ttttt t chapter 8 laboratory analysis and diagnostic studies dr. maha saud khalid ems 482

TTTTT TChapter 8

Laboratory Analysis and Diagnostic Studies

Dr. Maha Saud Khalid

EMS 482

Laboratory Tests

• May include laboratory examinations of patient’s:– Blood– Urine– Cerebrospinal fluid (CSF)– Other body fluids

CCTP Responsibilities

• Understand or feel comfortable with:– Normal ranges for each lab value– Associated physiologic meaning of test

• Understand purpose of performing tests– Not meant to satisfy curiosity– Not meant to reassure concerned family or staff

Precision and Accuracy

• Lab test with high precision– Value will be the same each time– Measure of tolerance or variation within multiple

measurements– Does not reflect how well measurements compare with true

value

• Lab test with high accuracy– Average value conforms to standard or true value

Sensitivity and Specificity (1 of 3)

• Sensitivity– High: Most people with condition would have positive

result– Low: Many people with condition would have negative

result

• Specificity – Proportion of people without target disorder who have

negative test result

Sensitivity and Specificity (2 of 3)

Sensitivity and Specificity (3 of 3)

Considerations for Abnormal Results

• Normal range represents values for 95% of healthy people.– 5% fall outside this range.

• Abnormal results may be desired for some treatments.• Part of context of patient’s entire clinical picture• Vary by laboratory

Specimen Cultures

• Blood, urine, sputum, other body fluid cultures used to identify micro-organisms, treat specific infections

• Include the following tests:– Culture tests– Sensitivity tests– Culture and sensitivity (C&S)

Biochemistry Review

• The human body contains thousands of different kinds of proteins.

• Enzymes– Proteins that act as catalysts for biochemical reactions– Tests measure amount present– Measured in units per liter (U/L)

Lab Values in Blood Samples (1 of 9)

• Basic metabolic panel (or Chem-7)• Sodium (Na+)– Normal range: 136 to 142 mEq/L (mmol/L)– Elevated: traumatic brain injuries– Decreased (hyponatremia): congestive heart failure, renal

failure, liver disease, diuretic therapy

Lab Values in Blood Samples (2 of 9)

Lab Values in Blood Samples (3 of 9)

• Potassium (K+)• Normal range: 3.5 to 5.0 mEq/L• Elevated: cardiac abnormalities, atrial arrest • Decreased (hypokalemia): arrhythmias, muscle

pain, hyporeflexia, nausea, vomiting, orthostatic hypotension

Lab Values in Blood Samples (4 of 9)

• Chloride (Cl–)– Normal range: 96 to 106 mEq/L– Decreased (hypochloremia): renal dysfunction– Elevated (hyperchloremia): numbness, tingling, hyper-

tonicity, decreased respiratory rate, nervousness, signs of CNS stimulation

Lab Values in Blood Samples (5 of 9)

• Carbon dioxide (CO2)

– Normal HCO3 value: 21 to 28 mEq/L

– Normal CO2 value: 22 to 28 mEq/L

– Decreased: May indicate metabolic acidosis, respiratory alkalosis

– Elevated: Metabolic alkalosis, respiratory acidosis

Lab Values in Blood Samples (6 of 9)

• Blood urea nitrogen (BUN)– Normal range: 8 to 23 mg/dL– Elevated: May occur with decreased renal function, high-

protein diet, crush injuries, burns

• Creatinine– Normal: 0.6 to 1.2 mg/dL– Elevated: May cause permanent kidney damage

Lab Values in Blood Samples (7 of 9)

• Total calcium– Normal range: 8.2 to 10.2 mg/dL– Decreased: Seen in renal insufficiency, hypomagnesemia,

hyperphosphatemia, massive blood transfusion, decreased parathyroid hormone states

– Elevated: Seen in hyperparathyroidism, parathyroid secreting tumors

Lab Values in Blood Samples (8 of 9)

• Glucose– Normal range: 70 to 110 mg/dL– Decreased: dizziness, unconsciousness– Elevated: coma, death

• Ionized calcium– Normal range: 4.60 to 5.08 mg/dL– Decreased: cause serious arrhythmias

Lab Values in Blood Samples (9 of 9)

• Magnesium (Mg)– Normal range: 1.3 to 2.1 mEq/L– Elevation caused by: renal defects, severe dehydration, Mg,

diabetic coma, aspiration of sea water– Decrease caused by: GI distress, vomiting and diarrhea,

cirrhosis, pancreatitis

Blood Components (1 of 6)

