CLINICAL CHEMISTRYI. PROTEINS AND TUMOR MARKERS

PROTEINS: PLASMA, URINARY, CSFTUMOR MARKERS: PSA, APP, CEA, B-HCG, CA 15-3, CA 125, CA 19-9

II. NONPROTEIN NITROGENOUS COMPOUNDSIII. CARBOHYDRATESIV. LIPIDS AND LIPOPROTEINSV. ENZYMES

PROTEINS AND TUMOR MARKERS

PROTEINS Macromolecules made up of amino acids, with each AA being linked to another via a peptide bond

Functions:o Energy production: Proteins can be broken down into AA that can be used in the citric acid cycle to produce

energyo Water distribution: Maintain the colloidal osmotic pressure between different body compartmentso Buffer: The ionisable R groups of the individual AA provide buffering capacity by binding or releasing H+ ions

as neededo Transporter: Binding of proteins to hormones, free Hgb, lipids, drugs, Ca, unconjugated bilirubin allows

movement of these and other molecules in the circulationo Antibodies: Function as receptors for hormones so that the hormonal message can activate cellular components;

some hormones are protein in nature e.g. ACTH, FSH, TSHo Structural proteins:Collagen is the fibrous component that maintains the structure of body partso Enzymes: catalysts that accelerate chemical reactions

PLASMA TOTAL PROTEIN1. REGULATION

The liver synthesizes most of the plasma proteins. Plasma cells synthesize the Igs. Proteins are synthesized from AA. When proteins degrade, their constituent AA undergoes deamination with the formation of ammonia, which is

converted to urea to excretion in the urine. Some cytokines released at the site of injury or inflammation cause the liver to increase synthesis of the acute-

phase reactant proteins (nonspecific response to inflammation that may be caused by autoimmune disorders, infections, tissue injury from tumors, MI, trauma, or surgical procedures)

Some proteins will decrease in concentration – negative acute-phase proteins, e.g. prealbumin (transthyretin), albumin, and transferrin.

Immunoglobulins – humoral Ab produced in response to foreign Ag for the purpose of destroying them Reference ranges: Total protein 6.5 – 8.3 g/dL

Changes in total protein concentration: Hypoproteinemia – caused by urinary loss, GIT inflammation, liver disorders, malnutrition, inherited

immunodeficiency disorders, and extensive burns Hyperproteinemia – caused by dehydration, increased protein production (gammopathies) and chronic

inflammatory disease associated with paraprotein production.

Clinical Significance of the Major Proteins1. Prealbumin (transthyretin)

Indicator of nutritional status; transports thyroid hormones Decreased in liver disorders, inflammation, malignancy, poor nutrition Increased in steroid therapy, CRF, alcoholism

2. Albumin Synthesized in the liver Highest concentration of all plasma proteins Binds many analytes for transport in blood, including unconjugated bilirubin steroids, ions such as Ca and

Mg, FA, and drugs Significantly contributes to plasma osmotic pressure Decreased in liver disorders, malabsorption, muscle-wasting diseases, severe burns, renal diseases

(nephrotic syndrome, glomerulonephritis), starvation, malnutrition

3. Alpha 1 – Antitrypsin Acute-phase reactant A protease inhibitor that neutralizes trypsin-type enzymes that can damage structural proteins Decreased in emphysema-associated pulmonary disease and severe juvenile hepatic disorders that may

result in cirrhosis Increased in inflammatory disorders

4. Alpha 1 – Fetoprotein (AFP) Is synthesized during gestation in the yolk sac and liver of the fetus, peaking at 13 wks and declining at 34

wks. Normally adult levels are very low. Maternal serum AFP is measured between 15 and 20 wks AOG and is reported as multiples of the median

(MoM) Increased level: neural tube defects, spina bifida, and fetal distress Decreased level: Down syndrome, trisomy 18

In adults, increased levels of AFP can be indicative of hepatocellular carcinoma and gonadal tumors. 5. Alpha 1 – Acid glycoprotein (orosomucoid)

