Clinical Chemistry Study Guide, Review Notes for Medical Laboratory Science, Study notes of Clinical chemistry

Download Clinical Chemistry Study Guide, Review Notes for Medical Laboratory Science and more Study notes Clinical chemistry in PDF only on Docsity! Clinical Chemistry Quality control TERMS TO REMEMBER:  Quality: a feature/characteristic of a product, which meets the expected criteria of a consumer (customer).  Control: a solution that resembles a human serum that is used for QC purposes only  Standard: a colorless solution with known concentration of substances used for calibration  Specificity: defined as the ability of a method to measure the analyte of interest ONLY.  Sensitivity: defined as the ability of a method to measure analytes even at its lowest concentration  Accuracy: nearness of measured value to that of the target value  Precision: nearness of measured values to each other  Diagnostic specificity: defined as the ability of a method to detect a population of individuals absent of a disease process  Diagnostic sensitivity: defined as the ability of a method to detect a population of individuals having the presence of disease  Intralab QC (internal QC): control samples are run simultaneously with a patient to ensure reliability of methods and result  Interlab QC (external QC): laboratories are given samples with unknown concentrations for them to test and results are compared with other laboratories thus maintaining “long term accuracy” to methods utilized.  Mean: average of a set of values (mean = Σx/n)  Median: midpoint of a set of values  Mode: the most frequent among all values/data  Standard Deviation: it is defined as the measure of dispersion of values to that of the mean 𝑆𝐷 = √ 𝚺(𝐱−𝐦𝐞𝐚𝐧)2 n−1  Coefficient of variation: mean expression in percentile | Ignacio, Allyson B. 𝑪𝑽 = 𝑺𝑫 𝒎𝒆𝒂𝒏 𝒙 𝟏𝟎𝟎  T-test: this is used to assess if there is a statistical difference between the means of 2 groups of data  F-test: this is used to assess if there is a statistical difference between the SD of 2 groups of data  Shewhart Levey-Jennings Chart: most widely used QC chart  Trend: six or more consecutive values that either increase or decrease gradually (will cross the mean) – main cause: reagent deterioration  Shift: six or more consecutive values that are distributed on one side or other side of the mean (does NOT cross the mean) – main cause: instrument calibration is improper WESTGARD RULES TYPE OF ERROR RULES SOURCES OF ERROR RANDOM - Tests for imprecision 12s (warning rule), 13s and R4S By chance errors: mislabeling, pipetting error, fluctuations in temperature & voltage SYSTEMATIC - Tests for inaccuracy 22S, 41S and 10x Improper calibration, reagent deterioration, contaminated solutions, instability of both samples and solutions  _________________: used to check if there are significant differences between present set of values to that of past values on the sample of same individual.  Six Sigma: a way of improving product processing to _______________ INSTRUMENTATION DEFINITION OF TERMS:  Energy: entity that this transmitted by electromagnetic waves  Wavelength: defined as the distance between two successive peaks  Nanometer: unit expression of wavelength  Frequency: number of waves that passes a point of observation per one unit of time  Light is absorbed by atoms at a specific wavelength and is emitted at a longer wavelength (with lower energy)  Light source: xenon lamp or mercury arc  There are two monochromators  Primary monochromator: selects wavelength that is best absorbed by solution that is to be measured  Secondary monochromator: this prevents the incident light from striking the detector  Disadvantage: Quenching TURBIDIMETRY  Measures light blocked by molecules  Used for immunoglobulins, immune complexes and complement NEPHELOMETRY  Measures