MedicosLecture.MLS

01/02/2026

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31/01/2026

Chemical analysis of Urine and their Methods.

31/01/2026

URINE ANALYSIS – CHEMICAL TESTS

1. Urine Glucose
Methods & Chemicals

Benedict’s test → Benedict’s reagent

GOD-POD method → Glucose oxidase, Peroxidase, Chromogen

Strip method → Glucose oxidase + Peroxidase

2. Urine Protein (Albumin)
Methods & Chemicals

Heat & Acetic acid test → Acetic acid

Sulphosalicylic acid test (SSA) → 3% Sulphosalicylic acid

Heller’s nitric acid test → Concentrated nitric acid

Dipstick method → Tetrabromophenol blue

3. Urine Ketone Bodies
Methods & Chemicals

Rothera’s test → Sodium nitroprusside, Ammonium sulphate, Ammonia

Legal’s test → Sodium nitroprusside, Sodium hydroxide

Strip method → Sodium nitroprusside

4. Urine Bile Salts
Method & Chemical

Hay’s sulphur test → Flowers of sulphur

5. Urine Bilirubin (Bile Pigment)
Methods & Chemicals

Diazo test → Sulfanilic acid + Sodium nitrite

Fouchet’s test → Ferric chloride + Trichloroacetic acid

Gmelin’s test → Concentrated nitric acid

6. Urine Urobilinogen
Methods & Chemicals

Ehrlich’s aldehyde test → Ehrlich’s reagent (p-Dimethylaminobenzaldehyde)

Dipstick method → Ehrlich reaction

7. Urine Blood / Hemoglobin
Methods & Chemicals

Benzidine test → Benzidine + Hydrogen peroxide

Orthotolidine test → Orthotolidine + Hydrogen peroxide

Strip method → Peroxidase-like reaction

8. Urine pH
Methods & Chemicals

Indicator paper → pH paper

Dipstick → Methyl red + Bromothymol blue

9. Urine Specific Gravity
Methods

Urinometer

Refractometer

Dipstick → Polyelectrolyte

10. Urine Nitrite
Method & Chemicals

Griess test → Sulfanilic acid + α-Naphthylamine

Strip method → Griess reaction

11. Urine Leukocytes
Method & Chemicals

Strip method → Leukocyte esterase reaction

Quick Memory Trick 🧠
Glucose → Benedict / GOD-POD

Protein → SSA / Heat

Ketone → Rothera

Bile salt → Hay’s

Bilirubin → Diazo

Urobilinogen → Ehrlich

Nitrite → Griess

30/01/2026

29/01/2026

AIIMS Gorakhpur Jr. Medical Laboratory Technologist CBT exam 30/ 1/ 2026.

28/01/2026

PT vs aPTT vs INR

1️⃣ PT (Prothrombin Time)
Measures:
➡️ Extrinsic + Common pathway

Factors assessed:
I (Fibrinogen), II (Prothrombin), V, VII, X

Main use:
✅ Monitoring Warfarin therapy
✅ Liver disease
✅ Vitamin K deficiency
✅ DIC

Normal range:
⏱️ ~ 11–15 seconds

2️⃣ aPTT (Activated Partial Thromboplastin Time)
Measures:
➡️ Intrinsic + Common pathway

Factors assessed:
I, II, V, VIII, IX, X, XI, XII

Main use:
✅ Monitoring Heparin therapy
✅ Hemophilia A & B
✅ von Willebrand disease
✅ DIC

Normal range:
⏱️ ~ 25–40 seconds

3️⃣ INR (International Normalized Ratio)
What it is:
➡️ Standardized form of PT

Main use:
✅ To monitor Warfarin more accurately worldwide

Normal values:

Normal person: ~1.0

Warfarin therapy (most cases): 2.0 – 3.0

Mechanical heart valve: 2.5 – 3.5

28/01/2026

Gram Staining is a fundamental microbiology staining technique used to differentiate bacteria into two major groups based on their cell wall structure:

👉 Gram-positive
👉 Gram-negative

🔬 Principle of Gram Staining
It is based on the ability of bacterial cell walls to retain the crystal violet–iodine complex.

