Clinical Chemistry Flashcards
Clone
Register
Clinical Chemistry Flashcards
View
CC PREMID.pdf Flashcards
Study
What are the two parts of meaningful quantitative results in laboratory results?
The numerical value and a label identifying the units (e.g., mass, length, time, volume, physical quantity, or dimension).
What is the significance of SI Units (Système International d'Units)?
SI Units provide a global standard for describing physical quantities and were adopted internationally in 1960.
What are the seven basic units in the SI system?
Length (meter), mass (kilogram), time (second), electric current (ampere), thermodynamic temperature (kelvin), amount of substance (mole), and luminous intensity (candela).
What is an example of an SI derived unit?
Velocity (meters per second, m/s).
What are some examples of non-SI units?
Hour, minute, day, gram, and liter.
What is a primary standard?
A primary standard is a highly purified chemical (100.00% purity) with an exact known concentration.
Why are NIST certified standard reference materials (SRMs) used in clinical chemistry?
Because biological constituents can't meet the strict criteria of traditional primary standards, SRMs are used to ensure calibration accuracy and are considered traceable to NIST.
What is a secondary standard?
A secondary standard has lower purity and is measured by comparison with a primary standard; however, true secondary standards don't exist in clinical chemistry due to the lack of primary physiological standards.
What are the types of reagent grade water?
Type I (highest purity), Type II (suitable for most analytic needs), Type III (acceptable for washing glassware but not for analytical use).
What storage considerations should be taken for reagent grade water?
Reagent grade water, especially Clinical Laboratory Reagent Water (CLRW), should be stored carefully to prevent changes in water quality and minimize chemical and bacterial contamination.
What is the purpose of quality testing parameters for reagent grade water?
To measure water quality through resistance (conductivity), resistivity, pH, and the presence of impurities.
What does the mnemonic LEO (Lose Electrons Oxidized) and GER (Gain Electrons Reduced) help recall?
It helps recall redox reactions.
What is the definition of a buffer in chemistry?
Buffers are weak acids or bases along with their related salts that help minimize changes in hydrogen ion concentration by dissociating in a controlled way.
How is pH mathematically expressed?
pH is expressed as the negative logarithm of the hydrogen ion concentration in a solution, where pH = -log[H].
What is the pH scale range and what does it indicate?
The pH scale ranges from 0 to 14; lower pH values indicate more acidic conditions and higher pH values indicate more basic conditions.
What are Erlenmeyer flasks used for?
General use with a wide base and narrow neck; not for exact measurements.
What is the main use of a Griffin beaker?
Flat-bottomed containers with wide mouths used for holding liquids in varying volumes, not for precision.
What are graduated cylinders used for?
Cylindrical vessels with calibration marks used for measuring liquid volumes, but less accurate than volumetric labware.
What are the general types of pipets?
They are used to transfer liquids and classified as TC (to contain) or TD (to deliver).
What distinguishes a Mohr pipet?
Mohr pipets are self-draining but not graduated to the tip.
What is the function of a micropipet?
It holds less than 1 mL for very small liquid transfers.
What is the purpose of transfer pipets?
Transfer pipets are designed to dispense one fixed volume.
CC PREMID.pdf Flashcards
Study
What are the varying pore sizes of filter papers used for in clinical chemistry?
Different filter papers have varying pore sizes; selection depends on separation needs and flow rates. Not suitable for strong acids or bases.
Describe the process of using filter paper in clinical chemistry.
The filter paper is placed in a funnel. The solution drains through the paper into a receiving vessel. The liquid that passes through is termed the filtrate.
What is the purpose of dialysis in clinical chemistry?
Dialysis separates macromolecules from solvents or smaller substances.
What historical device popularized dialysis in the 1970s?
Dialysis gained popularity with the Technicon AutoAnalyzer in the 1970s.
How does the mechanism of dialysis function?
A solution is placed in a bag or on one side of a semipermeable membrane. Larger molecules are retained while smaller molecules and solvents diffuse out.
What is the efficiency of the dialysis process?
The process is slow and manual dialysis is largely replaced by gel-filled columns in most analytical procedures.
Define significant figures (sig figs) in laboratory mathematics.
Significant figures or sig figs are the minimum number of digits required to accurately express a value in scientific notation without losing precision.
Provide an example of significant figures.
8142 has four significant figures.
How is normality (N) defined in clinical chemistry?
Normality N is expressed as equivalent weights per liter (Eq/L) or milliequivalents per milliliter (mmol/mL).
How is equivalent weight calculated?
Equivalent weight is calculated as gram molecular weight (gmw) divided by valence (V).
What is a key point regarding equivalent weight?
