Lecture 2Lecture 2An overview of Clinical An overview of Clinical

Laboratory Testing – Laboratory Testing – Basic Clinical Basic Clinical

ChemistryChemistry

Purpose of Clinical Chemistry Purpose of Clinical Chemistry TestsTests

– Measure levels of substances found normally in Measure levels of substances found normally in human blood that have biological functions. human blood that have biological functions. Examples: Glucose, CalciumExamples: Glucose, Calcium

– Detect or measure non-functional metabolites Detect or measure non-functional metabolites or waste products. Examples: Creatinine, or waste products. Examples: Creatinine, Blood Urea Nitrogen (BUN)Blood Urea Nitrogen (BUN)

– Detect or measure substances that indicate Detect or measure substances that indicate cell damage or disease. Examples: Liver cell damage or disease. Examples: Liver enzymes, such as ALT, Cardiac enzymes, such enzymes, such as ALT, Cardiac enzymes, such as CK-MBas CK-MB

– Detect or measure drugs or toxic substances. Detect or measure drugs or toxic substances. Examples: Dilantin, Drugs of abuse screenExamples: Dilantin, Drugs of abuse screen

Types of Specimens for Types of Specimens for Chemical AnalysisChemical Analysis

– Whole blood, serum or plasma. The Whole blood, serum or plasma. The most common specimen is serum, most common specimen is serum, collected in a tube with no anticoagulant collected in a tube with no anticoagulant so that the blood will clot. so that the blood will clot.

– Urine – often 24 hour collectionsUrine – often 24 hour collections– Others – Cerebrospinal Spinal Fluid Others – Cerebrospinal Spinal Fluid

(CSF) and other fluids(CSF) and other fluids

Collection and Handling of Collection and Handling of Blood Specimens for Chemical Blood Specimens for Chemical

AnalysisAnalysis

– Blood collection tubes for obtaining Blood collection tubes for obtaining serum - Serum Separator Tubes (SST) do serum - Serum Separator Tubes (SST) do not have an anticoagulant but do not have an anticoagulant but do contain a gel substance which will form contain a gel substance which will form an interface between the clot and the an interface between the clot and the serum when the blood specimen is serum when the blood specimen is centrifuged. These tubes are centrifuged. These tubes are sometimes referred to as “Tiger Tops”.sometimes referred to as “Tiger Tops”.

– Blood collection Blood collection tubes for obtaining tubes for obtaining plasmaplasma

Patient preparation; time of collection; Patient preparation; time of collection; & effects of eating on chemistry & effects of eating on chemistry

analysisanalysis

Some specimens are increased or decreased Some specimens are increased or decreased after eating (ex. Glucose, triglycerides), so it is after eating (ex. Glucose, triglycerides), so it is important to know what the test and collection important to know what the test and collection method call for. Specimens for these tests are method call for. Specimens for these tests are usually collected in a fasting state.usually collected in a fasting state.

Sometimes serum or plasma appearsSometimes serum or plasma appears

lipemia (milky) after a patient has lipemia (milky) after a patient has

eaten a fatty meal. Lipemia affects eaten a fatty meal. Lipemia affects

most chemistry analyses. The blood most chemistry analyses. The blood

must be recollected when the patientmust be recollected when the patient

is fasting.is fasting.

– Normal or Reference Values – range of Normal or Reference Values – range of values for a particular chemistry test values for a particular chemistry test from healthy individualsfrom healthy individuals

– Chemistry Panel grouping – some tests Chemistry Panel grouping – some tests are “bundled” according to the system are “bundled” according to the system or organ targeted. Examples: thyroid or organ targeted. Examples: thyroid panel, liver panel, cardiac panel, kidney panel, liver panel, cardiac panel, kidney panel, basic metabolic panel, etc.panel, basic metabolic panel, etc.

Clinical Chemistry TestsClinical Chemistry Tests

Commonly Performed Chemistry Tests or Commonly Performed Chemistry Tests or AnalytesAnalytes

– Proteins Proteins – essential components of – essential components of cells and body fluids. cells and body fluids.

– Some made by body, others acquired Some made by body, others acquired from diet. from diet.

– Provides information about state of Provides information about state of hydration, nutrition and liver function, hydration, nutrition and liver function, since most serum proteins are made in since most serum proteins are made in the liver.the liver.

