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Summary of Both Documents

These are clinical biochemistry exam case studies (MBBS level) - 10 minor cases (8 marks each) and 10 major cases (likely higher marks).

MINOR CASES (8 Marks Each)

Case 1 - Vitamin B12 Deficiency Anaemia (Post-Gastrectomy)

60-year-old female, post-partial gastrectomy | Hb 8g%, B12 150pg/mL, megaloblastic RBCs, hypersegmented neutrophils
  1. Diagnosis: Megaloblastic/pernicious anaemia due to Vitamin B12 deficiency
  2. Biochemical significance of gastric surgery: Partial gastrectomy removes parietal cells that produce Intrinsic Factor (IF). Without IF, B12 cannot be absorbed in the terminal ileum. B12 deficiency impairs DNA synthesis (needed for thymidylate synthesis via methyltetrahydrofolate), causing megaloblastic changes. B12 also needed for myelin synthesis - hence burning sensation in toes (subacute combined degeneration).
  3. Biochemical functions of B12:
    • Cofactor for methionine synthase (homocysteine → methionine, regenerates THF from methyl-THF)
    • Cofactor for methylmalonyl-CoA mutase (methylmalonyl-CoA → succinyl-CoA)
    • Required for normal myelin synthesis
    • Needed for DNA synthesis via folate metabolism
  4. Rich sources: Meat, liver, fish, eggs, dairy products (exclusively animal-based)

Case 2 - Iron Deficiency Anaemia

32-year-old female, koilonychia | Hb 8.7g%, microcytic hypochromic RBCs
  1. Diagnosis: Iron deficiency anaemia
  2. Common causes: Blood loss (menstruation, GI bleed), poor dietary intake, malabsorption, increased demand (pregnancy), hookworm infestation
  3. Biochemical significance: Iron is essential for haemoglobin (haem) synthesis. Deficiency impairs haemoglobin production → small pale RBCs (microcytic hypochromic). Iron also needed for myoglobin, cytochromes (energy production), hence fatigue. Koilonychia reflects iron-dependent enzyme deficiency in nail tissue.
  4. Rich dietary sources: Red meat, liver, green leafy vegetables (spinach), legumes, fortified cereals, jaggery

Case 3 - Metabolic Acidosis (High Anion Gap)

35-year-old AIDS patient, diarrhoea | pH 7.25, pCO2 27mmHg, HCO3 14mEq/L, Na 136, K 4, Cl 112
  1. Diagnosis: High anion gap metabolic acidosis
    • Anion gap = Na - (Cl + HCO3) = 136 - (112 + 14) = 10 mEq/L (borderline; actually this is normal anion gap). Given the clinical context (AIDS + diarrhoea), likely normal anion gap (hyperchloraemic) metabolic acidosis from diarrhoea (loss of HCO3).
    • pH 7.25 (acidotic), low HCO3 (14), compensatory low pCO2 (27) confirms metabolic acidosis with respiratory compensation.
  2. Normal ranges: pH 7.35-7.45, pCO2 35-45 mmHg, HCO3 22-26 mEq/L
  3. Respiratory compensation: Acidosis stimulates peripheral and central chemoreceptors → hyperventilation → increased CO2 exhalation → fall in pCO2 (Kussmaul breathing in severe cases) → partially corrects pH. Expected pCO2 = 1.5 × HCO3 + 8 ± 2 (Winter's formula) = 1.5 × 14 + 8 = 29 mmHg (observed 27 = adequate compensation).
  4. Causes:
    • Normal anion gap acidosis: Diarrhoea, renal tubular acidosis (RTA)
    • High anion gap acidosis: Diabetic ketoacidosis (DKA), lactic acidosis, uraemia, salicylate poisoning

Case 4 - Acute Renal Failure / Chronic Kidney Disease

27-year-old female, recurrent UTIs | Hb 6g%, creatinine 4.2mg/dL, urea 106mg/dL, haematuria, proteinuria
  1. Diagnosis: Acute-on-chronic renal failure (likely chronic pyelonephritis from recurrent UTIs leading to CKD)
  2. Biochemical finding indicating decreased GFR: Elevated serum creatinine (4.2 mg/dL; normal 0.6-1.2 mg/dL) and blood urea (106 mg/dL; normal 15-45 mg/dL). Creatinine is more specific as it is not affected by protein intake. Creatinine clearance directly reflects GFR.
  3. Cause of pedal oedema: Hypoproteinaemia from proteinuria → reduced oncotic pressure; also sodium and water retention due to reduced GFR → fluid accumulation in interstitium.
  4. Common causes of acute renal failure:
    • Pre-renal: Hypovolaemia, sepsis, cardiac failure
    • Renal (intrinsic): Glomerulonephritis, acute tubular necrosis, pyelonephritis
    • Post-renal: Urinary obstruction (stones, BPH)

Case 5 - Vitamin A Deficiency

3-year-old tribal child, xerophthalmia, Bitot's spots, corneal scarring, recurrent infections
  1. Diagnosis: Vitamin A (Retinol) deficiency
  2. Biochemical functions of Vitamin A:
    • Vision: 11-cis retinal is chromophore of rhodopsin (rod cells); deficiency → night blindness
    • Epithelial integrity: Retinoic acid regulates gene expression for epithelial differentiation
    • Immune function: Maintains mucosal barriers; supports lymphocyte function
    • Antioxidant (beta-carotene precursor)
    • Required for growth (IGF-1 signalling)
  3. RDA: 600 mcg RAE/day (children); 900 mcg/day (adult males)
  4. Rich sources: Liver (highest), fish liver oils, egg yolk, dairy, orange/yellow fruits and vegetables (beta-carotene: carrot, papaya, mango), dark leafy greens