light scattered by molecules  Used for measuring amount of antigen-antibody complexes CHROMATOGRAPHY  Separation is based upon differences in characteristics (both physical and chemical) of substances  Used for amino acid determination, drugs and sugars POTENTIOMETRY  Measures electric potential  pH electrode – glass electrode LIST DOWN ALL TYPES OF CHROMATOGRAPHY AND RESEARCH ON ITS PURPOSE/PRINCIPLE  pCO2 electrode  ion – selective electrode  Sodium: glass electrode  Potassium: Valinomycin ge  Chloride: Tri-N-octyl propyl ammonium chloride decanol ELECTROPHORESIS  Separation of proteins is aided by an electric current IONS POLE POSITIVE CATIONS CATHODE NEGATIVE ANIONS ANODE  pH of buffer: 8.6  support materials:  Agarose gel - separation by electric charges  Cellulose acetate – separation by molecular size  Polyacrylamine gel– separation by charge and molecular size ELECTROPHORETIC PATTERN OF CERTAIN CONDITIONS Alpha1-globulin flat curve Juvenile cirrhosis Alpha2-globulin band spike Nephrotic syndrome Beta-gamma bridging Hepatic cirrhosis Monoclonal gammopathy (gamma spike) Multiple myeloma Polyclonal gammopathy Rheumatoid arthritis and malignancy Small spike in Beta-region Iron deficiency anemia CARBOHYDRATES  Composed of carbon, hydrogen and oxygen  Are water soluble  Are important source of energy for the body’s mechanisms  Classifications:  Monosaccharides: Glucose, fructose and galactose  Disaccharides: maltose (glucose + glucose), lactose (galactose + glucose) and sucrose (fructose + glucose)  Polysaccharides: starch and glycogen GLUCOSE  Primary sugar found circulating in the body  Carbohydrate metabolism:  Glycolysis: glucose → lactate or pyruvate → energy (↑ glucose)  Glycogenolysis: breakdown of glycogen to glucose (↑ glucose)  Glycogenesis: formation of glycogen from sugars for storage (↓glucose)  Gluconeogenesis: formation of glucose from non-carbohydrate sources (↓ glucose)  Hormones for glucose regulation  Hypoglycemic o Insulin – released by β cells of islet of Langerhans  Hyperglycemic o Glucagon – released by α cells of islet of Langerhans o Somatostatin – released by delta cells of islet of Langerhans o Cortisol o Epinephrine o Growth hormone o Thyroxine  MUST KNOW FOR SPECIMEN FOR GLUCOSE DETERMINATION  FBS should be obtained from an 8-10 hours fasting sample  In terms of glucose levels: capillary > venous but < arterial  Glucose is metabolized at: o Room temperature: 7mg/Dl/hr o 4°C : 2 mg/dL/hr  Tube of choice: Gray top (anticoagulant: potassium oxalate ; anti- glycolytic agent: sodium fluoride) GLUCOSE DETERMINATION METHOD PRINCIPLE REAGENTS END PRODUCT/ COLOR REACTION Folin-Wu - Modification: Benedict’s Test Copper Reduction Alk. Copper reagent Phosphomolybdic Acid Molybdenum – BUE  Reversal of symptoms (if glucose is administered) GESTATIONAL DM Due to hormonal imbalance; occurs in pregnant women GLYCOGEN STORAGE DISEASES TYPE DEFECTS Ia – Von Gierke Glucose-6-phosphatase II – Pompe Lysosomal acid alpha glucosidase (GAA) acid maltase III – Cori-Forbes Glycogen debranching enzyme IV – Andersen Glycogen branching enzyme V – McArdle Muscle phosphorylase VI – Hers Glycogen phosphorylase VII – Tarui Phosphofructokinase XI – Fanconi-Bickel Glycogen transporter 2 0 Glycogen synthetase LIPIDS AND LIPOPROTEINS  Lipids are more commonly referred to as fats  Insoluble in water but soluble in organic solvents  Major forms of lipids:  FATTY ACIDS o Simplest o Building blocks of lipids o Saturated (no double bonds) or unsaturated (with double bonds)  TRIGLYCERIDES o Tri – three molecules of fatty acids + one molecule of glycerol o Breakdown is facilitated by lipoprotein lipase o Primary cause of turbid serum o Main storage form of lipid o Requires a fasting specimen (12-14 hours)  CHOLESTEROL o Not readily catabolized = not a source of fuel o No fasting is required