This document provides information about various components of a complete blood count (CBC) test, including white blood cell (WBC), red blood cell (RBC), and platelet counts. It describes what each test measures, its normal reference ranges, potential abnormal findings and their implications. Nursing considerations are outlined for preparing patients for CBC testing and interpreting results. The document also discusses the blood urea nitrogen (BUN) test and how it is used to evaluate kidney function. In summary, it reviews several common blood tests, what they indicate about a patient's health, and nursing responsibilities related to ordering and following up on the tests.
2. Complete blood count
The complete blood count (CBC) is a group of tests that
evaluate the cells that circulate in blood, including
Red blood cells (RBCs).
White blood cells (WBCs).
Platelets (PLTs).
3. Complete blood count - WBC
Description
A WBC count, also called a leukocyte count, is part of a
complete blood count.
It indicates the number of white cells in a microliter (μL, or
cubic millimeter) of whole blood.
WBC counts may vary by as much as 2000 cells/μL (SI, 2 ×
109/L) on any given day due to strenuous exercise, stress, or
digestion.
The WBC count may increase or decrease significantly in
certain diseases, but it’s diagnostically useful only when the
patient’s white cell differential and clinical status are
considered.
4. Complete blood count - WBC
Description
The WBC differential is used to evaluate the distribution and
morphology of WBCs, providing more specific information about a
patient’s immune system than a WBC count alone.
WBCs are classified as one of five major types of leukocytes—
neutrophils, eosinophils, basophils, lymphocytes, and monocytes—
and the percentage of each type is determined.
The differential count is the percentage of each type of WBC in the
blood. The total number of each WBC type is obtained by
multiplying its percentage by the total WBC count.
5. Complete blood count-WBC
Purpose
To determine infection or inflammation
To determine the need for further tests such as bone marrow
biopsy.
To monitor response to chemotherapy or radiation therapy
6. Complete blood count - WBC
Purpose-WBC Differential
To evaluate the body’s capacity to resist and overcome
infection.
To detect and identify various types of leukemia.
To determine the stage and severity of an infection.
To detect allergic reactions and parasitic infections and
assess their severity
To distinguish viral from bacterial infections
7. Complete blood count - WBC
Reference Values
4000 to 10,000/μL (SI, 4 to 10 × 109/L).
For an accurate diagnosis, differential test results always
must be interpreted in relation to the total white blood cell
(WBC) count.
9. Complete blood count - WBC
Elevated Levels- Nursing Implications
Report any abnormal findings to the practitioner.
Prepare to educate the patient about his diagnosis.
Prepare the patient for further testing or surgery, as indicated.
Provide emotional support to the patient and his family.
Prepare to administer antimicrobial therapy as indicated.
Institute isolation precautions as applicable
10. Complete blood count - WBC
Abnormal Findings- Decreased Levels (Leukopenia)
Bone marrow depression
Viral infections
Ingestion of mercury or other heavy metals
Exposure to benzene or arsenicals
Influenza
Typhoid fever
Measles
Infectious hepatitis
11. Complete blood count - WBC
Decreased Levels- Nursing Implications
Report any abnormal findings to the practitioner.
Prepare to educate the patient about his diagnosis.
Prepare the patient for further testing or surgery, as indicated.
Provide emotional support to the patient and his family.
Prepare to administer antimicrobial therapy as indicated.
Institute isolation precautions as applicable.
12. Complete blood count - WBC
Interfering Factors
WBC Count
Digestion, exercise, or stress
Anticonvulsants, such as phenytoin derivatives; nonsteroidal
anti-inflammatory drugs such as indomethacin (Indocin); and
thyroid hormone antagonists (decrease).
Precautions
Completely fill the sample collection tube.
Invert the sample gently several times to mix the sample and
the anticoagulant.
13. Complete blood count - WBC
Nursing Considerations- Before the Test
Confirm the patient’s identity using two patient identifiers
according to facility policy.
Explain to the patient that the WBC count and differential test
is used to detect an infection or inflammation (WBC count) or
evaluate the immune system (WBC differential).
Advise the patient that a blood sample will be taken. Explain
that he may feel slight discomfort from the tourniquet and
needle puncture.
