03 laboratory tests part 1

Diagnostic Tests Part I
HEALTH ASSESSMENT’ (NCM 101) SKILLS
Mr. JHONEE BALMEO

Diagnostic tests
 are tools that provide information about the client.
 Tests may be used for basic screening as part of a wellness
check.
 Frequently tests are used to help confirm a diagnosis,
monitor an illness, and provide valuable information about
the client’s response to treatment.

Diagnostic Testing Phases
 Diagnostic testing involves three
phases: pretest, intratest, and post-
test.

Pretest
 The major focus of the pretest phase
is client preparation.
 A thorough assessment and data
collection assist the nurse in
determining communication and
teaching strategies.

Pretest
 Some questions you may ask to yourself includes:
 What type of sample will be needed and how will it be
collected?
 Does the client need to stop oral intake for a certain
number of hours prior to the test?
 Does the test include administration of dye (contrast
media) and, if so, is it injected or swallowed?
 Are fluids restricted or forced?
 Are medications given or withheld? How long is the test?
 Is a consent form required?

Pretest
 CLIENT TEACHING (Preparing for Diagnostic Testing)
 Instruct the client and family about the procedure for the
diagnostic testing ordered (e.g., whether food is allowed
prior to or after testing, and the length of time of the
testing).
 Explain the purpose of the test.
 Instruct the client and family about activity restrictions
related to testing (e.g., remain supine for 1 hour after
testing is completed).

Pretest
 Instruct the client and family on the reaction the
diagnostic test may produce (e.g., flushing when the dye
is injected).
 Provide the client with detailed information about the
diagnostic testing equipment.
 Inform the client and family of the time frame for when
the results will be available.
 Instruct the client and family to ask any questions so that
the health care provider can clarify information and allay
any fears.

Intratest
 This phase focuses on specimen collection
and performing or assisting with certain
diagnostic testing. The nurse uses standard
precautions and sterile technique as
appropriate.

Post-Test
 The focus of this phase is on
nursing care of the client and
follow-up activities and
observations.
 As appropriate, the nurse
compares the previous and
current test results and modifies
nursing interventions as needed.

Lab Tests: Blood Tests
 Blood tests are commonly
used diagnostic tests that
can provide valuable
information about the
hematologic system and
many other body systems.

Blood Tests
 A venipuncture (puncture of a vein for collection of a
blood specimen) can be performed by various members of
the health care team.
 In some institutions, nurses may draw blood samples.

Blood Tests:
Complete Blood Count
 Specimens of venous blood are taken for a complete blood count
(CBC), which includes hgb and hct measurements, erythrocyte
(RBC) count, leukocyte (WBC) count, red blood cell indices, and a
differential white cell count.
 The CBC is a basic screening test and one of the most frequently ordered blood tests*

Blood Tests:
 Hemoglobin
is the main intracellular protein of erythrocytes. It is the iron-containing
protein in the red blood cells that transports oxygen through the body.
The hemoglobin test is a measure of the total amount of hemoglobin in the
blood.
 Normal Values:
Men: 13.5–18 g/dL
Women: 12–15 g/dL

Blood Tests:
 The hematocrit
measures the percentage of RBCs in the total blood volume.
Normal values for both hemoglobin and hematocrit vary,
with males having higher levels than females.
 Normal Values:
Men: 13.5–18 g/dL
Women: 12–15 g/dL

Blood Tests:
 Hemoglobin and hematocrit increase with dehydration as
the blood becomes more concentrated, and decrease with
hypervolemia and resulting hemodilution.

Blood Tests:
 Both the hemoglobin and hematocrit are related to the red blood
cell (RBC) count, which is the number of RBCs per cubic
millimeter of whole blood. Low RBC counts are indicative of
anemia. Clients with chronic hypoxia may develop higher than
normal counts, a condition known as polycythemia.
 Normal Values:
Men: 4.6–6.0 million/mm3
Women: 4.0–5.0 million/mm3

Blood Tests:
 The leukocyte or white blood cell (WBC) count determines
the number of circulating WBCs per cubic millimeter of whole
blood.
 This information is useful in diagnosing certain disorders that
have characteristic patterns of distribution

Blood Tests:
 High WBC counts are often seen in the presence of a
bacterial infection; by contrast, WBC counts may be low if
a viral infection is present.
 In the WBC differential, leukocytes are identified by type,
and the percentage of each type is determined.
 Normal Values:
4,500–11,000/mm3 both male and female

Blood Tests:
 Platelet Count
 Platelets are also known as thrombocytes. They circulate
in the bloodstream and bind together to form a clot over
any damaged blood vessel. Determining platelet count is
vital in assessing patients for tendencies of bleeding and
thrombosis.
 Normal range:
 150,000 to 350,000/mm3

Blood Tests:
Serum Electrolytes
 Serum electrolytes are often routinely ordered for any
client admitted to a hospital as a screening test for
electrolyte and acid–base imbalances.
 The most commonly ordered serum tests are for Na+, K+,
Cl+, and HCO3 ions.

