Fluid and Electrolytes

Electrolytes

• • Minerals in the body that can conduct electricity.

• • Found in urine, blood, tissues, as well as other body fluids.

• • Include potassium, sodium, calcium, and magnesium.

• • While naturally occurring in the body, can also be found in food, drinks, and supplements.

Electrolytes Are Responsible For

• • Balancing the amount of water in the body.

• • Balancing the body’s pH (acid/base) level.

• • Moving waste out of body cells.

• • Moving nutrients into body cells.

• • Allowing the body’s muscles, heart, nerves, and brain to function properly

Dehydration

• • The average person’s weight is one-half to two-thirds water. It is critical to the balance of water in the body. When a person is unable to drink enough fluids to compensate for excess water loss, dehydration can occur.

Water is 60% of body weight in an adult male.

• • Decreases with age

• • Less in women

• • Less in obese people because fat contains less water than muscle.

Fluid is water that contains substances such as

glucose, mineral salts (electrolytes), and proteins.

Extracellular Fluid (ECF)

• Outside the cells

• • 1/3 of total body water

• • 3 parts:

  • • Intravascular fluid

    • • Plasma of blood

  • • Interstitial fluid

    • • Between cells and outside of blood vessels

  • • Transcellular fluids

    • • CSF, pleural, peritoneal, synovia

• Contains Sodium (Na), Chloride (Cl), and Bicarbonate (HCO3)

Intravascular fluid

Plasma of blood

Interstitial fluid

Between cells and outside of blood vessels

Transcellular fluids

CSF, pleural, peritoneal, synovia

Intracellular Fluid (ICF)

• • Inside the cells

• • 2/3 of total body water

• • Balance maintained primarily through the cell membrane’s permeability

• • Contains potassium (K), Magnesium (Mg), Phosphates, and Proteins

Isotonic solution

Cells normal shape, no loss or gain of water 

Hypertonic solution

Cells lose water and shrink

Hypotonic solution

Cells swell rapidly as water rushes into them

 Osmolality of a fluid is a measure of

the number of particles per kilogram of water.

Some particles pass easily through cell membranes

urea

Some can’t cross easily through cell membranes

Na

Particles that can’t cross the cell membrane easily determine the

tonicity (concentration) of a fluid.

Isotonic

same as blood

Hypotonic

more dilute than blood

Hypertonic

more concentrated than

Thirst

Thirst results from nerve centers in the brain being stimulated when the body needs water. In order to conserve water, the pituitary gland secretes vasopressin (the antidiuretic hormone). The vasopressin stimulates the kidneys to excrete less urine which helps to conserve water.

Clinical Dehydration

• • ECV deficit and hypernatremia often occur at the same time

• • Causes: gastroenteritis (severe D, V)

• **Clinical Dehydration:

  • • ECV is too low and body fluids are too concentrated.

  • • See s/s of ECV deficit and hypernatremia slides

Movement of Fluids and Electrolytes

• • Active Transport

• • Diffusion

• • Osmosis

• • Filtration

Fluid Homeostasis Regulation:

• Fluid intake

• Fluid Distribution

• Fluid output

• 1. Fluid Intake

• • Drinking and eating

• • Food metabolism

• • IV

• • Rectal (enemas)

• • Irrigation of body cavities

• 2. Fluid Distribution

• • Movement of fluid

• • ECF vs ICF occurs by osmosis

  • • Vascular vs Interstitial ECF occurs by filtration

• 3. Fluid Output

• • Skin, lungs, GI, Kidneys

• • Insensible (not visible) losses via lung and skin

• Hormones Affecting Fluid Balance

• • Antidiuretic Hormone (ADH)

• • Renin-Angiotensin-Aldosterone System (RAAS)

• • Atrial Natriuretic Peptide (ANP)

• Fluid Imbalances

• • Extracellular Fluid Volume Imbalances

• • ECV deficit

• • ECV excess

• • Osmolality Imbalances

• • Sodium

Extracellular Fluid Volume Deficit Causes

• Sodium and water intake is less than output, causing isotonic loss

• • Decreased oral intake (anorexia, impaired swallowing, confusion, NPO)

• • Increased GI output (V, D, laxative use, drainage)

• • Increased renal output (diuretics, adrenal insufficiency)

• • Adrenal insufficiency decreases cortisol and aldosterone.