o Two forms: esterified (60-70%) and free cholesterol (30-40%)  PHOSPHOLIPIDS o Structure: 2 fatty acids + phospholipid attached to glycerol o Can also be found as surfactants in lungs o Forms: Lecithin/phosphatidylcholine (major, 70-75%), sphingomyelin (18-20%), phosphatidylserine and phosphatidylethanolamine (3-6%) and lysophosphatidylcholine (4-9%)  LIPOPROTEINS o Carrier proteins for lipids HDL LDL VLDL Chylomicrons Good cholesterol Bad cholesterol Carrier of endogenous TAG Carrier of exogenous TAG Migration Alpha Beta Pre-beta Origin Size 70-100 100-300 2000 > 2000 Density 1.063-1.125 (bottom layer) 1.019- 1.063 0.95- 1.006 <0.95 (top layer) Protein 50% 20% 4-8% 1-2% LIPID CONTENT (%) Free cholesterol 3-5 6-8 4-8 1-3 Esterified 15-20 45-50 16-22 2-4 TAG 2-7 4-8 45-65 80-95 Phospholipid 26-32 18-24 15-20 3-6 Lipid: protein ratio 50:50 80:20 90:10 99:1 Apolipoproteins A B C A, B, C, E o Minor lipoproteins: IDL, Lp(a) aka sinking pre-beta, linked to atherosclerosis o Abnormal lipoproteins: LpX – linked to obstructive jaundice, β-VLDL aka floating β lipoprotein APOLIPOPROTEINS  Apo A – major protein component of HDL  Apo A-I: LCAT activator  Apo A-II: may inhibit hepatic & lipoprotein lipases; increases plasma TAG  Apo B – major protein component of LDL  Apo B-48: found in chylomicro  Apo B-100: synthesized in liver; found in VLDL & LDL  Apo C – major protein component of VLDL; minor in HDL and LDL  Apo C-I: may inhibit the hepatic uptake of VLDL and cholesterol ester transfer protein  Apo C-II: if deficient – there would be reduced clearance of TAG- rich lipoproteins  Apo C-III: main form found in HDL. Lipolysis of TAG-rich lipoproteins is inhibited by this form  Minor apolipoproteins  Apo D: aids in the activation of LCAT  Apo E: Arginine rich o Apo E-I o Apo E-II: associated with type III hyperlipoproteinemia o Apo E-III: most common isoform o Apo E-IV: associated with high levels of LDL, increased risk for Alzheimer’s and CHD  Apo F, Apo H and Apo J LIPID QUANTITATION  TRIGLYCERIDES A. CHEMICAL METHOD (Van Handel and Zilversmit method and Modified Van Handel Zilversmit method) STEP 1: EXTRACTION BY ORGANIC SOLVENT  This is for the removal of lipids from proteins  here is an additional adsorption step to remove non-triglycerides STEP 2: SAPONIFICATION OR HYDROLYSIS BY KOH IN ETOH  TAG → fatty acids + glycerol STEP 3: OXIDATION  Oxidizes glycerol to measurable compounds STEP 4: COLORIMETRY  500-600nm B. ENZYMATIC METHOD – lipase and glycerokinase serve in the initial enzymatic reaction  In alkaline Ph = proteins are negatively charged  In acidic pH = proteins are positively charged  Structures:  Primary: amino acid sequence  Secondary: conformations could either be alpha-helix, beta- pleated, sheath and bend form  Tertiary: actual 3D configuration  Quaternary: protein already consists of 2 or more polypeptide chains ALBUMIN  Most abundant protein  Acts as a transport protein  Negative acute phase reactant  Analbuminemia: albumin absence  Bisalbuminemia: there are 2 bands seen in the albumin region Hypoalbuminemia: low levels of albumin PREALBUMIN  Aka transthyretin  Marker for malnutrition  2nd most predominant protein in the CSF GLOBULIN  Alpha-1-acid-glycoprotein: carrier proteins for steroid hormones  AFP: a tumor marker for hepatocellular carcinoma  Transferrin: transports iron  Haptoglobin: transports free hemoglobin  Ceruloplasmin: transports copper; Wilson’s disease : disease associated with low levels of ceruoplasmin FIBRINOGEN Protein present in plasma but not in serum  Method for measurement: Parfentjev method OTHERS  Bence-Jones protein: protein found in patients with Multiple Myeloma  Unique feature: Coagulates at 40-60°C and dissolves at 100°C  Method for measurement: Immunofixation  Electrophoretic pattern: “tall spike” or “monoclonal peak” FRACTIONS SPECIFIC PROTEINS Prealbumin Prealbumin Albumin Albumin Alpha1 globulin Alpha1 antitrypsin, AFP, AAG, Alpha1-anti- chymotrypsin, Gc-globulin Alpha2 globulin Ceruloplasmin, haptoglobin, alpha2 macroglobulin Beta globulin Beta2 microglobulin, complement system, CRP, fibrinogen, LDL, VLDL, hemopexin, transferrin Gamma globulin Immunoglobulins, CRP (in other references) METHODS FOR ALBUMIN QUANTITATION  Electrophoresis  Biuret Method  Principle: measurement of atleast 2 peptide bonds and formation of a violet colored chelate.  