Acute-phase reactant; bonds to basic drugs Increased in inflammatory disorders such as RA, pneumonia and conditions associated with cell

proliferation Decreased in nephrotic syndrome

6. Haptoglobin Alpha 2 – globulin that binds free hemoglobin; an acute-phase reactant

Increased in inflammatory conditions, burns, trauma Decreased in intravascular hemolysis because of formation of a haptoglobin-hemoglobin complex for

removal by the liver7. Ceruloplasmin

Ab acute phase reactant that is an a2-globulin, copper-containing protein with enzymatic activity 90% of serum copper is bound in ceruloplasmin

Increased in pregnancy, inflammatory disorders, malignancies, and with intake of oral estrogen and OCP Decreased in Wilson disease, malnutrition, malabsorption, severe liver disease

8. a2-Macroglobulin proteolytic enzyme inhibitor thatinhibits thrombin, trypsin, and pepsin

increased in nephrotic syndrome, contraceptive use, pregnancy, estrogen therapy decreased slightly in acute inflammatory disorders and prostatic cancer, decreased markedly in acute

pancreatitis9. Transferrin

β-globulin that transport iron decreased in infections, liver disease, and nephrotic syndrome increased in iron-deficiency anemia and pregnancy

10. C-reactive protein (CRP) β-globulin acute-phase reactant increased in tissue necrosis, RF, infections, MI, RA gout

11. Immunoglobulins (Ig): Antibodies Five major classes: IgA, IgD, IgE, IgG, and IgM Synthesized in plasma cells as an immune response One of the Igs will be increased in a monoclonal gammopathy (e.g. multiple myeloma) – generally

associated with increase in IgG, IgA, or IgM IgG can cross the placenta.

Increased in liver disorders, infection, and collagen disease Decreased in presence of increased susceptibility to infection and when a monoclonal

gammopathy is associated with an increase in another immunoglobulin IgA levels increase after birth.

Increased in liver disorders, infections, and autoimmune diseases Decreased in inhibited protein synthesis and hereditary immune disorders

IgM cannot cross the placenta; it is made by the fetus Increased in various bacterial, viral and fungal infections and Waldenstrom

macroglobulinemia Decreased in renal disease associated with protein loss and immunodeficiency disorders

IgD is increased in liver disorders, infections, connective tissue disorders IgE is increased in allergies, asthma, and hay fever, parasitic infections

Proteins In Other Body Fluids Urinary Proteins

Quantifications performed on 24-hour urine specimens Reference range urine total protein: 1-4 mg/dL; <100 mg/day

Clinical significance of proteinuria May result from tubular or glomerular dysfunction, multiple myeloma, Waldenstrom macroglobulinemia,

nephrotic syndrome Bence Jones protein may be found in urine of patients with multiple myeloma Glomerular membrane can be damaged in diabetes, amyloidosis, and collagen diseases. Glomerular dysfunction can be detected in its early stages by measuring microalbumin in urine. Microalbuminuria – the quantity of albumin in urine is greater than normal, yet it undetectable by urine

dipstick method; generally precedes nephropathy Reference range for urine albumin: < 30 mg/day

2. CSF Reference range 15-45 mg/dL

Clinical Significance Increased in viral, bacterial, and fungal meningitis, traumatic tap (bloodly), multiple sclerosis, herniated disk,

and cerebral infarction Decreased in hyperthyroidism and with CNS leakage of CSF

TUMOR MARKERS

Tumor Marker Utilization In general, tumor markers are not very useful in diagnosis. Useful in tumor staging, monitoring therapeutic responses, predicting patient outcomes, and detecting cancer recurrence.

Ideal Characteristic for Tumor Markers includes: Measured easily High analytical sensitivity of assay method High analytical specificity of assay method Cost-effective Test result contributes to patient care and outcome

Prostate Specific Antigen (PSA) Function:

1. Produced by epithelial cells of the prostate gland and secreted into seminal plasma2. Glycoprotein protease that functions in liquefaction of seminal coagulum

Forms of PSA found in the blood1. Enveloped by protease inhibitor, a2-macroglobulin; lacks immunoreactivity2. Complexed to another protease inhibitor, a1-antichymotrypsin; immunologically detectable3. Free PSA, not complexed to protease inhibitor, immunologically detectable4. Total PSA assays measure complexed and free PSA dorms, as they are immunologically detectable

