ detergents
c. W/ antiseptics
What may be the cause of a false-(+) trace reading (in rgnt strip rxn for protein)?
It may occur in sxs w/ a high SG
What is the meaning of SSA test?
Sulfosalicylic acid test
What is SSA test?
It is a cold precipitation test that reacts equally w/ all forms of protein
True or False
Various conc and amts of SSA can be used to precipitate protein, and methods vary greatly among labs
True
At what type of sxs must all precipitation tests be performed?
All precipitation tests must be performed on centrifuged sxs to remove any extraneous contamination
What is the purpose of developing several semiquantitative rgnt strip methods?
So that pts at risk for renal disease can be monitored
What type of sxs are used in terms of monitoring pts at risk for renal disease (via the use of several semiquantitative rgnt strip methods)?
1) Random
2) Or first morning sxs
What are the basis of several semiquantitative rgnt strip methods?
1) Immunochemical assays for albumin
a. Micral-Test
b. ImmunoDip
2) Or albumin-specific rgnt strips (w/c also measure creatinine to produce an albumin:creatinine ratio)
How are both rgnt strips (in relation to testing for microalbuminuria) read?
Both are read visually
What is the sx that is recommended for the use of several semiquantitative rgnt strip methods (to monitor the pts who are at risk for renal disease | in connection to testing for microalbuminuria)?
First morning sxs
What is the component contained by Micral-Test rgnt strips?
Gold-labeled antihuman albumin antibody-enzyme conjugate
How are Micral-Test rgnt strips used?
These strips are dipped into the urine up to a lvl marked on the strip and held for 5 secs
What is the action of the albumin in the urine (in Micral-Test)?
It binds to the Ab
What is the action of bound and unbound conjugates in Micral-Test?
These move up the strip by wicking action
True or False
The SG of the urine sx should be considered in evaluating urine protein
True
Why should SG of the urine sx be considered in evaluating urine protein?
Because a trace protein in a dilute sx is more significant than in a concentrated sx
How are unbound conjugates removed?
These are removed in a captive zone by combining w/ albumin embedded in the strip
What is the action of urine albumin-bound conjugates?
These continue up the strip and reach an area containing enzyme substrate
What is the action of conjugated enzyme?
It reacts w/ the substrate, producing colors ranging from white to red
True or False
The amt of color produced represents the amt of albumin present in the urine (in relation to testing for microalbuminuria)
True
How is the color (in testing for microalbuminuria) compared?
It is compared w/ a chart on the rgnt strip bottle after 1 min
What is the range of results (in testing for microalbuminuria)?
0 - 10 mg/dL
What is the technique used by ImmunoDip rgnt strip?
Immunochromographic technique
How are strips packaged and where are these packaged?
These are individually packaged in specially designed containers
*What is done to the container (of rgnt strips)?
This is placed in the urine sx for 3 mins
What is the procedure (in connection w/ testing for microalbuminuria) via the use of ImmunoDip rgnt strip?
1) A controlled amt of urine enters the container through a vent hole
2) The urine encounters blue latex particles coated w/ antihuman albumin Ab
3) Albumin (present in the urine) binds w/ the coated particles
4) The bound and unbound particles continue to migrate up the strip
- > the migration is controlled by the size of the particles
- > unbound particles do not migrate as far as the bound particles
5) First, a blue band is formed by the unbound particles
6) The bound particles continue to migrate and form a 2nd blue band further up the strip
7) The top band therefore represents the bound particles (urine albumin) and the bottom band represents unbound particles
On where is the color intensity of the bands (in connection w/ testing for microalbuminuria | via the use of ImmunoDip rgnt strips) compared?
It is compared against the manufacturer’s color chart
What is the representation of the darker bottom band (in connection w/ testing for microalbuminuria | via the use of ImmunoDip rgnt strips)?
< 1.2 mg/dL of albumin
What is the representation of the equal band colors (in connection w/ testing for microalbuminuria | via the use of ImmunoDip rgnt strips)?
1.2 - 1.8 mg/dL of albumin
What is the representation of the darker top band (in connection w/ testing for microalbuminuria | via the use of ImmunoDip rgnt strips)?
2.0 - 8.0 mg/dL of albumin
What is the interpretation of darker bottom band (in connection w/ testing for microalbuminuria | via the use of ImmunoDip rgnt strips)?
(-) results
What is the interpretation of equal band color (in connection w/ testing for microalbuminuria | via the use of ImmunoDip rgnt strips)?
Borderline results
What is the interpretation of darker top band (in connection w/ testing for microalbuminuria | via the use of ImmunoDip rgnt strips)?
