ISOENZYMES In Human body.10 Different clinically important enzymes

Isoenzymes and 10 Different liver enzymes

1. CHAPTER-IV CLINICAL ENZYMOLOGY ANJAN GOWDA 09.09.2025

2. Enzymes 2

3. What Are Enzymes? Enzymes are Proteins Proteins are folded in specific shapes. Enzymes act as biological Catalysts. Catalysts speed up chemical reactions The enzyme is not permanently changed in the process. 3

4. Enzymes Are specific for the substrate they will catalyze Are Reusable, which means they are not used up in the reaction. End in – ase -Sucrase -Lactase -Maltase 4

5. How do enzymes Work? Enzymes work by weakening chemical bonds, which lowers the activation energy. Molecules can be built up or broken down by the body. 5

6. Enzymes 6 Free Energy Progress of the reaction Reactants Products Free energy of activation Without Enzyme With Enzyme

7. Enzyme-Substrate Complex The substance (reactant) an enzyme acts on is the substrate The lock and key analogy is that the enzyme is the lock and the substrate is the key. 7 Enzyme Substrate Joins

8. Enzyme Active Site Where the substrate temporarily fits into the active site during the metabolic reaction. . 8 Substrate Active Site

9. Induced Fit A change in the shape of an enzyme’s active site Induced by the substrate The lock and key analogy is that the enzyme is the lock and the substrate is the key. 9

10. What Affects Enzyme Activity? Three factors: 1. Environmental Conditions 2. Cofactors and Coenzymes 3. Enzyme Inhibitors 10

11. 1. Environmental Conditions 1. Extreme Temperature are the most dangerous - high temps may denature (unfold) the enzyme. When an enzyme becomes denatured, it is essentially deactivated. 2. pH (most like 6 - 8 pH near neutral) 3. Ionic concentration (salt ions) 11

12. 2. Cofactors and Coenzymes I norganic substances (zinc, iron) and vitamins (respectively) are sometimes needed for proper enzymatic activity. Example: Iron must be present in the quaternary structure - hemoglobin in order for it to pick up oxygen. 12

13. 3.Two examples of Enzyme Inhibitors a. Competitive inhibitors : are chemicals that resemble an enzyme’s normal substrate and compete with it for the active site. 13 Enzyme Competitive inhibitor Substrate

14. Inhibitors 14 b. Noncompetitive inhibitors : Inhibitors that do not enter the active site, but bind to another part of the enzyme causing the enzyme to change its shape , which in turn alters the active site. Enzyme active site altered Noncompetitive Inhibitor Substrate

15. IMPORTANCE OF ENZYMES Cell shape and motility Surface receptor Cell cycle Metabolism Replication and Transcription Hormone release Muscle contraction Protein synthesis

16. 1. Cell Shape and Motility Enzymes regulate the cytoskeleton, which maintains cell shape and helps in movement. Example: Actin polymerization and depolymerization are regulated by enzymes like cofilin and gelsolin . Myosin ATPase hydrolyzes ATP to drive muscle contraction and cell motility (e.g., movement of WBCs to infection site – chemotaxis). 2. Surface Receptor Enzymes are involved in receptor-mediated signaling on the cell surface. Example: Tyrosine kinases (e.g., insulin receptor tyrosine kinase) phosphorylate proteins, transmitting signals inside the cell. Adenylyl cyclase (membrane enzyme) converts ATP → cAMP, a second messenger in hormone signaling .

17. 3. Cell Cycle Enzymes control progression through different stages of the cell cycle. Example: Cyclin-dependent kinases (CDKs) regulate checkpoints (G1, S, G2, M phases). CDK4/6 + Cyclin D → progression from G1 to S phase . 4. Metabolism Enzymes catalyze biochemical reactions of carbohydrate, fat, and protein metabolism. Examples: Hexokinase – phosphorylates glucose to glucose-6-phosphate (first step of glycolysis). Lipase – hydrolyzes triglycerides to fatty acids + glycerol. Pepsin – breaks proteins into peptides. 5. Replication and Transcription Enzymes play essential roles in DNA replication and RNA transcription. Examples: DNA polymerase – synthesizes new DNA strands during replication. Helicase – unwinds DNA helix. RNA polymerase – synthesizes mRNA from DNA template.

