NEET MDS Lessons
Periodontology
Pathophysiology
- Enzyme defect: Glucose-6-phosphate dehydrogenase deficiency
- Result: Impaired NADPH production → reduced glutathione → oxidative damage
- Inheritance: X-linked recessive (affects males predominantly)
Key Clinical Features
- Heinz bodies: Characteristic finding (precipitated denatured hemoglobin)
- Hemolytic episodes: Triggered by oxidative stress
- Chronic hemolysis: Usually absent between episodes
- Neonatal jaundice: May be severe
Important Clinical Points
- Estrogen does NOT induce hemolysis (unlike other conditions)
- Favism: Hemolysis after eating fava beans
- Drug-induced: Most common trigger for hemolytic crisis
Oxidative Stressors to Avoid
Medications
- Antimalarials: Primaquine, chloroquine
- Antibiotics: Sulfonamides, nitrofurantoin, chloramphenicol
- Analgesics: Aspirin (high doses), phenazopyridine
- Others: Methylene blue, naphthalene (mothballs)
Infections
- Bacterial infections
- Viral hepatitis
- Pneumonia
- Typhoid fever
Other Triggers
- Fava beans (favism)
- Diabetic ketoacidosis
- Severe illness/stress
🔁 Pulse Patterns
| Pulse Type | Condition |
|---|---|
| Slow rising pulse | Aortic stenosis (AS) |
| Pulsus alternans | CHF |
| Pulsus bigeminus | Digoxin therapy |
| Pulsus paradoxus | Tamponade, pericarditis, asthma |
| Water hammer pulse | Aortic regurgitation |
| Pulsus bisferiens | Best felt in radial artery |
🔊 Heart Sounds
- Loud S1: Short PR interval, tachycardia, mitral stenosis
- Fourth Heart Sound (S4): Heard during ventricular filling
- Opening snap: High-pitched, diastolic sound
- Junctional Epithelium: Attached to enamel via hemidesmosomes; to connective tissue via external basal lamina.
- Corneocyte Formation: Keratinohyalin granules disappear, forming filaggrin.
- Langerhans Cells: Suprabasal level; antigen-presenting with Birbeck granules.
- Keratinization: Oral epithelium is 0.2 – 0.3 mm thick; may be keratinized or parakeratinized.
🧬 Blood Disorders
- Polycythemia vera: Common cause of Budd – Chiari
- PNH: Rare cause of Budd – Chiari
- Thalassemia & Hemolytic anemia: Lead to unconjugated hyperbilirubinemia
- Anemia: Can cause high-output heart failure
- Hemophilia A: Deficiency of Factor VIII
- ITP vs TTP: ITP = isolated thrombocytopenia; TTP = microangiopathy
| Condition | Key Insight |
|---|---|
| Autoimmune Hemolysis | Spherocytes; seen in CLL, SLE |
| Cold AIHA | Donath – Landsteiner antibodies |
| Hereditary Spherocytosis | ↑ Osmotic fragility; Parvovirus risk |
| PNH | Stem cell disorder; thrombosis risk |
| Sickle Cell Disease | Hb defect: Glu → Val substitution |
| Commonest presentation | Bone pain (vaso-occlusive crisis) |
| Sickle Trait | Protection against malaria |
| Radiologic sign | Crew haircut, Gandy gamma bodies |
| Chronic cases | Splenomegaly often absent |
- Steroids, Thiazides, Niacin, Phenytoin
- Protease inhibitors, Alpha IF, Clozapine, Beta agonists
🧠 Endocrine-Related DM
- Cushing’s, Acromegaly, Pheochromocytoma
- Thyroid disorders, Glucagonoma, Somatostatinoma
- (Note: Hypoglycemia in Addison's disease)
💓 Cardiovascular & Renal
- ↑GFR → Earliest sign of diabetic nephropathy
- Microalbuminuria → Most reliable marker
- ACEIs → Nephroprotective, but contraindicated in CRF (hyperkalemia)
👁️🗨️ Complications
- Wet gangrene, Blindness, Amputation (2nd most common after trauma)
💊 Special Drug Mention
- Telmisartan → Only ARB acting on PPAR-γ → preferred in DM
Calculus Composition
- Brushite: More common in mandibular anterior
- Magnesium whitlockite: More common in posterior
- Ca:P ratio: Higher subgingivally
- Mineralization: 50% in 2 days, 60 – 90% in 12 days
Microbiology
- First colonizers: S. salivarius and S. mitis
- Red complex: P. gingivalis, T. denticola, T. forsythia (cause BOP)
- Growth enhancement: P. gingivalis grows better with succinate (C. ochracea) and protoheme (C. rectus)
Pellicle Structure
- Basal layer: Thin, difficult to remove
- Globular layer: 1 μm thick, easier to detach
Bacterial Recognition
- Gram positive: Activate TLR2 → IL – 8
- Gram negative: Activate TLR4 → TNF – α