Case 6 - Hypothyroidism

53-year-old female, weight gain, cold intolerance, constipation | TSH 20mIU/L (↑), FT4 4.0 pmol/L (↓)
  1. Diagnosis: Primary hypothyroidism
  2. Biochemical explanation for symptoms:
    • Thyroid hormones (T3/T4) regulate basal metabolic rate (BMR). Deficiency → reduced BMR → weight gain, fatigue, cold intolerance
    • Reduced Na/K-ATPase activity → myxoedematous changes (dry skin, coarse hair)
    • Reduced intestinal motility → constipation
    • Hyponatraemia and hypoalbuminaemia → dullness, aches
    • Anaemia (Hb 6.2g%) from reduced erythropoiesis (T3 stimulates EPO)
    • Diminished reflexes from delayed relaxation of deep tendon reflexes (myopathy)
  3. Common causes: Hashimoto's thyroiditis (autoimmune - most common), iodine deficiency, post-thyroidectomy, post-radioiodine therapy, drugs (amiodarone, lithium)
  4. Total vs Free T3/T4: Total T4/T3 includes protein-bound fractions (mainly TBG-bound); only free forms are biologically active. Pregnancy, liver disease, and drugs alter TBG → misleading total values. Free T4 (FT4) is better for evaluating thyroid function as it reflects the active unbound hormone.

Case 7 - Rickets (Vitamin D Deficiency)

4-year-old boy, bow legs, costochondral nodules (rachitic rosary), pigeon chest, poor muscle tone, convulsions
  1. Diagnosis: Rickets (Vitamin D deficiency in childhood)
  2. Role of Vitamin D:
    • Promotes intestinal absorption of calcium and phosphate
    • Promotes bone mineralisation (with PTH and calcitonin)
    • Renal reabsorption of calcium
    • Active form: 1,25-dihydroxycholecalciferol (calcitriol) - acts as a steroid hormone
    • Immunomodulation and cell differentiation (via VDR)
  3. RDA: 400-600 IU/day (10-15 mcg/day) for children; 600 IU for adults; 800 IU for >70 years
  4. Rich sources: Fatty fish (salmon, sardines), cod liver oil, fortified milk, egg yolk, sunlight (skin synthesis of D3 from 7-dehydrocholesterol)

Case 8 - Scurvy (Vitamin C Deficiency)

25-year-old male, perifollicular petechiae on legs, swollen bleeding gums, bloody stools - eating no fresh fruit/vegetables
  1. Diagnosis: Scurvy (Vitamin C / Ascorbic acid deficiency)
  2. Functions of Vitamin C:
    • Cofactor for prolyl and lysyl hydroxylase → collagen synthesis (hydroxylation of proline and lysine residues)
    • Antioxidant (reduces oxidative stress)
    • Enhances non-haem iron absorption (reduces Fe3+ to Fe2+)
    • Cofactor for dopamine-β-hydroxylase (noradrenaline synthesis)
    • Biosynthesis of carnitine, bile acids (cholesterol hydroxylation)
  3. RDA: 40-65 mg/day (India); 75-90 mg/day (WHO)
  4. Rich sources: Citrus fruits, guava, amla (Indian gooseberry - highest), capsicum, kiwi, tomatoes, broccoli

Case 9 - Hypocalcaemia / Tetany

10-year-old strict vegan boy, muscle cramps, spasms | Serum Ca 4 mg/dL (↓; normal 8.5-10.5 mg/dL)
  1. Diagnosis: Hypocalcaemia causing tetany (likely nutritional, with possible Vitamin D deficiency contributing)
  2. Functions of Calcium:
    • Muscle contraction (sliding filament mechanism via troponin C)
    • Neurotransmitter release (Ca2+ triggers vesicle fusion)
    • Bone and teeth mineralisation (as hydroxyapatite)
    • Blood coagulation (factor IV; multiple clotting steps)
    • Second messenger (via calmodulin and IP3 pathways)
    • Enzyme activation (lipase, ATPase)
  3. Causes of hypocalcaemia: Hypoparathyroidism, Vitamin D deficiency, malabsorption, chronic renal failure (reduced 1α-hydroxylation), hypoalbuminaemia, pancreatitis, hypomagnesaemia
  4. RDA: 800-1000 mg/day (children and adults); 1200 mg/day (adolescents and pregnant women)

Case 10 - Respiratory Acidosis

36-year-old chronic smoker, cough, wheeze, dyspnoea | pH 7.26 (note: "2.26" in document is likely a typo for 7.26), pCO2 52 mmHg, HCO3 26 mEq/L
  1. Diagnosis: Acute respiratory acidosis (likely acute exacerbation of COPD/chronic bronchitis from smoking)
    • pH < 7.35 (acidic), pCO2 > 45 mmHg (CO2 retention), HCO3 near normal (no metabolic compensation yet, acute event)
  2. Other causes of respiratory acidosis: Pneumonia, pulmonary oedema, neuromuscular disorders (GBS, myasthenia gravis), CNS depression (opioids, barbiturates), severe asthma, airway obstruction
  3. Normal ABG ranges: pH 7.35-7.45 | pCO2 35-45 mmHg | HCO3 22-26 mEq/L
  4. Role of respiratory system in acid-base balance: Lungs regulate CO2 (carbonic acid). CO2 + H2O ⇌ H2CO3 ⇌ H+ + HCO3- (via carbonic anhydrase). By changing rate/depth of breathing, the respiratory system adjusts CO2 levels within minutes - hyperventilation reduces H+ (corrects acidosis), hypoventilation retains CO2 (corrects alkalosis).