An equivalent weight of one substance is equal to the equivalent weight of any other chemical, facilitating comparisons across different substances.
Define specific gravity in clinical chemistry.
Specific gravity is the ratio of the density of a material compared to the density of pure water at a given temperature.
How is density measured?
Density is expressed as mass per unit volume, typically in grams per milliliter.
In what application is specific gravity commonly used?
Specific gravity is commonly used for very concentrated materials such as commercial acids (e.g., sulfuric and hydrochloric acids).
What are the elements involved in concentration calculation?
Actual concentration = Specific gravity x Assay or percent purity expressed as a decimal stated on the container label.
What does spectrophotometry measure?
Spectrophotometry measures electromagnetic radiation to determine the concentration of atoms or molecules through absorption or emission of radiant energy.
What do photometric instruments measure?
Photometric instruments measure light intensity without considering wavelength and use filters, prisms, or gratings to isolate a narrow range of incident wavelengths.
How is electromagnetic radiation described?
Electromagnetic radiation is described as photons traveling in waves.
What is Planck's formula?
Planck's formula is E = hν, where E is energy, h is Planck's constant (6.626 x 10^-34 erg·sec), and ν is frequency.
What is the relationship between energy and wavelength in electromagnetic radiation?
Energy is inversely proportional to wavelength.
What is the wavelength range of visible light?
Visible light ranges from violet (400 nm) to red (700 nm).
What do double beam spectrophotometers do?
Double beam spectrophotometers automatically correct for sample and reference absorbance, making them useful for measuring absorption spectra.
What modern innovations have replaced double beam instruments?
Computerized spectrophotometers with continuous zeroing systems have largely replaced double beam instruments, offering more convenience and accuracy in measurement.
What does atomic absorption spectrophotometry (AAS) measure?
AAS measures concentration by detecting the absorption of electromagnetic radiation by atoms, not molecules.
What is the usual light source in atomic absorption spectrophotometry?
The usual light source in AAS is a hollow cathode lamp composed of a cathode made of the metal being measured, an anode, and an inert gas (e.g., helium or argon).
What occurs when voltage is applied to the hollow cathode lamp in AAS?
When voltage is applied, metal atoms are knocked off, become excited, and emit light characteristic of the metal.
What is required for sample preparation in atomic absorption spectrophotometry?
The sample must contain the reduced metal in the atomic vaporized state, often done using a flame sample cell to break chemical bonds and form free atoms.
What is the common device used for sample introduction in AAS?
The premix long path burner is commonly used for sample introduction, aspirating the sample as a fine spray and mixing it with air.
What does turbidimetry measure?
Turbidimetry measures the concentration of particulate matter in a sample using a spectrophotometer, where the amount of light blocked depends on concentration and particle size.
What is critical for handling samples in turbidimetry?
Handling of the sample is critical to prevent particles from aggregating and settling.
CC PREMID.pdf Flashcards
Study
What are the most common types of pumps used in clinical chemistry?
Mechanical reciprocating pumps are the most common, allowing for constant flow.
What is the role of stationary phases in chromatography?
Columns packed with stationary phases, such as silica gel, can operate at ambient or elevated temperatures.
What is the function of loop injectors in sample introduction?
Loop injectors allow for precise and reproducible sample introduction.
What is the purpose of detectors in chromatography?
Detectors monitor the eluate, producing signals proportional to concentration, commonly using UV spectrophotometers.
What are some other types of detectors used in chromatography?
Other detectors include fluorescence and amperometric detectors.
What is a chromatogram?
A chromatogram is created by recording detector signals against time, which helps identify compounds based on retention time and peak area.
What is isocratic elution in chromatography?
Isocratic elution maintains a constant mobile phase composition throughout the separation.
What is gradient elution in chromatography?
Gradient elution varies the mobile phase composition to improve separation of compounds with differing affinities for the stationary phase.
What are the applications of chromatography?
Chromatography is used for separating a wide range of analytes, including drugs and biological samples, allowing for direct analysis without volatilization.
What is gas chromatography (GC)?
Gas chromatography separates volatile compounds or those that can be made volatile.
What is the function of Thermal Conductivity (TC) detectors?
TC detectors measure changes in electrical resistance due to temperature differences caused by the sample.
How do Flame Ionization Detectors (FID) work?
FID detectors are more sensitive than TC detectors; the column effluent is burned in a flame creating ions that produce a current proportional to the concentration of the sample.
What is the purpose of mass spectrometry (MS)?
MS is used for the definitive identification of samples eluting from chromatographic techniques like GC and HPLC.
What is the significance of combining GCMS and LCMS?
The combination of GCMS and LCMS offers powerful analytic capabilities with broad clinical applications.
What is the process overview of mass spectrometry?
