Medical Technology Board Examination Review Notes Must Know (Rodriguez) 3

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 Function	Excretion: -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 FilteredàNot secretedàCompletely reabsorbed (PCT) Indirect estimates of GFR Its presence in urine denotes damage to PCT
BUN	Synthesized from Ornithine or Kreb’s Henseleit cycle First metabolite to elevate in kidney diseases Better indicator of nitrogen intake and state of hydration
2.14	BUN à Urea (mg/dL)
Fluoride or citrate	Inhibit urease
Thiosemicarbazide Ferric ions	Enhance color development (BUN mtd)
Diacetyl monoxime method	Yellow diazine derivative
Urease method	Routinely used Urease: prepared from jack beans Urea ---(Urease)--> NH4 + Berthelot reagent (Measure ammonia)
Coupled urease	Glutamate dehydrogenase method UV enzymatic method
Isotope dilution mass spectrometry	Reference method 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) Produced by 3 amino acids (methionine, arginine, lysine) Most commonly used to monitor renal function
Enzymatic methods (Creatinine)	Creatinine Aminohydrolase – CK method Creatinase-Hydrogen Peroxide method – benzoquinonemine dye (red) Creatininase (a.k.a. creatinine aminohydrolase)
Direct Jaffe method	Formation of red tautomer of creatinine picrate
Interferences (Direct Jaffe)	Falsely increased: Ascorbate Glucose Uric acid Alpha-keto acids
Folin Wu Method	(+) Red orange tautomer
Lloyd’s or Fuller’s Earth method	True measure of creatinine 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 Foul breath Urine-like sweat
Uric acid	From purine (adenine and guanine) catabolism Excretion: 1g/day
Hyperuricemia	-Gout -Increased nuclear metabolism (leukemia, lymphoma, MM, polycythemia, hemolytic and megaloblastic anemia) – Tx: Allopurinol -Chronic renal disease -Lesch-Nyhan syndrome (HGPRT deficiency)
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 test	Measures excretion of dye proportional to renal tubular mass 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 (Osmolality)	Freezing point osmometry = popular method Vapor pressure osmometry (Seebeck effect)
Incr. plasma osmolality	Incr. vasopressin (H2O reabsorption) à decr. plasma osmolality
Tubular failure	Increased: BUN, creatinine, calcium Decreased: Phosphate
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 (Kidney Function Tests)	Creatinine Clearance: 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 [<290 mOsm/kg = kidney damage] Urine osmolality: Serum osmolality = 1:1 to 3:1 [>1:1 = Glomerular disease] [1.2:1 = loss of renal concentrating ability] [<1:1 = Diabetes Insipidus]
Liver Function Tests
Liver	Receives 15 mL of blood per minute Lobule: anatomic unit
Synthetic function	Proteins, CHO, lipids, LPP, clotting factors, ketone bodies, enzymes Albumin: 12g/day
Conjugation function	Bilirubin metabolism Bilirubin: 200mg/day
Detoxification and Drug metabolism	Drugs Ammonia à Urea à Excreted
Excretory and Secretory functions	Bile acids: cholic acid and chenodeoxycholic acid Bile salts: bile acids + amino acids (glycine and taurine)
Storage function	Vitamins Glycogen
Test measuring the Hepatic Synthetic Ability	Total Protein Determination: -Kjeldahl method -Biuret method -Folin-Ciocalteu (Lowry) method -UV absorption method -Electrophoresis -Refractometry -Turbidimetric and Nephelometric methods -Salt fractionation Prothrombin Time (Vitamin K Response Test)
Test measuring Conjugation/Excretion Function	Bilirubin Assay: -Evelyn and Malloy method -Jendrassik and Grof Bromsulfonphthalein (BSP) Dye Excretion test
Test for Detoxification Function	Enzyme tests: ALP, AST, ALT, 5’NT, GGT, OCT, LAP, LDH Ammonia: -Kjeldahl (Digestion) method -Nesslerization reaction -Berthelot reaction
Plasma protein	0.2-0.4 g/dL higher than serum due to fibrinogen
Kjeldahl (Digestion) mtd	Standard reference method Measurement of nitrogen content Serum + Tungstic acid à PFF 1g N2 = 6.54g protein 15.1-16.8% = N2 content of proteins Rgt: H2SO4 End product: NH3
Biuret method	Most widely used method (IFCC recommended) Req. at least 2 peptide bonds and an alkaline medium Rgts: Alkaline CuSO4 Rochelle salt (NaK Tartrate) NaOH KI End product: Violet color (545nm)
Folin-Ciocalteu (Lowry) method	Highest analytical sensitivity Oxidation of phenolic compounds (tyrosine, tryptophan, histidine) Rgts: Phenol (or phosphotungstic-molybdic acid) Biuret (color enhancer) End product: Blue color
Electrophoresis	MI: elevated APRs (AAT, HPG, a1­-x)
Gamma-spike	Monoclonal gammopathy (multiple myeloma)
Beta-gamma bridging	In serum: Hepatic cirrhosis (IgA) In plasma: normal (fibrinogen)
Alpha2-globulin band spike	Nephrotic syndrome
Alpha1-globulin flat curve	Juvenile cirrhosis (AAT deficiency)
Alpha1, alpha2, beta-globulin band spikes	Inflammation
Polyclonal gammopathy	Chronic inflammation (RA, malignancy)
