Ultra Summary - Clinical Chemistry PDF

sensitivity s mallest amount a nalyte specificityspecific MUST TO KNOW IN CLINICAL CHEMISTRY (From CC by Rodriguez)...

sensitivity s mallest amount a nalyte specificityspecific MUST TO KNOW IN CLINICAL CHEMISTRY (From CC by Rodriguez) Quality Control Practicability Method is easily repeated Reliability Maintain accuracy and precision goalofqualitycontrol Intralab/Interlab QC Daily monitoring of accuracy and precision daytoday Interlab/External QC Proficiency testing (Reference lab) NERAS Long-term accuracy Difference of >2: not in agreement w/ other lab QC materials Available for a min. of 1 yr Bovine control materials Preferred (Human: biohazard) Not for immunochem, dye-binding and bilirubin BID Matrix effect Improper product manufacturing unknowneffect Unpurified analyte Altered protein Precision study First step in method evaluation Nonlab. personnel 29% of errors (lab results) SD Dispersion of values from the mean CV Index of precision mian100 Relative magnitude of variability (%) Variance SD2 Measure of variability Inferential statistics Compare means or SD of 2 groups of data T-test Means of 2 groups of data F-test SD of 2 groups of data Cumulative Sum Graph V-mask (CUSUM) Earliest indication of systematic errors (trend) Youden/Twin Plot two mean Compare results obtained from diff. lab Shewhart Levey-Jennings Graphic representation of the acceptable limits of variation Chart w westaard partnered Trend resultsare either fora Gradual loss of reliability days consecutive Cause: Deterioration of reagents (Systematic error) Shift Values: one side or either side of the meanfor con Cause: Improper calibration (Systematic error) intesting is Outliers Values: far from the main set of values Highly deviating values Random or systematic errors Kurtosis Degree of flatness or sharpness iii iiiii iiiiiiii Precision Random error Accuracy Systematic error Random error Causes: sensitivity it resultw it disease diagnostic (Imprecision; -Mislabeling diagnosticspecificity ca onapatient resist Indeterminate) -Pipetting error -Improper mixing of sample and reagents -Voltage/Temperature fluctuation III yea and nighest -Dirty optics instrumenterror Parameters: SD and CV Systematic error Causes: aamataaormanana -Improper calibration any heaures (Inaccuracy/Determinate) tox 22s.us -Deterioration of reagents -Contaminated solution -Sample instability/unstable reagent blanks error clerical lec.mt 04 |Page | 1 stafferror  -Diminishing lamp power -Incorrect sample and reagent volume Parameter: Mean Multirule Shewhart Control rules + Control chart procedure Test method Westgard: at least 40 samples Reference method Westgard: preferably 100 samples Analytical Run Control and patient specimens assayed, evaluated, and report together Physiologic Limit Referred to as absurd value POCT Performed by nonlab personnel Quality Assurance Tripod: Program development Assessment and monitoring Quality improvement Quality Patient Care Test request forms, clear instruction for patient prep., specimen handling… Reference Range/ Interval At least 120 individuals should be tested in each age and sex category Range/ Reference Values Analytical Methods Wavelength Distance bet 2 successive peaks (nm) frequency wavelength Lower frequency = Longer wavelength (Ex. Red) Higher frequency = Shorter wavelength (Ex. Violet) Spectrophotometric meas. Meas. light intensity in a narrower wavelength Photometric measurement Meas. light intensity w/o consideration of wavelength Multiple wavelength (uses filter only) LASER Light Amplification by Stimulated Emission of Radiation Light source for spectrophotometry Visible region Tungsten light bulb 700mm'M 350 Mercury arc UV invisible Deuterium lamp Mercury arc HYDMX Xenon lamp Hydrogen lamp IR Merst glower in on Globar (Silicone carbide) Stray light Wavelength outside the band Most common cause