Measured at 540nm  Reagents: Rochelle salt (NaK tartrate), Alkaline CuSO4, NaOH and KI  Kjeldahl Method  Reference method  Based upon the digestion of protein and measurement of nitrogen content of proteins  Albumin nitrogen x 6.25 = albumin  Lowry (Folin-Ciocalteu) method  Reagent: Phosphotungstomolybdic acid  Dye-binding method  BCG: most commonly used  BCP: most sensitive, specific and precise  H-ABA: with salicylates and bilirubin interferences Non-protein nitrogen UREA  Most abundant (45-50%) NPN  Major end product of protein metabolism  Methods:  Micro-Kjeldahl Nesslerization method o Indirect method o Nitrogen x 2.14 = urea x 0.467 = BUN  Rosenthal method o Direct method o Diacetyl monoxime method  Enzymatic method o Urease  IDMS o Reference method CREATININE  Major end product of muscle catabolism  100% is excreted  Creatine: 100% is reabsorbed by kidney  Methods:  Jaffe reaction o Color reagent: Alkaline picrate o Lloyd’s reagent: sodium aluminum silicate o Fuller’s Earth: aluminum magnesium silicate AMINO ACIDS  Building blocks of proteins AMMONIUM  Used to monitor hepatic coma  Important indicator of Reye’s syndrome URIC ACID  Major product of purine metabolism  Forms crystals in joints (tophi)  Methods:  Folin method  Active site: site where enzymatic reaction occurs  Allosteric site: site other than the active site  Isoenzyme: forms of enzyme that are different from each other but still catalyzes same reaction CATEGORIES 1. Oxidoreductase  For oxidation/reduction reactions  Ex: LDH, G6PD and Malate dehydrogenase 2. Transferase  Catalyzes transfer of groups from one substrate unto another  Ex: AST, ALT, CK, GGT 3. Hydrolase  Hydrolysis  Ex: ACP, ALP, 5’NT, AMS, LPS, CHS 4. Lyase  Removal of groups but with no hydrolysis  Ex: Aldolas 5. Isomerase  Interconversion of isomers 6. Ligase  Joins to 2 substrate molecules  Ex: synthases ENZYME METHODS HEPATIC ENZYME PROFILE SUBSTRATES FACTS ALP Liver Kidney Bone Placenta Intestine WBC Bodansky Shenowara Jones King- Armstrong Bessy Lowry-Brock Β- glyceroPO4 Β- glyceroPO4 p- nitrophenylPO4 p- nitrophenylPO4 Optimum pH: 10 Greatly elevated in Paget’s disease Avoid using EDTA- Citrate- Oxalate ALT (SGPT) Liver RBCs Reitman-Frankel (DNPH) Alanine α-keto Marked elevation with viral hepatitis De ritis ratio: >1 = viral; <1 = non-viral LD All tissues Wacker Method (forward) Wrobleuski La Due (reverse) Wrobleuski Cabaud Berger Broida NAD+ (cofactor) LD4 and LD5 Storage: 25°C upto 24 hours GGT Canaliculi of hepatic cells, Kidney, Prostate and Pancreas SZAZ Gammaglutamyl p- nitroanilide Most sensitive marker for Alcoholic hepatitis ChE Pseudo- Michael; Ellman Acetylcholine ChE: CNS, RBC, Lungs, Spleen Pseudo: Liver – Succinylcholine (relaxant); anesthetic poisoning CARDIAC ENZYME PROFILE CK Cardiac, skeletal and brain tissues Tanzer-Gilvarg (forward) Oliver-Rosalki (reverse) CK-BB (fastest migrating; most anodal), CK-MB, CK- MM (slowest; least anodal) Sensitive indicator of AMI & Duchenne disorder Highest elevation of total CK: Duchenne’s muscular dystrophy Light and pH sensitive AST (SGOT) Liver, heart, skeletal muscle Karmen Method (Ph 7.5; 340 nm) Aspartate α-keto Most sensitive enzyme for skeletal muscle disease Inhibited by all anticoagulants except heparin (but ammonium heparin should not be used) LD All