• • Loss of blood volume or plamsa (hemorrhage, burns)

• • Massive sweating without water and salt replacement.

Extracellular Fluid Volume Deficit Signs and Symptoms

• • Sudden weight loss

• • Postural hypotension

• • Tachycardia

• • Thready pulse

• • Dry mm

• • Poor skin turgor

• • Slow vein filling

• • Flat neck veins when supine

• • Dark yellow urine

• Severe s/s:

• • Thirst

• • Restlessness

• • Confusion

• • Hypotension

• • Oliguria (UO < 30 mL/hr)

• • Cold, clammy skin

• • Hypovolemic shock

Extracellular Fluid Volume Deficit Treatment

• • Identify the underlying cause

• • Treat the underlying cause

• Replace fluids:

  • • Oral for mild losses

  • • IV for greater losses (isotonic)

Extracellular Volume Excess (Fluid Volume Overload) Causes

• • Sodium and water intake are greater than output causing isotonic gain

• • Excess administration of isotonic IVF or oral intake of salty foods and water

• • Renal retention of Na and water (HF, cirrhosis, aldosterone or glucocorticoid excess, oliguric renal disease)

• • Remember that aldosterone causes resportion of Na and H2O in kidneys → returns to blood.

Extracellular Volume Excess (Fluid Volume Overload) Signs and Symptoms

• • Sudden weight gain

• • Edema

• • Full neck veins when upright

• • Crackles in lungs

• Severe s/s:

  • • Confusion

  • • Pulmonary edema

Extracellular Volume Excess (Fluid Volume Overload) Treatment

• Identify and treat the underlying cause

• • Administer medications (diuretics).

• • Restricting sodium and fluids.

• • Sit the patient up in bed, so they can breathe!

Hypovolemia

• • Hypovolemia occurs when there is a decrease in blood volume within the body due to loss of body fluids or blood.

• • Excessive sweating, large burns, diuretics, inadequate fluid intake, and increased urination can lead to hypovolemia.

• • At first, hypovolemia causes the nose, mouth, and other mucous membranes to dry out; the skin to lose elasticity; and urine output to decrease.

• • The body then tries to compensate for volume loss by increasing the heart rate and strength of contractions.

• • Blood vessels are constricted in the extremities to preserve blood flow for the heart, brain, and kidneys.

• Untreated Hypovolemia

• • If hypovolemia goes untreated, serious symptoms may develop including:

  • • Blue discoloration of lips and nail beds

  • • Change in alertness or level of consciousness

  • • Chest pain, tightness, or pressure

  • • Palpitations

  • • No urine production

  • • Tachycardia – increased heart rate

  • • Tachypnea – rapid breathing

  • • Decreased blood pressure

  • • Weak pulse

• Hypovolemic Shock

• • A client may have no signs of hypovolemia or hypovolemic shock which is when the body has lost 20 percent or one-fifth of its blood or fluid supply. Treatment is aimed at controlling fluid or blood loss, replacing those components, and restoring overall circulation in the body.

• Hypervolemia

• Hypervolemia, or fluid overload, is a condition where the body has too much water. This is commonly caused by problems with the kidneys as they are responsible for balancing the salt and fluid in the body. The goal of treatment is to rid the body of excess fluid.

• Intravenous Rehydration

• • Small particles that can easily pass from the bloodstream into cells and tissues are known as crystalloid solutions.

• • Each crystalloid solution is categorized by its tonicity, or ability to make water move in or out of cells via osmosis.

• • Hypotonic solutions move water from extracellular space into cells.

• • Hypertonic solutions cause water to leave the cells.

• • There is no movement between extracellular and intracellular fluids in isotonic solutions.

• Osmolality Imbalances: Sodium

• • Body fluids become hypertonic or hypotonic, causing a shift of water across cell membranes.

• • This is a sodium (Na) problem.

• • Hypernatremia

• • Hyponatremia

• • Normal Serum Sodium (Na) Level is 136-145 mEq/L

• • Na is the major electrolyte found in ECF and is present in most body fluids or secretions.

• • Na is essential for maintenance of acid-base and fluid balance, active and passive transport mechanisms, and irritability and conduction of nerve and muscle tissue.

• Electrolyte Imbalance

• • Dehydration; overhydration; certain medications; history of heart, kidney, or liver disorders; and incorrect intravenous fluids or feedings can all lead to an electrolyte imbalance.