– ElectrolytesElectrolytes – sometimes called “lytes” – sometimes called “lytes” Includes sodium (Na), potassium (K), Includes sodium (Na), potassium (K),

chloride (Cl) and bicarbonate (HCOchloride (Cl) and bicarbonate (HCO3-3-))Collectively these have a great effect on Collectively these have a great effect on

hydration, acid-base balance and osmotic hydration, acid-base balance and osmotic pressure as well as pH and heart and muscle pressure as well as pH and heart and muscle contractioncontraction

Levels differ depending on if inside vs. Levels differ depending on if inside vs. outside cellsoutside cells

Important in transport of substances into Important in transport of substances into and out of cellsand out of cells

– MineralsMineralsCalciumCalcium

– Used in coagulation and muscle contractionUsed in coagulation and muscle contraction– 99% is in skeleton and is not metabolically active99% is in skeleton and is not metabolically active– Influenced by vitamin D, parathyroid hormone, Influenced by vitamin D, parathyroid hormone,

estrogen and calcitoninestrogen and calcitonin– Hypercalcemia – occurs in parathyroidism, bone Hypercalcemia – occurs in parathyroidism, bone

malignancies, hormone disorders, excessive malignancies, hormone disorders, excessive vitamin D, and acidosis; may cause kidney stonesvitamin D, and acidosis; may cause kidney stones

– Hypocalcemia – can cause tetany; occurs in Hypocalcemia – can cause tetany; occurs in hypoparathyroidism, vitamin D deficiency, poor hypoparathyroidism, vitamin D deficiency, poor dietary absorption and kidney diseasedietary absorption and kidney disease

PhosphorusPhosphorus– 80% in bone and rest in energy compounds such 80% in bone and rest in energy compounds such

as ATPas ATP– Influenced by calcium and certain hormonesInfluenced by calcium and certain hormones

IronIron– Essential for hemoglobinEssential for hemoglobin– Deficiency results in anemia; may be caused by Deficiency results in anemia; may be caused by

lack of iron in diet, poor absorption, poor release lack of iron in diet, poor absorption, poor release of stored iron or loss due to bleedingof stored iron or loss due to bleeding

– Increased in hemolytic anemia, increased iron Increased in hemolytic anemia, increased iron intake or blocked synthesis of iron-containing intake or blocked synthesis of iron-containing compounds, such as in lead poisoningcompounds, such as in lead poisoning

– Kidney Function TestsKidney Function Tests

??Serum CreatinineSerum Creatinine– Best test for overall kidney function; Best test for overall kidney function;

not affected by diet or hormone not affected by diet or hormone levelslevels

– Waste product of muscle metabolismWaste product of muscle metabolism– Serum creatinine rises when kidney Serum creatinine rises when kidney

function is impairedfunction is impaired

BUN (Blood Urea Nitrogen)BUN (Blood Urea Nitrogen)– BUN is surplus amino acids that are converted to BUN is surplus amino acids that are converted to

urea and excreted by kidneys as a waste producturea and excreted by kidneys as a waste product– BUN influenced by diet and hormones, so it is BUN influenced by diet and hormones, so it is

NOT as good an indicator of renal function as NOT as good an indicator of renal function as serum creatinine levelsserum creatinine levels

– BUN increased in kidney disease, high protein BUN increased in kidney disease, high protein diet, and after administration of steroidsdiet, and after administration of steroids

– BUN decreased in starvation, pregnancy and in BUN decreased in starvation, pregnancy and in persons on a low protein dietpersons on a low protein diet

Uric AcidUric Acid– Formed from breakdown of nucleic acids and Formed from breakdown of nucleic acids and

excreted as a waste product by kidneysexcreted as a waste product by kidneys– Increased in kidney disease, but most often used Increased in kidney disease, but most often used

to diagnosis gout (pain in joints, mainly big toe, to diagnosis gout (pain in joints, mainly big toe, due to precipitated uric acid crystals)due to precipitated uric acid crystals)

– Also increased in increased cell destruction, such Also increased in increased cell destruction, such as after massive radiation or chemotherapyas after massive radiation or chemotherapy

– Liver Function TestsLiver Function TestsLiver functions:Liver functions:

– Synthesizes glycogen from glucoseSynthesizes glycogen from glucose– Makes plasma proteins (albumin, lipoproteins, Makes plasma proteins (albumin, lipoproteins,

coagulation proteins)coagulation proteins)– Forms cholesterol and degrades it into bile acids, Forms cholesterol and degrades it into bile acids,

which emulsifies fats for absorptionwhich emulsifies fats for absorption– Stores iron, glycogen, vitamins and other Stores iron, glycogen, vitamins and other

substancessubstances– Destroys old blood cells and recycles components of Destroys old blood cells and recycles components of

hemoglobinhemoglobinTotal BilirubinTotal Bilirubin

– Waste production of hemoglobin breakdownWaste production of hemoglobin breakdown– Increased in excessive RBC breakdown, such as Increased in excessive RBC breakdown, such as

hemolytic anemia, or impaired liver function or hemolytic anemia, or impaired liver function or some sort of obstruction, such as a tumor or gall some sort of obstruction, such as a tumor or gall stonestone

Liver Enzymes – levels increase following Liver Enzymes – levels increase following damage to liver tissuesdamage to liver tissues

– Alkaline Phosphatase (ALP or AP) - Greatly Alkaline Phosphatase (ALP or AP) - Greatly increased in liver tumors and lesions; moderately increased in liver tumors and lesions; moderately increased in diseases such as hepatitisincreased in diseases such as hepatitis

– Alanine Aminotransferase (ALT; formerly called Alanine Aminotransferase (ALT; formerly called SGPT) - Increases up to 10x in cirrhosis, infections SGPT) - Increases up to 10x in cirrhosis, infections or tumors and up to 100x in viral or toxic hepatitisor tumors and up to 100x in viral or toxic hepatitis

– Asparate Aminotransferase (AST; formerly called Asparate Aminotransferase (AST; formerly called SGOT) - Increased in liver disease, but also in SGOT) - Increased in liver disease, but also in heart attacksheart attacks

– Gamma Glutamyl Transferase (GGT) - Often used Gamma Glutamyl Transferase (GGT) - Often used to monitor patients recovering from hepatitis and to monitor patients recovering from hepatitis and cirrhosiscirrhosis

– Lactate Dehydrogenase (LD) - Increased in liver Lactate Dehydrogenase (LD) - Increased in liver disease and following heart attacksdisease and following heart attacks

Cardiac Function TestsCardiac Function Tests– Creatine Kinase (CK) - Widely used to Creatine Kinase (CK) - Widely used to

diagnosis and monitor heart attacksdiagnosis and monitor heart attacks– TroponinsTroponins

Only present in heart muscle, making Only present in heart muscle, making it a more accurate indicator of heart it a more accurate indicator of heart attack than CKattack than CK

Cardiac Troponin T (cTnT)Cardiac Troponin T (cTnT)Cardiac Troponin I (cTnI)Cardiac Troponin I (cTnI)

Lipid Metabolism TestsLipid Metabolism Tests

– Cholesterol Cholesterol Present in all tissuesPresent in all tissues Serves as the skeleton for many hormonesServes as the skeleton for many hormones Recommended to be less than 200 mg/dL in Recommended to be less than 200 mg/dL in

adults)adults) LDL = “bad” cholesterol; HDL = “good” LDL = “bad” cholesterol; HDL = “good”

cholesterolcholesterol– TriglyceridesTriglycerides

Main storage form of lipids, comprising 95% of Main storage form of lipids, comprising 95% of fat tissuefat tissue

Hyperlipidemia – having high blood levels of Hyperlipidemia – having high blood levels of triglycerides – may increase risk of heart triglycerides – may increase risk of heart attackattack

Carbohydrate Metabolism TestsCarbohydrate Metabolism Tests– Glucose - Largely regulated by insulinGlucose - Largely regulated by insulin

Thyroid Function TestsThyroid Function Tests– Thyroid Stimulating Hormone (TSH) - Inverse Thyroid Stimulating Hormone (TSH) - Inverse

relationship to thyroid function (the higher the relationship to thyroid function (the higher the TSH, the lower the thyroid function and vice TSH, the lower the thyroid function and vice versa)versa)

– Other less common thyroid tests include T3 and Other less common thyroid tests include T3 and T4T4

– Hypothyroidism – underactive thyroid glandHypothyroidism – underactive thyroid gland– Hyperthyroidism – overactive thyroid glandHyperthyroidism – overactive thyroid gland

For more information on most clinical For more information on most clinical laboratory tests, visit:laboratory tests, visit:

http://www.labtestsonline.org/

Click on any lab test or condition or Click on any lab test or condition or disease and find all sorts of disease and find all sorts of

information!information!

Photos of some clinical chemistry Photos of some clinical chemistry laboratorieslaboratories