by over 4 hours Oxidation of bilirubin if examination is delayed 68 Concise Book of Medical Laboratory Technology: Methods and Interpretations 2. Iodine Ring Test A sensitive cum reliable test. Layer a solution of 10%
The three ketone bodies that can be detected in urine are:
3. β-Hydroxybutyric acid (78%).
Acetoacetic acid Hydroxybutyric acid
(Never heat urine specimen before performing the tests).
Saturate 5 mL of urine with ammonium sulfate, add a
few crystals of sodium nitroprusside. Shake it. Add liquor
ammonia from the side of the test tube, formation of a
purple ring at the junction indicates a positive test.
Sensitivity > 1–5 mg% acetoacetic acid, or > 10–25 mg%
Take 10 mL of urine in a test tube and add a few crystals
of sodium nitroprusside. Acidify with glacial acetic acid,
invert to mix. Overlay with strong liquor ammonia, let
stand for 5 minutes. A violet ring indicates a positive test.
The degree of positivity depends upon the speed of the
3. Paper Strip/Tablet Methods (Ketur Test—Boehringer)
These contain sodium nitroprusside, aminoacetic acid
and disodium phosphate. A positive test is indicated by
development of a purple color.
4. Diacetic Acid Test (Gerhardt’s Test)
Not a very sensitive test. Perform this test if the test for
acetone was positive. Precipitate the phosphates in 5 mL
of urine with 10% ferric chloride solution, drop-by-drop,
filter and add more ferric chloride. If a purple-red color
appears, it indicates presence of 0.05% or more of diacetic
acid. False-positive test may appear with salicylates,
Ketonuria indicates ketoacidosis and if unchecked may
go on to coma. Juvenile diabetics are more susceptible to
develop this. Whenever glycosuria is more than 2+, always
TABLE 5.3: Reactivity of usual methods
Sugars detected Benedict’s qualitative test Glucose oxidase
¾ Toxic states with vomiting, diarrhea, etc.
¾ Conditions where there is limited availability of glucose,
¾ Sometimes following exposure to cold or severe exercise.
a. Ketosis and ketonuria may occur whenever increased
amounts of fat are metabolized, carbohydrate intake
restricted, or the diet is fat rich.
b. Ketonuria occurs in association with:
• Gastrointestinal disturbances
c. In non-diabetics, ketonuria will frequently occur in
acute illness. Fifteen percent of hospitalized cases
will show ketone bodies in urine even though they are
d. Children are particularly prone to developing
e. Ketone bodies appear in urine before there is any
significant increase of ketone bodies in the blood.
a. Carbohydrate free diets as well as high protein and fat
b. Drugs that may cause false positive tests.
1. Presence of ketone bodies in the urine is helpful in
differentiating between a diabetic coma and an insulin
2. Any stressful condition that distorts the normal
regulation of a diabetic can be recognized at any early
point by a positive urine ketone test.
3. Urine ketones indicate caution, not a crisis situation,
in either a diabetic or a non-diabetic patient.
• Appearance of ketones in a diabetic implies that
the patient is not adequately controlled, and that
adjustments of either the medication or the diet
• In a non-diabetic, ketone bodies indicate a small
amount of CHO metabolism and excessive fat
Bile salts when present decrease the surface tension of
urine. When sulfur powder is added on the surface of
urine, sulfur particles sink to the bottom of the test tube. In
normal urine sample, sulfur particles float on the surface
1. Take about 10 mL urine in a test tube.
2. Sprinkle a little dry sulfur powder on the surface of
3. Observe the sulfur particles.
1. Sulfur particles sink to the bottom: Bile salts present
2. Sulfur particles remain floating: Bile salts absent.
Bile pigments (always use fresh specimen). Normal level of
bile pigments is urine in < 0.02 mg%.
Not very accurate as proteins can also form foam. Shake
5 mL of urine in a test tube, bile produces a yellowish foam
TABLE 5.4: Bile pigments: Reactivity of various methods
Diazo method Harrison/Fouchet’s test
Chlorpromazine Aspirin metabolites, urobilin
Oxidation of bilirubin if examination is delayed
68 Concise Book of Medical Laboratory Technology: Methods and Interpretations 2. Iodine Ring Test
A sensitive cum reliable test. Layer a solution of 10%
alcoholic iodine on urine in a test tube. A green ring
A sensitive test. To 5 mL of urine, add 5 mL of 10% barium
chloride in a test tube. Shake it. Filter it off. Let the filter
paper dry. When dry, add 1–2 drops of Fouchet’s reagent
to the dried precipitate. A green (disregard all other colors)
Comments
Post a Comment
اكتب تعليق حول الموضوع