Potassium (K+)

• 3.5-5.1 mEq/L

Sodium (Na+)

• 135-145 mEq/L

 Calcium (Ca2+)

• 8.5-10.5 mg/dL

Magnesium (Mg2+)

•  1.8-2.2 mg/dL

• • The electrolyte potassium 

• helps with nerve and muscle cell function while playing an important role in the muscle cells in the heart. Low potassium levels are called hypokalemia. High potassium levels are known as hyperkalemia.

• • The electrolyte sodium

•  Supports the function of nerves and muscles, helps maintain a normal blood pressure, and regulates the body’s fluid balance. Low sodium levels are called hyponatremia. High sodium levels are called hypernatremia.

Hypernatremia Causes

• Loss of more water than salt:

  • • Diabetes insipidus (ADH deficiency)

  • • Osmotic diuresis

  • • Large insensible loss (sweat or lungs)

• Gain of more salt than water:

  • • Tube feedings

  • • hypertonic IVFs

  • • Salt tablets

  • • Lack of water access (immobility, aphasia)

  • • Dysfunction of osmoreceptors (thirst)

Hypernatremia Signs and Symptoms

• • Decreased LOC

• • Confusion, lethargy, coma

• • Thirst, dry Mm

• • Seizures if rapid or severe

• • N, V

Hypernatremia Treatment

• • Limit dietary sodium intake (avoid cheese, condiments, canned goods, lunch meat, salty Snacks

• • IVF D5W or hypotonic solution

• • Seizure precautions

• • Neurom checks: Brain can become accustomed

• to high sodium and as the sodium level drops, water moves into the cerebral cells causing cerebral edema, so avoid rapid reduction of sodium

Hyponatremia Causes

• Gain of more water than salt:

• • Excessive ADH (SIADH)

• • Psychogenicpolydipsia orforcedexcessive water intake

• • Excessive IV administration of D5W

• • Use of hypotonic irrigating solutions

• • Tap-water enema

• Loss of more salt than water:

  • • Replacement of large body fluid output (D,V) with water but no Salt

Hyponatremia Signs and Symptoms

• • Decreased LOC

• • Confusion, lethargy, coma

• • HA

• • Seizures if rapid or severe

• • N,V

Hyponatremia Treatment

• • Treat the underlying cause

• If cause is:

  • • excessive water, oral intake may be limited.

  • • deficient sodium, oral intake may be increased.

•  Must correct sodium levels slowly to prevent cardiac overload

  • • IVF: NS

  • • Osmotic diuretics if hypervolemia is present

  • • Seizure precautions (protect the patient).

  • • Neurological Checks

Hypokalemia Causes

• • Decreased K intake

  • • Excessive use of K free IV solution

  • • Shift of K into cells due to alkalosis or treatment of DKA with insulin

• Increased K output:

  • • GI losses (D, V, NGT, fistula)

  • • Potassium- wasting diuretics

  • • Aldosterone excess

  • • Polyuria

  • • Glucocorticoid therapy

Hypokalemia Signs and Symptoms

• • Bilateral muscle weakness starting in quadriceps and ascends to respiratory Muscles

• • GI: ABD distention, constipation, decreased BS

• • CV: weak, irregular pulse, dysrhythmias

• • EKG: U waves, flattened or inverted T waves, ST segment depression.

Hypokalemia Treatment

• • Treat underlying cause

• • Administer potassium- diet, oral supplements, or IV *IV K is high

• alert drug. *Remember that patient needs good kidney function to excrete K

• • Watch carefully for s/s

• • May need to also replace magnesium if low (impairs correction)

• • Foods high in K (banana, cantaloupe, oranges, strawberries, potatoes, carrots, raisins, spinach, fish, pork, veal, and beef.