18. 6. Hormone Release Enzymes regulate hormone synthesis, activation, and degradation. Examples: Thyroid peroxidase – helps in thyroid hormone (T3, T4) synthesis. Aromatase – converts androgens → estrogens . Proteolytic enzymes (e.g., prohormone convertases) activate proinsulin → insulin. 7. Muscle Contraction Enzymes supply energy for contraction and relaxation. Examples: Myosin ATPase – hydrolyzes ATP, providing energy for actin-myosin cross-bridge cycling. Creatine kinase (CK) – regenerates ATP from creatine phosphate in muscle. 8. Protein Synthesis Enzymes aid in transcription, translation, and post-translational modifications. Examples: Aminoacyl-tRNA synthetase – attaches amino acids to their tRNA molecules. Peptidyl transferase (a ribozyme) – forms peptide bonds in ribosome during translation. Chaperone enzymes – help in correct protein folding.

19. Isoenzymes definition and significance Isoenzymes (or isozymes) are multiple molecular forms of the same enzyme that catalyze the same chemical reaction , but differ in: Amino acid sequence Kinetic properties (Km, Vmax) Regulatory properties Tissue distribution They are usually coded by different genes or sometimes by allelic variations of the same gene. Example: Lactate dehydrogenase (LDH) has 5 isoenzymes, all catalyzing conversion of pyruvate ↔ lactate, but distributed differently in tissues.

20. H & M Subunits in Isoenzymes Many isoenzymes (e.g., LDH, CK ) are tetrameric proteins made up of different combinations of two types of polypeptide chains (subunits). These subunits are named: H = Heart type subunit M = Muscle type subunit Lactate Dehydrogenase (LDH) LDH is a tetramer (4 subunits). Made from combinations of H (heart) and M (muscle) subunits. This creates 5 isoenzymes : Isoenzyme Subunit Composition Tissue Distribution LDH1 HHHH Heart, RBCs LDH2 HHHM Heart, RBCs LDH3 HHMM Lungs LDH4 HMMM Kidney, placenta, pancreas LDH5 MMMM Liver, skeletal muscle

21. Examples of Isoenzymes Lactate Dehydrogenase (LDH): 5 isoenzymes (LDH1–LDH5) – combinations of H (heart) and M (muscle) subunits. LDH1 (H4) → abundant in heart, RBCs . LDH5 (M4) → abundant in liver, skeletal muscle . Creatine Kinase (CK): CK-MM (skeletal muscle), CK-MB (heart), CK-BB (brain). Alkaline Phosphatase (ALP): Bone, liver, intestine, placenta isoenzymes. Glucokinase vs. Hexokinase: Both phosphorylate glucose, but differ in tissue location and regulation.

22. Properties of Isoenzymes 1. Catalytic Property All isoenzymes catalyze the same reaction . Example: All LDH isoenzymes convert pyruvate ⇌ lactate . 2. Structural Differences Isoenzymes differ in amino acid sequence and quaternary structure . Many are made up of different subunits (e.g., LDH = H and M subunits). Subunit composition gives rise to multiple isoenzyme forms. 3. Kinetic Properties Isoenzymes differ in: Km (affinity for substrate) Vmax (maximum velocity) Example: Hexokinase (low Km) → active even at low glucose (brain). Glucokinase (high Km) → active only at high glucose (liver).

23. 4.Tissue Distribution Each isoenzyme is found predominantly in certain tissues. Example: LDH1 (HHHH) → heart, RBCs LDH5 (MMMM) → liver, skeletal muscle CK-MB → heart CK-MM → skeletal muscle 5. Physicochemical Properties Differ in electrophoretic mobility, solubility, stability, isoelectric point ( pI ) . Example: LDH isoenzymes can be separated by electrophoresis into 5 distinct bands. 6. Genetic Basis Isoenzymes are usually encoded by different genes or gene families . Example: LDH-H and LDH-M are encoded by different genes. 7. Developmental Expression Some isoenzymes vary with age or developmental stage. Example: Fetal LDH isoforms differ from adult LDH. 8. Diagnostic Importance Isoenzymes act as clinical markers for tissue damage: CK-MB → Myocardial infarction LDH1 (↑) → Myocardial infarction, hemolysis ALP bone isoenzyme → Bone diseases ALP liver isoenzyme → Obstructive jaundice