Gram-positive bacteria → Thick peptidoglycan layer → Retain purple color

Gram-negative bacteria → Thin peptidoglycan + outer membrane → Lose purple, take pink color

🧪 Reagents Used (4 Steps)
Crystal Violet – Primary stain

Gram’s Iodine – Mordant (fixes dye)

Alcohol / Acetone – Decolorizer

Safranin – Counterstain

🪜 Procedure
Prepare smear & heat fix

Add Crystal violet (1 min) → Rinse

Add Iodine (1 min) → Rinse

Add Alcohol/Acetone (few seconds) → Rinse

Add Safranin (30–60 sec) → Rinse & dry

Observe under oil immersion (100x)

26/01/2026

Happy Republic day 2026

24/01/2026

Gram Staining is a fundamental microbiology staining technique used to differentiate bacteria into two main groups based on their cell wall structure:

Gram-positive bacteria → Purple/Violet

Gram-negative bacteria → Pink/Red

Principle
Gram staining depends on the ability of bacterial cell walls to retain crystal violet–iodine complex during decolorization.

Gram-positive: Thick peptidoglycan → retains violet color

Gram-negative: Thin peptidoglycan + outer membrane → loses violet, takes counterstain

Reagents (in order)
Crystal Violet – Primary stain

Gram’s Iodine – Mordant

Alcohol / Acetone – Decolorizer

Safranin – Counterstain

Procedure (Step-by-Step)
Prepare smear and heat fix

Add Crystal Violet – 1 minute → Rinse

Add Gram’s Iodine – 1 minute → Rinse

Add Alcohol/Acetone – 10–20 sec → Rinse

Add Safranin – 30–60 sec → Rinse & Dry

Observe under oil immersion (100×)

23/01/2026

ICMR Develop Single Test to The Diagnosis of Multiple Diseases.

22/01/2026

1. Red Top (Plain Tube)
Additive: None (or clot activator in some types)

Specimen: Serum

Used for: Serology & Immunology

Common tests:

Hormones

Toxicology

Drug levels

Antibody tests

2. Light Blue Top (Sodium Citrate)
Additive: Sodium citrate (anticoagulant)

Specimen: Plasma

Used for: Coagulation studies

Common tests:

PT

aPTT

INR

Anti-Xa

Fibrinogen

D-dimer

⚠️ Tube must be filled properly (9:1 blood to anticoagulant ratio).

3. Gold Top (SST – Serum Separator Tube)
Additive: Clot activator + gel separator

Specimen: Serum

Used for: Serum biochemistry

Common tests:

Urea

Creatinine

Electrolytes

Liver Function Tests (LFTs)

4. Green Top (Heparin)
Additive: Heparin (lithium or sodium)

Specimen: Plasma

Used for: STAT & routine chemistry

Common tests:

Emergency biomarkers

Routine chemistry panels

5. Lavender / Purple Top (EDTA)
Additive: EDTA

Specimen: Whole blood

Used for: Hematology

Common tests:

Complete Blood Count (CBC)

HbA1c

ESR (by automated methods)

6. Pink Top (EDTA)
Additive: EDTA

Specimen: Whole blood

Used for: Blood bank

Common tests:

Blood grouping

Cross-matching

Antibody screening

7. Gray Top (Fluoride / Oxalate)
Additive: Sodium fluoride + potassium oxalate

Specimen: Plasma

Used for: Glucose preservation

Common tests:

Blood glucose

Blood alcohol

Lactic acid

8. Black Top (ESR Tube)
Additive: Sodium citrate (different ratio)

Used for: ESR by Westergren method

Test:

Erythrocyte Sedimentation Rate (ESR)

21/01/2026

Stool Color in Jaundice – Detailed Explanation
The color of stool mainly depends on stercobilin, a pigment formed from bile that reaches the intestine.
In jaundice, bile metabolism or bile flow is altered, leading to changes in stool color.

1️⃣ Hemolytic Jaundice (Pre-hepatic)
Stool color: Dark brown

Reason:

Excessive breakdown of red blood cells (hemolysis)

Increased production of bilirubin

Liver function is normal

More bilirubin reaches the intestine

Increased stercobilin formation

➡️ This results in dark brown stool

2️⃣ Hepatic Jaundice (Hepatocellular)
Stool color: Normal or mildly pale

Reason:

Damage to liver cells (e.g., hepatitis, cirrhosis)

Bile formation is reduced but not absent

Some bile still reaches the intestine

➡️ Therefore, stool remains normal or slightly pale

3️⃣ Obstructive Jaundice (Post-hepatic)
Stool color: Pale / clay-colored

Reason:

Obstruction of bile flow (gallstones, tumors, strictures)

Bile cannot reach the intestine

Stercobilin is absent

➡️ This causes pale or clay-colored stool

🔑 Key Exam Points
Hemolytic jaundice → Dark brown stool

Hepatic jaundice → Normal or mildly pale stool

Obstructive jaundice → Pale / clay-colored stool