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CLINICAL CHEMISTRY QUALITY MANAGEMENT is a management philosophy and approach that focuses on processes and their improvement as the means to satisfy customer needs and requirements. As defined by CLSI and ISO, it is coordinated activities to direct and control an organization regarding quality.1. P...

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CLINICAL CHEMISTRY 321

Quality Management & Quality Control QUALITY MANAGEMENT is a management philosophy and approach that focuses on processes and their improvement as the means to satisfy customer needs and requirements. As defined by CLSI and ISO, it is coordinated activities to direct and control an organization regarding quality.

QUALITY CONTROL is a system of ensuring accuracy and precision in the Laboratory by including quality control reagents in every series of measurements. It is a process of ensuring that analytical results are correct by testing known samples that resemble patient samples. Objectives of Quality Control

3 phases of Clinical Chemistry Testing Process

1. PRE-ANALYTICAL PHASE Errors:  Incorrect patient identification  Mislabeled specimen  Incorrect order of draw  Incorrect anticoagulant to blood ration (short draw)  Improper mixing of blood and anticoagulant  Improper patient preparation  Incorrect specimen collection  Incorrect used of tubes for blood collection  Incorrect specimen preservation  Mishandled specimen (transport and storage)  Incorrectly interpreted/ordered laboratory test  Incomplete centrifugation  Incorrect data log-in 2. ANALYTICAL PHASE Errors:  Incorrect sample and reagent volume  Incorrect incubation of solution  Equipment/Instrument malfunction  Improper calibration of equipment or calibration error 3. POST-ANALYTICAL PHASE Errors  Unavailable or delayed laboratory results  Wrong transcription of the patient’s data and laboratory results  Long turnaround time  Incomplete laboratory results  Missing laboratory results  Laboratory results submitted to the wrong physician who did not request for the lab test

 To check the stability of the machine.  To check the quality of reagents  To check technical (operator) errors. Kinds of Quality Control

1. Intralab Quality Control (Internal)  DAY-TO-DAY performance of lab tests  PRECISION  Daily monitoring of QC sera  Immediate decisions: ACCEPT/REJECT results  Detects RANDOM/SYSTEMATIC error 2. Interlab Quality Control (External)  Long term ACCURACY  Lab tests of different laboratories  Peer to peer comparisons  Establish inter-lab comparability Parameters/Implications of Quality

 Standard Solution  Control Solution  Blank Parameters/Implications of Quality Control

 SENSITIVITY - the ability of an analytical method to measure the smallest concentration of the analyte of interest  SPECIFICITY - the ability of an analytical method to measure only the analyte of interest  DIAGNOSTIC SENSITIVITY - the ability of the analytical method to detect the proportion of individuals with the disease. It also indicates the ability of the test to generate more true-positive results and few false-negative results.

 DIAGNOSTIC SPECIFICITY - the ability of the analytical method to detect the proportion of individuals without the disease. It reflects the ability of the method to detect true-negatives with very few false-positives  ACCURACY - the nearness or closeness of the assayed value to the true or target value  PRECISION/REPRODUCIBILITY the ability of an analytical method to give repeated results on the same sample that agreed to one another  PRACTICABILITY - the degree by which a method is easily repeated  RELIABILITY - the ability to maintain accuracy and precision over an extended period during which equipment, reagents and personnel may change Benefits of obtained Control Program

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Quality

 Provision of a continuous record of reliability of laboratory results  Permits valid judgments on the accuracy of results by monitoring precision and permitting comparisons assay values on known control sera with stated values  Gives early warning of trends and shifts in control results so that remedial actions may be taken before serious loss of precision  Monitors the performance and stability of equipment used in the assay.

STATISTICAL TOOL OF QUALITY ASSURANCE AND QUALITY CONTROL

1. Arithmetic Value

2. Standard Deviation (SD)

3. Coefficient of Variation (CV)

Statistical Terminologies  INFERENTIAL STATISTICSused to compare the means or standard deviations of two groups of data  F-TEST – is used to determine whether there is a statistically significant difference between the standard deviations of two groups of data  T-TEST- is used to determine whether there is a statistically significant difference between the means of two groups of data  MEDIAN- is the value of the observation that divides the observations into two groups. It is the midpoint of a distribution  MODE – the most frequent observation  RANGE – the difference between the highest and lowest score in a data

VARIATIONS are errors encountered in the collection, preparation and measurement of samples including transcription and releasing of laboratory results

Types Of Error 1. RANDOM ERROR  Mislabeling  Improper Pipetting  Improper mixing of sample and reagent  Voltage/ Temperature Fluctuations  Dirty optics