24. Enzymes of Diagnostic Importance Liver Diseases-ALT,AST,ALP,GGT Myocardial infraction-CK,CARDIACTROPONINS,AST,LDH Muscle diseases-CK,ALDOLASE Bone diseases-ALP Prostate cancer-PSA,ACP

25. I. Liver Diseases-ALT,AST,ALP,GGT Liver enzymes can be grouped into three major categories : Markers of Hepatocellular Damage Enzymes normally present inside hepatocytes. Released into blood when hepatocytes are injured. Markers of Cholestasis (Bile Flow Obstruction) Enzymes located in the hepatocyte plasma membrane and bile canaliculi. Elevated in obstructive or cholestatic liver disease. Markers of Disturbed Liver Function (Synthetic Ability) Enzymes synthesized in hepatocytes. Altered activity indicates defective hepatocellular function.

26. a.Markers of hepatocellular damage-AST & ALT. When hepatocytes are damaged , enzymes normally contained inside them leak into the bloodstream. These are the most important markers of hepatocellular damage: 1. Alanine Aminotransferase (ALT / SGPT) Definition & Reaction ALT (SGPT) = Alanine Aminotransferase (also called Serum Glutamate Pyruvate Transaminase ). It is a pyridoxal phosphate–dependent enzyme that catalyzes : Cofactor: Vitamin B6 (pyridoxal phosphate, PLP) . This reaction is part of amino acid metabolism and gluconeogenesis.  

27. Clinical importance: Most specific marker for liver injury. Very high rise in acute viral hepatitis, ischemic hepatitis(Reduced blood flow/o2 supply), drug-induced injury . Levels can increase 10–20× normal . Location in the Body Cytoplasmic enzyme (predominantly in hepatocytes). Small amounts in kidney , heart, and skeletal muscle. Because of its high concentration in liver , ALT is more specific to liver injury than AST. Normal Values Male: <45 U/L Female: <34 U/L

28. 2.Aspartate Aminotransferase (AST / SGOT): Definition & Reaction AST (SGOT) = Aspartate Aminotransferase (also called Serum Glutamate Oxaloacetate Transaminase ). It is a pyridoxal phosphate–dependent enzyme that catalyzes : Cofactor: Vitamin B6 (pyridoxal phosphate, PLP) .  

29. Location in the Body Present in many tissues (not liver-specific): Liver – hepatocytes (cytoplasm + mitochondria). Heart – abundant in cardiac muscle. Skeletal muscle . Kidney, brain, pancreas, RBCs . Because it is widely distributed, AST is less specific for liver damage compared to ALT. Normal Values Male: <35 U/L Female: <31 U/L Clinical importance. Liver disease: Used with ALT to assess hepatocellular damage. Alcoholic liver disease: High AST/ALT ratio (>2). Cardiac marker: Previously used for MI diagnosis (now replaced by CK-MB and troponins). Muscle disorders: Helps detect skeletal muscle damage (with CK).

30. 2.Markers of Cholestasis-ALP & GGT What is Cholestasis? Cholestasis = impairment of bile formation or bile flow. Can be: Intrahepatic (within the liver: e.g., hepatitis, drugs, primary biliary cholangitis). Extrahepatic (outside the liver: e.g., gallstones, pancreatic carcinoma). When bile canaliculi or ducts are blocked, certain enzymes leak into the blood and serve as biochemical markers . 3. Alkaline Phosphatase (ALP) Definition & Reaction Alkaline phosphatase (ALP) is a hydrolase enzyme . Function: Removes phosphate groups (dephosphorylation) from nucleotides, proteins, and other molecules at an alkaline pH (~10) . Plays an important role in bone mineralization and bile secretion . Location & Isoenzymes ALP is widely distributed, with several tissue-specific isoenzymes:

31. Isoenzyme Tissue Source Liver ALP Hepatocytes (bile canalicular membrane) Bone ALP Osteoblasts (bone formation) Placental ALP Placenta (especially in 2nd–3rd trimester) Intestinal ALP Intestinal mucosa Regan isoenzyme (rare) Malignant tumors (cancer-associated form) Normal Values Adults: 40–120 U/L (varies by lab). Higher in children and pregnancy . Clinical importance Liver diseases: Best marker of cholestasis/obstruction. Bone diseases: Marker of osteoblast activity (rickets, Paget’s, bone metastasis). Tumors : Placental ALP (Regan isoenzyme) may be elevated in certain malignancies. Fracture healing monitoring.