Normal Electrolyte Values for Adults*

?
 The nurse is caring for a male patient with a hemoglobin
level of 12.3 g/dL. The nurse would expect this
hemoglobin level to be caused by:
A. Diabetes mellitus
B. Menstruation
C. Hyperthyroidism
D. Chronic renal failure.

?
 A 5-year-old boy was admitted due to abdominal pain and diarrhea.
Physical exam shows that the child has poor skin turgor and dry
mucous membranes. Blood tests were ordered and the nurse
expects that:
A. WBC is increased
B. Serum sodium is increased
C. Hematocrit level is elevated.
D. BUN is lowered

A.Potassium
Potassium is critical in nerve and muscle
function because it communicates impulses.
The movement of nutrients into the cell and
the transport of waste products out of the
cell are also mediated by potassium.
Whenever potassium levels are increased or
decreased, the heart rhythms are affected
as signified by EKG changes.
Normal range:
3.5 – 5.3 milliequivalents per liter (mEq/L)
Normal Electrolyte Values for Adults*

B. Sodium
Sodium reflects a part of renal function as
kidneys are responsible for eliminating it from
the body. It also plays a part in motor and
nerve function.
Patients are tested for serum sodium levels in
cases of dehydration, edema, abnormal blood
pressure levels, and changes in motor
functions.
Normal range:
135 to 145 milliequivalents per liter (mEq/L)

C. Chloride
Together with sodium, potassium
and carbon dioxide, chloride
maintains the normal acid-base
balance of the body through
balancing body fluids. Abnormal
changes in serum chloride levels
is usually an indicator of metabolic
changes in the body.
Normal range:
95 – 105 milliequivalents per liter
(mEq/L)

D. Calcium
Calcium is usually binded with protein in
the blood. For this reason, a standard
calcium test can be misleading and
determination of ionized calcium is
recommended.
Determining serum calcium levels is
important if the patient is suffering from
existing nerve and motor dysfunctions.
Normal range:
8.5 to 10.5 mEq/L

E. Magnesium
Magnesium is important in muscle and
nerve functions, blood pressure regulation,
and immune system. It also plays a role in
blood sugar regulation.
Although half of the magnesium in the body
is stored in bones, magnesium can also be
found in cells of organs and body tissues.
Normal range:
1.5 to 2.5 mEq/L

F. Phosphorus
Phosphorus is involved in the intracellular
metabolism of proteins, fats, and
carbohydrates. It also participates in the
production of ATP.
Phosphorus plays an important role in the
acid-base balance of the body and in
glycolysis.
Normal range:
1.8 – 2.6 mEq/L

Blood Tests:
BUN & Creatinine
 Blood levels of two metabolically produced
substances, urea and creatinine, are routinely
used to evaluate renal function.
 The kidneys, through filtration and tubular
secretion, normally eliminate both. Urea, the
end product of protein metabolism, is measured
as blood urea nitrogen (BUN).
Normal range: 7—18 mg/dL
 BUN is a by-product of protein metabolism*

Blood Tests:
BUN & Creatinine
 Creatinine is produced in relatively
constant quantities by the muscles
and is excreted by the kidneys. Thus,
the amount of creatinine in the blood
relates to renal excretory function.
 Normal range:
Male: 0.6 to 1.2 mg/dL
Female 0.5 to 1.1mg/dL

Blood Tests:
Serum Osmolality
 Serum osmolality is a measure of the solute concentration of the
blood.
 Serum osmolality can be estimated by doubling the serum sodium,
because sodium and its associated chloride ions are the major
determinants of serum osmolality. Serum osmolality values are used
primarily to evaluate fluid balance.
 An increase in serum osmolality indicates a fluid volume deficit; a
decrease reflects a fluid volume excess.
 Normal values are 280 to 300 mOsm/kg.

Blood Tests:
Drug Monitoring
 Therapeutic drug monitoring is often conducted when a client
is taking a medication with a narrow therapeutic range (e.g.,
digoxin, theophylline, aminoglycosides).
 This monitoring the therapeutic level and not a subtherapeutic
or toxic level.
 The peak level indicates the highest concentration of the drug
in the blood serum, and the trough level represents the
lowest concentration.

Blood Tests:
Arterial Blood Gases
 Measurement of arterial blood gases is another important
diagnostic procedure. Specialty nurses, medical
technicians, and respiratory therapists normally take
specimens of arterial blood from the radial, brachial, or
femoral arteries.
 pH, PCO2, HCO3
 Skip for further Lecture*

Blood Tests:
Blood Chemistry
 A number of other tests may be performed on blood serum
(the liquid portion of the blood).
 These are often referred to as a blood chemistry.
 For example, cardiac markers (e.g., CPK-MB, myoglobin,
troponin T, and troponin I) are released into the blood
during a myocardial infarction (MI, or heart attack).
Elevated levels of these markers in the venous blood can
help differentiate between an MI and chest pain that is
caused by angina or pleuritic pain.