14. Complete blood count - WBC
Nursing Considerations- Before the Test
Inform the patient that he doesn’t need to restrict food and
fluids but that he should avoid strenuous exercise for 24
hours before the test. Also tell him that he should avoid eating
a heavy meal before the test.
If the patient is being treated for an infection, advise him that
this test will be repeated to monitor his progress.
Notify the laboratory and physician of medications the patient
is taking that may affect test results; they may need to be
restricted
15. Complete blood count - WBC
After the Test
If a hematoma develops at the venipuncture site, apply pressure. If
the hematoma is large, monitor pulses distal to the venipuncture
site.
Instruct the patient that he may resume his usual diet, activity, and
medications discontinued before the test, as ordered.
Be aware that a patient with severe leukopenia may have little or
no resistance to infection and requires infection control
precautions.
16. Complete blood count-RBC
Description
The RBC count, also called an erythrocyte count, is part of a
complete blood count.
It’s used to detect the number of RBCs in a microliter (μL) or
cubic millimeter (mm3), of whole blood.
The RBC count itself provides no qualitative information
regarding the size, shape, or concentration of Hb within the
corpuscles, but it may be used to calculate two erythrocyte
indices:
o Mean corpuscular volume (MCV)
o Mean corpuscular hemoglobin (MCH)
17. Complete blood count-RBC
Purpose
To provide data for calculating mean corpuscular volume
(MCV) and mean corpuscular hemoglobin (MCH), which
reveal RBC size and hemoglobin (Hb) content.
To support other hematologic tests for diagnosing anemia or
polycythemia.
18. Complete blood count-RBC
Reference Values
Adult females: 4 to 5 million red blood cells (RBCs)/μL (SI, 4
to 5 × 1012/L) of venous blood
Adult males: 4.5 to 5.5 million RBCs/ μL (SI, 4.5 to 5.5 ×
1012/L) of venous blood
19. Complete blood count-RBC
Abnormal Findings- Elevated Levels
Absolute or relative polycythemia
Nursing Implications
Report abnormal findings to the practitioner.
Prepare to educate the patient about his diagnosis.
Prepare the patient for further testing as indicated.
20. Complete blood count-RBC
Abnormal Findings - Decreased Levels
Anemia
Dilution caused by fluid overload
Hemorrhage beyond 24 hours
Nursing Implications
Report abnormal findings to the practitioner.
Prepare to educate the patient about his diagnosis.
Prepare the patient for further testing as indicated.
21. Complete blood count-RBC
Interfering Factors
Hemoconcentration caused by prolonged tourniquet
constriction.
Hemodilution caused by drawing the sample from the same
arm used for IV fluid infusion
Diseases that cause RBCs to agglutinate or form rouleaux
(false decrease).
Hemolysis resulting from rough handling of the sample or
drawing the blood through a small-gauge needle for
venipuncture.
23. Complete blood count-RBC
Nursing Considerations-Before the Test
Confirm the patient’s identity using two patient identifiers
according to facility policy.
Explain to the patient that the RBC count is used to evaluate the
number of RBCs and to detect possible blood disorders.
Advise the patient that a blood sample will be taken. Explain that
he may feel slight discomfort from the tourniquet and needle
puncture.
Inform the patient that he doesn’t need to restrict food and fluids
for the test.
24. Complete blood count-RBC
During the Test
Fill the collection tube completely.
Invert the tube gently several times to mix the sample and the
anticoagulant.
After the Test
Apply pressure to the venipuncture site until bleeding stops.
If a hematoma develops at the venipuncture site, apply direct
pressure.
25. Complete blood count- Platelet Count
Description
Platelets, or thrombocytes, are the smallest formed elements
in blood.
They promote coagulation and the formation of a hemostatic
plug in vascular injury.
Platelet count is one of the most important screening tests of
platelet function. Accurate counts are vital.
26. Complete blood count-Platelet Count
Purpose
To evaluate platelet production.
To assess the effects of chemotherapy or radiation therapy on
platelet production.
To diagnose and monitor severe thrombocytosis or
thrombocytopenia.
27. Platelet Count
Reference Values
Adults: 140,000 to 400,000/μL (SI, 140 to 400 × 109/L)
Critical Values
Less than 50,000/μL (can cause spontaneous bleeding).