Specificity1. A tissue-specific marker but not tumor specific2. Small amount present in serum normally3. Lacks specificity because serum level of PSA is increased in BPH as well as in adenocarcinoma of the prostate

Prostate cancer detection1. Early detection guidelines endorse lower cutoff of PSA up to 2.5 ng/mL2. PSA >2.5 ng/mL perform biopsy3. PSA velocity is measurement of the rate of change per year.

a. Biopsy recommended when PSA rises more than 0.75 ng/mL/year even when PSA is <2.5 ng/mL.4. Free PSA: Men with prostate cancer tend to have lower % free PSA (free PSA/total PSA) than men with benign

disease. Lower % free PSA is associated with a higher risk of prostate cancer.5. PSA is used to monitor therapeutic response and to follow radical prostatectomy.

α1-Fetoprotein (AFP) Oncofetal glucoprotein antigen

1. Synthesized in liver, yolk sac, and GI tract of fetus2. Fetal serum AFP peaks at 12-15 weeks of gestation with levels of 2-3 mg/mL.3. At birth levels fall to 50 µg/mL, and at 2 years of age only trace amounts are present.

4. Adult levels <20 ng/mL

Clinical Significance Increased level of AFP in adults are associated with hepatocellular carcinoma, testicular, and ovarian

teratocarcinomas, pancreatic carcinoma, gastric and colonic carcinomas. Increased levels in adults are also seen in non-malignant disorders, including viral hepatitis and chronic active

hepatitis Useful in monitoring therapeutic response of cancer patient to treatment protocols In pregnancy, increased maternal serum levels are associated with spina bifida, neural tube defects, and fetal

distress. Decreased levels of maternal serum AFP are associated with increased incidence of Down syndrome.

Carcinoembryonic antigen (CEA) Oncofetal glycoprotein antigen Normally found in epithelial cells of the fetal GI tract

Clinical Significance in adults1. Increased levels of CEA are associated with adenocarcinoma of digestive tract and colorectal carcinoma.2. Elevations are seen in other malignancies and noncancerous disorders.3. Useful in monitoring therapeutic response of cancer patients to treatment protocols.

Enzyme immunoassay methods are used for measurement.

4. Human chorionic gonadotropin (hCG) A glycoprotein composed of α- and β- subunits. The β- subunit is unique and not common to other hormones; α-

subunit is common to other hormones. Normally secreted by the trophoblast cells of the placenta Increased secretion is associated with trophoblastic tumors, choriocarcinoma, nonseminomatous testicular tumors,

and ovarian tumors. Useful for monitoring the progress of patients Immunoassay measurement is made of β-hCG

5. CA 125 Mucin glycoprotein antigen Marker for ovarian and endometrial cancer Useful for monitoring the progress of patients

6. CA 19-9 Glycolipids blood group antigen-related marker Marker for pancreatic, colorectal, lung, and gastric carcinomas Useful for monitoring the progress of patients

7. CA 15-3 Mucin glycoprotein antigen Useful for monitoring therapeutic response and for detecting recurrence of breast cancer in patients previously treated Elevated levels observed in non-malignant diseases such as chronic hepatitis, tuberculosis, and SLE.

NONPROTEIN NITROGENOUS COMPOUNDS UREA CREATININE URIC ACID AMMONIA

1. UREARegulation of Urea

Major nitrogen-containing compound in the blood Results from protein catabolism Synthesized in the liver from the deamination of AAs Excreted by the kidneys

Clinical Significance Abnormal urea levels may be due to prerenal, renal or post renal d/o ↑ Renal failure, GN, UTI, CHF, dehydration, increased protein catabolism ↓ Severe liver disease, vomiting, diarrhea, malnutrition

Blood urea nitrogen (BUN) – an older term still in use, terminology based on previous methodology where nitrogen was measured. To convert BUN to urea: BUN x 2.14 = Urea

2. CREATININERegulation:

A waste product of muscle contraction that is formed from phosphocreatinine, a high energy comp. Levels regulated by kidney excretion. Measurements of creatinine in serum and urine (creatinine clearance) are used to assess the glomerular filtration rate Levels not changed by diet or rate of urine flow Creatinine is not reabsorbed by renal tubules.