• Complete blood count (CBC) test• Hematocrit (Hct)– Normal range: 41% to 50%

• Hemoglobin (Hg or Hb)– Males: 135 to 175 g/L; females: 120 to 160 g/L– Elevated: Hemoconcentration caused by dehydration,

burns, or excessive vomiting– Decreased: Most types of anemia

Blood Components (2 of 6)

Blood Components (3 of 6)

Blood Components (4 of 6)

• Carboxyhemoglobin (COHb)– Normal levels: Not to exceed 0.02 (2%) – Assessment used to diagnose carbon monoxide poisoning

• Red blood cell (RBC) count– Normal range: 3.9 to 5.5 X 106/μL– Decreased: All types of anemias

Blood Components (5 of 6)

• White blood cell (WBC) count– Normal range: Between 4,500/μL and 11,000/μL– Decreased: aplastic anemia, vitamin deficiencies, sepsis– Elevated: inflammation, infection, malignancies, vascular

conditions, steroid use, stress from trauma

Blood Components (6 of 6)

• Platelet count (Plt)– Normal range: 150 to 350 X 103/μL– Elevated: myeloproliferative disorders

(are a group of diseases of the bone marrow in which excess cells are produced. They are related to, and may evolve into, myelodysplastic syndrome and acute myeloid leukemia)– Decreased: thrombocytopenia, disseminated

intravascular coagulation, high levels of platelet antibodies

Proteins (1 of 7)

• Total protein– Normal range: 6.0 to 8.0 g/dL

• Albumin– Normal range: 3.5 to 5.0 g/dL– Decreased: increased protein catabolism, decreased

production, edema in spaces between cells and tissues; hypoalbuminemia

– Elevated: not pathologic

Proteins (2 of 7)

• C-reactive protein (CRP)– Normal range: 0.08 to 3.1 mg/L– Elevated: May indicate significant inflammatory disease

• Myoglobin– Normal range: 19 to 92 μg/L– Elevated: May indicate myocardial infarction

Proteins (3 of 7)

• Lactate dehydrogenase (LDH)– Normal range: 100 to 200 U/L– Elevated: Ratio over 85% indicates possible AMI, also

helps diagnose pneumonia, pancreatitis

• Creatine kinase (CK)– Normal range: 40 to 150 U/L– Elevated: Muscle damage, possibly related to AMI

Proteins (4 of 7)

• Troponin I– Normal range: 0 to 0.04 ng/mL (for cTnI)– Elevated: Indicate MI up to 7 days following event

• B-type natriuretic peptide (BNP)– Normal range: Less than 167 pg/mL– Elevated: Indicates abnormal ventricular function,

congestive heart failure

Proteins (5 of 7)

• Aspartate aminotransferase (AST)– Normal range: 10 to 30 U/L– Elevated: liver damage, alcoholic cirrhosis, hepatitis,

cancer

• Alanine aminotransferase (ALT)– Normal range: 10 to 40 U/L– Elevated: liver damage, alcoholic cirrhosis, hepatitis,

cancer

Proteins (6 of 7)

• Total bilirubin– Normal range: 0.3 to 1.2 mg/dL– Elevated: liver disease, biliary tract obstruction, RBC

hemolysis

• Direct bilirubin– Normal range (direct): 0.1 to 0.3 mg/dL – Normal range (indirect): 0.2 to 0.9 mg/dL

Proteins (7 of 7)

• Alkaline phosphatase– Normal range: 30 to 120 U/L

• Amylase– Normal range: 27 to 131 U/L– Decreased: Seen in cystic fibrosis

• Lipase– Normal range: 31 to 186 U/L– Elevated: bile duct obstruction, biliary disease

Coagulation (1 of 2)

• Prothrombin time (PT)– Normal range: 10 to 13 seconds– Elevated: liver disease, warfarin therapy– Decreased: vitamin K deficiency, in DIC(disseminated

intravascular coagulation) , following massive transfusion

Coagulation (2 of 2)

• Activated partial thromboplastin time (aPTT)– Normal range: 25 to 40 seconds

• International normalized ratio (INR)– Normal range: 0.9 to 1.3– Elevated: liver disease, warfarin therapy, anticoagulant use

Other Lab Profiles (1 of 2)