Less than 5000/μL (possible fatal central nervous system
bleeding or massive GI hemorrhage)
28. Platelet Count
Abnormal Findings- Elevated Levels (thrombocytosis)
Hemorrhage.
Infectious or inflammatory disorders
Iron deficiency anemia
Splenectomy or other recent surgery
Pregnancy
Chronic myelogenous leukemia
29. Platelet Count
Elevated Levels- Nursing Implications
Prepare the patient for additional testing, including a complete
blood count (CBC), bone marrow biopsy,
Report abnormal findings to the practitioner.
Prepare to educate the patient about his diagnosis
30. Platelet Count
Abnormal Findings-Decreased Levels
Splenectomy.
Leukemia.
Disseminated infection
Folic acid or vitamin B12 deficiency
Pooling of platelets in an enlarged spleen.
Increased platelet destruction caused by drugs or an immune
disorder
Disseminated intravascular coagulation
Mechanical injury to platelets
31. Platelet Count
Nursing Implications -Decreased Levels
(thrombocytopenia)
Prepare the patient for additional testing, including a CBC,
bone marrow biopsy, direct antiglobulin test (direct Coombs’
test), and serum protein electrophoresis.
Report abnormal findings to the practitioner.
Prepare to educate the patient about his diagnosis.
33. Platelet Count
Precautions
To prevent hemolysis, avoid excessive probing at the
venipuncture site and handle the sample gently.
Nursing Considerations- Before the Test
Confirm the patient’s identity using two patient identifiers
according to facility policy.
Explain to the patient that the platelet count test is used to
determine if the patient’s blood clots normally.
34. Platelet Count
Nursing Considerations- Before the Test
Advise the patient that a blood sample will be taken. Explain
that he may feel slight discomfort from the needle puncture
and the tourniquet.
Inform the patient that he doesn’t need to restrict food and
fluids for the test.
Notify the laboratory and practitioner of medications the
patient is taking that may affect test results; they may need to
be restricted.
35. Platelet Count
During the Test
Completely fill the collection tube and invert it gently several
times to mix the sample and the anticoagulant thoroughly.
After the Test
Apply pressure to the venipuncture site until bleeding has
stopped.
If a hematoma develops at the veni puncture site, apply direct
pressure. If the hematoma is large, monitor pulses distal to
the venipuncture site.
Tell the patient that he may resume any medications that were
discontinued before the test as ordered.
37. Blood Urea Nitrogen (BUN)
Description
The blood urea nitrogen (BUN) test is used to measure the
nitrogen fraction of urea, the chief end product of protein
metabolism.
urea Formed in the liver from ammonia and excreted by the
kidneys, urea constitutes 40% to 50% of the blood’s
nonprotein nitrogen content.
BUN level reflects protein intake and renal excretory capacity,
but it’s a less reliable indicator of uremia than the serum
creatinine level.
38. Blood Urea Nitrogen
Purpose
To evaluate kidney function and aid in the diagnosis of renal
disease
To aid in the assessment of hydration.
39. Blood Urea Nitrogen
Reference Values
8 to 20 mg/dL (SI, 2.9–7.5 mmol/L)
Elderly patients: slightly higher, possibly to 69 mg/dL (SI, 25.8
mmol/L.
Critical Values
Less than 2 mg/dL (SI, 0.71 mmol/L)
Greater than 80 mg/dL (SI, 2.85 mmol/L)
40. Blood Urea Nitrogen
Abnormal Findings- Elevated Levels
Renal disease (greater than 100 mg indicates serious
impairment of renal function).
Reduced renal blood flow (due to dehydration, for example).
Urinary tract obstruction.
Increased protein catabolism (such as with burns).
Nursing Implications
Prepare the patient for further testing.
Explain the underlying problem associated with the elevated
level.
41. Blood Urea Nitrogen
Decreased Levels
Severe hepatic damage.
Malnutrition
Overhydration
Nursing Implications
Prepare the patient for additional testing.
Institute measures, as ordered, to correct nutritional and fluid
imbalances.
42. Blood Urea Nitrogen
Interfering Factors
Chloramphenicol and tetracyclines (possible decrease)
Overhydration and underhydration will affect BUN levels
43. Blood Urea Nitrogen
Nursing Considerations-Before the Test
Confirm the patient’s identity using two patient identifiers
according to facility policy.
Tell the patient that the BUN test is used to evaluate kidney
function.
