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

2 Contact Hours
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 Wednesday, December 7, 2022
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 LPNs in any state are earned by completing this course. This 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. The live presentation is not provided by

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. did not endorse any product, or receive any commercial support or sponsorship for this course. The Planning Committee and Authors do not have any conflict of interest.

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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 internal systems of the body 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 and/or restore the fluid and electrolyte balance in the body. Our bodies are composed largely of fluid. In fact, 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 the age of 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 and include: 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. Part of the interstitial fluid is also made up of 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 happens when a cellular membrane allows water and fluid to enter but not exit. For example, with severe burns, fluids will pool in the burn site, causing depletion of the intracellular fluid (ICF) and Extracellular fluid (ECF). If pancreatitis fluids "leak out" into the peritoneal cavity this causes depletion in the ICF and ECF. Patients undergoing long and extensive surgeries will collect third-space fluids and will 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

Distribution of fluids depends on the hydrostatic and colloid osmotic pressures in the capillaries. Fluid volumes and concentration are regulated by the interaction of two hormones antidiuretic hormone (ADH) and aldosterone. 

ADH is secreted when plasma osmolarity increases or circulating blood volume decreases and blood pressure drops. 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 than this, they may have fluid overload. Whereas 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 side of the membrane. When there is an imbalance, these molecules will move between the compartments by various routes including:

  • 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,  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

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.1 It expands the intravascular compartment. It can be used to treat hypotension that is 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.1 When given they help hydrate the cells and can decrease the amount of fluid in the circulatory system. This is used when diuretic therapy dehydrates the cells, to lower serum sodium levels, in the treatment of diabetic ketoacidosis, and to treat hyperglycemic nonketotic syndrome. 

Hypotonic fluids include:

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

Hypertonic solutions have a higher osmolality than the serum.1 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 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

Select one of the following methods to complete this course.

Take TestPass an exam testing your knowledge of the course material.
Reflect on Practice ImpactDescribe how this course will impact your practice.   (No Test)


  1. Nettina, Sandra M., “The Lippincott Manual of Nursing Practice” 11th Ed. Wolter Kluwer, Philadelphia, 2019.