Clinical Significance ↑ Renal disease, renal failure

3. URIC ACID Regulation

Major waste product of purine (adenosine and guanisine) catabolism Synthesized in the liver Elimination from the blood is regulated by the kidneys through glomerular filtration Some excreted through the GI tract

Clinical Significance ↑ Gout, renal d/o, tx of myeloproliferative d/o, lead poisoning, lactic acidosis, toxaemia of pregnancy, Lesch-Nyhan

syndrome ↓ severe liver disease as a secondary d/o, tubular reabsorption d/o, drug induced

4. AMMONIARegulation

Ammonia produced from deamination of AAs Hepatocytes convert ammonia to urea for excretion With severe liver cell malfunction, blood levels of ammonia increase Ammonia is neurotoxic

Clinical Significance ↑ hepatic failure and Reye syndrome

CARBOHYDRATES

Glucose Metabolism During fast, the blood glucose level is kept constant by mobilizing the glycogen stores in the liver. During long fast, gluconeogenesis is required to maintain blood glucose levels because glycogen stores are used up in

about 24-48 hours.Hypoglycemia: FBS < 50 mg/dLHyperglycemia: FBS> 200 mg/dL

Hormones Affecting Blood Glucose Levels Insulin

Beta cells of the islets of Langerhans Promotes entry of glucose into the liver, muscle, and adipose tissue to be stored as glycogen and fat Inhibits the release of glucose from the liver

Somatostatin Delta cells of the islets of Langerhans Inhibits secretion of insulin, glucagon, and growth hormone Results in an increase in plasma glucose level

Growth hormone and adenocorticotropic hormone (ACTH) Secreted by the anterior pituitary Raise blood glucose

Cortisol Secreted by the adrenal glands Stimulates glycogenolysis, lipolysis, and gluconeogenesis

Epinephrine Secreted by the medulla of the adrenal glands Stimulates glycogenolysis, lipolysis, and gluconeogenesis Inhibits secretion of insulin Physical or emotional stress causes increased secretion of epinephrine and an immediate increase in blood glucose

levels. Glucagon

Secreted by the α cells Increases blood glucose by stimulating glycogenolysis and gluconeogenesis

Thyroxine Secreted by the thyroid gland Stimulates glycogenolysis and gluconeogenesis Increase glucose absorption from the intestines

Renal Threshold for Glucose (RTG) Glucose is filtrated by the glomeruli, reabsorbed by the tubules, and normally not present in urine. If the blood glucose level is elevated, glucosuria occurs. RTG varies between 160 and 180 mg/dL. When blood glucose reaches this level or exceeds it, the renal tubular transport mechanism becomes saturated, which

causes glucose to be excreted into the urine.

ABNORMAL CARBOHYDRATE METABOLISM Diabetes mellitus

Type 1 DM Insulinopenia Required tx with insulin to sustain life An autoimmune disorder affecting β cells Peak incidence in childhood and adolescence, but may occur at any age Primary sx include polyuria, polydipsia and weight loss Ketosis-prone: Can produce excess ketones, resulting in diabetic ketoacidosis (DKA)

Type 2 DM Defect in insulin secretion and cellular resistance to insulin Generally responds to dietary intervention and oral hypoglycemic agents, but some may require insulin

therapy. Associated with obesity and sedentary lifestyle Sx include polyuria, polydipsia, and weight loss Associated with age over 40, but becoming a significant problem in children and adolescents Non-ketosis prone: without exogenous insulin or oral hypoglycemic medication, these individuals will have

an elevated glucose but will not go into DKA.Gestational diabetes mellitus (GDM)

Onset of DM during pregnancy Return to normal metabolism seen after childbirth There is an increased chance that type 2 DM may develop later in life.

2. Inherited disorders of carbohydrate metabolismGlycogen storage disease

Inherited diseases involving the deficiency of particular enzymes Deficiencies cause defects in the normal metabolism of glycogen Von Gierke, type I: G6PD Pompe, type II: α-1, 4-glucosidase deficiency

3. Galactosemia A deficiency or absence of galactokinase, galactose 1-phosphate uridyl transferase, or uridyl diphosphate

galactose Galactose is found in milk as a component of lactose, with galactosemia generally identified in infants.