MAJOR CASES

Case 1 - Gout (Hyperuricaemia)

40-year-old male, post-alcohol party, acute monoarthritis of ankle | Uric acid 10 mg/dL (↑), normal RBS/urea/creatinine
a) Diagnosis: Acute gouty arthritis b) Common drug & biochemical basis:
  • Colchicine (acute): Inhibits microtubule polymerisation → prevents neutrophil migration and phagocytosis of urate crystals → reduces inflammation
  • Allopurinol (chronic prevention): Structural analogue of hypoxanthine → competitive inhibitor of xanthine oxidase → reduces uric acid production
  • NSAIDs/Indomethacin (acute): Inhibit COX enzymes → reduce prostaglandin-mediated inflammation c) Increased uric acid: Alcohol metabolism increases NADH → promotes lactate production (lactic acidosis reduces uric acid excretion) and increases purine synthesis/degradation. Alcohol also dehydrates, increasing urate concentration. Final product of purine catabolism in humans (lack uricase) is uric acid via xanthine oxidase. d) Conditions associated with hyperuricaemia: Gout, Lesch-Nyhan syndrome (HGPRT deficiency), Von Gierke disease (glucose-6-phosphatase deficiency), polycythaemia vera, leukaemia (high cell turnover), renal failure, diuretic use (thiazides), obesity

Case 2 - Diabetic Ketoacidosis (DKA)

Known diabetic, unconscious, Kussmaul breathing, acetone breath | BSL 526 mg/dL, pH 7.1, Benedict's and Rothera's positive
e) Diagnosis: Diabetic ketoacidosis (DKA) f) Cause of decreased pH: Insulin deficiency → uncontrolled lipolysis → excess free fatty acids → hepatic β-oxidation → acetyl-CoA excess (TCA cycle saturated) → ketone body synthesis (acetoacetate, β-hydroxybutyrate, acetone). Acetoacetate and β-hydroxybutyrate are organic acids → accumulate → consume HCO3 → fall in pH (metabolic acidosis) g) Purpose of Rothera's test: Detects ketone bodies (acetoacetate and acetone) in urine. Sodium nitroprusside + ammonium sulphate gives purple/violet ring in positive test. Used to confirm ketosis/ketonuria in DKA. h) Ketone bodies: (1) Acetoacetate (2) β-hydroxybutyrate (3) Acetone. Synthesised in liver from acetyl-CoA, utilised by extrahepatic tissues (brain, muscle) as fuel. i) Detection of acetone by physical examination: Fruity/sweet odour on the breath (acetone is volatile and exhaled). Detected by smelling the patient's breath.

Case 3 - Pre-hepatic (Haemolytic) Jaundice

Post-malaria treatment | Total bilirubin 2.5 mg/dL, direct 0.4 mg/dL, indirect 2.1 mg/dL, SGOT/SGPT normal, ALP normal, urine urobilinogen +, bile pigments absent
a) Diagnosis: Pre-hepatic (haemolytic) jaundice - likely malaria-induced haemolysis b) Cause of increased bilirubin: Malaria causes RBC lysis → excess haemoglobin released → converted to haem → biliverdin → unconjugated bilirubin by reticuloendothelial system. Liver conjugation capacity overwhelmed → unconjugated (indirect) bilirubin rises predominantly. c) Test for serum bilirubin estimation: Van den Bergh reaction (diazotisation reaction with diazonium sulphanilic acid). Direct bilirubin reacts immediately (aqueous); indirect needs methanol (Van den Bergh indirect/total reaction). d) Reason for increased urobilinogen: Excess bilirubin delivered to intestine → gut bacteria convert it to urobilinogen (increased quantity) → absorbed into portal circulation → excreted in urine (urobilinogen). Some urobilinogen is oxidised to urobilin (gives dark urine/stool). e) Urinary urobilinogen detected by: Ehrlich's aldehyde test (p-dimethylaminobenzaldehyde in HCl → cherry red colour)

Case 4 - Alkaptonuria

Child, urine darkens on air exposure, napkin stains dark | Benedict's positive, GOD-POD negative, ferric chloride transient blue
a) Diagnosis: Alkaptonuria (Ochronosis) b) Enzyme defect: Homogentisate oxidase (homogentisic acid oxidase) deficiency - in the tyrosine/phenylalanine catabolism pathway c) Urine darkens on air exposure: Homogentisic acid accumulates in urine. On exposure to air, it undergoes oxidative polymerisation to a dark brownish-black melanin-like pigment (alkapton). This is the hallmark. d) Benedict's positive, GOD-POD negative: Benedict's test detects all reducing sugars AND other reducing substances (including homogentisic acid, which is a reducing compound). GOD-POD (glucose oxidase-peroxidase) is specific only for glucose. Homogentisic acid is not glucose → GOD-POD negative. e) Useful biochemical investigation: Urine homogentisic acid measurement by HPLC or colorimetric method; paper chromatography for urine; ferric chloride test (transient blue-green colour, fades quickly); urine on alkali turns dark rapidly.