2. SYSTEMIC ERROR  Calibration problems  Deterioration of reagents and Control Materials  Improperly made standard solutions  Contaminated solutions

4. Variance (V)  Unstable and Inadequate reagent blanks  Leaky ion selective electrode

 Failing instrumentation  Poorly written procedures

3. CLERICAL ERRORS  Problems with handwritten labels and request forms ---Note: Online computer input is the most error-free means of requesting laboratory tests

3. CUMULATIVE SUM GRAPH  It calculates the difference between QC results and the target means.  Also referred as CUSUM

Quality Control Charts (Histograms) 1. SHEWHART-LEVEY JENNINGS CHART  Most commonly used chart for QC recording  Also referred as DOT CHART  Graphic representation of the acceptable limits of variation in the result of an analytical method

Errors Which Can Be Observed on LJ Chart  Trend- formed by control values that either increase or decrease for six consecutive days  Shift- formed by control values that distribute themselves on one side or either side of the mean for six consecutive days  Outliers- these are control values that are far from the main set of values

4.

YOUDEN PLOT  It displays the results of the analyses by plotting the mean values for one specimen on the with x and y axis.  Also referred as TWIN PLOT

Interpretation of Results  In control  Out of control

5. WESTGARD CONTROL CHART  This uses the term “control rule” to indicate if the analytical process is out of control.

Westgard Control Rules

2. GAUSSIAN CURVE  It will group any series of measurement in the same sample in a cluster around the mean in a bell-shaped curve  Also known as BELL-SHAPED CURVE  It occurs when the data set can be accurately described by the SD and the mean.  The total area under the curve is 1.0-100%

Carbohydrates CARBOHYDRATES are the major food source and energy supply of the body and are stored primarily as liver and muscle glycogen. Disease states involving carbohydrates are split into groups— hyperglycemia and hypoglycemia. Early detection of diabetes mellitus is the aim of the American Diabetes Association (ADA) guidelines established in 1997. Acute and chronic complications may be avoided with proper diagnosis, monitoring, and treatment. The laboratory plays an important role through periodic measurements of glycosylated hemoglobin and microalbumin.

functional group. The two forms of carbohydrates are ALDOSE and KETOSE. The aldose form has a terminal carbonyl group (O=CH) called an aldehyde group, whereas the ketose form has a carbonyl group (O=C) in the middle linked to two other carbon atoms (called a ketone group).

Stereoisomers

The central carbons of a carbohydrate are asymmetric (chiral)—four different groups are attached to the carbon atoms. This allows for various spatial arrangements around each asymmetric carbon (also called STEREOGENIC CENTERS) forming molecules called stereoisomers. Stereoisomers have the same order and types of bonds but different spatial arrangements and different properties. For each asymmetric carbon, Carbohydrates there are 2n possible isomers; therefore, there are 21, or two, forms of glyceraldehyde. Because an  Carbohydrates are compounds containing C, aldohexose contains four asymmetric carbons, there are 24, or 16, possible isomers. H, and O.  The general formula for a carbohydrate is Cx(H2O)y. Monosaccharides, Disaccharides, And  All carbohydrates contain C=O and =OH Polysaccharides functional groups.  The classification of carbohydrates is based on four different properties: Another classification of carbohydrates is based on (1) the size of the base carbon chain, number of sugar units in the chain: (2) the location of the CO function monosaccharides, disaccharides, oligosaccharides, group, and polysaccharides. (3) the number of sugar units, and are (4) the stereochemistry of the  MONOSACCHARIDES simple sugars that cannot be compound. hydrolyzed to a simpler form. These sugars can contain three, four, five, and six or Classification of Carbohydrates more carbon atoms (known as trioses, tetroses, pentoses, and hexoses, respectively). The most Carbohydrates can be grouped into generic common include GLUCOSE, FRUCTOSE, AND classifications based on the number of carbons in GALACTOSE. the molecule.    

TRIOSES contain three carbons, TETROSES contain four, PENTOSES contain five, HEXOSES contain six.

 DISACCHARIDES are formed when two monosaccharide units are joined by a glycosidic linkage. On hydrolysis, disaccharides will be split into two In actual practice, the smallest carbohydrate is monosaccharides by disaccharide enzymes GLYCERALDEHYDE, a three-carbon compound. (e.g., lactase) located on the microvilli of the Carbohydrates are hydrates of aldehyde or ketone intestine. These monosaccharides are then derivatives based on the location of the CO actively absorbed. The most common

disaccharides are MALTOSE (comprising 2--Dglucose molecules in a 1→ 4 linkage), LACTOSE, and SUCROSE.  OLIGOSACCHARIDES are the chaining of 2 to 10 sugar units, whereas polysaccharides are formed by the linkage of many monosaccharide units.  POLYSACCHARIDES will yield more than 10 monosaccharides. Amylase hydrolyzes starch to disaccharides in the duodenum. The most common polysaccharides STARCH (glucose molecules) and are GLYCOGEN.