Inform the patient that he doesn’t need to restrict food and
fluids, but should limit his meat intake (protein intake affects
BUN levels).
Explain to the patient that the test requires a blood sample
from a venipuncture. Advise him that he may experience
slight discomfort from the tourniquet and needle puncture.
44. Blood Urea Nitrogen
After the Test
Handle the sample gently and send it to the laboratory
immediately.
Apply direct pressure to the venipuncture site until bleeding
stops.
Inform the patient that he may resume medications that were
discontinued before the test, as ordered
45. Creatinine, Serum
Description
Serum creatinine levels provide a more sensitive measure of
renal damage than do blood urea nitrogen levels.
Creatinine is a nonprotein end product of creatine metabolism
that appears in serum in amounts proportional to the body’s
muscle mass.
Purpose
To assess glomerular filtration
To screen for renal damage
46. Creatinine, Serum
Reference Values
Females: 0.6 to 0.9 mg/dL (SI, 53–97 μmol/L)
Males: 0.8 to 1.2 mg/dL (SI, 62–115 μmol/L)
Critical Values
Less than 0.4 mg/dL (SI, 35 μmol/L) or
More than 2.8 mg/dL (SI, 247 μmol/L)
47. Creatinine, Serum
Abnormal Findings- Elevated Levels
Plasma creatinine of 2 mg/dL indicates that renal disease has
seriously damaged 50% or more of the nephrons.
Gigantism and acromegaly.
Nursing Implications
Anticipate the need for additional testing.
Prepare the patient for follow-up and treatment.
Monitor fluid balance and intake and output.
48. Creatinine, Serum
Abnormal Findings- Decreased Levels
Liver disease
Deficient levels of protein in the diet.
Small build
Loss of muscle mass
Nursing Implications
Anticipate the need for additional testing.
Prepare the patient for follow-up and treatment.
Monitor fluid balance and intake and output.
49. Creatinine, Serum
Interfering Factors
Ascorbic acid, barbiturates, and diuretics (possible increase)
Exceptionally large muscle mass, such as is found in athletes
(possible increase despite normal renal function)
50. Creatinine, Serum
Nursing Considerations- Before the Test
Confirm the patient’s identity using two patient identifiers
according to facility policy.
Explain to the patient that the serum creatinine test is used to
evaluate kidney function.
Tell the patient that the test requires a blood sample.
Instruct the patient that he doesn’t need to restrict food and
fluids.
Notify the laboratory and the practitioner of medications the
patient is taking that may affect test results; they may need to
be restricted.
51. Creatinine, Serum
Nursing Considerations- During the Test
Handle the sample gently to prevent hemolysis.
After the Test
Send the sample to the laboratory immediately.
Apply direct pressure to the venipuncture site until bleeding stops.
Assess the venipuncture site for hematoma formation; if one
develops, apply pressure.
Inform the patient that he may resume his usual medications that
were discontinued before the test, as ordered.
52. Liver Function Tests (LFT)
Liver function tests are blood tests that measure different
enzymes, proteins, and other substances made by the liver.
The different substances are often tested at the same time on
a single blood sample, and may include the following:
Albumin.
Total protein.
ALP (alkaline phosphatase), ALT (alanine transaminase), AST
(aspartate aminotransferase),
Bilirubin, a waste product made by the liver.
53. Albumin
Description
The test measures the amount of albumin in serum.
Albumin is the most abundant protein, composing almost 54%
of plasma proteins
Purpose
To help determine whether a patient has liver or kidney
disease
To determine whether enough protein is being absorbed by
the body.
55. Albumin
Abnormal Findings- Elevated Levels (Hyperalbuminemia)
Dehydration
Severe vomiting
Severe diarrhea
Nursing Implications
Report abnormal findings to the practitioner.
Prepare to administer IV fluids to restore volume and
electrolytes.
Educate the patient about his disease and treatment options.
56. Albumin
Abnormal Findings- Decreased Levels (Hypoalbuminemia)
Cirrhosis
Acute liver failure
Severe burns
Severe malnutrition
Ulcerative colitis
Nursing Implications
Prepare to administer IV albumin.
Educate the patient about his disease and treatment options.
58. Albumin
Nursing Considerations - Before the Test
Confirm the patient’s identity using two patient identifiers
according to facility policy.