32. Condition ALP Level Notes Extrahepatic cholestasis ↑↑↑ (≥4×) Gallstones, carcinoma Intrahepatic cholestasis ↑↑ Drugs, biliary cirrhosis Rickets / Osteomalacia ↑↑ Vitamin D deficiency Paget’s disease ↑↑↑ Excessive bone turnover Bone metastasis / Osteosarcoma ↑↑ Osteoblastic activity Fracture healing ↑ Temporary rise Osteoporosis Normal No osteoblast activity Children Physiological ↑ Bone growth Pregnancy Mild ↑ Placental ALP

33. 4.Gamma-Glutamyl Transferase (GGT / γ- GT) Definition & Reaction GGT is a microsomal membrane enzyme . Function: Transfers γ- glutamyl groups from glutathione to amino acids or peptides. Plays a role in: Glutathione metabolism (antioxidant defense ). Amino acid transport across membranes. Location in the Body Highest activity in: Liver (bile duct epithelium, hepatocytes – endoplasmic reticulum) . Kidney, pancreas, spleen, prostate . Very low activity in bone and muscle . 👉 This helps distinguish liver vs bone origin of ALP . Normal Values Male: <55 U/L Female: <38 U/L

34. Clinical importance Cholestasis marker (with ALP). Sensitive indicator of alcoholic liver disease. Drug monitoring (detects microsomal enzyme induction). Helps differentiate liver vs bone origin of ALP elevation. Condition GGT Levels Notes Cholestasis / Obstructive jaundice ↑↑ Parallels ALP rise Alcoholic liver disease ↑↑ Earliest and most sensitive marker Drug induction (phenytoin, barbiturates) ↑ Enzyme induction Bone disease (rickets, Paget’s, metastasis) Normal Helps distinguish from liver ALP Pancreatic disease / Prostate disease ↑ (moderate) Extrahepatic tissues

35. II.Enzymes & Biomarkers in Myocardial Infarction (MI) CK,CARDIAC TROPONINS,AST,LDH Myocardial infarction (MI) = death of cardiac muscle due to prolonged ischemia (blocked blood flow). When cardiomyocytes die → intracellular enzymes and proteins leak into the bloodstream , which serve as diagnostic markers . 1. Creatine Kinase (CK, CPK) 1. Definition & Reaction Creatine Kinase (CK) , also called Creatine Phosphokinase (CPK) , is an enzyme of energy metabolism . It catalyzes : Role: Maintains ATP supply in tissues with high, fluctuating energy demand (muscle contraction, brain activity).   Structure & Isoenzymes CK is a dimeric enzyme with two subunits: M (muscle) B (brain) Combination of these forms three major isoenzymes :

36. Isoenzyme Composition Tissue Source CK-MM M + M Skeletal muscle (98% of muscle CK) CK-MB M + B Heart (15–40% of total CK in myocardium) CK-BB B + B Brain, smooth muscle, lung, GI tract 3. Diagnostic Importance in Myocardial Infarction (MI) CK-MB as a Cardiac Marker CK-MB is the first specific enzyme marker of myocardial injury. Timeline after MI: Rise: 4–6 hours after chest pain. Peak: 18–24 hours. Normalizes: 2–3 days. 👉 Because it returns to baseline quickly, it is useful for diagnosing reinfarction (a second MI within a few days). Sensitivity & Specificity More specific than AST and LDH , but less specific than troponins . False positives: Can also rise in skeletal muscle injury, surgery, muscular dystrophy .

37. Normal Values Total CK: 25–200 U/L (varies by lab). CK-MB: Normally <6% of total CK. Other Clinical Uses of CK CK-MM: Rises in muscular dystrophies, myositis, rhabdomyolysis, trauma, vigorous exercise. CK-BB: Rarely measured; may rise in brain injury, stroke, certain cancers. Total CK: Elevated in generalized muscle damage, but not specific to heart.