Case 5 - Multiple Myeloma

30-year-old male (ex-radiology technician), back pain, bone density decrease | Total protein 10 g/dL (↑), albumin 2.8 g/dL (↓), Bence Jones protein in urine, M-band on electrophoresis
a) Diagnosis: Multiple myeloma (plasma cell dyscrasia) b) Cause of increased total protein: Monoclonal proliferation of plasma cells → massive overproduction of a single class of immunoglobulin (M-protein/paraprotein) → raised total protein despite low albumin (reversed A:G ratio) c) Past history of radiation exposure: X-ray technicians have prolonged low-dose ionising radiation exposure, which is a known risk factor for multiple myeloma (DNA damage/mutations in plasma cell precursors). Yes, occupational history is relevant. d) Bence Jones proteins: Monoclonal free light chains (kappa or lambda) produced in excess by myeloma cells. They are small enough to pass through glomerular filtration → excreted in urine. Classically precipitate at 50-60°C and redissolve at boiling (heat test). Detected by urine protein electrophoresis/immunofixation. e) Conditions with M-band (monoclonal band) on electrophoresis: Multiple myeloma, Waldenström's macroglobulinaemia, MGUS (monoclonal gammopathy of undetermined significance), primary amyloidosis, heavy chain disease, solitary plasmacytoma

Case 6 - Beta-Thalassaemia Major

6-month-old child, consanguineous parents | Hb 3g%, MCV 45fL, microcytic hypochromic, target cells, anisocytosis, poikilocytosis | Hb electrophoresis: ↑HbA2, ↑HbF, fused bands; HbS solubility negative, unstable Hb test positive
a) Diagnosis: Beta-thalassaemia major (Cooley's anaemia) b) Biochemical defect: Mutations in the beta-globin gene (chromosome 11) → absent or severely reduced beta-globin chain synthesis. Excess alpha chains precipitate → damage RBC membrane → haemolysis. Compensatory ↑HbF (α2γ2) and ↑HbA2 (α2δ2). c) Why HbF and HbA2 increased: Absence of beta chains leads to compensatory increased production of gamma (γ) chains (forming HbF = α2γ2) and delta (δ) chains (forming HbA2 = α2δ2) to use the excess alpha chains. This is a compensatory gene switching back to fetal programmes. d) Why Hb, PCV, MCV are decreased (not increased - likely a typo in the question): Severe anaemia from haemolysis of abnormal RBCs containing excess alpha chain precipitates, ineffective erythropoiesis, and destruction of RBC precursors in bone marrow. Microcytic (low MCV) due to reduced haemoglobin content per cell. e) Treatment: Regular blood transfusions (every 2-4 weeks to maintain Hb >9g/dL), iron chelation therapy (desferrioxamine or deferasirox to prevent iron overload), folic acid supplementation, splenectomy (if hypersplenism), bone marrow/stem cell transplantation (curative), hydroxyurea (increases HbF)

Case 7 - Kwashiorkor (Protein Energy Malnutrition)

2.5-year-old girl, low socioeconomic family | Hb 5g%, total protein 5.2g/dL, albumin 2g/dL (↓), generalised oedema, distended abdomen, no urine protein, ↓Cu, ↓Mg, ↓K
a) Diagnosis: Kwashiorkor (protein-energy malnutrition with predominant protein deficiency) b) Normal levels:
  • Total protein: 6-8 g/dL
  • Albumin: 3.5-5.0 g/dL
  • Globulin: 2.3-3.5 g/dL
  • A:G ratio: 1.5-2.5:1 c) Conditions with decreased total serum protein: Kwashiorkor, nephrotic syndrome, liver cirrhosis (reduced synthesis), malabsorption, chronic infections, protein-losing enteropathy, burns, starvation d) Daily protein requirement: 0.8-1.0 g/kg/day (adults); 1.5-2.0 g/kg/day (children); 1.1 g/kg/day (pregnancy) e) Cause of generalised oedema: Severe hypoalbuminaemia → reduced plasma oncotic pressure → fluid shifts from intravascular to interstitial space (decreased Starling forces for fluid retention) → generalised pitting oedema and ascites. No urinary protein loss (urine protein negative) distinguishes this from nephrotic syndrome.

Case 8 - Glycogen Storage Disease (Von Gierke's / GSD Type Ia vs Type III)

3-month-old girl, liver/muscle glycogen accumulation 6%, hepatomegaly, fasting hypoglycaemia, hyperlipidaemia, ketoacidosis | pH 7.25, SGOT/SGPT normal
a) Diagnosis: Glycogen storage disease - given muscle and liver involvement with normal transaminases, most consistent with GSD Type III (Cori's disease / debranching enzyme deficiency), though Type Ia (Von Gierke) also fits liver features. Type I (Von Gierke) classically has liver only (not muscle) and very high lactate; Type III involves both liver and muscle. b) Morning hypoglycaemia and hyperlipidaemia: In GSD, glycogenolysis and gluconeogenesis are impaired → cannot maintain blood glucose during fasting → hypoglycaemia. Hypoglycaemia triggers lipolysis → elevated free fatty acids → hyperlipidaemia (also impaired glucose uptake by adipose drives continued fat mobilisation). c) Biochemical defect:
  • Type Ia: Glucose-6-phosphatase deficiency (liver/kidney)
  • Type III: Amylo-1,6-glucosidase (debranching enzyme) deficiency d) Ketoacidosis: Hypoglycaemia + impaired glucose utilisation → cells shift to fat oxidation → excess acetyl-CoA → ketone body overproduction → ketoacidosis (pH 7.25, low CO2) e) Treatment: Frequent high-carbohydrate feedings, raw cornstarch (slow-release glucose), avoid fasting, nasogastric feeds overnight, liver transplantation (for severe Type I), high-protein diet (in Type III, protein can provide gluconeogenic substrates)