Chemical Properties of Carbohydrates Some carbohydrates are reducing substances; these carbohydrates can reduce other compounds. To be a reducing substance, the carbohydrate must contain a ketone or an aldehyde group. This property was used in many laboratory methods in the past in the determination of carbohydrates. All monosaccharides and many disaccharides are reducing agents. This is because a free aldehyde or ketone (the open chain form) can be oxidized under the proper conditions. As disaccharide remains a reducing agent when the hemiacetal or ketal hydroxyl group is not linked to another molecule. Both maltose and lactose are reducing agents, whereas sucrose is not.

Glucose Metabolism

Glucose is the only carbohydrate to be directly used for energy or stored as glycogen. Galactose and fructose must be converted to glucose before they can be used. After glucose enters the cell, it is quickly shunted into one of three possible metabolic pathways, depending on the availability of substrates or the nutritional status of the cell. The ultimate goal of the cell is to convert glucose to carbon dioxide and water.  The first step for all three pathways requires glucose to be converted to glucose-6phosphate using the high energy molecule, ATP. This reaction is catalyzed by the enzyme hexokinase.  Glucose-6-phosphate can enter the EMBDENMYERHOF PATHWAY or the HEXOSE MONOPHOSPHATE PATHWAY or can be converted to GLYCOGEN.  The first two pathways are important for the generation of energy from glucose; the conversion to glycogen pathway is important for the storage of glucose.

Pathways In Glucose Metabolism

 GLYCOLYSIS Metabolism of glucose molecule to pyruvate or lactate for production of energy  GLUCONEOGENESIS - Formation of glucose6-phosphate from noncarbohydrate sources  GLYCOGENOLYSIS - Breakdown of glycogen to glucose for use as energy  GLYCOGENESIS- Conversion of glucose to glycogen for storage

GLUCOSE is a primary source of energy for humans. The nervous system, including the brain,  LIPOGENESIS- Conversion of carbohydrates totally depends on glucose from the surrounding to fatty acids extracellular fluid (ECF) for energy. Nervous tissue cannot concentrate or store carbohydrates;  LIPOLYSIS- Decomposition of fat therefore, it is critical to maintain a steady supply of glucose to the tissue. For this reason, the concentration of glucose in the ECF must be Regulation Of Carbohydrate maintained in a narrow range. When the Metabolism concentration falls below a certain level, the nervous tissue loses the primary energy source and Control of blood glucose is under two major hormones: INSULIN and GLUCAGON, both are incapable of maintaining normal function. produced by the pancreas. Their actions oppose each other. Other hormones and neuroendocrine Fate of Glucose substances also exert some control over blood glucose concentrations, permitting the body to

respond to increased demands for glucose or to survive prolonged fasts. It also permits the conservation of energy as lipids when excess substrates are ingested. . .

INSULIN  the primary hormone responsible for the entry of glucose into the cell.  It is synthesized by the cells of islets of Langerhans in the pancreas.  When these cells detect an increase in body glucose, they release insulin.  The release of insulin causes an increased movement of glucose into the cells and increased glucose metabolism  Insulin is normally released when glucose levels are high and is not released when glucose levels are decreased.  It decreases plasma glucose levels by increasing the transport entry of glucose in muscle and adipose tissue by way of nonspecific receptors.  It also regulates glucose by increasing glycogenesis, lipogenesis, and glycolysis and inhibiting glycogenolysis.  Insulin is the only hormone that decreases glucose levels and can be referred to as a HYPOGLYCEMIC agent. GLUCAGON  Glucagon is the primary hormone responsible for increasing glucose levels.  It is synthesized by the cells of islets of Langerhans in the pancreas and released during stress and fasting states.  When these cells detect a decrease in body glucose, they release glucagon.  Glucagon acts by increasing plasma glucose levels by glycogenolysis in the liver and an increase in gluconeogenesis.  It can be referred to as a HYPERGLYCEMIC agent.