of loss of linearity Diffraction gratings Most commonly used monochromator Cutting grooves Prisms Rotatable Nickel sulfate Prevents stray light 1 Cutoff filter Bandpass Anti-stray light ½ peak transmittance totalrangeofwavelengthtransmitted Alumina silica glass cuvet Most commonly used cuvet Quartz/plastic cuvet UV Borosilicate glass cuvet Strong bases Photodetector Converts transmitted light into photoelectric energy Barrier layer cell/ Simplest detector photocell/ photovoltaic cell No external voltage For filter photometers Phototube Contains anode and cathode Req external voltage Photomultiplier tube Most common type iitiiiiiiiii i iti.iiiiiiiii if it readout meter deviceammeterg alvanometer lec.mtam 04 |Page | 2  e misionp hotometryexcitationofelectronsatomsusuallysodium name potassium Most sensitive UV and visible region Galvanometer/Ammeter Meter or read-out device Absorbance A = abc (a = absorptivity; b = length of light (1cm); c = concentration) A = 2 – log%T Double beam spectro. Splits monochromatic light into two components: One beam  sample One beam  reference soln or blank (corrects for variation in light source intensity) Double-beam in space 2 photodetectors (sample beam and reference beam) Double-beam in time 1 photodetector Monochromatic light  sample cuvet and reference cuvet Dydimium filter 600 nm Holmium oxide filter 360 nm Reagent blank Color of reagents Sample blank Optical interference (Hgb) FEP Meas. light emitted by a single atom burned in a flame Principle: Excitation Lt. source and cuvette: Flame For excited ions (Na+, K+) Cesium and Lithium Internal standards (FEP) Correct variations in flame Lithium Preferred internal std Potent antidepressant AAS Meas. light absorbed by atoms dissociated by heat Principle: Dissociation (unionized, unexcited, ground state) Lt. source: Hollow-cathode lamp For unexcited trace metals (Ca++ and Mg++) More sensitive than FEP Atomizer (nebulizer) Convert ions  atoms Chopper Modulate the light source Lanthanum/Strontium Complex with phosphate chloride Avoid calcium interference Volumetric (Titrimetric) Unknown sample is made to react with a known solution in the presence of an indicator Turbidimetry Light blocked by themacromolecule likeprotein macromolecules Meas. abundant large particles (Proteins) Depend on specimen concentration and particle size Nephelometry Meas. amt of Ag-Ab complexes antigenantibodycomplexes Scattered light Depends on wavelength and particle size Electrophoresis Migration of charged particles in an electric field albuministhefastestmigratingprotein Iontophoresis Migration of small charged ions Zone electrophoresis Migration of charged macromolecules Endosmosis Movement of buffer ions and solvent relative to the fixed support Ex: gamma globulins Cellulose acetate Molecular size Agarose gel Electrical charge Polyacrylamide gel Charge and molecular size 20 fractions (ex. isoenzymes) Electrophoretic mobility Directly proportional to net charge Inversely proportional to molecular size & viscosity of the supporting medium lec.mt 04 |Page | 3  team iii ion I Isoelectric focusing it Molecules migrate through a pH gradient pH = pI For isoenzymes: same size, different charge Densitometry Scan & quantitate electrophoretic pattern Capillary electrophoresis Electro-osmotic flow Southern blot DNA Northern blot RNA Western blot Proteins Chromatography Separation by specific differences in physical-chemical characteristics of the different constituents Paper chromatography Fractionation of sugar and amino acid Sorbent: Whatman paper TLC Screening: Drugs Retention factor (Rf) value Relative distance of migration from the point of application Rf = Distance leading edge of component moves Total distance solvent front moves Gas chromatography Separation of steroids, barbiturates, blood, alcohol, and lipids Volatile compounds Specimens  vaporized Mobile phase: Inert gases Gas Solid chromatography Differences in absorption at the solid phase surfaces Gas Liquid chromatography Differences in solute partitioning between the gaseous mobile phase and the liquid stationary phase Mass Spectrometry Fragmentation and ionization GC-MS Gold standard for drug testing MS/MS Detect 20 inborn errors of metabolism from a single blood spot HPLC Most widely used liquid chromatography Fractionation of drugs, hormones, lipids, carbohydrates and proteins Hydrophilic gel Gel filtration Separation of enzymes, antibodies and proteins Ex: Dextran and agarose Hydrophobic gel Gel permeation Separation of triglyceride and fatty acid Ex: Sephadex Ion exchange Separation depends on the sign and ionic charge density chromatography Partition chromatography Based on relative solubility in an organic solvent (nonpolar) and an aqueous solvent (polar) Affinity chromatography For lipoproteins, CHO and glycated hemoglobins Adsorption Based on differences between the adsorption and desorption of solutes at the chromatography surfaces of a solid particle Fluorometry/Molecular Det. amt. of lt. emitted by a molecule after excitation by electromagnetic Luminescence Spectro. radiation Lt. sources: Mercury arc and Xenon lamp (UV) Lt. detector: Photomultiplier tubes 2 monochromators: Primary filter – selects wavelength absorbed by the solution to be measured Secondary filter – prevents incident light from striking the photodetector Sensitivity: 1000x than spectro Quenching Major disadvantage of fluorometry pH and temperature changes, chemical contaminants, UVL changes lec.mt 04 |Page | 4  Instrumentation Borosilicate glasswares For heating and sterilization Ex: Pyrex and Kimax Boron-free/Soft glasswares High resistance to alkali Corex (Corning) Special alumina-silicate glass Strengthened chemically than thermally 6x stronger than borosilicate Vycor (Corning) For high thermal, drastic heat and shock Can be heated to 900OC Flint glass Soda-lime glass + Calcium, Silicon, Sodium oxides Easy to melt For making disposable glasswares TD: To deliver Exact amount TC: To contain Does not disperse the exact volume canholdaparticularvolume Blowout w/ etched rings on top of pipet Self-draining w/ o etched rings Drain by gravity Transfer pipet Volumetric: for non-viscous fluid; self-draining Ostwald folin: for viscous fluid; w/ etched ring Pasteur: w/o consideration of a specific volume Automatic macro-/micropipets Graduated or measuring Serological: w/ graduations to the tip (blowout) pipet Mohr: w/o graduations to the tip (self-draining) Bacteriologic Ball, Kolmer and Kahn Micropipettes: 400mg/dL sea Icterisia Bilirubin: 25.2 mg/dL a Icteric samples Interfere with: "TACGu” Total Protein Albumin Cholesterol Glucose Upright/supine (lying) Preferred position forbloodcollection position Patient should be seated/supine at least 20 mins before blood collection to prevent hemodilution or hemoconcentration Supine  Sitting/Standing Vasoconstriction  Reduced plasma volume Increased: “ECA” Enzymes Calcium Albumin Sitting  Supine Hemoconcentration lec.mt 04 |Page | 7  Increased: “P(u)BLIC” Proteins BUN Lipids Iron Calcium Standing  Supine Hemodilution Decreased: “TLC” Triglycerides Lipoproteins Cholesterol Prolonged standing Increased: K+ (muscles) Prolonged bedrest Decreased: Albumin (Fluid retention) Tourniquet Recommended: 1 minute application prolonged albuminenzymescholesterolchemoconcentration Prolonged tourniquet app. Hemoconcentration Anaerobiosis Increased: “C2LEA2K” Calcium Cholesterol Lactate Enzymes Ammonia Albumin K+ Tobacco smoking (Nicotine) Increased: “TUNG2C3” Triglycerides Urea Nonesterified fatty acid Glucose GH Catecholamines Cortisol Cholesterol Alcohol ingestion Increased: “THUG” Triglycerides Hypoglycemia (chronic alcoholism) Uric acid/Urates GGT chronicalcoholism Ammonia Increases by 100-200μg/L/cigar Stress (anxiety) Increased: “LAGIC” Lactate Albumin Glucose Insulin Cholesterol Drugs Medications affecting plasma volume can affect protein, BUN, iron, calcium Hepatotoxic drugs: increased liver function enzymes Diuretics: decreased sodium and potassium Diurnal variation "CA3PI2TG” in increased morning Cortisol decreased night ACTH ACP lec.mt 04 |Page | 8  Aldosterone Prolactin Iron Insulin Thyroxine GH Specimen Collection and Handling Sleeping patients Must be awakened before blood collection Unconscious patients Ask nurse or relative Identification bracelet Venipuncture Median Cubital (1st)  Cephalic (2nd)  Basilic (3rd) Tourniquet Velcro or Seraket type 3-4 inches above the site microminance coagulation Hematoma Not exceed 1 minute Needle Bevel up 15-30O angle Length: 1 or 1.5 inch (Butterfly needle: ½ to ¾ inch) After blood collection Cotton  site Apply pressure for 3-5 minutes BP cuff as tourniquet Inflate to 60 mmHg Benzalkonium chloride Disinfectant for ethanol testing (Zephiran) Dilution – 1:750 IV line on both arms Discontinue IV for 2 minutes Collect sample below the IV site Initial sample (5mL)  discard IV fluid contamination Increased: Glucose (10% contam. w/ 5% dextrose  increased bld glucose by 500 mg/dL) Chloride Potassium Sodium Decreased: Urea Creatinine Renin blood level Collected after a 3-day diet, from a peripheral vein Basal state collection Early morning blood collection 12 hours after the last ingestion of food Lancet 1.75mm: preferred length to avoid penetrating the bone Incision (Skin puncture) 500 mg/dL  nonketotic hyperosmolar coma Gestational DM Screening: 1hr GCT (50g) – bet. 24 and 28 weeks of gestation 56weeks Confirmatory: 3-hr GTT (100g) Infants: at risk for respiratory distress syndrome, hypocalcemia, hyperbilirubinemia After giving birth, evaluate 6-12 weeks postpartum Converts to DM w/in 10 years in 30-40% of cases OGTT (GDM) FBS = ≥95 mg/dL RBS200maldi 1-Hr = ≥ 180 mg/dL 2-Hr = ≥ 155 mg/dL 15200maldi PM 3-Hr = ≥ 140 mg/dL GDM = 2 plasma values of the above glucose levels are exceeded Impaired fasting glucose FBS = 100-125 mg/dL (Pre-diabetes) Impaired glucose tolerance FBS = Ferrocyanide method (Hagedorn-Jensen) (Yellow) (Colorless) Ortho-toluidine Schiff’s base (Dubowski method) Glucose oxidase Measures beta-D-glucose (65%) Mutarotase Converts alpha-D-glucose (35%) to beta-D-glucose (65%) NADH/NADPH Absorbance at 340nm Polarographic glucose Consumption of oxygen on an oxygen-sensing electrode oxidase O2 consumption α glucose concentration Hexokinase method Most specific method Reference method Uses G-6-PD G-6-PD Most specific enzyme rgt for glucose testing Interfering substances False-decreased (Glucose oxidase) Bilirubin Uric acid Ascorbate Hemolysis (>0.5 g/dL Hgb) Major interfering substance in hexokinase method (false-decreased) Dextrostics Cellular strip Strip w/ glucose oxidase, peroxidase and chromogen OGTT Janney-Isaacson method (Single dose) = most common Exton Rose (Double dose) Drink the glucose load within 5 mins IVGTT For patients with gastrointestinal disorders (malabsorption) Glucose: 0.5 g/kg body weight Given w/in 3 mins 1st blood collection: after 5 mins of IV glucose Requirements for OGTT Ambulatory Fasting: 8-14 hours Unrestricted diet of 150g CHO/day for 3 days Do not smoke or drink alcohol Glucose load 75 g = adult (WHO std) 100 g = pregnant 1.75 g glucose/kg BW = children HbA1c 2-3 months Glucose = beta-chain of HbA1 lec.mt 04 |Page | 15  1% increase in HbA1c = 35 mg/dL increase in plasma glucose 18-20% = prolonged hyperglycemia 7% = cutoff diagnostic 2.6.1isnormal Specimen: EDTA whole blood Test: Affinity chromatography (preferred) IDA and older RBCs High HbA1c RBC lifespan disorders Low HbA1c Fructosamine 2-3 weeks (Glycosylated albumin/ Useful for patients w/ hemolytic anemias and Hgb variants plasma protein ketoamine) Not used in cases of low albumin Specimen: Serum Galactosemia