• Lactate– Normal range: 5.0 to 15 mg/dL– Elevated: inadequate perfusion, oxygenation of cells,

tissues, end organs • Ethanol (EtOH)– Elevated: Intoxication defined as more than 80 mg/dL

Other Lab Profiles (2 of 2)

• Calculated values– AST:ALT determines cause of liver dysfunction– BUN:Creatinine determines cause of increased levels of

these two metabolites

Acid-Base Status (1 of 2)

• Hydrogen ion concentration (pH)– Normal range for arterial: 7.35 to 7.45– Normal range for venous: 7.31 to 7.41

• Partial pressure of carbon dioxide– Respiratory derangement present either above or below

normal range of 35 to 45 mm Hg

Acid-Base Status (2 of 2)

• Bicarbonate– Normal range: 21 to 28 mEq/L– Derangement seen with acidosis- or alkalosis-related

conditions with metabolic aspect

• Base excess (BE)– Normal range of –2 to +3– Negative: Excess acid or lack of base– Positive: Excess base or lack of acid

Oxygenation Status

• Partial pressure of oxygen– Normal range: 80 to 100 mm Hg– Decrease: Hypoxia at levels below 80 mm Hg

• Oxygen saturation– Normal range: Greater than 93%

Blood Group Testing

• Four blood types result from two primary antigens (A, B)– Type A carries A antigen– Type B carries B antigen– Type AB carries A and B (universal recipient)– Type O carries neither A nor B (universal donor)

Rh Antigen D (Rh Factor)

• Found in majority of the population (Rh positive)

• May cause immune response reaction when given to Rh negative patients– Especially dangerous in Rh negative pregnant women

Venous Blood Samples (1 of 3)

• Obtain prior to administration of IV fluids or medications, when possible.

• Use to monitor some antibiotic treatments.• Use extremity without IV line or stop flow of fluid or

medication to avoid contamination• Use blood tubes preferred by individual laboratories.

Venous Blood Samples (2 of 3)

Venous Blood Samples (3 of 3)

Components of Urinalysis (1 of 4)

• Color– Yellow, pale, clear, brown– Indicates presence of particulates

• Appearance– Clear or turbid

• Specific gravity– Normal range: 1.003 to 1.035– More concentrated samples have higher density.

Components of Urinalysis (2 of 4)

• pH– Normal range: 4.5 to 8.0– Useful marker for metabolic acidosis– Presence of RTA (renal tubular acidosis ): Arterial pH of

less than 7.35; urine pH of greater than 6.0

Components of Urinalysis (3 of 4)

• Glucose (glycosuria)– Normal: 0; presence almost always indicative of elevated

serum glucose levels– Graded on scale of mild to severe: +1, +2, +3, +4– Diabetes mellitus

• Ketone bodies (ketonuria)– Diabetes mellitus, alcoholic ketoacidosis, starvation

ketosis– Graded on scale of mild to severe: +1, +2, +3, +4

Components of Urinalysis (4 of 4)

• Protein– Normal reference value negative– Positive may indicate numerous kidney diseases

• Blood and hemoglobin– Hemoglobinuria and hematuria may indicate kidney or

urinary tract damage.

Cerebrospinal Fluid

• Used to detect– Increased intracranial pressure– Diabetic coma – Diabetes– Bacterial or fungal meningitis

Normal Results for CSF

• Pressure: 50 to 180 mm H2O• Appearance: clear, colorless• Total protein: 10 to 45 mg/100 mL• Glucose: 50 to 80/100 mL• Cell count: 0 to 5 WBCs, no RBCs• Chloride: 110 to 125 mEq/L

Common Errors in Specimen Collection

• Incorrect patient identification and mislabeling of samples– Always write identifying information about patient on

label.

• Improper technique or handling in the field– Exacerbated by temperature extremes, blood sample

hemolyzation, contamination by medications

Examples of Diagnostic Imaging Technologies (1 of 2)

• Standard radiographs– Used for quick diagnostics in patient care– Obtained in a lateral or AP (anterior posterior)view

• Computed tomography (CT)– Cross-sectional images of body structures– Evaluates different characteristics of tissues, bone, organs

Examples of Diagnostic Imaging Technologies (2 of 2)

• Magnetic resonance imaging (MRI)– Used to visualize internal structure and function of body– Useful when performed on brain, spinal cord,

musculoskeletal, cardiovascular, oncologic imaging

• Ultrasonography

Normal and Abnormal Lab Values