Inform the patient that he doesn’t need to restrict fluids.
Describe the venipuncture procedure to the patient.
Explain that certain medications can increase albumin
measurements, including anabolic steroids, androgens,
growth hormones, and insulin.
The patient may need to stop taking these drugs before the
test.
59. Albumin
During the Test
Perform a venipuncture, and collect 5 to 10 mL in a red-top
tube.
After the Test
Apply direct pressure to the venipuncture site until bleeding
stops.
Encourage the patient to eat a high protein diet, if not
contraindicated.
60. Bilirubin (Serum)
Description
The bilirubin test is used to measure serum levels of bilirubin,
the predominant pigment in bile.
Bilirubin is the major product of hemoglobin catabolism.
Serum bilirubin measurements are especially significant in
neonates because elevated unconjugated bilirubin can
accumulate in the brain, causing irreparable damage.
61. Bilirubin (Serum)
Purpose
To evaluate liver function.
To aid in the differential diagnosis of jaundice and monitor its
progress.
To help diagnose biliary obstruction and hemolytic anemia.
62. Bilirubin (Serum)
Reference Values
Adults: indirect serum bilirubin levels, 0.1 to 1.0 mg/dL (SI,
1.7–17.1 μmol/L);
Direct serum bilirubin levels, less than 0.5 mg/dL (SI, less
than 6.8 μmol/L)
63. Bilirubin (Serum)
Abnormal Findings- Elevated Levels
Hepatic damage or severe hemolytic anemia (elevated
indirect serum bilirubin).
Hemolysis (elevated indirect and direct serum bilirubin levels).
Biliary obstruction (elevated direct serum bilirubin levels).
Nursing Implications
Prepare the patient for additional testing as indicated.
64. Bilirubin (Serum)
Interfering Factors
Exposure of the sample to direct sunlight or ultraviolet light
(possible decrease).
Barbiturates and sulfonamides (possible decrease).
Precautions
Protect the sample from strong sunlight and ultraviolet light.
Handle the sample gently.
65. Bilirubin (Serum)
Nursing Considerations - Before the Test
Confirm the patient’s identity using two patient identifiers
according to facility policy.
Explain to the patient that the bilirubin test is used to evaluate
liver function and the condition of red blood cells.
Inform the patient that the test requires a blood sample from a
venipuncture.
Advise the patient that he may experience slight discomfort
from the tourniquet and needle puncture.
Inform the patient that he doesn’t need to restrict fluids, but
should fast for at least 4 hours before the test.
66. Bilirubin (Serum)
After the Test
Apply direct pressure to the venipuncture site until bleeding
stops.
Assess the venipuncture site for hematoma formation; if one
develops, apply direct pressure.
67. Coagulation Studies
Coagulation testing is useful for assessing patients' ability to
clot; for investigating the cause of a patient's coagulopathy;
and for therapeutic monitoring of certain anticoagulant
medications.
The classical coagulation profile includes:
Prothrombin time (PT)
Activated partial thromboplastin time (PTT).
68. Partial Thromboplastin Time (PTT)
Description
Also called the activated partial thromboplastin test (APTT).
The partial thromboplastin time (PTT) test is used to evaluate
all the clotting factors of the intrinsic pathway, except
platelets, by measuring the time required for formation of
a fibrin clot after calcium and phospholipid emulsion is
added to a plasma sample.
69. Partial Thromboplastin Time (PTT)
Purpose
To screen for clotting factor deficiencies in the intrinsic
pathways.
To monitor response to heparin therapy.
Reference Values
21 to 35 seconds (SI, 21–35 seconds)
Therapetic heparin therapy: 2 to 2.5 times normal limit
70. Partial Thromboplastin Time (PTT)
Abnormal Findings- Elevated Levels
Certain plasma clotting factor deficiencies.
Presence of heparin.
Vitamin K deficiency.
Genetic or acquired deficiency of clotting factors
Hemophilia A
Nursing Implications
Report abnormal findings to the practitioner.
Prepare to adjust the patient’s anticoagulant therapy as
indicated.
71. Partial Thromboplastin Time (PTT)
Decreased Levels
Extensive cancer
Nursing Implications
Report abnormal findings to the practitioner.