Small spikes in beta region	IDA (transferrin)
Free hemoglobin	“Blip” in the late alpha2 or early beta region
Refractometry	Refractive index
Turbidimetric and nephelometric methods	SSA TCA
Salt fractionation	Salt: Sodium sulfate
Albumin	Soluble: Water Moderately concentrated salt solution Concentrated salt solution Insoluble: Hydrocarbon solvents Highly concentrated salt solution Saturated salt solution
Globulin	Soluble: Hydrocarbon solvents Weak salt solution Insoluble: Water Saturated salt solution Concentrated salt solution
Prothrombin time	Differentiates intrahepatic disorder (prolonged PT) from extrahepatic obstructive liver disease (normal PT)
Albumin	Inversely proportional to the severity of the liver disease
Hepatic cirrhosis	Low total protein + low albumin
Bromcresol green	Most commonly used dye for albumin
Bromcresol purple	Most specific dye for albumin
Other dyes for albumin	Hydroxyazobenzene benzoic acid (HABA) Methyl orange (MO)
Nephrotic syndrome	Albumin excretion: 20-30 g/day
Analbuminemia	(-) albumin
Bisalbuminemia	EP: 2 albumin bands Therapeutic drugs in serum
Inverted A/G ratio	Hepatic cirrhosis (IgA) Multiple Myeloma (IgG) Waldenström’s macroglobulinemia (IgM) Chronic inflammation
Bilirubin	Derived from hemoglobin myoglobin, catalase and cytochrome oxidase
Heme oxygenase	Protoporphyrin à Biliverdin
Biliverdin reductase	Biliverdin àB1
Urobilinogen	Deconjugated bilirubin
Bilirubin 1	Non-polar bilirubin Free/Slow bilirubin
Bilirubin 2	Polar bilirubin One-minute/prompt bilirubin Regurgitative bilirubin
Delta bilirubin	Bilirubin tightly bound to albumin Delta bilirubin = TB-DB+IB
Jaundice	Bilirubin >2 or 3 mg/dL
Pre-hepatic jaundice	Hemolytic B1 = increased B2 = normal UG = increased UB = negative
Hepatic jaundice	Hepatocellular B1 = increased B2 = increased UG = increased UB = positive ALT = increased AST = increased
Post-hepatic jaundice	Obstructive B1 = normal B2 = increased UG = decreased/negative UB = positive ALP = increased GGT = increased Cholesterol = increased
Gilbert’s syndrome	Bilirubin transport deficit (uptake) B1 = increased B2 = decreased
Crigler-Najjar syndrome	Conjugation deficit Type I = total UDPGT deficiency Type II = partial UDPGT deficiency B1 = increased B2 = decreased Danger: Kernicterus Bile is colorless
Dubin-Johnson syndrome & Rotor syndrome	Bilirubin excretion deficit Blockade of excretion into the canaliculi TB = increased B2 = increased
Lucey-Driscoll syndrome	Circulating inhibitor of bilirubin conjugation B1 = increased
Methods (Bilirubin)	Free from hemolysis and lipemia Store in the dark Measured ASAP or w/in 2-3 hours
Van den Berg reaction	Diazotization of bilirubin
Evelyn and Malloy method	Accelerator: Methanol Diazo rgts: Diazo A (0.1% Sulfanilic acid + HCl) Diazo B (0.5% Sodium nitrite) Diazo blank (1.5% HCl) (+) pink to purple azobilirubin Affected by hemolysis
Jendrassik and Grof	Candidate reference method Accelerator: Caffeine sodium benzoate Buffer: Sodium acetate Ascorbic acid: terminates the initial reaction and destroys the excess diazo rgt Not falsely elevated by hemolysis Total bilirubin is measured 15 minutes after adding methanol or caffeine soln
Bilirubin	Absorbs light maximally at 450nm
Rosenthal White method	Double collection method Collection: -After 5 mins (50% dye retention) -After 30 mins (0% dye retention)
Mac Donald method	Single collection method Collection: -After 45 mins (+/- 5% dye retention)
Ammonia	From deamination of amino acids Elevated levels are neurotoxic and often associated w/ encephalopathy and acetaminophen poisoning Diagnosis of hepatic failure and Reye’s syndrome In severe liver disorder: áNH3 à circulation à brain (conv. to glutamine) à increases pH à compromise the Kreb’s cycle à Coma due to lack of ATP for the brain
Methods (Ammonia)	Specimen: Heparin or EDTA plasma Fasting is required Avoid smoking Prolonged standing of specimen: increased NH3 due to deamination Place on iced water immediately Avoid hemolysis
Kjeldahl (Digestion) method	Specimen à PFF N2 ----------(hot conc. H2SO4 + CuSO4 + Hg + Selenium)----------> NH3
Nesslerization of ammonia	NH3 + K2Hg2I2 ----------(Gum Ghatti)----------> NH2Hg2I2 End color: Yellow (low to moderate N2) Orange brown (high N2)
Berthelot reaction	NH3 + Phenol + Hypochlorite -----(Na Nitroprusside)-----> Indophenol blue
Normal Values (Liver Function Tests)	Total protein = 6.5-8.3 g/dL Albumin = 3.5-5.0 g/dL Globulin = 2.3-3.5 g/dL α1-globulin = 0.1-0.3 g/dL α2-globulin = 0.6-1.0 g/dL β-globulin = 0.7-1.1 g/dL γ-globulin = 0.8-1.6 g/dL Total bilirubin = 0.2-1.0 mg/dL Indirect bilirubin = 0.2-0.8 mg/dL Direct bilirubin = 0-0.2 mg/dL Urobilinogen: Urine = 0.1-1.0 Ehrlich units/2hrs (or 0.54 Ehrlich units/day) Stool = 75-275 Ehrlich units/100g feces (or 75-400 Ehrlich units/24hrs) Ammonia = 19-60 μg/dL