Case 9 - Acute Myocardial Infarction (in a Diabetic)

60-year-old diabetic male, chest pain, sweating | Glucose 300, Cholesterol 350, SGOT 50 (↑), SGPT 10 (normal), LDH 10 (low/normal), CK-MB 40 (↑)
a) Diagnosis: Acute myocardial infarction (AMI) with underlying Type 2 diabetes mellitus and hypercholesterolaemia b) Normal ranges:
  • Serum cholesterol: < 200 mg/dL (desirable)
  • SGOT (AST): 10-40 IU/L
  • SGPT (ALT): 7-56 IU/L
  • LDH: 140-280 IU/L
  • CK-MB: < 5% of total CK (< 25 IU/L); elevated in AMI within 4-8 hours, peaks at 12-24h c) LDH isoenzymes in AMI: Yes - LDH1 (H4 tetramer) predominates in heart muscle; in AMI, LDH1 > LDH2 ("flipped LDH ratio"). Normally LDH2 > LDH1. This flip is diagnostic. LDH rises 24-48h after AMI, peaks at 3-6 days, useful for late diagnosis when troponin window is missed. d) CK isoenzymes:
  • CK-MM: skeletal muscle (predominant)
  • CK-MB: cardiac muscle (diagnostic marker for AMI - rises 4-8h, peaks 24h, returns to normal 48-72h)
  • CK-BB: brain
  • CK-MB elevated in: AMI (most specific), myocarditis, cardiac surgery, Duchenne muscular dystrophy (also skeletal muscle damage) e) Why cholesterol increased: Diabetes → insulin deficiency/resistance → increased VLDL synthesis → hyperlipidaemia. Also reduced LPL activity (insulin-dependent) → impaired VLDL clearance → elevated triglycerides and LDL.

Case 10 - Nephrotic Syndrome

4-year-old boy, facial and generalised oedema | Total protein 3g/dL (↓↓), cholesterol 600mg/dL (↑↑), urea 80mg/dL (↑), creatinine 4.5mg/dL (↑), urine protein ++++
a) Diagnosis: Nephrotic syndrome (most likely minimal change disease at this age) b) Cause of hypoproteinaemia: Massive proteinuria (urine protein ++++) - glomerular basement membrane loses its negative charge and size-selectivity → proteins (especially albumin, small size ~69 kDa) leak into urine → severe hypoalbuminaemia → reduced total protein c) Cause of oedema: Hypoalbuminaemia → reduced plasma oncotic pressure → fluid moves from intravascular to interstitial space → generalised oedema (face, ankles, ascites) d) Reason for hyperlipidaemia: Hypoalbuminaemia → liver compensatory response: increased lipoprotein synthesis (especially VLDL and LDL) to maintain plasma oncotic pressure by producing other proteins. Reduced catabolism of lipoproteins (low LPL activity due to low albumin). Cholesterol-carrying lipoproteins spill into blood → hypercholesterolaemia (+ lipiduria/oval fat bodies in urine). e) Increased blood urea and creatinine: Reduced renal blood flow (due to hypovolaemia from low oncotic pressure) → reduced GFR → accumulation of nitrogenous waste products (urea from protein catabolism, creatinine from muscle metabolism) in blood. Also, progression of glomerular disease can directly impair filtration.
Quick Reference - Diagnoses at a Glance:
FileCaseDiagnosis
Minor1Vitamin B12 deficiency anaemia (post-gastrectomy)
Minor2Iron deficiency anaemia
Minor3Metabolic acidosis (normal anion gap, from diarrhoea)
Minor4Acute/chronic renal failure (from recurrent UTI/pyelonephritis)
Minor5Vitamin A deficiency (xerophthalmia)
Minor6Primary hypothyroidism
Minor7Rickets (Vitamin D deficiency)
Minor8Scurvy (Vitamin C deficiency)
Minor9Hypocalcaemia / Tetany
Minor10Respiratory acidosis (acute exacerbation of COPD)
Major1Acute gouty arthritis
Major2Diabetic ketoacidosis (DKA)
Major3Pre-hepatic (haemolytic) jaundice (post-malaria)
Major4Alkaptonuria
Major5Multiple myeloma
Major6Beta-thalassaemia major
Major7Kwashiorkor
Major8Glycogen storage disease (Type I/III)
Major9Acute myocardial infarction (in diabetic)
Major10Nephrotic syndrome

Can you please answer in simpler form

Here are all 20 cases answered in simple, easy-to-read form:

MINOR CASES (8 Marks)

Case 1 - Vitamin B12 Deficiency

Patient: 60-year-old woman, had stomach surgery, weak, breathless, burning in toes. Hb low, B12 low, big RBCs.
1. Diagnosis: Vitamin B12 deficiency anaemia (Megaloblastic anaemia)
2. Why surgery caused this: The stomach makes a protein called Intrinsic Factor (IF). Without it, B12 can't be absorbed. No stomach = no IF = no B12. B12 is needed to make DNA (so RBCs grow properly) and for nerve coverings (so toes burn/tingle).
3. Functions of B12:
  • Makes DNA (cell division)
  • Maintains myelin sheath (nerve covering)
  • Converts homocysteine to methionine
  • Converts methylmalonyl-CoA to succinyl-CoA (energy)
4. Rich sources: Meat, liver, fish, eggs, milk, cheese (only animal foods)