Congenital deficiency of 1 of 3 enzymes in galactose metabolism Galactose-1-phosphate uridyl transferase (most common) Galactokinase Uridine diphosphate galactose-4-epimerase Essential fructosuria Autosomal recessive Fructokinase deficiency Hereditary fructose Defective fructose-1,6-biphosphate aldolase B activity intolerance Fructose-1,6-biphosphate Failure of hepatic glucose generation by gluconeogenic precursors such as deficiency lactate and glycerol Glycogen Storage Disease Autosomal recessive Defective glycogen metabolism Test: IVGTT (Type I GSD) Ia = Von Gierke Glucose-6-Phosphatase deficiency (most common worldwide) II = Pompe Alpha-1,4-glucosidase deficiency (most common in the Philippines) III = Cori Forbes Debrancher enzyme deficiency IV = Andersen Brancher enzyme deficiency V = McArdle Muscle phosphorylase deficiency VI = Hers Liver phosphorylase deficiency VII = Tarui Phosphofructokinase deficiency XII = Fanconi-Bickel Glucose transporter 2 deficiency CSF glucose Collect blood glucose at least 60 mins (to 2 hrs) before the lumbar puncture (Because of the lag in CSF glucose equilibrium time) < 0.5 Normal CSF : serum glucose ratio C-peptide Formed during conversion of pro-insulin to insulin 5:1 to 15:1 Normal C-peptide : insulin ratio D-xylose absorption test Differentiate pancreatic insufficiency from malabsorption (low blood or urine xylose) Gerhardt’s ferric chloride Acetoacetate test Nitroprusside test 10x more sensitive to acetoacetate than to acetone Acetest tablets Acetoacetate and acetone Ketostix Detects acetoacetate better than acetone KetoSite assay Detects beta-hydroxybutyrate but not widely used Normal Values RBS = anabolism Excessive tissue destruction Positive nitrogen balance Anabolism > catabolism Growth and repair processes Prealbumin (Transthyretin) Transports thyroxine and retinol (Vit. A) Landmark to confirm that the specimen is really CSF Albumin Maintains osmotic pressure nianest iiiiniiiii inii concent Alpha1-antitrypsin t.in um Negative acute phase reactant Acute phase reactant Major inhibitor of protease activity 90% of alpha1-globulin band Alpha1-fetoprotein Gestational marker Tumor marker: hepatic and gonodal cancers Screening test for fetal conditions (Spx: maternal serum) Amniotic fluid: confirmatory test Increased: Hepatoma, spina bifida, neural tube defects Decreased: Down Syndrome (Trisomy 21) Alpha1-acid glycoprotein/ Low pI (2.7) orosomucoid Negatively charged even in acid solution Alpha1-antichymotrypsin Acute phase reactant Binds and inactivates PSA Increased: Alzheimer’s disease, AMI, infection, malignancy, burns Haptoglobin (alpha2) Acute phase reactant Binds free hemoglobin (alpha chain) Ceruloplasmin (alpha2) Copper binding (6-8 atoms of copper are attached to it) Has enzymatic activities lec.mt 04 |Page | 21  Decreased: Wilson’s disease (copper  skin, liver, brain, cornea [Kayser- Fleisher rings]) Alpha2-macroglobulin Larges major nonimmunoglobulin protein Increased: Nephrotic syndrome (10x) Forms a complex w/ PSA Group-specific component Affinity w/ vitamin D and actin (Gc)-globulin (bet. alpha1 and alpha2) Hemopexin (beta) Binds free heme Beta2-microglobulin HLA Filtered by glomeruli but reabsorbed Transferrin/Siderophilin Negative acute phase reactant (beta) Major component of beta2-globulin fraction Pseudoparaproteinemia in severe IDA Increased: Hemochromatosis (bronze-skin), IDA Complement (beta) C3: major Fibrinogen (bet. beta and Acute phase reactant gamma) Between beta and gamma globulins CRP (gamma) General scavenger molecule Undetectable in healthy individuals hsCRP: warning test to persons at risk of CAD Immunoglobulins (gamma) Synthesized by the plasma cells IgG>IgA>IgM>IgD>IgE 9 Is incredible Myoglobin he If'm'enatal has Marker: Ischemic muscle cells, chest pain (angina), AMI Troponins Most important marker for AMI TnT (Tropomyosin-binding Specific for heart