Fluids and Electrolytes
• Nancy Lin, RN, MS
Reading Assignments
• Med/Surg:
• CH 16
• Ebersole & Hess’ (6th ed)
• CH 11 pp. 148-151
Fluid Compartments of the Body
Fig. 16-2
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2
Electrolytes
• Substances whose molecules dissociate into ions
when placed in water
• Cations: positively charged
• Anions: negatively charged
• Concentration of electrolytes is expressed in
milliequivalents (mEq)/L
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3
Electrolyte Composition
• ICF
• Prevalent cation is K+
• Prevalent anion is PO43−
• ECF
• Prevalent cation is Na+
• Prevalent anion is Cl−
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4
Concentrations of Cations and Anions in
ICF and Plasma
Fig. 16-3
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5
Sodium-Potassium Pump
Fig. 16-5
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6
Osmotic Movement of Fluids
• The osmolality of the fluid surrounding cells affects them
• Isotonic—same as cell interior
• Hypotonic—solutes less concentrated
than in cells/ hypoosmolar
• Hypertonic—solutes more concentrated
than in cells/ hyperosmolar
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7
Regulation of Water Balance
(1 of 5)
• Hypothalamic-pituitary regulation
• Osmoreceptors in hypothalamus
sense fluid deficit or increase
• Deficit stimulates thirst and
antidiuretic hormone (ADH) release
• Decreased plasma osmolality (water
excess) suppresses ADH release
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8
Regulation of Water Balance
(2 of 5)
• Renal regulation
• Primary organs for regulating fluid
and electrolyte balance
• Adjusting urine volume
• Selective reabsorption of water and electrolytes
• Renal tubules are sites of action of ADH and aldosterone
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9
Regulation of Water Balance
(3 of 5)
• Adrenal cortical regulation
• Releases hormones to regulate
water and electrolytes
• Glucocorticoids
• Cortisol
• Mineralocorticoids
• Aldosterone
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10
Regulation of Water Balance
(4 of 5)
• Cardiac regulation
• Natriuretic peptides are antagonists to
the RAAS
• Hormones made by cardiomyocytes in
response to increased atrial pressure
• They suppress secretion of aldosterone,
renin, and ADH to decrease blood
volume and pressure
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11
Regulation of Water Balance
(5 of 5)
• GI regulation
• Oral intake accounts for most water
• Small amounts of water are
eliminated by GI tract in feces
• Diarrhea and vomiting can lead to
significant fluid and electrolyte loss
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12
Gerontologic Considerations
• Structural changes in kidneys decrease
ability to conserve water
• Hormonal changes include a decrease
in renin and aldosterone and increase
in ADH and ANP
• Subcutaneous tissue loss leads to
increased moisture lost
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13
Fluid and Electrolyte Imbalances
• Directly caused by illness or disease
(burns or heart failure)
• Result of therapeutic measures
(colonoscopy preparation, diuretics)
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14
Sodium
• Imbalances typically associated with parallel changes in
osmolality
• Plays a major role in
• ECF volume and concentration
• Generating and transmitting nerve
impulses
• Muscle contractility
• Regulating acid-base balance
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15
Hypernatremia
• High serum sodium may occur with
inadequate water intake, excess water
loss or sodium gain
• Causes hyperosmolality leading to
cellular dehydration
• Primary protection is thirst
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16
Hypernatremia: Causes
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Model
Medications, meals
Osmotic diuretics
Diabetes insipidus
Excessive water loss
Low water intake
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Hypernatremia
• Manifestations
• Thirst
• Changes in mental status, ranging
from drowsiness, restlessness,
confusion and lethargy to seizures
and coma
• Symptoms of fluid volume deficit
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18
Hypernatremia: Signs & Symptoms
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Fried
Fever (low grade), flushed skin
Restless and irritable
Increased fluid retention and increased BP
Edema (peripheral and pitting)
Decreased urinary output, dry mouth
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Nursing Diagnoses
• Electrolyte imbalance
• Fluid imbalance
• Risk for injury
• Potential complication: Seizures and
coma
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20
Nursing Implementation
• Treat underlying cause
• Primary water deficit—replace fluid
orally or IV with isotonic or hypotonic
fluids
• Excess sodium—dilute with sodium-free
IV fluids and promote sodium excretion
with diuretics
• Reduce level gradually
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21
Hyponatremia
• Results from loss of sodium-containing fluids and/or
from water excess
• Clinical manifestations
• Mild—headache, irritability,
difficulty concentrating.