38. 2.Cardiac Troponins ( cTnI & cTnT ) Definition & Function Troponins are regulatory proteins in cardiac and skeletal muscle contraction . They form part of the troponin–tropomyosin complex on the thin filament of muscle fibers . Subunits: Troponin T ( cTnT ): Binds to tropomyosin. Troponin I ( cTnI ): Inhibits actin-myosin ATPase → prevents contraction in the absence of Ca²⁺. Troponin C ( cTnC ): Binds calcium (not cardiac-specific). 👉 cTnI and cTnT are cardiac-specific → found only in heart muscle, making them highly specific markers of myocardial damage.

39. Sensitivity & Specificity Troponin I: More specific for cardiac injury. Troponin T: Very sensitive but can also rise in renal failure, sepsis(Organ disfunctioning), myocarditis(inflammation of heart mussles ) (false positives). Serial measurements (every 3–6 hrs ) improve diagnostic accuracy. Clinical Importance Diagnosis of MI: Best biomarker to confirm myocardial necrosis(Heart attack) Late diagnosis: Remains elevated for 1–2 weeks → detects infarcts missed by CK-MB. Risk stratification: Elevated troponins in unstable angina = higher risk of adverse events. Prognosis: The degree of troponin elevation correlates with infarct size and mortality risk. Troponin Specificity Rise after MI Peak Duration of Elevation Clinical Use cTnI Highly specific 3–6 hrs 12–24 hrs 7–10 days Best test for MI, detects small infarcts cTnT Sensitive but less specific 3–6 hrs 12–24 hrs 10–14 days Useful for late diagnosis, but ↑ in renal failure

40. 3.AST Aspartate Aminotransferase (AST / SGOT) in Myocardial Infarction-(Repeated) Definition & Reaction AST (SGOT) = Aspartate Aminotransferase , a pyridoxal phosphate (Vitamin B6)-dependent enzyme . Reaction:   Diagnostic Importance in MI One of the first enzymes used (historically) for MI diagnosis, before CK-MB and troponins became available. Timeline after MI: Rises: 6–8 hrs after onset of chest pain. Peaks: 18–24 hrs. Returns to normal: 3–5 days. Sensitivity & Specificity Less specific than CK-MB or Troponins. Elevated in liver diseases (hepatitis, cirrhosis) , skeletal muscle injury , hemolysis , and renal infarction(death of tissues by interruption of blood) . Thus, it is now used only as a supportive marker , not as a primary test. Normal Values Male: <35 U/L Female: <31 U/L (values may vary by lab)

41. Feature AST (SGOT) Location Heart, liver, muscle, kidney, brain, RBCs Specificity Low (not heart-specific) Rise after MI 6–8 hrs Peak 18–24 hrs Normalizes 3–5 days Clinical Use Historical; supportive marker, replaced by CK-MB & Troponins

42. 4.Lactate Dehydrogenase (LDH) in Myocardial Infarction Definition & Reaction LDH (Lactate Dehydrogenase) is a cytoplasmic enzyme involved in glycolysis. Reaction: Important in anaerobic metabolism .   Structure & Isoenzymes LDH is a tetrameric enzyme made of two types of subunits: H (Heart type) M (Muscle type) Different combinations → five isoenzymes : Isoenzyme Composition Tissue Distribution LDH1 HHHH Heart, RBCs LDH2 HHHM Heart, RBCs LDH3 HHMM Brain, lungs LDH4 HMMM Kidney, placenta, pancreas LDH5 MMMM Liver, skeletal muscle

43. Diagnostic Importance in MI Normally: LDH2 > LDH1 in serum. In MI: LDH1 > LDH2 → called the “flipped pattern” (highly suggestive of MI). Timeline after MI: Rises: 12–24 hrs after chest pain. Peaks: 48–72 hrs. Remains elevated: 7–10 days. 👉 Useful for late diagnosis of MI (when patient presents several days after chest pain and CK-MB has normalized). Sensitivity & Specificity More sensitive than AST, but less specific (also elevated in: Hemolysis (RBC destruction → LDH1, LDH2 rise). Liver disease (LDH5 rise). Muscle injury, renal infarction, some cancers. Thus, LDH isoenzyme analysis (especially LDH1/LDH2 ratio ) is needed for specificity. Normal Values Total LDH: 140–280 U/L (varies by lab). Isoenzyme distribution in normal serum: LDH2 > LDH1 > LDH3 > LDH4 > LDH5. Clinical importance Late diagnosis of MI (up to 7–10 days after event). Helpful in retrospective diagnosis (patients presenting late). Rarely used today → largely replaced by troponins , which are more specific.