Prepare to adjust the patient’s anticoagulant therapy as
indicated.
72. Partial Thromboplastin Time (PTT)
Precautions
To prevent hemolysis, avoid excessive probing at the
venipuncture site and handle the sample gently.
73. Partial Thromboplastin Time (PTT)
Nursing Considerations- Before the Test
Confirm the patient’s identity using two patient identifiers
according to facility policy.
Explain to the patient that the PTT test is used to determine if
blood clots normally.
When appropriate, tell the patient receiving heparin therapy
that this test may be repeated at regular intervals to assess
his response to treatment.
Do not draw from a closed-loop blood sampling system in an
arterial line where heparin flush has been used. Do not draw
from an arm into which heparin is infused.
74. Partial Thromboplastin Time (PTT)
During the Test
Completely fill the collection tube, invert it gently several
times, and send it on ice to the laboratory
After the Test
Ensure subdermal bleeding has stopped before removing
pressure.
For a patient on anticoagulant therapy, apply additional
pressure at the venipuncture site to control bleeding.
If a hematoma develops at the venipuncture site, apply direct
pressure. If the hematoma is large, monitor pulses distal to
the venipuncture site.
75. Prothrombin Time (PT)
Description
PT measures the time required for a fibrin clot to form in a
citrated plasma sample after the addition of calcium ions and
tissue thromboplastin (factor III).
Purpose
To evaluate the extrinsic coagulation system (factors V, VII,
and X, and prothrombin and fibrinogen)
To monitor response to oral anticoagulant therapy
76. Prothrombin Time (PT)
Reference Values
10 to 14 seconds (SI, 10–14 seconds)
For a patient receiving oral anticoagulants: 1 to 2½ times the
normal control value.
Abnormal Findings
Prolonged prothrombin time (PT) (exceeding 2½ times the
control value; may result from deficiencies in fibrinogen,
prothrombin, vitamin K, or factor V, VII, or X)
Nursing Implications
Report abnormal findings to the practitioner.
Prepare to adjust the patient’s anticoagulant dosage as
indicated.
77. Prothrombin Time (PT)
Interfering Factors
Salicylates, more than 1 g/day (increase).
Antihistamines, corticosteroids, digoxin (Lanoxin), diuretics,
vitamin K (possible decrease).
Heparin IV (within 5 hours of sample collection) vitamin A, or
alcohol in excess (prolonged PT).
Antibiotics, barbiturates (possible increase or decrease).
78. Prothrombin Time (PT)
Precautions
To prevent hemolysis, avoid excessive probing during
venipuncture and handle the sample gently.
79. Prothrombin Time (PT)
Nursing Considerations- Before the Test
Confirm the patient’s identity using two patient identifiers
according to facility policy.
Explain to the patient that the PT test is used to determine if
the blood clots normally. When appropriate, explain that this
test is used to monitor the effects of oral anticoagulants.
The test will be performed daily when therapy begins and will
be repeated at longer intervals when medication levels
stabilize.
80. Prothrombin Time (PT)
Nursing Considerations- Before the Test
Inform the patient that he doesn’t need to restrict food and
fluids for the test.
Notify the laboratory and practitioner of medications the
patient is taking that may affect test results; they may need to
be restricted.
During the Test
Completely fill the collection tube and invert it gently several
times to mix the sample and the anticoagulant thoroughly.
81. Prothrombin Time (PT)
After the Test
Apply direct pressure to the venipuncture site until bleeding
stops.
If a hematoma develops at the venipuncture site, apply
pressure. If the hematoma is large, monitor pulses distal to
the venipuncture site.
Tell the patient that he may resume his usual diet and
medications discontinued before the test, as ordered.
82. Electrolyte
Electrolytes are involved in many essential processes in your
body.
They play a role in conducting nervous impulses, contracting
muscles, keeping you hydrated and regulating your body’s pH
levels.
Electrolytes found in your body include:
Sodium
Potassium
Chloride
Calcium
Magnesium
Phosphate
Bicarbonate
83. Sodium, Serum
Purpose
To evaluate fluid, electrolyte, and acid–base balance and
related neuromuscular, renal, and adrenal functions.