Volatilization (conversion to gas), Ionization (creation of charged molecular ions and fragments), Separation (based on mass to charge ratio), Detection.
What is the primary energy source for the brain, erythrocytes, and retinal cells in humans?
Carbohydrates are the primary energy source, stored mainly as glycogen in the liver and muscles.
What are some disease states related to carbohydrates?
Hyperglycemia and hypoglycemia.
What is the general formula for carbohydrates?
CxHOy, containing carbonyl (CO) and hydroxyl (OH) functional groups.
How are carbohydrates classified?
Based on size, location of the carbonyl group, number of sugar units, and stereochemistry.
What are examples of monosaccharides?
Simple sugars such as glucose and fructose.
What are disaccharides?
Two monosaccharides linked together, such as maltose and sucrose.
What are oligosaccharides?
Carbohydrates containing 2 to 10 sugar units.
What are polysaccharides?
Many monosaccharide units linked together, such as starch and glycogen.
What are reducing substances in carbohydrates?
Carbohydrates with aldehyde or ketone groups that can reduce other compounds, examples include glucose, maltose, and lactose.
What is hyperglycemia?
Defined as an elevated level of glucose in the plasma.
What is the role of insulin in glucose metabolism?
Insulin enhances cellular uptake of glucose in the liver, muscle, and adipose tissue, and alters glucose metabolic pathways.
What is Diabetes Mellitus?
A group of metabolic disorders characterized by chronic hyperglycemia stemming from defects in insulin secretion, insulin action, or both.
What are the key categories of diabetes as classified by the International Expert Committee?
Type 1 Diabetes, Type 2 Diabetes, Other Specific Types of Diabetes, and Gestational Diabetes Mellitus.
What characterizes Type 1 Diabetes Mellitus?
Results from autoimmune destruction of pancreatic cells leading to an absolute deficiency of insulin, often with sudden onset in childhood or adolescence.
What is the Hyperosmolar Nonketotic State related to Type 2 Diabetes?
Marked by overproduction of glucose and a failure to excrete it in urine, often with severe dehydration and high glucose levels.
CC PREMID.pdf Flashcards
Study
What is the revised recommendation for screening nondiabetic pregnant women for GDM?
All nondiabetic pregnant women should be screened for GDM at 24 to 28 weeks of gestation using a 2-hour OGTT with a 75 g glucose load.
What are the glucose measurement criteria for diagnosing GDM?
Fasting plasma glucose: 92 mg/dL (5.1 mmol/L), 1-hour plasma glucose: 180 mg/dL (10.0 mmol/L), 2-hour plasma glucose: 153 mg/dL (8.5 mmol/L). Any one of these criteria met is diagnostic for GDM.
When should GDM testing be performed?
Testing should be performed in the morning after an overnight fast of at least 8 hours.
What is hypoglycemia characterized by?
Hypoglycemia is characterized by decreased plasma glucose levels.
What are some causes of hypoglycemia?
Hypoglycemia can have various causes ranging from transient and minor to life-threatening conditions.
What is the critical plasma glucose concentration for the release of glucagon and other glycemic factors?
The critical plasma glucose concentration for the release of glucagon and other glycemic factors is between 65 and 70 mg/dL (3.6 to 3.9 mmol/L).
At what glucose levels do symptoms of hypoglycemia typically appear?
Symptoms of hypoglycemia typically appear when glucose levels drop to around 50 to 55 mg/dL (2.8 to 3.1 mmol/L).
What is the hormonal response when plasma glucose levels fall?
When plasma glucose levels fall, glucagon is released from the pancreas to raise glucose levels, while epinephrine from the adrenal glands increases glucose metabolism and inhibits insulin release. Cortisol and growth hormone also contribute by increasing glucose metabolism.
What are some warning signs of hypoglycemia related to the central nervous system?
Increased hunger, sweating, nausea, dizziness, nervousness, shaking, blurred speech and vision, and mental confusion.
What is the D-glucose enzymatic method used for?
The D-glucose enzymatic method is specific for converting D-glucose to gluconic acid and producing hydrogen peroxide.
What are some interferences in the D-glucose enzymatic method?
The D-glucose enzymatic method is subject to interference from substances like uric acid and ascorbic acid.
What is the Hexokinase Method?
The Hexokinase Method is a more accurate and specific method where glucose is converted to glucose 6-phosphate, which is then measured by the production of NADPH.
What makes the Hexokinase Method preferred?
The Hexokinase Method is not affected by ascorbic acid or uric acid, making it a preferred reference method.
How often does the American Diabetes Association recommend individuals with Type 1 Diabetes monitor their blood glucose levels?
Individuals with Type 1 Diabetes should monitor their blood glucose levels 3 to 4 times daily.