44. III.Muscle diseases-CK,ALDOLASE Muscle diseases (myopathies) such as muscular dystrophy, polymyositis, rhabdomyolysis, and trauma cause muscle cell injury → enzymes leak into blood. The two most important markers are Creatine Kinase (CK) and Aldolase . 1. Creatine Kinase (CK / CPK) Reaction & Function Maintains ATP levels in muscle during contraction. Isoenzymes & Muscle Diseases CK-MM: Major isoenzyme in skeletal muscle (98%). CK-MB: Heart muscle (15–40% in myocardium). CK-BB: Brain, smooth muscle. 👉 In muscle diseases , CK-MM is the predominant marker .   Normal Values Men: 25–200 U/L Women: 25–170 U/L (varies by lab)

45. Clinical Importance Very sensitive marker of muscle damage. Elevated in: Duchenne Muscular Dystrophy (DMD): Earliest and most sensitive test . CK can rise up to 50–100× normal before clinical weakness appears. Polymyositis, dermatomyositis (inflammatory myopathies). Rhabdomyolysis (crush injury, trauma, drugs, toxins) . Myocarditis (muscle inflammation of the heart). Monitoring: CK levels reflect progression of disease or response to therapy. Muscular dystrophy- progressive muscle weakness and degeneration Polymyositis - autoimmune inflammatory myopathy . Rhabdomyolysis- acute breakdown of skeletal muscle fibers DMD-genetic disorder characterized by progressive muscle degeneration and weakness due to mutations in the dystrophin gene located on the X chromosome . FOR YOUR UNDESTANDING Myositis refers to inflammation of the skeletal muscles , leading to muscle weakness, swelling, and sometimes pain .

46. 2. Aldolase Reaction & Function Aldolase catalyzes a key step in glycolysis : Location Found in skeletal muscle, liver, brain, erythrocytes . Muscle → Aldolase A isoenzyme . Clinical Importance Elevated in muscle diseases, but less specific than CK . Still useful in some conditions: Duchenne Muscular Dystrophy (DMD): Both CK and Aldolase are high early in disease. In late stages, when muscle is replaced by fat/fibrosis, CK falls but Aldolase may remain elevated . Polymyositis / Dermatomyositis : Aldolase often elevated along with CK. Muscle trauma, rhabdomyolysis : Aldolase rises, but CK is preferred.   Normal Values Adults: 1.0–7.5 U/L

47. Feature Creatine Kinase (CK) Aldolase Function Energy metabolism (ATP buffer) Glycolysis enzyme Isoenzymes CK-MM (muscle), CK-MB (heart), CK-BB (brain) Aldolase A (muscle) Specificity More specific & sensitive for muscle Less specific (also in liver, brain, RBCs) Rise in DMD Earliest, most sensitive test Also rises, but less reliable Use in late DMD Falls (as muscle replaced by fat) May stay elevated Other uses Rhabdomyolysis, trauma, myositis Supportive marker in myositis Preferred test ✅ CK ❌ Aldolase (supportive only)

48. IV.Bone diseases-ALP Alkaline Phosphatase (ALP) in Bone Diseases ALP Overview Alkaline Phosphatase (ALP) is a hydrolase enzyme that removes phosphate groups at an alkaline pH (~10). In bone, it is produced by osteoblasts and plays a key role in bone mineralization (provides inorganic phosphate for hydroxyapatite formation and hydrolyzes inhibitors like pyrophosphate). Thus, ALP activity reflects osteoblastic activity . Normal Values Adults: 40–120 U/L Children & Adolescents: Higher (due to bone growth). Pregnancy: Mild increase (placental ALP). Diagnostic Importance in Bone Diseases