Reference Values
Adults and children: 135 to 145 mEq/L (SI, 135–145 mmol/L)
84. Sodium, Serum
Critical Values
Less than 120 mEq/L (SI, 120 mmol/L) or
greater than 160 mEq/L (SI, greater than 160 mmol/L)
86. Sodium, Serum
Nursing Implications
Report abnormal findings to the practitioner.
Observe the patient for hypernatremia (Na+ greater than 135)
and associated water loss, signs of thirst, restlessness, dry
and sticky mucous membranes, flushed skin, oliguria, and
diminished reflexes.
If increased total body sodium causes water retention,
observe for hypertension, dyspnea, edema, and heart failure.
Prepare the patient for further testing as indicated.
88. Sodium, Serum
Nursing Implications - Decreased Levels
Report abnormal findings to the practitioner.
In the patient with hyponatremia, watch for apprehension,
headache, decreased skin turgor, abdominal cramps, and
tremors that may progress to seizures.
Prepare the patient for further testing as indicated.
89. Sodium, Serum
Interfering Factors
Most diuretics (decrease by promoting sodium excretion).
Corticosteroids (increase by promoting sodium retention).
Antihypertensives (possible increase due to sodium and water
retention)
90. Sodium, Serum
Precautions
Handle the sample gently to prevent hemolysis.
Nursing Considerations- Before the Test
Confirm the patient’s identity using two patient identifiers
according to facility policy.
Explain to the patient that the serum sodium test is used to
determine the sodium content of the blood.
Inform the patient that he doesn’t need to restrict food and
fluids for the test.
91. Sodium, Serum
After the Test
Apply direct pressure to the venipuncture site until bleeding
stops.
If a hematoma develops at the venipuncture site, apply direct
pressure.
Instruct the patient to resume any medications that were
discontinued before the test, as ordered.
92. Potassium, Serum
Purpose
To evaluate clinical signs of potassium excess (hyperkalemia)
or potassium depletion (hypokalemia).
To monitor renal function, acid–base balance, and glucose
metabolism.
To evaluate neuromuscular and endocrine disorders.
To detect the origin of arrhythmias.
94. Potassium, Serum
Nursing Implications - Elevated Levels
Report abnormal findings to the practitioner
Observe the patient with hyperkalemia for weakness, malaise,
nausea, diarrhea, colicky pain, muscle irritability progressing
to flaccid paralysis, oliguria, and bradycardia.
Observe the electrocardiogram (ECG) changes
95. Potassium, Serum
Decreased Levels
Cushing’s syndrome.
Body fluids loss (such as long term diuretic therapy, vomiting,
or diarrhea).
Draining wounds.
Cystic fibrosis.
Severe burns.
Diuretic, antibiotic.
96. Potassium, Serum
Nursing Implications - Decreased Levels
Observe the patient with hypokalemia for decreased reflexes;
a rapid, weak, irregular pulse; mental confusion; hypotension;
anorexia; muscle weakness; and paresthesia.
Monitor the ECG changes.
97. Potassium, Serum
Interfering Factors
Repeated clenching of the fist before venipuncture (possible
increase).
Excessive or rapid potassium infusion, spironolactone or
penicillin (increase)
Insulin and glucose administration; diuretic therapy
(especially with thiazides decrease)
98. Potassium, Serum
Precautions
Draw the sample immediately after applying the tourniquet
because a delay may increase the potassium level.
Handle the sample gently to prevent hemolysis.
In severe cases, ventricular fibrillation, respiratory paralysis,
and cardiac arrest can develop. (Cardiac arrest may occur
without warning.)
99. Potassium, Serum
Nursing Considerations - Before the Test
Confirm the patient’s identity using two patient identifiers
according to facility policy.
Explain to the patient that the serum potassium test is used to
determine the potassium content of blood.
Advise the patient that the test requires a blood sample.
Explain that he may experience slight discomfort from the
needle puncture and the tourniquet.
Inform the patient that he doesn’t need to restrict food and
fluids for the test.
100. Potassium, Serum
After the Test
Apply direct pressure to the venipuncture site until bleeding
stops.
If a hematoma develops at the venipuncture site, apply direct
pressure.
Tell the patient to resume medications that were discontinued
before the test, as ordered.
101. Reference
Brunner & Suddarth’s. (2010). Handbook of Laboratory and Diagnostic Tests.
Wolters Kluwer Health, Lippincott Williams & Wilkins.