Case 2 - Iron Deficiency Anaemia

Patient: 32-year-old woman, dizzy, breathless, spoon-shaped nails (koilonychia). Hb low, small pale RBCs.
1. Diagnosis: Iron deficiency anaemia
2. Common causes:
  • Heavy periods (blood loss)
  • Poor diet
  • Hookworm infection
  • Pregnancy (increased demand)
  • Malabsorption
3. Why these symptoms: Iron makes haemoglobin. Less iron = less Hb = less oxygen to body = tiredness, breathlessness. Nails become spoon-shaped due to iron-dependent enzyme deficiency.
4. Rich sources: Red meat, liver, spinach, beans, jaggery, fortified cereals

Case 3 - Metabolic Acidosis

Patient: 35-year-old with AIDS, diarrhoea, fever. pH 7.25 (low), HCO3 14 (low), pCO2 27 (low).
1. Diagnosis: Metabolic acidosis (from diarrhoea causing bicarbonate loss)
2. Normal ranges:
  • pH: 7.35 - 7.45
  • pCO2: 35 - 45 mmHg
  • HCO3: 22 - 26 mEq/L
3. Role of respiratory system: Body breathes faster to blow out CO2 → lowers acid level → partially fixes the pH. This is called respiratory compensation.
4. Causes:
  • Normal anion gap: Diarrhoea, Renal Tubular Acidosis (RTA)
  • High anion gap: Diabetic ketoacidosis, kidney failure, lactic acidosis

Case 4 - Renal Failure

Patient: 27-year-old woman, recurrent UTIs, swollen feet, low urine output, high BP. Creatinine 4.2, Urea 106, blood and protein in urine.
1. Diagnosis: Chronic kidney disease (from repeated urinary infections)
2. Biochemical finding for poor filtration: High serum creatinine and blood urea - these waste products build up when kidneys can't filter properly.
3. Cause of swollen feet: Protein leaks into urine → blood protein falls → fluid leaks into tissues → swelling (oedema).
4. Common causes of renal failure:
  • Pre-renal: Dehydration, blood loss
  • Renal: Infection, glomerulonephritis, tubular damage
  • Post-renal: Blocked urine flow (stones, BPH)

Case 5 - Vitamin A Deficiency

Patient: 3-year-old tribal child, dry eyes, Bitot's spots, corneal scarring, frequent infections.
1. Diagnosis: Vitamin A deficiency (Xerophthalmia)
2. Functions of Vitamin A:
  • Night vision (part of rhodopsin in rod cells)
  • Keeps skin and mucous membranes healthy
  • Supports immune system
  • Needed for growth
3. RDA: 600 mcg/day for children
4. Rich sources: Liver, egg yolk, dairy, carrots, papaya, mango, dark green leafy vegetables

Case 6 - Hypothyroidism

Patient: 53-year-old woman, weight gain, cold intolerance, constipation, dry skin, slow reflexes. TSH high (20), FT4 low (4.0).
1. Diagnosis: Primary Hypothyroidism
2. Why these symptoms: Thyroid hormones control body's metabolism (how fast everything works). Less hormone = slower everything = weight gain, feeling cold, constipation, tiredness, dry skin.
3. Common causes:
  • Hashimoto's disease (autoimmune - most common)
  • Iodine deficiency
  • Thyroid surgery
  • Radioiodine treatment
4. Total vs Free T4/T3: Total includes protein-bound (inactive) form. Only free form is active. Free T4 is better for testing thyroid function because it shows what's actually available to the body.

Case 7 - Rickets (Vitamin D Deficiency)

Patient: 4-year-old boy, bow legs, bead-like ribs (rachitic rosary), pigeon chest, poor muscle tone, convulsions.
1. Diagnosis: Rickets (Vitamin D deficiency in children)
2. Role of Vitamin D:
  • Helps absorb calcium and phosphate from food
  • Strengthens bones and teeth
  • Helps kidneys retain calcium
  • Supports immune system
3. RDA: 400-600 IU/day (10-15 mcg) for children
4. Rich sources: Fatty fish, cod liver oil, egg yolk, fortified milk, sunlight (most important natural source)

Case 8 - Scurvy (Vitamin C Deficiency)

Patient: 25-year-old man eating only bread, eggs, cheese - no fresh fruits. Bleeding gums, red spots on legs, bloody stools.
1. Diagnosis: Scurvy (Vitamin C deficiency)
2. Functions of Vitamin C:
  • Makes collagen (holds tissues together) - most important function
  • Antioxidant
  • Helps absorb iron from food
  • Supports immune system
3. RDA: 40-65 mg/day
4. Rich sources: Guava, amla (highest), citrus fruits, capsicum, kiwi, tomatoes, broccoli

Case 9 - Hypocalcaemia / Tetany

Patient: 10-year-old strict vegan boy, muscle cramps and spasms in hands and feet. Serum calcium 4 mg/dL (very low, normal is 8.5-10.5).
1. Diagnosis: Hypocalcaemia causing tetany
2. Functions of Calcium:
  • Muscle contraction
  • Nerve signal transmission
  • Bone and teeth formation
  • Blood clotting
  • Acts as a cell messenger
3. Causes of low calcium:
  • Vitamin D deficiency
  • Underactive parathyroid gland
  • Kidney failure
  • Malabsorption
  • Vegan diet with no dairy
4. RDA: 800-1000 mg/day

Case 10 - Respiratory Acidosis

Patient: 36-year-old smoker, cough, wheeze, breathless. pH 7.26 (low), pCO2 52 (high), HCO3 26 (normal).
1. Diagnosis: Respiratory acidosis (acute COPD exacerbation from smoking)
2. Other causes:
  • Severe asthma
  • Pneumonia
  • Lung collapse
  • Nerve/muscle disease (e.g. Guillain-Barré)
  • Overdose of sleeping pills or opioids
3. Normal ABG values: pH 7.35-7.45 | pCO2 35-45 mmHg | HCO3 22-26 mEq/L
4. Role of respiratory system in acid-base balance: Lungs control CO2 levels. More CO2 = more acid. By breathing faster or slower, the body can quickly raise or lower blood acid levels within minutes.