muscle subunit) Det. unstable angina (angina at rest) TnI (Inhibitory subunit or Only found in the myocardium Actin-binding unit) Greater cardiac specificity than TnT Highly specific for AMI 13x more abundant in the myocardium than CK-MB Very sensitive indicator of even minor amount of cardiac necrosis TnC Binds calcium ions and regulate muscle contractions Glomerular proteinuria Most common and serious type Often called albuminuria Tubular proteinuria Defective reabsorption Slightly increased albumin excretion Overload proteinuria Hemoglobinuria Myoglobinuria Bence-Jones proteinuria Postrenal proteinuria Urinary tract infection, bleeding, malignancy Microalbuminuria Type 1 DM Albumin excretion ≥30 mg/g creatinine (cutoff: DM) but ≤300 mg/g creatinine Microalbuminuria: 2 out of 3 specimens submitted are w/ abnormal findings (w/in 6 months) CSF Oligoclonal banding 2 or more IgG bands in the gamma region: Multiple sclerosis Encephalitis Neurosyphilis Guillain-Barre syndrome Neoplastic disorders lec.mt 04 |Page | 22 Serum Oligoclonal banding Leukemia Lymphoma Viral infections Alkaptonuria Ochronosis (tissue pigmentation) Homocystinuria Impaired activity of cystathione beta-synthetase Elevated homocysteine and methionine in blood and urine Screen: Modified Guthrie test (Antagonist: L-methionine sulfoximine) MSUD Markedly reduced or absence of alpha-ketoacid decarboxylase 4 mg/dL of leucine is indicative of MSUD Screen: Modified Guthrie test (Antagonist: 4-azaleucine) Diagnostic: Amino acid analysis (HPLC) PKU Deficiency of tetrahydrobiopterin (BH4)  elevated blood phenylalanine Normal Values Total protein = 6.5-8.3 g/dL (Proteins) Albumin = 3.5-5.0 g/dL Globulin = 2.3-3.5 g/dL Kidney Function Tests Tests for GFR Clearance: -Inulin clearance -Creatinine clearance -Urea clearance Phenolsulfonphthalein dye test Cystatin C Tests for Renal Blood Flow BUN Creatinine Uric acid Tests Measuring Tubular Excretion: Function -Para-amino hippurate test (Diodrast test) -Phenolsulfonphthalein dye test Concentration: -Specific gravity -Osmolality GFR Decreases by 1.0 mL/min/year after age 20-30 years 150 L of glomerular filtrate is produced daily Inulin clearance Reference method Creatinine clearance Best alternative method Measure of the completeness of a 24-hour urine collection Excretion: 1.2-1.5 g creatinine/day Urea clearance Demonstrate progression of renal disease or response to therapy Cystatin C Low MW protease inhibitor FilteredNot secretedCompletely reabsorbed (PCT) Indirect estimates of GFR Its presence in urine denotes damage to PCT BUN majormostabundant Synthesized from Ornithine or Kreb’s Henseleit cycle end of a p roduct protein nd a amino cidcatabolism First metabolite to elevate in kidney diseases Better indicator of nitrogen intake and state of hydration 2.14 BUN  Urea (mg/dL) Fluoride or citrate Inhibit urease Thiosemicarbazide Enhance color development (BUN mtd) Ferric ions Diacetyl monoxime method Yellow diazine derivative Urease method Routinely used Urease: prepared from jack beans lec.mt 04 |Page | 23  Urea ---(Urease)--> NH4 + Berthelot reagent (Measure ammonia) Coupled urease Glutamate dehydrogenase method UV enzymatic method Isotope dilution mass Reference method spectrometry For research purposes NPN 45% Urea 20% Amino acid 20% Uric acid 5% Creatinine 1-2% Creatine 0.2% Ammonia Creatinine Derived from alpha-methyl guanidoacetic acid (creatine) taste reaction Produced by 3 amino acids (methionine, arginine, lysine) MAL Most commonly used to monitor renal function Enzymatic methods Creatinine Aminohydrolase – CK method (Creatinine) Creatinase-Hydrogen Peroxide method – benzoquinonemine dye (red) Creatininase (a.k.a. creatinine aminohydrolase) Direct Jaffe method Formation of red tautomer of creatinine picratecasespicricacidand101NaOH Interferences (Direct Jaffe) Falsely increased: Ascorbate Glucose Uric acid