Most commonly, galactose 1-phosphae uridyl transferase is deficient, which leads to excessive galactose in blood and excretion in urine.

Laboratory Diagnosis Fasting plasma glucose

Normal < 100 mg/dLImpaired 100-125 mg/dL

Provisional Dx of DM is made when FPG ≥ 126 mg/dL. The Dx must be confirmed by one of the three methods described in the following outline:

Diagnosis of DM: A plasma glucose analysis that yields any one of the following results is diagnostic for the presence of DM,

provided that unequivocal hyperglycemia is apparent. If unequivocal hyperglycemia is not apparent, the glucose result must be confirmed by repeat analysis on a

subsequent day using any one of the ff. 3 methods:a. Physical sx and a casual plasma glucose level of ≥ 200 mg/dLb. FPG level that is ≥ 126 mg/dL (fasting defined as no caloric intake for minimum of 8 hours)c. Plasma glucose level of ≥ 200 mg/dL at 2-hr point of an OGTT.

GDM A woman at high risk of GDM should have an initial screening early in the pregnancy, and if found

negative, retesting done 24-28 weeks of AOG For women of average risk, testing should be performed at 24-28 AOG For GDM, FPG ≥ 126 mg/dL or a casual plasma glucose ≥ 200 mg/dL is diagnostic If unequivocal hyperglycemia is not apparent, retesting must be performed on a subsequent day.

Two-step approach: GCT + OGTT Initial screening: Glucose Challenge Test

a. 50-g oral glucose load (time of day or time of last meal not relevant)b. Plasma is tested at 1 hour, and if glucose threshold value ≥ 140 mg/dL, an OGTT is performedc. Some experts recommended using a threshold value of ≥ 130 mg/dL

OGTT – oral ingestion of 100 g of glucose Must meet or exceed two or more of the ff criteria:

1. FPG > 95 mg/dL2. 1-hr > 180 mg/dL3. 2-hr > 155 mg/dL

Alternatively, a 75-g glucose load may be used and glucose measured through the 2-hour period.

OGTT Patient preparation:

Unrestricted CHO-rich diet for 3 days before the test with physical activity, restrict medication on the test day, 12-hr fast required, no smoking

Adult patient ingests 75 g of glucose in 300-400 mL of water and children 1.75 g/kg up to 75 g of glucose. For assessment of GDM, 50 g, 75 g, or 100 g of glucose may be used (see previous)

Plasma glucose specimen is collected fasting at 10 min, before glucose load and 2-hr after. Urine glucose may be measured.

Impaired fasting glucose: FPG is between 110 and 125 mg/dL Impaired glucose tolerance (IGT): FPG ≤ 126 mg/dL and 2-hr plasma glucose level (OGTT) between

140-199 mg/dL DM: FPG ≥ 126 mg/dL or the 2-hour glucose is ≥ 200 mg/dL

HbA1c Glycated/glycosylated hemoglobin HbA composed of 3 forms, HbA1a, HbA1b, and HbA1c, which are referred to as glycated or glycosylated

hemoglobin. HbA1c is the main form. Glycated Hb is formed from the nonenzymatic, irreversible attachment of glucose to HbA1a

Measurement of glycated Hb reflects blood glucose levels for the past 2-3 months. Useful in monitoring effectiveness and tx and compliance of diabetic individual to tx protocol Specimen collection: Nonfasting blood drawn in EDTA tubes Reference range: 4-6 % HbA1c

Effective treatment range < 7% HbA1c

LIPIDS AND LIPOPROTEINS

LIPID STRUCTURE1. FAs

Exist as short, medium, and long chains of molecules that are major constituents of triglycerides and phospholipids. Minimal amounts bound to albumin and circulate free (unesterified)

2. Triglyceride (TG) Formed from one glycerol molecule with 3 FA molecules attached viva ester bonds Comprise 95% of all fats stored in adipose tissue Transported by chylomicrons and VLDL (very low density lipoprotein) Metabolism involves releasing the FA to the cells for energy, then recycling the glycerol into the TG Lipase, lipoprotein lipase, epinephrine, and cortisol break sown TGs.