(+) results
Answer the ff questions regarding the given protein rgnt strip:
1) What is/are the rgnt/s present?
2) What is the sensitivity?
3) What is/are the source/s of error/s / interference/s?
4) What is/are the other test/s that can be correlated w/ results of protein rgnt strip?
Given protein rgnt strip: Multistix
1) Tetrabromophenol blue
2) 15 - 30 mg/dL albumin
3) False-(+):
a. Highly buffered interference alkaline urine
b. Pigmented sxs, phenazopyridine
c. Quaternary ammonium compounds (detergents)
d. Antiseptics, chlorhexidine
e. Loss of buffer from prolonged exposure of the strip to the sx rgnt
f. High SG
3. 1) False-(-):
a. Proteins other than albumin
b. Microalbuminuria
4) Blood
Answer the ff questions regarding the given protein rgnt strip:
1) What is/are the rgnt/s present?
2) What is the sensitivity?
3) What is/are the source/s of error/s / interference/s?
4) What is/are the other test/s that can be correlated w/ results of protein rgnt strip?
Given protein rgnt strip: Chemstrip
1) 3’, 3”, 5’, 5”-tetrachlorophenol and 3, 4, 5, 6-tetrabromosulfonphthalein
2) 6 mg/dL albumin
3) False-(+):
a. Highly buffered interference alkaline urine
b. Pigmented sxs, phenazopyridine
c. Quaternary ammonium compounds (detergents)
d. Antiseptics, chlorhexidine
e. Loss of buffer from prolonged exposure of the strip to the sx rgnt
f. High SG
3. 1) False-(-):
a. Proteins other than albumin
b. Microalbuminuria
4) Nitrite, leukocytes, and microscopic
What is the action of Clinitek Microalbumin rgnt strips and the Multistix rgnt strips?/
Both of these provide simultaneous measurement of albumin/protein and creatinine that permits an estimation of the 24-hr microalbumin excretion
True or False
Creatinine is produced and excreted at a consistent rate for each individual
True
How can albumin reading be corrected for overhydration and dehydration in a random sx?
By comparing the albumin excretion to the creatinine excretion
True or False
In addition to including creatinine on the rgnt strip, the albumin low-test pad is changed to a dye-binding rxn that is more sp for albumin than the protein error of indicators’ rxn on strips measuring protein
True
What is the dye used by albumin rgnt strips?
Bis(3’, 3”-diiodo-4’, 4”-dihydroxy-5’, 5”-dinitrophenyl)-3, 4, 5, 6-tetrabromosulphonphthalein (DIDNTB)
What is the characteristic of DIDNTB?
It has a higher sensitivity and specificity for albumin
In comparison w/ albumin rgnt strips, what is the sensitivity of conventional protein rgnt pads?
30 mg/dL or greater
In comparison w/ DIDNTB, what are included (/ what are the components that it measure) in conventional rgnt pads?
It may include proteins other than albumin
In comparison w/ conventional protein pads, what are the components that DIDNTB can measure?
It can measure albumin between 8 and 15 mg/dL (80 - 150 mg/L) w/out inclusion of other proteins
What is the concern always w/ conventional rgnt strips?
Rxn interference by highly buffered alkaline urine
How is rxn interference by highly buffered alkaline urine controlled?
Via using paper treated w/ bis-(heptapropylene glycol) carbonate
What is the action of addition of polymethyl vinyl ether?
It decreases the nonspecific binding of polyamino acids to the albumin pads
What is the color range present in conventional rgnt strips?
From pale green to aqua blue
What is the cause of falsely elevated results (in conventional rgnt strips)?
Visibly bloody urine
What can cause interference w/ the readings if conventional rgnt strips are used?
Abnormally colored urines
The principle of the rgnt strip for creatinine is based on what?
Pseudoperoxidase activity of copper-creatinine complexes
Is the rxn (for creatinine) follows the same principle as the rxn for blood on the rgnt strips?
Yes
What are the components contained in the rgnt strips for creatinine?
1) Copper sulfate (CuSO4)
2) 3, 3’, 5, 5’-tetramethylbenzidine (TMB)
3) Diisopropyl benzene dihydroperoxide (DBDH)
What is the action of creatinine (present in the urine) in connection w/ the rxn of rgnt strip for creatinine?
It combines w/ the CuSO4 to form copper-creatinine peroxidase
Creatinine (present in pt’s urine) + CuSO4 = Copper-creatinine peroxidase
What is the action of copper-creatinine peroxidase?
It reacts w/ the peroxide DBDH
What happens next after copper-creatinine peroxidase react w/ the peroxide DBDH?