• More severe—confusion, vomiting,
seizures, coma
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22
Hyponatremia: Signs & Symptoms
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Salt Loss
Stupor and coma
Anorexia, N&V
Lethargy
Tendon reflexes decreased
Limp muscles (weakness)
Orthostatic hypotension
Seizures and headaches
Stomach cramping
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Nursing Implementation
If the cause is water excess,
• Fluid restriction may be only
treatment
• Loop diuretics and demeclocycline
• Severe symptoms (seizures)
• Give small amount of IV hypertonic saline solution (3%
NaCl)
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24
Nursing Implementation
• If the cause is abnormal fluid loss,
• Fluid replacement with isotonic
sodium-containing solution
• Encouraging oral intake
• Withholding diuretics
• Drugs that block vasopressin (ADH)
• Convaptan (Vaprisol)
• Tolvaptan (Samsca)
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25
Chloride
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Primary anion in ECF (nl: 95-108 mEq/L)
Combines w/Na to create neutrality
Assists in reabsorption of Na in kidney
Essential for reabsorbing hydrogen ion to
buffer alkalosis
• Lost through vomiting, excessive sweating
• Normally excreted in urine
Potassium (1 of 2)
• Major ICF cation
• Necessary for
• Resting membrane potential of
nerve and muscle cells
• Cellular growth
• Maintenance of cardiac rhythms
• Acid-base balance
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27
Potassium (2 of 2)
• Sources
• Protein-rich foods
• Fruits and vegetables
• Salt substitutes
• Potassium medications (PO, IV)
• Stored blood
• Regulated by kidneys
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28
Hyperkalemia
• High serum potassium caused by
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Impaired renal excretion
Shift from ICF to ECF
Massive intake of potassium
Some drugs
• Most common in renal failure
• Common in massive cell destruction
– Burn, crush injury, tumor lysis
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29
Hyperkalemia: Causes
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Machine
Medications - ACE inhibitors, NSAIDS
Acidosis – metabolic & respiratory
Cellular destruction – burns, traumatic injury
Hypoaldosteronism, hemolysis
Intake – excessive
Nephrons, renal failure
Excretion – impaired
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Hyperkalemia
• Manifestations
• Dysrhythmias
• Fatigue, confusion
• Tetany, muscle cramps
• Weak or paralyzed skeletal muscles
• Abdominal cramping or diarrhea
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31
Hyperkalemia: Manifestations
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Murder
Muscle weakness
Urine, oliguria, anuria
Respiratory distress
Decreased cardiac contractility
ECG changes
Reflexes, hyperreflexia, or areflexia (flaccid)
•
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ECG Effects of Hyperkalemia
Fig. 16-14
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33
Potassium Imbalances: Hyperkalemia
Clinical manifestations
Hyperkalemia in Acidosis
• As blood [H+] rises in
cases of acidosis, more
H+ ions are pumped
intracellularly in
exchange for K+ ions
that are pumped
extracellularly to
maintain electrical
neutrality.
Nursing Implementation
• Stop oral and parenteral K+ intake
• Increase K+ excretion (diuretics, dialysis,
Veltessa and/or Kayexalate)
• Force K+ from ECF to ICF by IV insulin with
dextrose and a -adrenergic agonist or
sodium bicarbonate
• Stabilize cardiac cell membrane by
administering calcium gluconate IV
• Use continuous ECG monitoring
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36
Nursing Implication
Hyperkalemia
• CBIGKD “see big kid”
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Calcium chloride or gluconate
Bicarbonate
Insulin
Glucose
Kayexalate
Dialysis/Diuretics
Hypokalemia (1 of 2)
• Low serum potassium caused by
• Increased loss of K+ via the kidneys
or gastrointestinal tract
• Increased shift of K+ from ECF to ICF
• Dietary K+ deficiency (rare)
• Renal losses from diuresis
• Magnesium deficiency
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38
Hypokalemia (2 of 2)
• Manifestations
• Cardiac most serious
• Skeletal muscle weakness (legs)
• Weakness of respiratory muscles
• Decreased GI motility
• Hyperglycemia
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39
Hypokalemia: Signs & Symptoms
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6 L’s
Lethargy
Leg cramps
Limp muscles
Low, shallow respirations
Lethal cardiac dysrhythmias
Lots of urine (polyuria)
•
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ECG Effects of Hypokalemia
Fig. 16-14
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41
Potassium Imbalances
Hypokalemia
• Clinical Manifestations:
• “SUCTION”
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Skeletal muscle weakness
U wave
Constipation
Toxic effects of digoxin
Irregular, weak pulse
Orthostatic hypotension
Numbness (paresthesia)
Nursing Implementation
• KCl supplements orally or IV
• Always dilute IV KCl
• NEVER give KCl via IV push or as
a bolus
• Should not exceed 10 mEq/hr
• Use an infusion pump
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43
ECG changes associated with alterations in potassium status
Calcium
• Functions
• Formation of teeth and bone
• Blood clotting
• Transmission of nerve impulses
• Myocardial contractions
• Muscle contractions
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45
Calcium
• Obtained from dietary intake
• Need vitamin D to absorb
• Present in bones and plasma