• • Assess pt. On digoxin because hypokalemia increases the risk of dig toxicity

Hyperkalemia Causes

• Increased Potassium Intake

  • IV K⁺ infusion

  • Rapid infusion of stored blood

  • Excess ingestion of potassium (K⁺) salt substitutes

• 2. Shift of Potassium Out of Cells

  • Massive cellular damage (e.g., crushing injury)

  • Cytotoxic chemotherapy

  • Insufficient insulin (Diabetic Ketoacidosis – DKA)

  • Acidosis

• 3. Decreased Potassium Output

  • Oliguria / End-Stage Renal Disease (ESRD)

  • Potassium-sparing diuretics

  • Adrenal insufficiency

  • Deficit of cortisol and aldosterone

Hyperkalemia Signs and Symptoms

• 1. Neuromuscular

  • Bilateral muscle weakness (especially quadriceps)

• 2. Gastrointestinal (GI)

  • Abdominal cramps

  • Diarrhea

• 3. Cardiovascular (CV)

  • Slow, weak pulse

  • Dysrhythmias

  • Cardiac arrest

• 4. EKG Changes

  • Peaked T waves

  • Wide QRS complex

  • Prolonged PR interval (PRI)

  • Terminal sine-wave pattern

Hyperkalemia Treatment

• 1. Treat the Underlying Cause

  • If acidosis → Give Sodium Bicarbonate

  • Calcium gluconate → Stabilizes myocardium & minimizes dysrhythmias

  • Insulin + D50 → Drives potassium (K⁺) into cells via H⁺/K⁺ exchange

• 2. Increase Potassium Excretion

  • Dialysis

  • Medications

  • Kayexalate (sodium polystyrene sulfonate)

  • Diuretics (avoid potassium-sparing like Aldactone; use loop/thiazide instead)

  • IV fluids (to promote renal clearance, if kidneys functioning)

Hypocalcemia Causes

• 1. Decreased Calcium Intake & Absorption

  • Calcium-deficient diet

  • Vitamin D deficiency (e.g., ESRD)

  • Chronic diarrhea or laxative misuse

  • Steatorrhea

• 2. Shift of Calcium into Bone or Inactive Form

  • Hypoparathyroidism

  • Rapid administration of citrated blood

  • Hypoalbuminemia

  • Alkalosis

  • Pancreatitis

  • Hyperphosphatemia (e.g., ESRD)

• 3. Increased Calcium Output

  • Chronic diarrhea

  • Steatorrhea

Hypocalcemia Signs and Symptoms

• 1. Neurological / Neuromuscular

  • Numbness & tingling (fingers, toes, circumoral area)

  • Positive Chvostek’s sign → contraction of facial muscles when facial nerve tapped

  • Hyperactive reflexes

  • Muscle twitching & cramping

  • Carpal & pedal spasms

  • Tetany

  • Seizures

  • Laryngospasm (airway risk!)

• 2. Cardiovascular

  • Dysrhythmias

• 3. EKG Changes

  • Prolonged ST segment

• Hypocalcemia causes increased neuromuscular excitability, which explains the majority of signs and symptoms.

Hypocalcemia Treatment

• Treat the underlying cause

• Administer Ca²⁺ (oral or IV)

• Vitamin D + Calcium (needed together for absorption)

• Seizure precautions

• Dietary teaching: foods high in calcium (dairy, broccoli, oranges, salmon)

• Encourage weight-bearing exercise

• Some medications require calcium to work effectively

Hypercalcemia Causes

• Increased Calcium Intake & Absorption

• Milk-alkali syndrome → excessive intake of:

  • Antacids

  • Calcium

  • Vitamin D

• 2. Shift of Calcium Out of Bone

  • Prolonged immobilization

  • Hyperparathyroidism

  • Bone tumors

  • Non-osseous cancers that secrete bone-resorbing factors

• 3. Decreased Calcium Output

  • Use of thiazide diuretics

Hypercalcemia Signs and Symptoms

• 1. Gastrointestinal (GI)

  • Anorexia

  • Nausea & Vomiting (N/V)

  • Constipation (C)

• 2. Neuromuscular / Neurological

  • Fatigue

  • Decreased reflexes

  • Lethargy (most common)

  • ↓ LOC, confusion, personality changes

• 3. Severe Complications

  • Cardiac arrest

  • 4. EKG Changes

  • Heart block

  • Shortened ST segment

• Hypercalcemia decreases neuromuscular excitability, which explains the majority of its signs and symptoms.