MAJOR CASES

Case 1 - Gout

Patient: 40-year-old man, drank excess alcohol, woke up with severe ankle pain. Uric acid 10 mg/dL (very high).
a) Diagnosis: Acute Gouty Arthritis
b) Drug and how it works:
  • Allopurinol (long-term): Blocks xanthine oxidase → less uric acid produced
  • Colchicine (acute attack): Stops white cells from attacking urate crystals → reduces pain and swelling
  • NSAIDs (acute): Reduce inflammation
c) Why uric acid is high: Alcohol breaks down into purines → more uric acid made. Alcohol also causes lactic acid build-up → kidneys excrete less uric acid. Result = uric acid piles up in joints as sharp crystals.
d) Conditions with high uric acid:
  • Gout
  • Kidney failure
  • Leukemia / polycythaemia (high cell breakdown)
  • Von Gierke disease
  • Lesch-Nyhan syndrome
  • Thiazide diuretic use

Case 2 - Diabetic Ketoacidosis (DKA)

Patient: Known diabetic, unconscious, deep fast breathing (Kussmaul), fruity breath. Blood sugar 526, pH 7.1.
e) Diagnosis: Diabetic Ketoacidosis (DKA)
f) Why pH falls: No insulin → fat breaks down → fatty acids → liver makes ketone bodies (acids) → these acids lower blood pH → acidosis.
g) Purpose of Rothera's test: Detects ketone bodies in urine. Positive = purple/violet colour. Confirms ketosis in DKA.
h) Ketone bodies (3 types):
  1. Acetoacetate
  2. Beta-hydroxybutyrate
  3. Acetone
i) How acetone detected on exam: Smell the patient's breath - it has a sweet, fruity odour (because acetone is exhaled from the lungs).

Case 3 - Haemolytic Jaundice (Post-Malaria)

Patient: Post-malaria treatment. Total bilirubin raised, mostly indirect. Liver enzymes normal. Urobilinogen in urine, no bile pigments in urine.
a) Diagnosis: Pre-hepatic (Haemolytic) Jaundice
b) Why bilirubin is high: Malaria destroys RBCs → lots of haemoglobin released → converted to unconjugated (indirect) bilirubin → liver can't keep up → bilirubin rises in blood.
c) Test for bilirubin: Van den Bergh test (uses diazonium reagent - direct reacts without methanol, indirect needs methanol)
d) Why urobilinogen is high: More bilirubin reaches the gut → gut bacteria make more urobilinogen → some absorbed back into blood → excreted in urine.
e) Test to detect urinary urobilinogen: Ehrlich's aldehyde test (gives cherry-red colour)

Case 4 - Alkaptonuria

Patient: Child whose urine turns dark in air, diaper stains dark. Benedict's +ve, GOD-POD -ve, ferric chloride transient blue.
a) Diagnosis: Alkaptonuria
b) Enzyme defect: Homogentisate oxidase (enzyme missing in tyrosine breakdown pathway)
c) Why urine darkens in air: Homogentisic acid builds up in urine. When exposed to air (oxygen), it oxidises and polymerises into a dark brown-black pigment.
d) Why Benedict's +ve but GOD-POD -ve:
  • Benedict's detects ALL reducing substances (including homogentisic acid)
  • GOD-POD detects ONLY glucose (enzyme-specific)
  • Homogentisic acid is not glucose → GOD-POD negative
e) Useful test: Urine homogentisic acid estimation; ferric chloride test; urine turns black rapidly on adding alkali

Case 5 - Multiple Myeloma

Patient: 30-year-old ex-radiology technician, severe back pain. Total protein 10 (high), albumin low, Bence Jones protein in urine, M-band on electrophoresis, bones less dense.
a) Diagnosis: Multiple Myeloma
b) Why total protein is high: Cancerous plasma cells produce massive amounts of one type of abnormal antibody (M-protein) → total protein rises even though albumin is low.
c) Does past history help? Yes - prolonged radiation exposure (X-ray work) damages DNA in blood cell precursors → increases risk of myeloma.
d) Bence Jones proteins: Free antibody light chains (kappa or lambda) made by myeloma cells. They're small enough to pass into urine. Classically they precipitate at 50-60°C and dissolve again at boiling temperature.
e) Conditions with M-band:
  • Multiple myeloma
  • Waldenström's macroglobulinaemia
  • MGUS (benign condition)
  • Primary amyloidosis

Case 6 - Beta-Thalassaemia Major

Patient: 6-month-old baby (parents are relatives), very pale, enlarged liver and spleen, big head. Hb 3g%, microcytic RBCs, target cells. HbF and HbA2 raised on electrophoresis.
a) Diagnosis: Beta-Thalassaemia Major (Cooley's anaemia)
b) Biochemical defect: Mutation in beta-globin gene → beta chains not made → excess alpha chains pile up → damage RBCs → severe anaemia.
c) Why HbF and HbA2 are high: To compensate for missing beta chains, the body switches to making gamma chains (→ HbF) and delta chains (→ HbA2) to use up the excess alpha chains.
d) Why Hb, PCV, MCV are LOW (question likely has a typo): RBCs are destroyed rapidly (haemolysis) + bone marrow can't make enough normal RBCs → severe anaemia with small, poorly-haemoglobinised cells.
e) Treatment:
  • Regular blood transfusions
  • Iron chelation (desferrioxamine) to prevent iron overload
  • Bone marrow transplant (curative)
  • Folic acid
  • Hydroxyurea (increases HbF)