tissues Wacker Method (forward) – pH 8.8 Wrobleuski La Due (reverse) – pH 7.2 Wrobleuski Cabaud Berger Broida LD1 (anodic & heat stable) LD2 (heat stable & major isoenzyme in the sera of healthy persons) LD5 (cathodic & cold labile) Flipped ratio: LD1>LD2 LD/HBD(LD1) ratio: 1.2-1.6; if 0.8-1.2 suspect for MI Myoglobin Responsible for O2 supply of striated muscle Troponin 3 subunits: I (inhibitory), T (tropomyosin-binding) & C (calcium-binding) ACUTE PANCREATITIS PROFILE Salivary glands, Pancreas Saccharogenic Iodometric/Amyloclastic Chromogenic Kinetic Method Pancreatic AMS: diastase Salivary AMS: ptyalin MicroAMS: unbound (free) MacroAMS: bound to IgG and IgA Earliest pancreatic marker Smallest enzyme in size Salivary AMS: inhibited by wheat germ lectin LPS Pancreas Cherry-Crandall Sigma- Tietz Titration Olive Oil/Triolein (pure form of TAG) End product: Fatty Acids Most specific pancreatic marker PROSTATIC CANCER PROFILE ACP RBC Prostate Chemical Inhibition Test RBC-ACP: inactivated by Cu++, unaffected by Tartrate P-ACP: unaffected by Cu++, inactivated by Tartrate Organophosphates Very labile (add 5M acetate buffer/citrate tablet to preserve) PSA Most useful for tumor marker for prostate cancer RR: 0-4ng/mL ACUTE MYOCARDIAL INFARCTION MARKERS (Bishop, Rodriguez, Coderes) Marker Onset (hrs) Peak (hrs) Duration (hrs) Myoglobin 1-3 5-12 18-30 Trop I 3-4 10-24 7days up to 10- 14days Trop T 3-6 12-18 5-10 days CK-MB 4-6 12-24 48-72 AST 6-8 24 5 days LDH 48-72 10-14 days Acts as buffer Diffuses out of the cell in exchange for chloride Increased levels: alkalosis, vomiting, hypokalemia Decreased levels: acidosis Methods: ISE – Clark electrode Enzymatic method: Phosphoenolpyruvate carboxylase & dehydrogenase Phosphorus Unstable ion Inversely proportional to calcium and PTH Best preserved by acidic filtrate SUMMARY (memorize this ☺) ELECTROLYTES FUNCTION HCO3, K, Cl Acid-Base Balance Ca, Mg Blood coagulation Mg, Ca, Zn Cofactors in enzyme activation K, Mg, Ca Myocardial rhythm and contractility K, Ca, Mg Neuromuscular excitability Mg, PO4 Production and use of ATP from glucose Mg Regulation of ATPase pumps Na, K, Cl Volume and osmotic regulation BLOOD GAS DEFINITION OF TERMS:  Acid: a compound that could donate a H+ ion  Base: a compound that could accept a H+ ion  Acid-Base Balance: a mechanism by which the pH of blood is maintained at 7.35-7.45 for homeostasis  Buffer: a weak acid/base with its conjugate salt that resists changes in Ph ACID BASE BALANCE HENDERSON-HASSELBACH EQUATION  Implicates the relationship between pH, and the two involved organs - lungs and kidneys 𝑝𝐻 = 6.1 + 𝑙𝑜𝑔 𝐻𝐶𝑂3 (𝑃𝐶𝑂2 𝑥 0.0307) EXPANDED FORM: 𝑝𝐻 = 6.1 + log [TCO2−(PCO2 x 0.03)] PCO2 x 0.03 FOUR BASIC ABNORMAL STATES Imbalance pH pCO2 H2CO3 HCO3 Primary compensation Seen in: Respiratory Acidosis ↓ ↑ ↑ N Kidneys retain & excrete hydrogen Pneumonia, emphysema Respiratory Alkalosis ↑ ↓ ↓ N Reverse of respiratory acidosis Hyperventilation, Metabolic Acidosis ↓ N N ↓ Hyperventilate (CO2 blew off) Diabetic ketoacidosis, renal disease and prolonged diarrhea Metabolic Alkalosis ↑ N N ↑ (CO2 retention) Vomiting, antacids, NaHCO3 infusion EVALUATING ACID-BASE DISORDERS 1. Determine if the pH is high (alkalosis) or low (acidosis) 2. Compare pCO2 and HCO3 to normal values  If pCO2 is opposite to pH = Respiratory  If HCO3 is in the same direction with pH = metabolic 3. If pH is within normal range, full compensation has occurred 4. if main compensatory mechanism has already occurred yet the pH is still out of range, partial compensation happened. NORMAL VALUES  pH: 7.35 – 7.45  pCO2: 35-45 mmHg  pO2: 81-100 mmHg  HCO3: 21-28 mEq/L  TCO2: arterial (19-24 mmol/L); venous (22-26 mmol/L)  H2CO3: 1.05-1.035 mmol/L  O2 saturation: 94-100% COMMON SOURCES OF ERROR Error pCO2 pH pO2 Effect Sample sitting at room temperature