Dipstick Reactions

pH reaction principle

Double Indicator System

pH reagent

Methyl red and bromothymol blue

pH sensitivity

5.0-9.0

pH false positives and negatives

None

pH clinical significance

Alkaline-old urine

Protein reaction principle

Protein error of indicators

Protein reagent

Tetrabromphenol blue

Protein sensitivity

15-30mg/dl Albumin

Protein false positives

High alkaline urine

Protein false negatives

High salt

Protein clinical significance

Best single indicator of early disease

Glucose reaction principle

Double sequential enzyme

Glucose reagent

Glucose oxidase, peroxidase, chromogen buffer

Glucose sensitivity

75-125mg/dL

Glucose false positive

Bleach

Glucose false negative

Ascorbic acid

Glucose clinical significance

Diabetes mellitus

Ketone reaction principle

Sodium nitroprusside

Ketone reagent

Sodium nitroprusside

Ketone sensitivity

5-10mg/dL acetoacetic acid

Ketone false positive

Highly pigmented urine and medication

Ketone false negative

Ascorbic acid and increased SG

Ketone clinical significance

Uncontrolled diabetes mellitus high protein

Blood reaction principle

Pseudo-peroxidase activity

Blood reagent

Hydrogen peroxide and tetramethylbenzidine

Blood sensitivity

0.015-0.062mg/dL hemoglobin

Blood false positive

Bleach

Blood false negative

Ascorbic acid, ketones, high SG with low pH

Blood clinical significance

Bleeding disorders, renal disorders, and cystitis

Bilirubin reaction principle

Diazo reaction

Bilirubin reagent

Diazonium salt

Bilirubin sensitivity

0.4-0.8mg/dL Bilirubin

Bilirubin false positive

Medication and color

Bilirubin false negative

Ascorbic acid and increased SG

Bilirubin clinical significance

Bile duct obstruction and liver damage

Urobilinogen reaction principle

Ehrlich’s reaction

Urobilinogen reagent

p-dimethylaminobenzaldehyde

Urobilinogen sensitivity

0.2mg/dL urobilinogen

Urobilinogen false positive

Highly pigmented urine medication

Urobilinogen false negative

Nitrite

Urobilinogen clinical significance

Liver damage and hemolytic anemia

Nitrite reaction principle

Griess’s reaction

Nitrite reagent

P-a

Nitrite sensitivity

0.06-0.1 mg/dL nitrite ion

Nitrite false positive

Medication

Nitrite false negative

Ascorbic acid

Nitrite clinical significance

Bacteria

Leukocyte reaction principle

Enzymatic reaction

Leukocyte reagent

Pyrrole amino acid

Leukocyte sensitivity

5-15 cells/hpf

Leukocyte false positive

Bleach

Leukocyte false negative

Glucose protein, high SG, antibiotics

Leukocyte clinical significance

Bacteria

Specific gravity reaction principle

PKA (Dissociation constant)

Specific gravity reagent

Bromthymol blue

Specific gravity sensitivity

1.000-1.030

Specific gravity false positive

Protein

Specific gravity false negative

Alkaline urine

Specific gravity clinical significance

Diabetes insipidus and radiographic dye