3. Cholesterol Unsaturated steroid alcohol; exists in the esterified form. Where a FA forms an ester bond at carbon-3, & free

(unesterified) form Precursor for synthesis of bile acids, steroid hormones, & vit. D LDL is the primary carrier of cholesterol

4. Phospholipid Composed of one glycerol molecule and 2 FA molecules attached via ester bonds Found on the surface of lipid layers Major constituents of cell membranes and outer shells of lipoprotein molecules

Classification of Lipoproteins (Lp)1. Lipoproteins

are molecules that combine water insoluble dietary lipids and water-soluble proteins (apolipoproteins) so that lipids can be transported throughout the body. Micelles are spherical and have an inner core of neutral fat.

2. Chylomicrons are the largest Lps and have the lowest density Formed in the intestines and transport TGs after a meal, giving serum a turbid appearance. Low density: chylomicrons will float to the top and form a creamy layer when plasma is stored overnight Composed of 86% TG, 5% cholesterol, 7% phospholipid, and 2% apolipoprotein Enter the circulation and are metabolized to remnant particles for uptake and further modification by the liver.

3. Very-low-density lipoprotein (VLDL) Carries endogenous TGs synthesized in the liver Composed of 55% TG, 19% cholesterol, 18% phospholipid, 8% apolipoprotein Secreted into the blood by the liver for metabolism in peripheral tissues

4. Intermediate-density lipoprotein (IDL) A transitional form, as it is formed from VLDL and then further modified in the liver to LDL IDLs carry endogenous TGS cholesterol esters Composed of 23% TG, 38% cholesterol, 19% phospholipid, 19% apolipoprotein

5. Low-density lipoprotein (LDL) Major cholesterol carrier Transports a large amount of endogenous cholesterol LDL is easily taken up by cells, so elevated levels are associated with increased risk for atherosclerosis Composed of 50% cholesterol, 22% phospholipid, 6% TG and 22% protein Brings cholesterol to peripheral cells for membrane synthesis and formation of adrenal and reproductive

hormones.

6. High-density lipoprotein (HDL) Synthesized in the intestine and liver cells Recycled chylomicron and VLDL molecules 50% protein, 28% phospholipids, 19% cholesterol and 3% TG Has apoproteins A-I, mainly, and A-II on its surface Removes excess cholesterol from peripheral tissues and transports it to other catabolic sites (antiatherogenic effect)

7. Lp(a) Composed primarily of cholesterol esters, phospholipids and apolipoprotein (a) and B-100 Elevated levels assoc. with increased risk for coronary heart disease, MI, and cerebrovascular disease

Clinical Significance Abnormal lipid metabolism can be due to genetic defects or it can be acquired. Abnormal lipid metabolism is associated with risk of CAD and other disorders. The National Cholesterol Education Program established the Adult Treatment Panel III Classification (ATP III), which

sets cutoff values for cholesterol and triglyceride levels based on a 9- to 12- hour fast.

TOTAL CHOLESTEROL REFERENCE RANGEDesirable Borderline High High

Total Cholesterol (mg/dL) < 200 200-239 ≥240

HDL CHOLESTEROL REFERENCE RANGEProtective against

Heart DiseaseThe Higher, the

BetterMajor Risk Factor for

Heart DiseaseHDL Cholesterol (mg/dL)

≥60 40-59 <40

LDL CHOLESTEROL REFERENCE RANGEOptimal Near

optimalBorderline High Very High

<100 100-129 130-159 160-189 ≥190

TRIGLYCERIDE REFERENCE RANGENormal Borderline High Very High

Triglyceride (mg/dL)

<150 150-199 200-499 ≥500

Clinical SignificanceCholesterol

↑ linked to atherosclerosis, CAD and increased for MI ↓ various forms of liver disease, most notably alcoholic cirrhosis

HDL Cholesterol ↑ HDL decreases the atherosclerotic process – decreased risk of CAD ↓ increased risk of coronary artery disease

LDL Cholesterol LDL is directly associated with atherosclerosis and CAD

Triglyceride Test ↑ in Type I, IIb, IV, and V hyperlipoproteinemias, pancreatitis alcoholism, obesity, hypothyroidism, nephrotic syndrome,

and storage diseases (Gaucher, Niemann-Pick)

