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LPN IV Series: Homeostasis and Regulatory Functions Relationship to IV Therapy

2 Contact Hours
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This peer reviewed course is applicable for the following professions:
Licensed Practical Nurse (LPN), Licensed Vocational Nurses (LVN)
This course will be updated or discontinued on or before Saturday, December 7, 2024

Nationally Accredited

CEUFast, Inc. is accredited as a provider of nursing continuing professional development by the American Nurses Credentialing Center's Commission on Accreditation. ANCC Provider number #P0274.

This course is 1 of 8 courses available on CEUfast to meet the 24 hour written portion of the Florida LPN IV Certification requirement. The remaining 6 hours on the return demonstration of IV skills must be completed in person. To find a provider, or if you are interested in becoming a provider, refer to our Provider Information page.

Contact hours for L.P.N.s in any state are earned by completing this course. This course is part of a series of 24 contact hours of courses to prepare for LPN IV Certification in Florida. Florida certification participants must schedule a 6-hour live presentation and return demonstration to complete IV Certification. does not provide the live presentation.

The purpose of this continuing education course is to enable the participants to safely administer IV Fluids.


After completing this continuing education course, the participant will be able to meet the following objectives:

  1. Discuss hemostasis.
  2. Identify the function of electrolytes.
  3. Discuss the cause of major electrolyte imbalances.
  4. Identity IV fluid differences.
  5. Discuss the use of Isotonic, hypotonic and hypertonic fluids.
CEUFast Inc. and the course planners for this educational activity do not have any relevant financial relationship(s) to disclose with ineligible companies whose primary business is producing, marketing, selling, re-selling, or distributing healthcare products used by or on patients.

Last Updated:
To earn of certificate of completion you have one of two options:
  1. Take test and pass with a score of at least 80%
  2. Reflect on practice impact by completing self-reflection, self-assessment and course evaluation.
    (NOTE: Some approval agencies and organizations require you to take a test and self reflection is NOT an option.)
Authors:    Wesley Hunter (RN, PMT) , Julia Tortorice (RN, MBA, MSN, NEA-BC, CPHQ)


The type of IV fluid seems very benign. It is not. The IV fluid that you hang must be correct. Otherwise, you can cause the patient to get worse or die.


Homeostasis is the steady-state of the body by which the body's internal systems maintain a balance. It is maintained by adaptive responses that promote healthy functioning of the body.

One of the primary objectives of I.V. therapy is to maintain or restore the fluid and electrolyte balance in the body. Our bodies are composed largely of fluid. These fluids will account for about 60% of total body weight in an adult male and 45%-50% in an adult woman. In infants, fluids account for about 80% of total body weight and will steadily decrease throughout childhood until it reaches adult percentages at around 8.

Body fluids are composed of water and solutes. Solutes are classified as either electrolytes or nonelectrolytes. The nonelectrolytes are solutes without an electrical charge, including glucose, proteins, lipids, oxygen, carbon dioxide, and organic acids. The electrolytes will be discussed later.

Fluids help:

  • regulate the body's temperature
  • transport nutrients and gases throughout the body
  • carry cellular waste products to excretion sites

The body fluids are distributed between two major compartments: intracellular fluid is inside the cells, and extracellular is fluid outside of the cells.

The extracellular fluid occurs in two forms: interstitial fluid surrounding each cell and lymph gland: and intravascular fluid, which is blood plasma. The interstitial fluid comprises the cerebrospinal, pleural, peritoneal, or synovial fluids and the secretions from the salivary glands, pancreas, liver, and sweat glands. The distribution of fluids between these two compartments is constant when the body is healthy. The heart, kidneys, liver, adrenal and pituitary glands, and nervous system all play a part in maintaining fluid balance in the body.