Case 7 - Kwashiorkor

Patient: 2.5-year-old girl, poor family, swollen all over, big belly, low appetite, frequent diarrhoea. Albumin 2g/dL (very low), no protein in urine, low copper/potassium/magnesium.
a) Diagnosis: Kwashiorkor (Protein deficiency malnutrition)
b) Normal values:
  • Total protein: 6-8 g/dL
  • Albumin: 3.5-5.0 g/dL
  • Globulin: 2.3-3.5 g/dL
  • A:G ratio: 1.5-2.5:1
c) Causes of low total protein:
  • Kwashiorkor / starvation
  • Liver disease (less synthesis)
  • Nephrotic syndrome (loss in urine)
  • Malabsorption
  • Chronic infections
d) Daily protein requirement: 0.8-1 g/kg/day (adults); 1.5-2 g/kg/day (children)
e) Cause of oedema: Low albumin → low blood pressure (oncotic) → fluid leaks out of blood vessels into tissues → generalised swelling. (No protein in urine rules out nephrotic syndrome.)

Case 8 - Glycogen Storage Disease

Patient: 3-month-old girl, enlarged liver AND muscles, hypoglycaemia in morning, high fat levels, ketoacidosis. Glycogen 6% in biopsy. pH 7.25.
a) Diagnosis: Glycogen Storage Disease (Type III - Cori's disease, or Type I - Von Gierke's)
b) Why morning hypoglycaemia and high fats:
  • Can't break down stored glycogen properly → blood sugar crashes during overnight fast
  • Low blood sugar → body burns fat instead → fat levels rise in blood
c) Biochemical defect:
  • Type I (Von Gierke): Glucose-6-phosphatase missing
  • Type III (Cori): Debranching enzyme (amylo-1,6-glucosidase) missing
d) Why ketoacidosis: Can't use glucose → fat burns instead → makes ketone bodies (acids) → blood becomes acidic (pH 7.25)
e) Treatment:
  • Frequent small meals, never skip food
  • Raw cornstarch (provides slow-release glucose)
  • Overnight tube feeding
  • High-protein diet (for Type III)
  • Liver transplant in severe cases

Case 9 - Acute Myocardial Infarction (Heart Attack)

Patient: 60-year-old diabetic, chest pain, sweating. CK-MB 40 (↑), SGOT 50 (↑), cholesterol 350 (↑↑). Blood sugar 300.
a) Diagnosis: Acute Myocardial Infarction (heart attack) in a diabetic with high cholesterol
b) Normal ranges:
TestNormal
Cholesterol< 200 mg/dL
SGOT10-40 IU/L
SGPT7-56 IU/L
LDH140-280 IU/L
CK-MB< 25 IU/L
c) LDH isoenzymes in AMI: Yes, useful. Normally LDH2 > LDH1. In heart attack, LDH1 > LDH2 (called "flipped ratio"). Helpful when patient comes late and CK-MB has already normalised.
d) CK isoenzymes:
  • CK-MM: Skeletal muscle
  • CK-MB: Heart muscle (rises in AMI, also in myocarditis)
  • CK-BB: Brain
e) Why cholesterol is high: Diabetes causes insulin resistance → liver makes more fat (VLDL) → LDL rises → more cholesterol in blood. High cholesterol causes atherosclerosis → blockage → heart attack.

Case 10 - Nephrotic Syndrome

Patient: 4-year-old boy, puffy face, generalised swelling. Total protein 3 g/dL (very low), cholesterol 600 (very high), creatinine 4.5, urea 80, urine protein ++++.
a) Diagnosis: Nephrotic Syndrome (likely Minimal Change Disease in a child)
b) Why protein is low: Damaged kidney filter → lots of protein (especially albumin) leaks into urine → blood protein drops severely.
c) Why oedema occurs: Low albumin in blood → low oncotic pressure → water leaks out of blood vessels into body tissues → swelling everywhere (face, legs, abdomen).
d) Why cholesterol is high: Low albumin → liver works harder to make proteins → also makes more fats (VLDL, LDL) as a side effect → cholesterol builds up in blood.
e) Why urea and creatinine are high: Less blood reaches kidneys (due to fluid loss into tissues) → kidneys filter less → waste products (urea, creatinine) accumulate in blood.
Summary Table:
CaseDiagnosis
Minor 1B12 deficiency anaemia
Minor 2Iron deficiency anaemia
Minor 3Metabolic acidosis
Minor 4Chronic kidney disease
Minor 5Vitamin A deficiency
Minor 6Hypothyroidism
Minor 7Rickets
Minor 8Scurvy
Minor 9Hypocalcaemia / Tetany
Minor 10Respiratory acidosis
Major 1Gout
Major 2Diabetic Ketoacidosis
Major 3Haemolytic Jaundice
Major 4Alkaptonuria
Major 5Multiple Myeloma
Major 6Beta-Thalassaemia Major
Major 7Kwashiorkor
Major 8Glycogen Storage Disease
Major 9Myocardial Infarction
Major 10Nephrotic Syndrome
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