HORMONES THAT INCREASE GLUCOSE     

Cortisol Catecholamine Growth hormone Thyroid hormone Adrenocorticotrophic hormone

Clinical conditions of Carbohydrate Metabolism Hypoglycemia  65-70mg/dL - glucagon and other glycemic hormones are released into the circulation or less strongly suggest  60mg/dL Hypoglycemia.  It involves decreased plasma glucose levels and can have many causes—some are transient and relatively insignificant, but others can be life threatening.  The plasma glucose concentration at which glucagon and other glycemic factors are released is between 65 and 70 mg/dL (3.6– 3.9 mmol/L).  At about 50 to 55 mg/dL (2.8–3.0 mmol/L), observable symptoms of hypoglycemia appear. The warning signs and symptoms of hypoglycemia are all related to the central nervous system.  The release of EPINEPHRINE into the systemic circulation and of NOREPINEPHRINE at nerve endings of specific neurons act in unison with glucagon to increase plasma glucose.  GLUCAGON is released from the islet cells of the pancreas and inhibits insulin.  EPINEPHRINE is released from the adrenal gland and increases glucose metabolism and inhibits insulin.  In addition, CORTISOL and GROWTH HORMONE are released and increase glucose metabolism. A diagnosis should not be made unless the patient meets the criteria of WHIPPLE'S Triad:  Low blood glucose concentration  Typical Symptoms  Symptoms alleviated by administration

 Laboratory findings include:  decreased plasma glucose levels during hypoglycemic episode  extremely elevated insulin levels in patients with pancreatic -cell tumors (insulinoma). Test: 5-hour glucose  Diagnostic tolerance test (hypoglycemic "dip" often is not seen until after 3 hours) 50 mg/dL or less (2.8 mmol/L) in infants is considered ABNORMAL and requires diagnostic assessment.

Causes and Classification of Hypoglycemia  Drug Administration – insulin, alcohol, salicylates, sulfonamides, pentamidine, propranolol.  Critical Illnesses – hepatic failure, sepsis, renal, cardiac failure, malnutrition  Hormonal Deficiency – epinephrine, glucagon, cortisol, growth hormone, thyroid hormone, adrenocorticotrophic hormone  Endogenous Hyperinsulinism – pancreatic beta disorder  Autoimmune Hypoglycemia – insulin antibodies  Non- beta cell tumors – leukemia, hepatoma, pheochromocytoma, lymphoma  Hypoglycemia of infancy and childhood – galactosemia, GSD, Reye’s syndrome  Alimentary (reactive) hypoglycemia – post gastric surgery  Idiopathic (functional) postprandial hypoglycemia – other symptomatic except

glucose

 Symptoms of hypoglycemia are increased:  tremors,  palpitations,  anxiety,  diaphoresis (neurogenic symptoms),  hunger,  sweating, nausea and vomiting,  dizziness, nervousness and shaking,  blurring of speech and sight, and mental confusion (neuroglycopenic symptoms).

decreased sugar levels

 Is an increase in blood glucose concentration. It is toxic to beta cell function and impairs insulin secretion.

Hyperglycemia

 FBS: 126 mg/dL or more  It is an increase in plasma glucose levels.  In healthy patients, during a hyperglycemia state, insulin is secreted by the cells of the pancreatic islets of Langerhans. Insulin enhances membrane permeability to cells in the liver, muscle, and adipose tissue. It also alters the glucose metabolic pathways. Hyperglycemia, or increased plasma glucose levels, is caused by an imbalance of hormones.  Causes:  Stress,  severe infection,  dehydration,  pregnancy,  pancreatectomy,  hemochromatosis,  insulin deficiency or abnormal insulin receptor.  FBS: 126 mg/dL or more  Random plasma glucose: 200 mg/dL or more (11.1 mmol/L), with symptoms of diabetes  Laboratory Findings:  Increase glucose in plasma and urine  Increase urine specific gravity  Ketones in serum and urine (Type 1 DM patients)  Decrease blood and urine pH (acidosis)  Electrolyte Imbalance (Decrease Sodium and Bicarbonate, increase Potassium)  180 mg/dL- glucose will excrete in the urine  300-500mg/dL - (period of plateau)

Diabetes Mellitus  It is a group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both. In 1979, the National Diabetes Data Group developed a classification and diagnosis scheme for diabetes mellitus.  This scheme included dividing diabetes into two broad categories: type 1, insulindependent diabetes mellitus (IDDM); and type 2, non–insulin-dependent diabetes mellitus (NIDDM).  The ADA/World Health Organization (WHO) guidelines recommend the following categories of diabetes:

  

Type 2 diabetes Other specific types of diabetes Gestational diabetes mellitus (GDM)

Type 1 Diabetes Mellitus  Type 1 diabetes is characterized by inappropriate hyperglycemia primarily a result of pancreatic islet -cell destruction and a tendency to ketoacidosis  Type 1 diabetes mellitus is a result of cellularmediated autoimmune destruction of the cells of the pancreas, causing an...