Blood Tests:
Blood Chemistry
 In addition to serum electrolytes, common chemistry
examinations include determining certain enzymes that
may be present (including lactic dehydrogenase [LDH],
creatine kinase [CK], aspartate aminotransferase [AST],
and alanine aminotransferase [ALT]), serum glucose,
hormones such as thyroid hormone, and other substances
such as cholesterol and triglycerides. These tests provide
valuable diagnostic cues.

Blood Tests:
Blood Chemistry (Cardiac Markers )
 CK (creatine kinase) An enzyme found in the heart and skeletal
muscles.
 Possible causes of increase includes acute myocardial infarction
(MI), myocarditis, acute cerebrovascular disease, muscular
dystrophy, chronic alcoholism.
 Normal Values:
Men: 38–174 unit/L
Women: 26–140 unit/L

Blood Tests:
 Myoglobin
After an MI, serum levels of myoglobin rise in 2–4 hours,
making it an early marker for muscle damage in MI
Possible cause of increase include MI, angina, other muscle
injury (e.g., trauma), renal failure, rhabdomyolysis
 Normal Values:
5–70 ng/mL

Blood Tests:
 Troponin I Troponin T
 Cardiac troponin is highly concentrated in the heart muscle. This
test is used in the early diagnosis of MI. After an MI, troponin I
begins to increase in 4–6 hours and remains elevated for 5–7 days
Troponin T begins to increase in 3–4 hours and remains elevated for
10–14 days
 Normal Values:
Troponin I: 0.35 ng/mL
Troponin T: 0.2 ng/mL

Blood Tests:
Blood Chemistry (Liver Function Test)
 ALT (alanine aminotransferase), formerly known as serum
pyretic transaminase (SGPT
 Marker of hepatic injury; more specific of liver damage
than AST
 Normal Values
Men: 10–55 unit/L

Blood Tests:
 AST (aspartate aminotransferase) formerly known as
serum glutamic-oxaloacetic transaminase (SGOT)
 Found in heart, liver, and skeletal muscle. Can also be
used to indicate liver injury.
 Normal Values:
Men: 10–40 unit/L

Blood Tests:
 Prothrombin
 A protein produced by the liver for clotting of blood
 Normal Values:
11–13 seconds
Critical value:
20 seconds for non-anticoagulated persons

Blood Tests:
Blood Chemistry (Lipoprotein Profile)
 Cholesterol
 This test is an important screening test for heart disease
 Adults: Desirable: <200 mg/dL

Blood Tests:
 HDL-C (high-density lipoprotein cholesterol)
 A class of lipoproteins produced by the liver and
intestines; the “good” cholesterol
 Normal Values:
Men: 35–65 mg/dL Women: 35–80 mg/dL

Blood Tests:
 LDL (low-density lipoprotein)
 Up to 70% of the total serum cholesterol is present in LDL;
the “bad” cholesterol
 Adults: Desirable: 130 mg/dL

Blood Tests:
 Triglycerides
 This test evaluates suspected atherosclerosis and
measures the body’s ability to metabolize fat
 Desirable: <150 mg/dL

Blood Tests:
Blood Chemistry (HbA1C)
 A common laboratory test is the glycosylated hemoglobin or hemoglobin A1C
(HbA1C), which is a measurement of blood glucose that is bound to
hemoglobin.
 HemoglobinA1C is a reflection of how well blood glucose levels have been
controlled during the prior 3 to 4 months.
 The normal range is 4.0% to 5.5%.
(The American Diabetic Association recommends an A1C of 7% below)
An elevated HbA1C reflects hyperglycemia in diabetics.

Blood Tests:
Capillary Blood Glucose
 A capillary blood specimen is often taken to measure
blood glucose when frequent tests are required or when a
venipuncture cannot be performed.
 This technique is less painful than a venipuncture and
easily performed. Hence, clients can perform this
technique on themselves.

Blood Tests:
 Glucose meters can vary in the
following ways: amount of blood
needed, testing speed, size, ability
to store results, cost of the meter,
and test strips

Blood Tests:
 Normal blood sugar levels are less than 100 mg/dL after
not eating (fasting) for at least eight hours. And they're
less than 140 mg/dL two hours after eating.
 During the day, levels tend to be at their lowest just
before meals.
 Source: https://www.webmd.com/diabetes/qa/what-are-normal-blood-
sugar-levels

?
 The nurse checks the blood glucose of an unconscious
diabetic patient. The nurse would consider the patient
hypoglycemic and administer intravenous dextrose if the
blood glucose is under:
A. 65 mg/dL
B. 70 mg/dL.
C. 75 mg/dL
D. 80 mg/dL

?
 The nurse takes a blood sample from a diabetic patient to
measure his glycosylated hemoglobin (Hgb A1C). The
patient's goal is to achieve a level lower than:
A. 7.5%
B. 8%
C. 5.5%
D. 7%.

References:
 Audrey Berman . . . [et al.]. – 9th ed. (2012) KOZIER &
ERB’S Fundamentals of NURSING Concepts, Process, and
Practice.

03 laboratory tests part 1

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