ENZYMES AND CARDIAC ASSESSMENT

ENZYMES Proteins that function as biological catalyst Neither consumed nor permanently altered during a chemical reaction Appear in the serum in increased amounts after cellular injury or tissue damage Based on the px sxs, several enzymes may be chosen for analysis to determine if a pattern develops that aids in

identifying the tissue source source of the enzyme elevation1. Lactate dehydrogenase (LD)Tissue location

1. Highest concentrations: liver, heart, skeletal muscle, kidney, erythrocytes2. LD isoenzymes

a. Each LD isoenzymes is a tetramer with five isoenzymes types:LD-1 & LD-2 – asso. with AMI and RBC destructionLD-3- asso. with pulmonary disorders, pancreatitis and lymphocytosisLD-4 & LD-5 – asso. With liver & skeletal muscle d/o

Clinical significance:1. ↑ cardiac disorders (AMI)

Hepatic diseases (viral hepatitis, cirrhosis, infectious mononucleosis), skeletal muscle dses Haemolytic and hematologic d/o, pernicious anemia, neoplastic d/o (ALL)

2. In AMI, LD levels rises within 8-12 hours, peak at 24-48 hours, and returns to normal in 7-10 d.

2. Creatinine kinase (CK) and CK isoenzymes Tissue location

1. Highest concentrations: Skeletal muscle, heart muscle, brain tissue2. CK isoenzymes

a.Two subunits: M for muscle and B for brainb. CK-MM (CK-3), CK-MB (CK-2), and CK-BB (CK-1)c. CK-MB ↑ indicative of AMI when used in conjunction with other markers, such as troponin

DDx: skeletal muscle damageCK-MM ↑ assoc. with skeletal muscle and heart muscle d/oCK-BB ↑ in CNS d/o & tumor of various organs, e.g. prostate

Clinical Significance1. ↑ total CK asso. with cardiac d/o, such as AMI, skeletal m. d/o, e.g. muscular dystrophy

Occasionally, d/o of the CNS, incl. seizures and CVA2. CK-MB >6% of total CK: suggestive of AMI

When AMI suspected, troponin is assayed in conjunction with CK-MB, and sometimes myoglobin too.Following AMI, CK-MB levels rise within 4-6 hrs, peak at 12-24 hrs, and return to normal within 2-3d.

3. Aspartate aminotransferase (AST) Highest in heart, liver, and skeletal m.

Clinical Significance1. AST is used to evaluate hepatocellular disorders (up to 100x upper reference limit in viral hepatitis,

hepatitis, up to 20x in infectious mononucleosis, and up to 4x in cirrhosis)Skeletal m. d/o (up to 8x)Pulmonary emboli (up to 3x)Acute pancreatitis

2. In AMI, AST rises within 6-8 hours, peaks at 18-24 hrs, & returns to normal within 4-5 d.

4. Alanine aminotransferase (ALT) Highest in liver, with lesser amounts in other tissues, including kidneys and erythrocytes

Clinical Significance: Hepatocellular d/o (hepatitis, cirrhosis) exhibit higher ALT. ALT is more specific for liver disease than AST. Elevated ALT & AST = to assess liver involvement in an AMI

5. Alkaline phosphatase (ALP) Highest in liver, bone, intestine, spleen, kidney, placenta

Clinical Significance: ↑ in hepatobiliary and bone d/o (with osteoblastic involvement) In obstructive hepatobiliary d/o – ALP levels are increased more significantly than ALT and AST

a. In biliary tract obstruction, synthesis of ALP is induced by cholestasis, which cause ALP levels to rise 3-10xb. In hepatitis and cirrhosis, (hepatocellular conditions) – ALP rise up to 3xc. Highest elevations of ALP seen in Paget disease

6. Acid phosphatase (ACP) Highest in prostate gland, with lesser amount in bone (osteoclasts), liver spleen, erythrocytes, platelets

Clinical Significance1. Increased in prostate cancer, BPH, bone disease, Paget disease, breast cancer with bone metastases, Gaucher

disease, platelet damage, idiopathic thrombocytopenic purpura2. Use of ACP in forensic cases involving rape – vaginal washings containing seminal fluid would exhibit

ACP activity

7. Gamma-glutamyltransferase (GGT) Found in liver (canaliculi of hepatic cells and epithelial cells lining biliary ductules), kidneys, pancreas,

intestine, etc.