Oxygen ions are released w/c oxidize the chromogen TMB and producing a color change from orange through green to blue
What is the rxn in the rgnt strip for creatinine?
CuSO4 + CRE -> Cu(CRE) peroxidase
Cu(CRE) peroxidase
DBDH + TMB —————————–> oxidized TMB + H2O
(peroxidase) (chromogen) (orange to blue)
How are results reported via the use of rgnt strip for creatinine?
All in mg/dL:
1) 10
2) 50
3) 100
4) 200
5) 300
All in mmol/L (of creatinine):
1) 0.9
2) 4.4
3) 8.8
4) 17.7
5) 26.5
Are rgnt strips (for creatinine) able to detect the absence of creatinine?
No
What can be the causes of falsely elevated results (if rgnt strips for creatinine) is used?
1) Visibly bloody urine
2) Presence of gastric acid-reducing medication cimetidine (Tagamet)
True or False
All creatinine readings are considered abnormal
False, because no creatinine readings are considered abnormal
Why are there no creatinine readings that are considered abnormal?
Because creatinine readings is normally present in concentrations of 10 - 300 mg/dL
What is the purpose of creatinine measurement (via the use of rgnt strip for creatinine)?
To correlate the albumin conc to the urine conc, producing a semiquantitative albumin:creatinine ratio (A:C) ratio
What are methods available for determining the albumin/protein:creatinine ratio (A:C ratio)?
1) Automated methods
2) Manual methids
The Clinitek Microalbumin rgnt strips are designed for what?
These are designed for instrumental use only
What is used for reading strips for determining the A:C ratio (/ where are the strips read)?
Clinitek Urine Chemistry Analyzers
What are the actions of the rgnt strips (w/c are used in determining the A:C ratio)?
These measure only:
1) Albumin
2) Creatinine
Also, these calculate the A:C ratio
What are done to the results (w/c are obtained via the use of rgnt strips for determining the A:C ratio)?
1) These are displayed
2) These are printed
a. For albumin
b. For creatinine
c. For A:C ratio
What are the units used in printing A:C ratio (obtained via the use of rgnt strips [w/c are used to calculate the A:C ratio])?
Both conventional and S.I. units
What are the abnormal results for the A:C ratio?
30 - 300 mg/g or 3.4 - 33.9 mg/mmol
What are the components included in the Siemens Multistix Pro 10 rgnt strips?
1) Creatinine
2) Protein-high
3) Protein-low (albumin)
4) Pads
a. For glucose
b. Ketones
c. Blood
d. Nitrite
e. LE
f. pH
g. Bilirubin
h. SG
Is urobilinogen included in the Siemens Multistix Pro 10 rgnt strips?
No
How are the Siemens Multistix Pro 10 rgnt strips read?
Either:
1) Manually
2) Automated Clinitek instruments
What is the principle used by protein-high rxn (w/c is present / included in the Siemens Multistix Pro 10 rgnt strips)?
Protein error of indicators principle
What is the principle used by protein-low rxn (w/c is present / included in the Siemens Multistix Pro 10 rgnt strips)?
Dye-binding method
How are results (obtained via the use of Siemens Multistix Pro 10 rgnt strips) reported?
These are reported as the protein:creatinine ratio
What result (w/c is obtained via the use of Siemens Multitstix Pro 10 rgnt strips) used in the calculation?
Protein-low result
What is done to the results from the Clinitek (whereas Siemens Multistix Pro 10 rgnt strips are used)?
These are automatically calculated
How are results (from Clinitek | w/c are obtained via the use of Siemens Multistix Pro 10 rgnt strips) reported?
These are reported as:
1) Normal
2) Or abnormal
What is the indication if the result is normal dilute sx?
It indicates that the sx should be recollected, making sure that it’s a 1st morning sx
How is the rgnt strip (Siemens Multistix Pro 10) read if manual reading is done?
A manufacturer supplied chart is used to determine the ratio based on the results of the protein-high, protein-low, and creatinine readings
What is result used when the chart supplied by the manufacturer (when the Siemens Multistix Pro 10 rgnt strips are read manually)?
The higher or the protein-low or protein-high result is used
What is the detailed procedure of the SSA test?
1) Add 3 mL of 3% SSA rgnt to 3 mL of centrifuged urine
2) Mix by inversion and observe for cloudiness
3) Grade the degree of turbidity
Answer the ff questions w/ regards to the given grading (in terms of reporting SSA turbidity):
1) What is the turbidity (/ explanation of turbidity)?
2) What is the protein range (in mg/dL)?
Given grading: Negative
1) No increase in turbidity
2) <6
