Chemical Examination - Kulang Flashcards by Mark James Mateo

are used to perform the routine chemical tests on urine

Reagent Strips

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consist of chemical-impregnated absorbent
pads on a plastic strip

○ each test has a specific chemical that is
impregnated on the pad

Reagent Strips

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Test performed for Reagent Strips

pH
protein
glucose
ketones
blood
bilirubin
urobilinogen
nitrite
leukocyte esterase
specific gravity (SG)

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What parameters are in the 2 Parameters Reagent Strips?

Protein
Glucose

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What parameters are in the 11 parameters Reagent Strips?

pH
protein
glucose
ketones
blood
bilirubin
urobilinogen
nitrite
leukocyte esterase
specific gravity (SG)
+ Creatinine

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Major Types of Reagent Strips

○ Multistix (Siemens)
○ Chemstrip (Roche)

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Reagent strips are also used with _________

automated instruments

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Some VARIATIONS occur between the strips with regard to ________ and _________ and _____________

sensitivity; specificity; interfering substances

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are supplied by the manufacturer → located at the bottle

Color Comparison Charts

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Reagent Strip Technique

Dip strip
Remove excess urine
Blot edge of strip
Wait
Compare color of reaction
Hold horizontally

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results of Reagent Strip can be read from (time)

30-120 secs

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Dip strip briefly into well-mixed specimen at (temperature)

room temperature

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RBCs and WBCs sink to the bottom of an unmixed specimen → can cause

false negative results

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Enzyme reactions on strip are based on (readings)

room temperature readings

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leukocyte esterase amount of time for reactions to occur

the LONGEST at 2 minutes

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strips are stored with

DESICANT in an opaque, tightly closed
container

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What is generated when strips are refrigerated?

Freezing can generate moist

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HANDLING AND STORAGE OF STRIPS

● Store with DESICANT in an opaque, tightly closed container
● Store below 30C, DO NOT FREEZE
● Do not expose to volatile fumes
● Do not use past the expiration date
● Do not use if pads are discolored
● Remove strips immediately prior to use

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characteristics of pads

hydroscopic

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QC for Protein

sulfosalycilic acid / acidify specimen

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QC for Galactose

Clinitest

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QC for Ketones

Acetest

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QC for Bilirubin

Ictotest (primary confirmatory test)

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are major regulator of acid-base balance
○ Make sure that blood pH is maintained

kidneys

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specimen that is normally acidic (5-6)

First Morning Specimen

specimen that is more alkaline

Postprandial specimen

Normal Range of Urine pH

4.5-8.0

cannot reach pH 9→ indicates old bacteria-contaminated urine (highly alkaline urine; recollect)

Normal fresh urine

DIET AND MEDICATION REGULATION Meat = ? Vegetables = ? Medications for URINARY TRACT INFECTION = ?

● MEAT = acid pH ● VEGETABLES = alkaline pH ● Medications for URINARY TRACT INFECTION = acid pH

exception for alkaline pH for vegetables

cranberry juice

Causes Acid Urine

Emphysema Diabetes mellitus Starvation Dehydration Diarrhea Presence of acid-producing bacteria (E. coli) High Protein diet Cranberry Juice Medication

Example of Medications that can cause Acidic Urine

methenamine mandelate [Mandelamine], fosfomycin tromethamine [Monurol]

Causes Alkaline Urine

Hyperventilation Vomiting Renal Tubular Acidosis Presence of urease-producing bacteria Vegetarian diet Old specimens

Double Indicator Reaction

Methyl Red Bromthymol blue

4–6 red/orange to yellow (DIR)

Methyl Red

6–9 green to blue (DIR)

Bromthymol blue

(DIR) Interference: Only runover between acid from protein pad →

False Positive Results

Most indicative of renal disease

Protein

seen in early renal disease

Proteinuria

Normal protein of Urine

NORMAL = <10 mg/dL or 100 mg/24 hr

is primary protein of concern

Albumin

● Conditions affecting the PLASMA, not the kidney ○ Inflammation can cause proteinuria; overrides the reabsorptive capacity of the kidneys

Prerenal Proteinuria

● Transient, increase levels of low molecular weight plasma proteins, acute phase reactants, exceed reabsorptive capacity ● Rarely seen on reagent strip (not albumin)

Prerenal Proteinuria

urine test is used most often to diagnose and check on multiple myeloma, a type of cancer.