How frequently should individuals with Type 2 Diabetes monitor their blood glucose levels?
Frequency of blood glucose monitoring in individuals with Type 2 Diabetes may vary based on individual needs.
What is the purpose of glucose tolerance testing (GTT)?
The 2-hour postprandial test involves administering a standardized 75 g glucose load and measuring plasma glucose levels.
What does the enzymatic method detect related to 3-hydroxybutyrate?
The enzymatic method uses the enzyme 3-hydroxybutyrate dehydrogenase to detect either 3-beta hydroxybutyric acid or acetoacetic acid depending on pH.
What is microalbuminuria and its significance in diabetic nephropathy?
Microalbuminuria is defined as persistent albuminuria in two out of three urine collections with 30 to 300 mg/24h (20 to 200 µg/min). It indicates early detection of nephropathy which can help delay progression through aggressive glycemic control.
What is the definition of macroalbuminuria?
Macroalbuminuria is defined by an albumin creatinine ratio of 300 mg/24h (200 µg/min) or 300 µg/mg creatinine.
What is the preferred screening method for microalbuminuria?
The preferred method is a random spot collection for the albumin creatinine ratio.
What are chylomicrons responsible for?
Chylomicrons transport dietary triglycerides from the intestines to the liver.
What do very low density lipoproteins (VLDLs) do?
VLDLs distribute triglycerides to peripheral tissues for energy or storage.
What is the role of low density lipoproteins (LDLs)?
LDLs deliver cholesterol to cells after offloading triglycerides.
What is the function of high density lipoproteins (HDLs)?
HDLs collect excess cholesterol from tissues and transport it back to the liver for disposal.
What is the importance of lipids in the body?
Lipids, primarily triglycerides, phospholipids, and cholesterol, serve as energy sources, structural components of cell membranes, and precursors for hormones.
What is a significant health concern associated with elevated blood lipid levels?
Elevated blood lipid levels are associated with coronary heart disease (CHD), especially in populations with high fat intake.
What are fatty acids composed of?
Fatty acids are linear chains of carbon and hydrogen ending with a carboxyl group (COOH). They exist mainly as part of triglycerides or phospholipids.
How are intermediate density lipoproteins (IDLs) classified?
IDLs are transitional particles between VLDL and LDL, generally do not accumulate in normal plasma but can be elevated in type III hyperlipoproteinemia.
What are some characteristics of LDLs?
LDLs are cholesterol-rich particles formed from VLDL lipolysis, primarily contain apo B-100, and infiltrate vessel walls contributing to atherosclerosis by macrophage uptake forming foam cells.
What is lipoprotein(a) [Lp(a)]?
Lipoprotein(a) [Lp(a)] are LDL-like particles containing apo(a) linked to apo B-100, associated with increased risk of CHD and stroke, and competes with plasminogen affecting clotting processes.
CC PREMID.pdf Flashcards
Study
What is Hyperlipoproteinemia?
A disorder characterized by elevated levels of lipoproteins in serum.
What are Dyslipidemias?
Disorders that can be divided into Hyperlipoproteinemias, which are characterized by elevated lipoprotein levels, and Hypolipoproteinemias, which are characterized by decreased lipoprotein levels.
What are the types of Hyperlipoproteinemias?
1. Hypercholesterolemia 2. Hypertriglyceridemia 3. Combined hyperlipidemia (elevations in both cholesterol and triglycerides).
What is Hypercholesterolemia?
A condition characterized by elevated levels of cholesterol in the blood.
What is Hypertriglyceridemia?
A condition characterized by elevated levels of triglycerides in the blood.
What is Combined hyperlipidemia?
A condition characterized by elevations in both cholesterol and triglycerides.
What are Hypolipoproteinemias?
Disorders characterized by decreased lipoprotein levels.
How is Hypercholesterolemia associated with Heart Disease?
It is strongly linked to coronary heart disease (CHD).
What is Familial Hypercholesterolemia (FH)?
A genetic disorder that results in high cholesterol levels.
What are the characteristics of Homozygotes in Familial Hypercholesterolemia?
Rare, with total cholesterol that can exceed 800 mg/dL, leading to early heart attacks in teens.
What are the characteristics of Heterozygotes in Familial Hypercholesterolemia?
More common, with total cholesterol ranging from 300 to 600 mg/dL, leading to symptoms typically appearing in their twenties to fifties.
What are the symptoms of Hypercholesterolemia?
Tendinous and tuberous xanthomas, arcus.
What is the mechanism behind Familial Hypercholesterolemia?
Defective LDL receptors lead to cholesterol accumulation.
What are LDL Receptor Mutations?
Several classes (1-5) affecting receptor function and transport.