49. A. Rickets & Osteomalacia - bone softening, deformities, and impaired growth . Cause: Vitamin D deficiency → defective mineralization of bone. ALP: Markedly ↑ because osteoblasts are hyperactive but cannot mineralize bone. Other findings: Low serum calcium & phosphate, high PTH. B. Paget’s Disease of Bone (Osteitis Deformans)- enlarged, deformed, and structurally weak bones- More common in older adults (>50 years). Cause: Increased bone remodeling (excessive osteoclastic resorption + osteoblastic activity). ALP: Very high (up to 10–25× normal). Other findings: Serum calcium & phosphate usually normal. Clinical Use: ALP is the best biochemical marker of disease activity and response to therapy. C. Bone Tumors & Metastasis(Spreading of myloma cells) Osteogenic sarcoma (primary bone tumor ) → ALP markedly ↑ due to uncontrolled osteoblast activity. Metastasis to bone (esp. prostate carcinoma metastasis) → ALP significantly ↑. Used as a tumor marker for bone involvement . D. Fracture Healing During healing, osteoblasts are activated → transient ALP rise . Marker of active bone formation. E. Osteoporosis( R educed bone mass and microarchitectural deterioration) Cause: Loss of bone mass due to resorption exceeding formation. ALP: Usually normal (no osteoblast hyperactivity). Important to distinguish from osteomalacia - softening of bones (where ALP is ↑).

50. Bone Disease ALP Levels Notes Rickets / Osteomalacia ↑↑ Vitamin D deficiency; defective mineralization Paget’s Disease ↑↑↑ (very high) Best marker of disease activity Osteogenic Sarcoma ↑↑ Uncontrolled osteoblast activity Bone Metastasis (Prostate CA) ↑↑ Tumor-induced osteoblastic activity Fracture Healing ↑ Temporary rise Osteoporosis Normal No osteoblast hyperactivity

51. V.Prostate cancer-PSA,ACP 1. Prostate-Specific Antigen (PSA) Definition & Nature PSA = Prostate-Specific Antigen . A serine protease enzyme produced by the epithelial cells of the prostate gland . Normally secreted into seminal fluid → helps liquefy semen. Normal Values <4 ng/mL = considered normal (varies slightly with age). 4–10 ng/mL = borderline (may need further evaluation). >10 ng/mL = highly suggestive of prostate cancer. Clinical Importance Best screening & diagnostic marker for prostate cancer . Elevated in: Prostate cancer (adenocarcinoma). Benign prostatic hyperplasia (BPH)( non-cancerous enlargement of the prostate gland) Prostatitis (inflammation) .

52. Uses of PSA: Screening: Early detection of prostate cancer (with caution due to false positives). Diagnosis: Along with digital rectal exam & imaging. Monitoring therapy: PSA levels fall after surgery/radiation; rise in recurrence/metastasis. Prognosis: Higher PSA = larger tumor burden . Limitations Not 100% specific – may be elevated in non-cancerous conditions (BPH, prostatitis, even after prostate manipulation like biopsy or catheterization). Hence, used in combination with other tests.

53. 2. Acid Phosphatase (ACP) Definition & Nature ACP = Acid Phosphatase , a lysosomal enzyme that hydrolyzes phosphate esters in acidic pH (~5). Prostatic isoenzyme = most important clinically. Normal Values Serum ACP: 0.2–0.8 U/L . Clinical Importance Historically, ACP (prostatic isoenzyme) was the marker for prostate cancer. Elevated in: Advanced prostate cancer with metastasis (esp. bone metastasis) . Trauma, manipulation of prostate (biopsy, surgery). Some non-prostatic conditions (Paget’s disease, Gaucher’s disease).

54. Feature PSA ACP (Prostatic Isoenzyme) Nature Serine protease Lysosomal acid phosphatase Normal value <4 ng/mL 0.2–0.8 U/L Sensitivity High (early detection) Lower Specificity Moderate (↑ in BPH, prostatitis too) Better for metastasis Use Screening, diagnosis, prognosis, therapy monitoring Marker of metastasis & therapy monitoring Current role Gold standard marker Supportive marker (advanced cancer)