If there is fluid accumulation in a compartment other than the intracellular or extracellular space, it is referred to as third-space fluid shifting. This accumulation happens when a cellular membrane allows water and fluid to enter but not exit. For example, fluids will pool in the burn site with severe burns, causing depletion of the intracellular fluid (I.C.F.) and Extracellular fluid (E.C.F.). If pancreatitis fluids "leak out" into the peritoneal cavity, this causes depletion in the I.C.F. and E.C.F. Patients undergoing long and extensive surgeries will collect third-space fluids and become intravascularly depleted despite the administration of large volumes of I.V. fluids and blood. Third-space fluid shifting can also occur due to acute bowel obstruction, ascites, and sepsis. These patients will experience tachycardia, hypotension, weight gain, low urine output, poor skin turgor, and hyponatremia.

Fluid balance is also affected by:

  • fluid volume
  • distribution of fluids in the body
  • concentration of solutes in the fluid

The distribution of fluids depends on the hydrostatic and colloid osmotic pressures in the capillaries. Fluid volumes and concentration are regulated by interacting with two hormones, antidiuretic hormone (ADH) and aldosterone.

ADH is secreted when plasma osmolarity increases or circulating blood volume decreases, and blood pressure drop. ADH restores blood volume by reducing diuresis and increasing water retention.

Aldosterone is secreted when the serum sodium level is low, the potassium level is high, or the circulation volume of fluid decreases. It causes the kidneys to retain sodium and water.

Osmolarity is the concentration of a solution. Usually, the serum has the same osmolarity as other body fluids, approximately 300 mOsm/L. If your patient has a serum osmolarity lower, they may have a fluid overload. A higher serum osmolarity indicates the patient may be experiencing hemoconcentration of the fluid and dehydration.

Body fluids are in constant motion moving between the fluid compartments through membranes. Homeostasis is maintained when the solutes and fluids are distributed evenly on each membrane side. When there is an imbalance, these molecules will move between the compartments by various routes, including:

  • In diffusion, molecules move from areas of higher concentration to areas of lower concentration
  • Active transport requires energy for molecules to move from areas of lower
  • concentration to areas of higher concentration. These molecules are moved by physiologic pumps (sodium-potassium pump)
  • Passive transport, solutes are affected by the electrical potential across cell membranes
  • Filtration is the movement of substances from an area of high hydrostatic pressure to an area of lower hydrostatic pressure
  • Capillary filtration forces fluid and solutes through capillary wall pores
  • Osmosis fluids flow passively from an area of higher water concentration to an area of lower concentration. The process stops when the solute concentrations on both sides of the membrane are equal. Responds to osmolality changes because of osmotic and hydrostatic pressures