• Ionized calcium is biologically active
• Changes in pH and serum albumin affect levels
• Inverse relationship with phosphorus
• Blocks sodium transport
• Stabilizes cell membrane
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46
Calcium
• Balance controlled by
• Parathyroid hormone
• Increases bone resorption, GI absorption, and renal
tubule reabsorption of calcium
• Calcitonin
• Increases calcium deposition into bone, increases renal
calcium excretion, and decreases GI absorption
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47
Calcium
• Balance controlled by
– Parathyroid hormone
– Calcitonin
– Vitamin D
Hypercalcemia (1 of 2)
• High levels of serum calcium
caused by
• Hyperparathyroidism (two-thirds
of cases)
– Malignancy
– Vitamin D overdose
– Prolonged immobilization
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49
Hypercalcemia (2 of 2) - Manifestations
• Dec. excitability
– Skeletal muscle
– Cardiac muscle
– Nervous system
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Fatigue, lethargy, weakness, confusion
Hallucinations, seizures, coma
Dysrhythmias
Bone pain, fractures, nephrolithiasis
Polyuria, dehydration
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50
Hypercalcemia: Signs & Symptoms
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Groans, Moans, Bones, Stones, and Overtones
Groans: constipation
Moans: pain – joint aches
Bones: loss of calcium from bones, bone
metastasis
• Stones: kidney stones
• Overtones: psychiatric overtones – depression,
confusion
•
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Nursing Implementation
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Excretion of Ca with loop diuretic
Low calcium diet
Increased weight-bearing activity
Increased fluid intake
Hydration with isotonic saline infusion
Bisphosphonates—gold standard
Synthetic calcitonin (IM or SC)
Mobilization
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52
Hypocalcemia (1 of 2)
• Low serum Ca levels caused by
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Decreased production of PTH
Multiple blood transfusions
Alkalosis
Increased calcium loss
Acute pancreatitis
Multiple blood transfusions
Decreased intake
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53
Hypocalcemia (2 of 2)
• Manifestations
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Positive Trousseau’s or Chvostek’s sign
Laryngeal stridor
Dysphagia
Numbness and tingling around the
mouth or in the extremities
• Dysrhythmias
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54
Hypocalcemia: Signs & Symptoms
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Cats
Convulsions
Arrhythmias
Tetany
Spasms and stridor
•
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Tests for Hypocalcemia
Fig. 16-15
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56
Nursing Implementation
• Treat cause
• Calcium and Vitamin D supplements
• Not IM to avoid local reactions
• IV calcium gluconate
• Rebreathe into paper bag
• Treat pain and anxiety to prevent
hyperventilation-induced respiratory
alkalosis
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57
Phosphate
• Primary anion in ICF
• Essential to function of muscle, red blood
cells, and nervous system
• Deposited with calcium for bone and tooth
structure
• Involved in acid-base buffering system, ATP
production, cellular uptake of glucose, and
metabolism of carbohydrates, proteins, and
fats
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58
Phosphate
• Serum levels controlled by parathyroid
hormone
• Maintenance requires adequate renal
functioning
• Reciprocal relationship with calcium
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59
Hyperphosphatemia (1 of 3)
• High serum PO43− caused by
• Acute kidney injury or chronic
kidney disease
• Chemotherapy
• Excess intake of phosphate or
vitamin D
• Hypoparathyroidism
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60
Hyperphosphatemia (2 of 3)
• Manifestations
• Tetany, muscle cramps, paresthesias, hypotension,
dysrhythmias, seizures (hypocalcemia)
• Calcified deposition in soft tissue such as joints,
arteries, skin, kidneys, and corneas (cause organ
dysfunction)
• Neuromuscular irritability and tetany (hypocalcemia)
• Calcified deposition in soft tissue such as joints,
arteries, skin, kidneys, and corneas (can cause organ
dysfunction)
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61
Hyperphosphatemia (3 of 3)
•
Management
• Identify and treat underlying cause
• Restrict intake of foods and fluids containing
phosphorus
• Oral phosphate-binding agents
• Hemodialysis
• Volume expansion and forced diuresis
• Correct any hypocalcemia
• Adequate hydration and correction of hypocalcemic
conditions
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62
Hypophosphatemia (1 of 3)
• Low serum PO43− caused by
• Malnourishment/malabsorption
• Diarrhea
• Use of phosphate-binding antacids
• Inadequate replacement during
parenteral nutrition
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63
Hypophosphatemia (2 of 3)
• Manifestations
• CNS depression
• Muscle weakness and pain
• Respiratory and heart failure
• Rickets and osteomalacia
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64
Hypophosphatemia (3 of 3)
• Management
• Oral supplementation
• Ingestion of foods high in
phosphorus
• IV administration of sodium or
potassium phosphate
• Monitor serum calcium and phosphorus levels every 6 to
12 hours
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65
Self Assessment
• The nurse anticipates that the patient with
hyperphosphatemia secondary to renal
failure will require
a. calcium supplements.
