PART 3 routine examination of urine (week 4) Flashcards
- Urine is examined routinely to detect or determine the presence or absence of glucose. This is done either as screening procedure or as a guide to insulin therapy.
- Other sugars may also appear in urine in certain conditions and interfere with the detection and determination of glucose. Blood level, glomerular blood flow, tubular reabsorption rate, and urine flow influence the appearance of glucose in urine.
GLUCOSE
It is called as the glucose in urine
- More than 180-200 mg/dl
Glucosuria
The blood level at which tubular reabsorption stops
160 to 180 mg/dL
Renal thresold
- Diabetes mellitus
- Pancreatitis
- Pancreatic Cancer
- Acromegaly
- Cushing’s syndrome
- Hyperthyroidism
- Pheochromocytoma
- CNS damage
- Stress
- Gestational Diabetes
Hyperglycemia-associated
- Fanconi’s syndrome
- Advanced renal disease
- Osteomalacia
- Pregnancy
Renal associated
- Softening of the bones due to defective bone mineralization
Osteomalacia
Principle: Double sequential enzyme (Glucose oxidase & peroxidase) use two enzymes
1st step: Glucose oxidase catalyzes a reaction between glucose and oxygen to produce gluconic acid and peroxide
2nd step: Peroxidase catalyzes a reaction between peroxide and chromogen to form an oxidized chromogen (colored compound)
Reagent strip method specific test for glucose
chromogen is oxidized
positive result
REAGENT STRIP METHOD - SPECIFIC TEST FOR GLUCOSE
- Oxdizing cleaning agent
False positive
REAGENT STRIP METHOD - SPECIFIC TEST FOR GLUCOSE
- Cold specimen, high concentration of vitamin C, ketones, improperly preserved specimen, high specific gravity
false negative
an antioxidant which prevents oxidation
Vitamin C (ascorbic acid)
- Potassium iodide chromogen
- Negative: Blue
- Positive: Green —> Brown in 30 seconds
Multistix
- Aminopropyl-carbazol chromogen
- Color changes from yellow —> Orange brown in 60 seconds
Chemistrip
- O-toluidine chromogen
- Color changes from pink —> purple
Clinistix
Principle: Copper Reduction
It is the ability of glucose to reduce copper
sulfate to cuprous oxide in the presence of alkali & heat .
- The glucose in urine reduces the blue alkaline copper sulfate to cuprous oxide.
BENEDICT’S TEST
powerful reducing agents; cupric to
coprous
Enediols
Principle: Copper Reduction
a. Store in dry, away from sunlight
b. Normal: spotted bluish white tablet
c. Dark blue to brown tablet – (discard)
CLINITEST (Copper Reduction Tablet Test)
Contains copper sulfate,
sodium hydroxide, sodium carbonate, citric acid
Tablet (rgts)
reacts with reducing substances in the urine converting copper (in cupric form) sulfate to cuprous oxide
Copper sulfate
COPPER REDUCTION TEST
Negative result
Blue
COPPER REDUCTION TEST
Positive result
Orange/Red
- Involves “Pass-through phenomenon” if
sugar in urine is more than 2 g/dL when the glucose in urine is very high - Color produced passes through the orange/red stage and returns to a green brown color because of re-oxidation of cuprous oxide to cupric oxide
- Passes through orange to a dark shade of greenish brown. Re-oxidation of cuprous oxide to cupric oxide
- Commonly, ang ginagawa ay five drop method because the two-drop method is only performed if there’s pass through
phenomenon
COPPER REDUCTION TEST
Principle: Copper reduction
(+) result: Green, yellow, orange, red
sugar measured: Glucose and other reducing sugars
Benedict and Clinitest tablet
Principle: Double sequential Enzyme reaction (glucose oxidase)
(+) result: Green to brown
(-) result: Blue
Sugar measured
- Glucose only
Reagent strip
Ascorbic acid in reagent strip testing
False negative
Ascorbic acid in Clinitest
False positive
Oxidizing agents in reagent strip testing
False positive