Table 1: Electrolyte
ElectrolyteNormal ValuePrincipal FunctionsSigns of Imbalance
  • Major cation in ECF
135-145 mEq/L
  • Maintains ECF osmolarity
  • Helps maintain BP
  • Influences water distribution
  • Helps regulate acid-base balance
  • Aids nerve/muscle fiber impulse transmission
  • Hypernatremia: Irritability, thirst, fever, decreased urine output, flushed skin, hypertension
  • Hyponatremia: Irritability, fatigue, muscle weakness, tachycardia, headache, hypotension, increased urine cutout
  • Major cation in ICF
3.5-5.0 mEq/L
  • Maintains fluid balance in cells
  • Maintains cell osmolarity
  • Contracts skeletal, cardiac, and smooth muscles
  • Major role is acid-base balance
  • Promotes cell growth
  • Hyperkalemia: muscle weakness, nausea, diarrhea, lethargy, bradycardia, hypotension, cardiac arrhythmias
  • Hypokalemia: fatigue, weakness, leg cramps, weak/irregular pulse, hypotension, hyperglycemia, bradycardia, cardiac arrhythmias
  • Major anion in ECF
96-106 mEq/L
  • Maintains serum osmolarity
  • Combines with other major cations to create important compounds: NaCl, HCI, KCI, CaCI
  • Hyperchloremia: stupor, rapid/ deep breathing, muscle weakness
  • Hypochloremia: increased muscle excitability, tetany, decreased respirations
  • 99% found in bones and teeth
8.9-10.1 mg/di
  • Enhances bone strength Maintains muscle tone
  • Maintains cell membrane structure, function, permeability
  • Enzyme co-factor for clotting
  • Affects activation, excitation, and contraction of cardiac and skeletal muscles
  • Hypercalcemia: anorexia, nausea, fatigue, constipation, dehydration, headache, hypertension, cardiac arrhythmias
  • Hypocalcemia: muscle spasms or cramping in calf muscles, tetany, positive Chvostek or Trousseau sign, hyperreflexia, laryngospasm, cardiac arrhythmias
  • Major anoin in ICF
2.5-4.5 mg/di
  • Maintains cell integrity
  • Maintains bones/teeth
  • Major role in acid-base balance as a urinary buffer
  • Essential to muscle, red blood cell, and neurologic functions
  • Hyperphosphatemia: anorexia, nausea, tetany, tingling, cramps, nervousness, cardiac arrhythmias
  • Hypophosphatemia: lethargy, stuttering/stammering, joint stiffness, memory loss, muscle pain
  • Major cation in ICF
1.5-2.5 mg/di
  • Active in carbohydrate and protein metabolism
  • Facilitates sodium and potassium movement across all membranes
  • Influences calcium levels
  • Affects muscular irritability and contractions
  • Hypermagnesemia: muscle weakness, lethargy, nausea, hypotension, slow/weak pulse, bradycardia, decreased L.O.C.
  • Hypomagnesemia: dizziness, confusion, leg cramps, nausea, difficulty swallowing, cardiac arrhythmias
Table 2: Electrolyte Imbalance
Causes of ImbalanceTreatment


  • high sodium intake
  • not drinking enough fluids
  • excessive fluid loss (fever, diarrhea)
  • major burns
  • osmotic diuretics
  • diabetes insipidus
  • diuretic therapy
  • hydration
  • treat underlying cause
  • fluid overload (IV or PO)
  • hyperglycemia
  • heart failure
  • aggressive diuretic therapy
  • NG suctioning
  • vomiting
  • diarrhea
  • excessive sweating
  • giving hypotonic solutions
  • treat underlying cause
  • administer hypertonic solutions (slowly)
  • foods containing sodium
  • acidosis
  • renal failure
  • trauma,
  • burns
  • crush injury
  • tumor lysis syndrome
  • hemolysis
  • hyponatremia
  • loop diuretic
  • Kayexalate
  • IV Insulin
  • IV Sodium Bicarbonate
  • IV Calcium Gluconate
  • limit potassium containing foods
  • dialysis
  • diarrhea
  • vomiting
  • severe diaphoresis
  • prolonged diuretic therapy
  • gastric suctioning
  • OKA
  • hepatic disease
  • metabolic
  • respiratory alkalosis
  • KCL infusion (slow)
  • oral KCL supplement
  • foods high in potassium
  • diarrhea
  • hyperparathyroidism
  • respiratory alkalosis
  • hypernatremia
  • treat underlying cause
  • vomiting
  • diarrhea
  • sweating
  • prolonged fever
  • hyponatremia
  • respiratory acidosis
  • treat underlying cause
  • hyperparathyroidism
  • excessive intake of vitamin D or calcium containing antacids
  • prolonged immobilization
  • malignancies
  • I.V. fluids followed by a loop diuretic
  • I.V. calcitonin
  • dialysis
  • malignancies
  • vitamin D deficiency
  • alkalosis
  • hypoparathyroidism
  • pancreatitis
  • medications (Phenobarbital, Dilantin, Lasix) hyperphosphatemia
  • hypomagnesemia
  • malnutrition
  • IV calcium gluconate (slow)
  • vitamin D if chronic
  • acute/chronic renal failure
  • large intake of vitamin D
  • hypoparathyroidism
  • excessive use of laxatives or enemas containing phosphate
  • chemotherapy
  • calcium supplements
  • calcium based phosphate binders (Tums)
  • dialysis
  • malabsorption
  • respiratory alkalosis
  • prolonged vomiting
  • long term alcohol abuse
  • hyperparathyroidism
  • phosphate-binding antacids
  • IV infusion of phosphate
  • foods high in phosphorus
  • oral supplements
  • renal failure
  • diabetes mellitus
  • OKA
  • ALL
  • AML
  • excessive amounts of magnesium containing antacids (Tums, Maalox, Mylanta) or laxatives (MOM) severe preeclampsia (receiving IV magnesium)
  • Dialysis (renal failure)
  • loop diuretics,
  • fluid bolus
  • IV calcium
  • malabsorption (IBD, bowel resection, gastric bypass)
  • alcoholic patient going through withdrawal
  • hypothyroidism
  • hypoparathyroidism
  • hypercalcemia
  • high-dose steroid use
  • sepsis
  • pancreatitis
  • some meds (Amphotericin B, Cisplatin, Cyclosporine, Tobramycin,Gentamicin)
  • IV replacement (slow)
  • oral supplements

