Urinalysis Chart for Reagent Strips Review - 2024/2025 Fall

## Urinalysis | **Test** | **Reference Range** | **Chemical Reaction** | **Clinical Significance** | **False negatives** | **False Positives** | |---|---|---|---|---|---| | **Specific Gravity** | 1.003-1.035 | Polyectrolytes + ions in urine→ H+ liberated and cause colour change | Urine Concentrati...

## Urinalysis | **Test** | **Reference Range** | **Chemical Reaction** | **Clinical Significance** | **False negatives** | **False Positives** | |---|---|---|---|---|---| | **Specific Gravity** | 1.003-1.035 | Polyectrolytes + ions in urine→ H+ liberated and cause colour change | Urine Concentration ↓- fluid intake, D. insipidus, renal tubular damage, diuretic ↑- dehydration, glucosuria, protienuria, x-ray contrast media | Dipstick method only detects ionic solutes | Genital discharge, bleach or H2O2 | | **pH** | 5-8 | Methyl red & bromothymol blue change from orange → yellow, green → blue | Acidic - metabolic or respiratory acidosis, bacteria, medications Alkaline - metabolic or respiratory alkalosis, ammonia producing bacteria (Proteus, Pseudomonas), medications | | Drugs that turn red in acid | | **Leukocytes** | Negative | Ester + granulocytic esterases → aromatic compound + diasomium salt → purple colour | Bacterial infection, inflammation of the urinary tract | Large amounts of glucose or high SG cause WBCs to crenate and prevent esterase release. Bacteria does not reduce nitrate, insufficient incubation time, absence of dietary nitrate | Old specimens (contaminated). | | **Nitrite** | Negative | Greiss reaction: NO2- + aromatic amine → diazonium + quinoline → pink | Bacteria that commonly cause UTI's reduce dietary nitrate → nitrite | | Drugs that turn red in acid | | **Protein (Very sensitive to albumin)** | Negative | Buffered indicator (pH3); protein error of indicators. Indicator releases H ions in the presence of protein → colour change (yellow green-blue) | Glomerular proteinuria, overload protienurea, tubular protienurea, inflammation of lower urinary tract. Persistent proteinuria may indicate renal disease or lower UT inflammation. | Jones & Globulins, Bence-mucoprotiens less reactive. | High alkaline urine (acidify urine & rpt protein) | | **Glucose** | Normal Normal renal threshold is 8.9-10.0 mmol/L | Glucose oxidase (GOD) & peroxidase (POD) on dipstick Glucose & O2 →GOD gluconic acid + H2O2 →POD H2O + O2 + chromogen → oxidized chromogen(colour change) | Diabetes Mellitus, lowered renal threshold | Ascorbic acid (Vit C) | Dipstick held in urine to long. Drugs that turn red in acid | | **Ketones** | Negative negligible amounts of acetoacetic acid & acetone are present normally | Acetoacetic acid + sodium nitroprusside buffer → purple Less sensitive to acetone | Gluconeogenesis Starvation, dietary imbalance, prolonged strenuous exercise, pyrexia Diabetes mellitus with production of ketoacids | | Urine contaminated with H2O2 or bleach | | **Urobilinogen** | Normal - Small amounts of urobilinogen/urobilen | Siemens: Erlich's aldehyde +urobilinogen =salmon colour Roche: Diazonium salt + urobilinogen-red azo dye (salmon) | Pre-hepatic or hepatic jaundice ↑ in hemolytic conditions and liver disease | Old samples where urobilinogen is oxidized to urobilin (yellow) | Bayer - Indole, skatole, porphobilinogen (lg intestine disease) | | **Bilirubin** | Negative - No bilirubin | Diazotization reaction Roche: Diazo rgt +conjugated bilirubin→ azobilirubin (rose-beige) Siemens: Diazo rgt+conjugated bilirubin→ Azobilirubin (brown-purple) | Only conjugated bilirubin can be excreted in the urine Hepatic Jaundice, post-hepatic jaundice | Old samples where bilirubin is oxidized to biliverden (green) or hydrolyzed to unconjugated (insoluble & less reactive), ascorbic acid (Vit C) | Drugs that turn red in acid | | **RBCs/Hemoglobin** | Negative | "Based on the peroxidase activity of hemoglobin" H2O2 + Hemoglobin → H20 & O2 + chromagen → oxidized chromogen (green) | Hematuria - Kidney trauma, bleeding, strenuous exercise, prolonged exposure to cold, menstruation Hemoglobinuria – incompatible blood transfusion, lysis due to infection, hemolytic anemia, prolonged pounding | Ascorbic acid (Vit. C) | Lg quantities of chloropromazine (tranquilizer) Drugs that turn red in acid |