for more than 30 mins ↑ ↓ ↓ Acidosis Bubbles in syringe, ↓ ↑ ↑ Alkalosis Hyperventilation Alkalosis Specimen exposed to air Alkalosis SAMPLE: 1. pH = 7.25, pCO2 = 42 and HCO3 = 16  determine acid-base status ENDOCRINOLOGY  study of endocrine glands and the hormones they secrete HORMONES  are chemical signals that are secreted by cells into the blood stream that travels to its target tissues POSITIVE FEEDBACK NEGATIVE FEEDBACK Parathyroid gland: smallest gland in the body PTH Produced and secreted by chief cells of parathyroid gland For bone resorption Primary hyperparathyroidism: increased ionized calcium Secondary hyperparathyroidism: decreased ionized calcium Adrenal gland Cortisol Secreted by zona fasciculata Highest levels in: 6am-9am Lowest levels: 11pm-3am Cushing’s syndrome: increased levels of cortisol and ACTH but decreased levels of aldosterone and renin are notable  screening test: 24hrs urine free cortisol test  Confirmatory: low dose dexamethasone suppression test and CRH stimulation test Cushing’s disease: increased levels of ACTH due to tumor on the pituitary gland Methods: Porter-Silber reaction (corticosteroids); + reaction = yellow pigment Zimmerman reaction (ketosteroids) + reaction = reddish purple color Aldosterone Secreted by zona glomerulosa Most important mineralocorticoid Responsible to Na+ and K+ retention Barterr’s syndrome: there is a defect in the kidney’s ability to reabsorb sodium Conn’s syndrome (1’ hyperaldosteronism): there is hypokalemia and hypernatremia Liddle’s syndrome: there is an excess sodium reabsorption and excretion of potassium due to defect in the DCT Catecholamines Secreted in medulla 80% epinephrine, 20% norepinephrine Pheochromocytoma: tumor that results to overproduction of catecholamines Reproductive glands Testosterone Principal androgen in the blood Most potent male androgen Synthesized by the Leydig cells Estrogen Estrone: most abundant in Menopausal women Estradiol: most potent; most abundant in pre-menopausal women Estriol: major estrogen detected during pregnancy; produced by placenta; marker for down syndrome Kober reaction: used to analyze estrogens Progesterone Single best hormone to evaluate if ovulation has occurred Pancreas Insulin Hypoglycemic agent Glucagon Hyperglycemic agent METABOLITES OF HORMONES!  Dopamine: Homovanilic acid  Serotonin: 5-HIAA  Epinephrine: Vanillyl mandelic acid and metanephrine  Norepinephrine:  Urine: 3-methoxy-4-hydroxyphenylglycol  Blood: vanillyl mandelic acid  TOXICOLOGY TOXIC AGENTS  Alcohol o Ethanol (grain alcohol): most commonly abused chemical substance SIGNS AND SYMPTOMS BLOOD ALCOHOL (% w/v) STAGES OF IMPAIRMENT 0.01 – 0. 05 No obvious impairment, some changes observable on performance testing 0.03 – 0.12 Mild euphoria, decreased inhibitions, some impairment of motor skills 0.09 – 0.25 Decreased inhibitions, loss of critical judgment, memory impairment, diminished reaction time Mental confusion, dizziness, strongly impaired motor skills (staggering, slurred speech) 0.27 – 0.40 Unable to stand or walk, vomiting, impaired consciousness 0.35 – 0.50 >0.10 – PRESUMPTIVE EVIDENCE OF DRIVING UNDER ALCOHOL INFLUENCE  Cyanide  Odor bitter almonds  Arsenic  Odor of garlic; keratinophilic  Carbon monoxide  Odorless, colorless and tasteless gas  Binds to hemoglobin 250 times (in terms of affinity) as compared to oxygen  Makes blood cherry-red in color  Mercury  Nephrotoxic and can bind myelin (in neurons)  Lead  Specimen of choice: whole blood  Inhibits enzymes D-ALA synthetase & pyrimidine-5’-nucleotidase  Organophosphates  Found in insecticides and pesticides  Hepatotoxic  Can inhibit enzyme acetylcholinesterase DRUGS OF ABUSE DRUG METABOLITE Amitriptyline Nortryltyline Cocaine Benzoylecgonine Heroin Morphine Marijuana Tetrahydrocannabinol Primodine Phenobarbital Procainamide NAPA