IV Fluids

There are three basic types of fluids that are utilized for IV therapy. They are:

  1. Isotonic
  2. Hypotonic
  3. Hypertonic

Tonicity and Osmosis

Isotonic fluids have the same osmolality as the serum and other body fluids (Nettina, 2019). It expands the intravascular compartment. It can treat hypotension secondary to hypovolemia or as maintenance fluids.

Isotonic fluids include:

  • 2.5% dextrose/0.45% sodium chloride
  • 0.9% sodium chloride (Normal Saline)
  • 5% dextrose and water
  • Normosol® 3
  • Plasmalyte® A
  • Plasmalyte® R
  • lsolyte® 4 E · Ringer's
  • Lactated Ringer's
  • 2.5% dextrose in 1/2 lactated Ringer's
  • 6% dextran and 0.9% sodium chloride
  • 10% dextran and 0.9% sodium chloride

Hypotonic fluids have a lower osmolality than the serum (Nettina, 2019). When given, they help hydrate the cells and can decrease the amount of fluid in the circulatory system. This treatment is used when diuretic therapy dehydrates the cells to lower serum sodium levels, treat diabetic ketoacidosis, and treat the hyperglycemic nonketotic syndrome.

Hypotonic fluids include:

  • 0.45% N.S. (Half-normal saline)
  • 0.33% N.S. (One-third saline)
  • O2.5W (Dextrose 2.5% in water)

Hypertonic solutions have a higher osmolality than the serum (Nettina, 2019). These fluids pull fluid from the interstitial and intracellular compartments back into the blood vessels. Can be used to treat hypovolemia, low serum sodium levels or to help reduce the risk of edema and low blood pressure in post-op patients.

Hypertonic fluids include:

  • 5% dextrose/0.2% sodium chloride
  • 5% dextrose/0.3% sodium chloride
  • 5% dextrose/0.45% sodium chloride
  • 5% dextrose/0.9% sodium chloride
  • 10% dextrose/0.2% sodium chloride
  • 10% dextrose/0.45% sodium chloride
  • 10% dextrose/0.9% sodium chloride
  • 3% sodium chloride
  • 5% sodium chloride
  • 10% dextrose and water
  • 50% dextrose and water
  • 5% dextrose in Ringer's
  • 5% dextrose in lactated Ringer's
  • 5% dextrose and 5% alcohol
  • 5% sodium bicarbonate injection
  • 10%, 15%, and 20% mannitol injection
  • 6% dextran and 0.9% sodium chloride
  • 10% dextran and 0.9% sodium chloride

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  • Nettina, Sandra M., "The Lippincott Manual of Nursing Practice" 11th Ed. Wolter Kluwer, Philadelphia, 2019.