Alpha-keto acids Folin Wu Method (+) Red orange tautomer Lloyd’s or Fuller’s Earth True measure of creatinine method Sensitive and specific Uses adsorbent to remove interferences (UA, Hgb, Bili) Lloyd’s reagent Sodium aluminum silicate Fuller’s earth reagent Aluminum magnesium silicate Jaffe reagent (Alk. picrate) Satd. picric acid + 10% NaOH Kinetic Jaffe method Popular, inexpensive, rapid and easy to perform Requires automated equipment Azotemia Elevated urea and creatinine in blood Pre-renal azotemia Decreased GFR but normal renal function Dehydration, shock, CHF Increased: BUN Normal: Creatinine Renal azotemia True renal disease Decreased GFR Striking BUN level but slowly rising creatinine value BUN = >100 mg/dL Creatinine = >20 mg/dL Uric acid = >12 mg/dL Post renal azotemia Urinary tract obstruction Decreased GFR Nephrolithiasis, cancer or tumors of GUT Creatinine = normal or slightly increased Uremia Marked elevation of urea, accompanied by acidemia and electrolyte imbalance (K+ elevation) of renal failure Normocytic, normochromic anemia Uremic frost (dirty skin) Edema lec.mt 04 |Page | 24  Foul breath Urine-like sweat Uric acid From purine (adenine and guanine) catabolism ofnucleicacidsin thimtiganbreakdown Excretion: 1g/day Hyperuricemia -Gout d isease goutkidney -Increased nuclear metabolism (leukemia, lymphoma, MM, polycythemia, hemolytic and megaloblastic anemia) – Tx: Allopurinol -Chronic renal disease -Lesch-Nyhan syndrome (HGPRT deficiency)Hypoxanthineguaninephosphoribosyltransferasedef Hypouricemia Fanconi’s syndrome Wilson’s disease Hodgkin’s disease Methods (Uric acid) Stable for 3 days Potassium oxalate cannot be used Major interferences: Ascorbate and bilirubin Phosphotungstic acid mtd Uric acid + Phosphotungstic acid ---(NaCN/NaCO3)--> Tungsten blue + Allantoin NaCN Folin Newton Brown Benedict NaCO3 Archibald Henry Caraway Lagphase Incubation period after the addition of an alkali to inactivate non-uric acid reactants Uricase method Simplest and most specific method Candidate reference method Uric acid (Absorbance at 293nm) ---[Uricase]--> Allantoin (No absorbance) Decrease in absorbance α uric acid concentration Para-amino hippurate test Measures renal plasma flow Reference method for tubular function Phenolsulfonphthalein dye Measures excretion of dye proportional to renal tubular mass test 6 mg of PSP is administered IV Concentration tests Collecting tubules and loops of Henle Specimen: 1st morning urine Specific gravity Affected by solute number and mass SG >1.050: X-ray dye and mannitol 1.010 = SG of ultrafiltrate in Bowman’s space Osmolality Total number solute particles present/kg of solvent (moles/kg solvent) Affectted only by number of solutes present Urine osmolality = due to urea Serum osmolality = due to sodium and chloride Det. by Colligative properties: Freezing point (incr. osm. = decr. FP) Vapor pressure (incr. osm. = decr. VP) Osmotic pressure (incr. osm. = incr. OP) Boiling point (incr. osm. = incr. BP) Direct methods Freezing point osmometry = popular method (Osmolality) Vapor pressure osmometry (Seebeck effect) Incr. plasma osmolality Incr. vasopressin (H2O reabsorption)  decr. plasma osmolality Tubular failure Increased: BUN, creatinine, calcium Decreased: Phosphate lec.mt 04 |Page | 25 Osmolal gap Difference between measured and calculated osmolality Sensitive indicator of alcohol or drug overdose Osmolal gap: >12 mOsm/kg DKA Drug overdose Renal failure Normal Values Creatinine Clearance: (Kidney Function Tests) Male = 85-125 mL/min Female = 75-112 mL/min BUN = 8-23 mg/dL Creatinine = 0.5-1.5 mg/dL Uric acid: Male = 3.5-7.2 mg/dL Female = 2.6-6.0 mg/dL Renal plasma flow (PAH) = 600-700 mL/min Renal blood flow (PSP) = 1200 mL/min SG = 1.005-1.030 Osmolality: Serum = 275-295 mOsm/kg Urine (24-hr) = 300-900 mOsm/kg [1:1 = Glomerular disease] [1.2:1 = loss of renal concentrating ability] [