b. potassium supplements.
c. magnesium supplements.
d. fluid replacement therapy.
Magnesium (1 of 2)
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Second most abundant intracellular cation
Essential for proper neuromuscular function
Levels controlled by kidneys
Cofactor in enzyme for metabolism of
carbohydrates
Required for DNA and protein synthesis
Blood glucose control
BP regulation
Needed for ATP production
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67
Magnesium (2 of 2)
• Acts directly on myoneural junction
• Important for normal cardiac function
• 50% to 60% contained in bone
• Only 1% in ECF
• Absorbed in GI tract
• Excreted by kidneys
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68
Hypermagnesemia (1 of 3)
• High serum Mg caused by
• Increased intake of products
containing magnesium when renal
insufficiency or failure is present
• Excess IV magnesium
administration
• Advanced CKD
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69
Hypermagnesemia (2 of 3)
• Manifestations
• Hypotension, facial flushing
• Lethargy
• Nausea and vomiting
• Impaired deep tendon reflexes
• Muscle paralysis
• Respiratory and cardiac arrest
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70
Hypermagnesemia (3 of 3)
• Management
• Prevention first—restrict magnesium
intake in high-risk patients
• IV CaCl or calcium gluconate if
symptomatic
• Fluids and IV furosemide to promote
urinary excretion
• Dialysis
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71
Hypomagnesemia
• Low serum Mg caused by
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•
Prolonged fasting or starvation
Chronic alcoholism
Fluid loss from GI tract
Prolonged parenteral nutrition without
supplementation
• Diuretics, proton-pump inhibitors
• Hyperglycemic osmotic diuresis
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72
Hypomagnesemia
• Manifestations
• Resembles hypocalcemia
• Muscle cramps, tremors
• Hyperactive deep tendon reflexes
• Chvostek’s and Trousseau’s signs
• Confusion, vertigo, seizures
• Dysrhythmias
• Corresponding hypocalcemia and
hypokalemia
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73
Hypomagnesemia
Manifestations
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3 T’s
Tremors
Twitching
Tetany
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STARVED
SZ
Tetany
Anorexia & Arrhythmias
Rapid HR
Vomiting
Emotional lability
DTRs (hyperactive)
Hypomagnesemia
• Management
• Treat underlying cause
• Oral supplements
• Increase dietary intake
• Parenteral IV or IM magnesium
when severe
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75
Audience Response Question (1 of 2)
A patient is admitted with renal failure
and an arterial blood pH level of 7.29.
Which lab result would the nurse expect?
a. Serum sodium 138 mEq/L
b. Serum glucose 145 mg/dL
c. Serum potassium 5.9 mEq/L
d. Serum magnesium 0.4 mg/dL
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76
Audience Response Question (2 of 2)
Answer: C
Serum potassium 5.9 mEq/L
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77
References
Fluids & Electrolytes made Incredibly Easy! 7th
edition. (2019). Lippincott Williams & Wilkins.
Harding , Kwong, Hagler, Roberts & Reinisch (2020).
Lewis’s Medical surgical nursing: assessment and
management of clinical problems (11th Ed.).
Mosby/Elsevier
Touhy, T., & Jett, K (2021). Ebersole and Hess’
Gerontological nursing & healthy aging (6th Ed.)
Mosby/Elsevier