Clinical Significance1. Increased levels in all hepatobiliary disease:

2-5x – viral hepatitis, alcoholic cirrhosis Very sensitive indicator for these conditions

2. Higher levels (5030x) observed in intra- and posthepatic biliary tract obstruction, increases before and remains elevated longer than ALP, AST, ALT

3. GGT activity induced by drugs (e.g., phenobarbital and phenytoin) and by alcohol consumption

8. Amylase Found in pancreas, salivary glands, SI, FT, and other tissues

Clinical Significance1. Acute pancreatitis: increased levels in 2-12 hrs after the onset of pain, peak hrs, return to normal in 3-4 d.2. Increased: Mumps, perforated peptic ulcer, intestinal obstruction, cholecystitis, ruptured ectopic pregnancy,

mesenteric infarction, acute appendicitis

9. Lipase (LPS)Tissue location

Found in pancreas, with lesser amounts in gastric mucosa, intestinal mucosa, adipose tissue

Clinical significance1. Acute pancreatitis – increased levels in 4-8 hours after the onset of pain, peak in 24 hrs, return to normal in

8-14 d.2. Increased: Perforated peptic ulcer, duodenal ulcers, intestinal obstruction, cholecystitis

10. Glucose-6-phosphate dehydrogenase (G6PD) Found in RBCs, adrenal glands, thymus, lymph nodes, spleen

Clinical significance1. Decreased: Primary importance of G6PD is in cases of deficiency, inherited as a sex-linked trait (x-

chromosome)In G6PD deficiency a hemolysis occurs with administration of antimalarial drugs or primaquine, infections and after ingestion of fava beans.

2. Increased: Megaloblastic anemias and AMI

CARDIAC PROFILE Upon arrival to the ER, a cardiac profile would be ordered to establish baseline values. Then the cardiac profile would be

ordered for several sampling in 3- to 8—hr intervals over a 12-24 hr pd. Frequently blood is drawn every 3 hrs for analysis during the 1st 12 hrs.

Laboratory tests to assess AMI include cardiac troponin T or I, CK-MB, and sometimes myoglobin. In many institutions, sampling and testing is halted since it is considered diagnostic for AMI.

1. TROPONIN Troponins T, I, and C form a complex of 3 proteins that bind to filaments of skeletal muscle and cardiac muscle

to regulate muscle contraction.

Clinical Significance1. cTnT or cTnI (cardiac troponin T or cardiac troponin I) is used as an AMI indicator because of specificity

and early rise of serum concentration following AMI.2. In cases of AMI cTnT increases in 3-4 hrs, peaks in 10-24 hrs and returns to normal in 10-14 d. whereas,

cTnI increases in 3-6 hrs, peaks in 14-20 hrs, and returns to normal in 5-10 d.

2. MYOGLOBIN

Found in skeletal and cardiac muscles

Clinical significance1. Increased in skeletal muscle injuries, muscular injuries, muscular dystrophy and AMI2. Released early in cases of AMI, rising in 1-3 hrs, peaks in 5-12 hrs, and returns to normal in 18-30 hrs.

However, it is not tissue specific.It is better used as a negative predictor in the first 2-4 hrs following chest pain.

NATRIURETIC PEPTIDES: POLYPEPTIDE HORMONESa. Three forms: ANP, CNP, BNPb. Effects are minimal;

Function – promote excretion of Na and H2O by increasing the GFR and decreasing the renal tubular reabsorption of Na.

c. B-type (brain) natriuretic peptide (BNP) is synthesized in and secreted from myocardial ventricles in response to ventricular volume expansion and pressure overload.BNP causes vasodilation and promotes Na and H2O loss, thus reducing fluid load in the heart to improve cardiac function.

d. Clinical significance: BNP increased in CHF

High Sensitivity CRP (hs-CRP)1. C-reactive protein (CRP): β-globulin that is an acute-phase reactant2. Refers to the sensitivity of the assay to determine low level in serum.3. Clinical significance: Used as a predictor for cardiovascular risk; increased levels seen in inflammation, infection, stress,

trauma, and AMI