Bence Jones Protein (BJP)

○ Proliferative disorder of plasma cells ○ Excessive division of plasma cells results to the immunoglobulin light chains in the urine (BJP)

Multiple Myeloma

Immunoglobulin light chains

Bence Jones Protein

Screening Test for BJP

BJP coagulates between 40-60°C and dissolves at 100 degrees (solubility property) ○ Proteins other than BJP remain uncoagulated

Confirmatory Test for BJP

serum electrophoresis

Prerenal Tubular Disorders

1. Intravascular hemolysis 2. Muscle Injury 3. Acute phase reactants 4. Multiple Myeloma

Clinical proteinuria range

= 30 mg/dL, 300 mg/24 hr ○ Higher results → pathologic cause

Proteinuria - Variety of Causes

Prerenal Renal Postrenal

Renal Proteinuria

1. Glomerular proteinuria 2. Tubular proteinuria

Glomerular Proteinuria is caused by what factors?

● Damage to glomerular membrane ● Impaired selective filtration causes increased protein filtration ● Abnormal substances deposit on the membrane ● Increased pressure on the filtration mechanism ● Benign proteinuria (transient

Primarily immune disorders result in immune complex formation

■ Lupus erythematosus ■ Streptococcal glomerulonephritis

Increased pressure on the filtration mechanism can caused of

○ Hypertension ○ Strenuous exercise (physiologic cause) ○ Dehydration ○ Pregnancy (Preeclampsia)

↑ blood flow in kidneys = ?

↑ pressure at glomerular basement membrane = CAUSES DAMAGE IN THE GBM

○ Exposure to cold, exercise, dehydration, high fever ○ Observed in young adults ○ Long hours of standing/sitting (in vertical position) → detection of protein in urine

Orthostatic Proteinuria

ORTHOSTATIC (POSTURAL) PROTEINURIA

● Benign (increased pressure on renal vein) ● Occurs in vertical position, disappears in horizontal position ● Frequently picked up on random specimen ● Empty bladder before bed ● Collect specimen immediately on arising ● Specimen will be NEGATIVE for protein

Glomerular Disorders

1) Immune complex disorders 2) Amyloidosis 3) Toxic agents 4) Diabetic nephropathy 5) Strenuous exercise 6) Dehydration 7) Hypertension 8) Preeclampsia 9) Orthostatic or postural proteinuria

Tubular Proteinuria is caused by what factors?

● Tubular damage affecting reabsorptive ability ● AMOUNT OF PROTEIN

■ Toxic substances, heavy metals, viral infections, Fanconi syndrome (generalized proximal convoluted tubule defect)

○ ACUTE TUBULAR NECROSIS

Patients (children) with cystinuria may develop ___________________

Fanconi syndrome

disorder where the reabsorptive capacity of kidney tubules are impaired

Fanconi syndrome

Amount of Protein in Glomerular

up to 4 g/day (directly from circulation)

Amount of Protein in Tubular

much lower levels (from damaged tubules)

Factors that causes Postrenal Proteinuria

● Protein added in the lower urinary and genitourinary tract ● Microbial infections causing inflammations and release (leakage) of interstitial fluid protein ● Menstrual contamination ● Semen / Prostatic fluid ● Vaginal secretions ● Traumatic injury

TRADITIONAL PRINCIPLE of Protein Reagent Strip Reactions

○ Protein error of indicators ○ Certain indicators change color in the presence of protein at a constant pH ○ Protein, primarily ALBUMIN, accepts H+ from the indicator ○ Most sensitive to albumin because albumin has more amino groups to accept H+ than other proteins ○ Color change is directly proportional to the amount of protein present in the urine

Indicator of Reaction in Protein

Tetrabromophenol blue or tetrachlorophenol tetrabromsulfonphthalein and an acid buffer

pH Level for Protein

In protein strip reaction, color progresses through ____ to ______

green to blue

trace values of protein are

<30 mg/dL