Clin Chem

Clinical Chemistry Review of Polansky Flashcards

Diurnal Variation

Inc in AM, ACTH, cortisol, iron, Inc in PM, growth hormone, PTH, TSH

Recent food ingestion

Inc glucose, insulin, gastrin triglycerides, Na+, uric acid, Fe, LD, Ca2+; Dec chloride, phosphate, K; Fasting required, fasting glucose, triglycerides, lipid panel

Alcohol

Dec glucose, inc triglycerides, GGT

Posture

inc albumin, cholesterol, Ca, when standing

Activity

inc in ambulatory patients: creatinine kinase; inc with exercise: K, phosphate, lactic acid, creatinine, protein, CK, AST, LD

stress

inc ACTH, cortisol, catecholamines; inc sympathetic nervous system activity.

use of isopropyl alcohol wipes to disinfect sites

can compromise blood alcohol determination

squeezing site of capillary puncture

inc K

pumping fist during venipuncture

inc K, lactic acid, Ca, phosphorus; dec pH

tourniquet >1min

inc K, total protein, lactic acid

IV fluid contamination

inc glucose, K, Na, Cl, dilute other analytes

Hemolysis

inc K, Mg, phosphorus, LD, AST, iron, ammonia

exposure to light

dec bilirubin, carotene

temperature between collection and testing

chilling required for lactic acid, ammonia, blood gases

inadequate centrifugation

poor barrier formation in gel tubes can result in inc K, LD, AST, iron, phosphorus

recentrifugation

hemolysis, inc K

delay in separating serum plasma unless gel tube is used

inc ammonia, lactic acid, K, Mg, LD; dec glucose (unless collected in fluoride)

storage temperature at room temp

inc lactic acid, ammonia; dec glucose unless collected in fluoride

storage temperature at 4C

inc ALP dec LD

difference higher in plasma than in serum

total protein, LD, Ca

difference higher in serum than plasma

K, phosphate, glucose, CK, bicarbonate, ALP, albumin, AST, triglycerides

higher in plasma than WB

glucose

higher in capillary blood than venous blood

glucose (in postprandial specimen), K

higher in venous blood than capillary blood

Ca, total protein

higher in rbcs than plasma

K, phosphate, Mg

higher in plasma than rbcs

Na, chloride

spectrophotometry

rxn produces colored light that absorbs a specific wavelength that is directly proportional to analyte conc, tungsten lamp, very common

atomic absorption spectrophotometry AAS

measures light absorbed by ground state atoms, hallow cathode lamp, sensitive ad used for trace metals

Fluorometry

atoms absorb light of specific wavelength and emit light of one longer and lower, xenon lamp, detector at 90, drugs, hormones

chemiluminescence

oxidation rxn that produces light, does not require excitation radiation of monochromators, very sensitive, used for immunoassays

turbidimetry

measures reduction in light transmission, measure proteins in urine and CSF

nephelometry

similar to turbidimetry but at an angle for ag-ab rxns

thin layer chromatography TLC

screening test for drugs in urine, substances identified by Rf value,

high performance liquid chromatography

separation of thermolabile compounds, conc determined by peaks ratio

gas chromatography

separation of volatile compounds, therapeutic and toxic drugs, identified by retention time, peaks are proportional to conc

ion selective electrodes

potential difference between 2 electrodes directly proportional to analyte, pH, Pco, Po, Na, K, Ca, Li, Cl

osmometry

determines osmolality based on freezing point depression, serum and urine osmolality

electrophoresis

separation of charged particles in electrical field, anions move to positive charge (anode), cations move to negative charge (cathode), serum protein and hemoglobin electrophoresis

basic metabolic panels

Na, K, chloride, CO2, glucose, creatinine, BUN, Ca2

comprehensive metabolic panel

Na, K, chloride, CO2, glucose, creatinine, BUN, albumin, total protein, ALP, AST, bilirubin, Ca

electrolyte panel

Na, K, Cl, CO2

hepatic function panel

albumin, ALT, AST, ALP, bilirubin, total protein

lipid panel

total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides

renal function panel

NA, K , Co2, glucose, creatinine, BUN, Ca2, albumin, phosphate

glucose fasting

70—99mg/dL major source of cellular energy, levels dec at RT, NaFl prevent glycolysis, glucose oxidase and hexokinase are most common methods,

cholesterol total

desirable <200mg/dL not so great for detecting CAD by itself, pair with HDL and LDL cholesterol

HDL cholesterol

desirable >=60mg/dL, inverse to CAD, homogenous assays don’t require pretreatment to remove non HDL, 1st reagents blocks non HDL, 2nd reacts with it

LDL cholesterol

optimal, <100 mg/dL, risk factor for CAD, calculated by Friedewald formula if triglycerides aren’t >400, or measured by direct homogenous assays

triglycerides

desirable <150 mg/dL, risk factor for CAD, main form of lipid storage, enzymatic methods using lipase, requires fasting specimen

total protein

6.4-8.3 g/dL inc dehydration, inflammation, myeloma, dec nephrotic syndrome, hepatic insufficiency, malnutrition

total protein <4.5

peripheral edema, biuret method, alkaline copper reagent reacts with peptide bonds

albumin

3.5-5 g/dL inc dehydration, dec malnutrition, liver disease, nephrotic syndrome, largest fraction of plasma proteins, regulates osmotic pressure, measure by dye binding bromocresol green and bomocresol purple

microalbumin on urine

50-200 mg/ 24hr predictive of diabetic nephropathy inc in diabetics at risk of nephropathy