Hypercalcemia Treatment

• 1. Address the Underlying Cause

  • Treat primary disorder (e.g., hyperparathyroidism, cancer, immobilization, excessive intake)

• 2. Promote Calcium Excretion

  • Rehydration → increases urinary calcium excretion

  • IV fluids + diuretics (loop diuretics preferred; avoid thiazides since they ↑ Ca²⁺)

• 3. Reduce Calcium Levels

  • Oral phosphate (inverse relationship with calcium)

  • Calcitonin → limits bone resorption & ↑ renal calcium excretion

  • Corticosteroids → prevent Vitamin D activation (↓ calcium absorption)

  • Bisphosphonates → inhibit osteoclast-mediated bone resorption

• 4. Supportive Measures

  • Increase mobility → reduces bone resorption & hypercalcemia risk

Magnesium’s

• role in the body is to assist in the regulation of nerve and muscle function, blood pressure and blood sugar levels; as well as making bone, protein, and DNA. Low magnesium levels are known as hypomagnesemia. High levels are called hypermagnesemia.

Hypomagnesemia Causes

• 1. Decreased Magnesium Intake & Absorption

  • Malnutrition

  • Chronic alcoholism

  • Chronic diarrhea

  • Laxative misuse

  • Steatorrhea

• 2. Shift of Magnesium into Inactive Form

  • Rapid administration of citrated blood

• 3. Increased Magnesium Output

  • Chronic diarrhea

  • Steatorrhea

  • GI losses → vomiting, nasogastric tube (NGT), fistula

  • Thiazide or loop diuretics

  • Aldosterone excess

Hypomagnesemia Signs and Symptoms

• 1. Neuromuscular

  • Positive Chvostek’s sign

  • Hyperactive deep tendon reflexes (DTRs)

  • Muscle cramps & twitching

  • Grimacing

  • Dysphagia

  • Tetany

  • Seizures

• 2. Neurological

  • Insomnia

• 3. Cardiovascular

  • Hypertension (HTN)

  • Dysrhythmias

• 4. EKG Changes

  • Prolonged QT interval

• Hypomagnesemia and hypocalcemia share similar S/S because both increase neuromuscular excitability.

Hypomagnesemia Treatment

• • Magnesium supplements

• • Food high in Mg: whole grains, green leafy veggies, meat, seafood

• • Seizure precautions

Hypermagnesmia Causes

• 1. Increased Magnesium Intake or Absorption

  • Excessive use of magnesium-containing:

  • Laxatives

  • Antacids

• 2. Decreased Magnesium Output

  • Oliguric End-Stage Renal Disease (ESRD)

  • Adrenal insufficiency

Hypermagnesmia Signs and Symptoms

• 1. Neurological / Neuromuscular

  • Lethargy, drowsiness

  • Hypoactive deep tendon reflexes (DTRs)

  • Muscle weakness

• 2. Cardiovascular

  • Bradycardia

  • Hypotension

  • Dysrhythmias

  • Cardiac arrest (severe cases)

• 3. Respiratory

  • Decreased respiratory rate (RR) (with severe hypermagnesemia), cardiac arrest 

• 4. Acute Magnesium Elevation

  • Flushing

  • Sensation of warmth

• 5. EKG Changes

  • Prolonged PR interval (PRI)

• Hypermagnesemia decreases neuromuscular excitability, the opposite of hypomagnesemia.

Hypermagnesmia Treatment

• 1. Monitoring & Prevention

  • Monitor respiratory status

  • Monitor reflexes (DTRs)

  • Avoid foods high in magnesium

• 2. Promote Magnesium Excretion

  • Diuretics (loop diuretics preferred if renal function intact)

  • Dialysis (if severe or renal failure present)

• 3. Counteract Magnesium’s Effects

  • IV Calcium Gluconate → stabilizes cardiac muscle & minimizes Mg effects

• Nursing Process: Assessment

• • Through the patient’s eyes

• • Nursing history

  • • Age: very young and old at risk

  • • Environment: excessively hot?

  • • Dietary intake: fluids, salt, foods rich in potassium, calcium, and magnesium

  • • Lifestyle: alcohol intake history

  • • Medications: include over-the-counter (OTC) and herbal, in addition to prescription medications

• • Medical history

  • • Recent surgery (physiological stress)

  • • Gastrointestinal output

  • • Acute illness or trauma

    • • Respiratory disorders

    • • Burns

    • • Trauma

  • • Chronic illness

    • • Cancer

    • • Heart failure

    • • Oliguric renal disease

• Focused Nursing Assessment

• • What does the patient look like?

• NEXT: Plan

  • • Who do you consult with?

  • • Maintain or restore F&E balance

  • • Involve the pt and or family

• NEXT: Goals and Outcomes