Chapter 6: electrolytes Flashcards
What percentage of body weight does the intracellular fluid compartment make up?
40%
What percentage of body weight does the extracellular fluid compartment make up?
20%
tissue - 14
plasma (vascular)- 5
transcellular- 1
What is tonicity?
osmotic pressure of two solutions separated by a semipermeable membrane
How is the thirst mechanism triggered?
Triggered by decreased blood volume and increased osmolarity
What does ADH promote?
Promotes reabsorption of water in the kidneys
What does aldosterone do?
Increases reabsorption of sodium and water in the kidneys
What does atrial natriuretic peptide do?
Stimulates renal vasodilation and suppresses aldosterone, increasing urinary output
What is edema?
Excess fluid in the interstitial space
What is hypervolemia?
Excess fluid in the intravascular space
What is water intoxication?
Excess fluid in the intracellular space
How much is interstitial fluid increased with edema?
2.5 liters
What does edema do to capillary filtration pressure?
Increased
What happens when capillary filtration pressure is increased?
increased volume, heart failure, gravity, venous obstruction
What does edema do to colloid osmotic pressure?
decreased
What happens when colloid osmotic pressure is decreased?
liver disease, starvation
What does edema do to capillary permability?
Increase
What happens when capillary permeability is increased?
immune response, shock, sepsis
What does edema do to lymph flow?
Obstructs it
What causes an excessive sodium or water intake?
High-sodium diet Psychogenic polydipsia Hypertonic fluid administration Free water Enteral feedings
What causes an inadequate sodium or water elimination?
Hyperaldosteronism Syndrome of inappropriate antidiuretic hormone Renal failure Liver failure Heart failure
What are the manifestations of fluid excess?
peripheral edema, periorbital edema, pulmonary edema, bounding pulse, tachycardia, jugular vein distension, hypertension, polyuria, rapid weight gain
What is decreased with hypovolemia or fluid volume deficit?
Decreased fluid in the intravascular space
Does fluid deficit have to occur with electrolyte defects?
No
What happens with a fluid deficit?
- Decrease in fluid level leads to increase in level of blood solutes
- Cell shrinkage
- Hypotension
What causes an excessive fluid or sodium loss?
- Gastrointestinal losses
- Excessive diaphoresis
- Hemorrhage
- Diuresis
- Surgery
- Open wounds
- Third spacing – transcellular c-ompartment ex. burns
- Excessive use of diuretics
- Osmotic diuresis
What are the manifestations of fluid deficit?
thirst, altered level of consciousness, hypotension, tachycardia, weak pulse, flat jugular veins, dry mucous membranes, decreased skin turgor, decreased urine output, weight loss
What is the treatment for fluid deficit?
identify and manage underlying cause along with fluid replacement
What is the normal range of sodium?
135–145 mEq/L.
Facts about sodium
Most significant cation and prevalent electrolyte of extracellular fluid.
What does sodium control?
Controls serum osmolality and water balance.
Does sodium play a role in acid-base balance?
yes
What does sodium facilitate
Facilitates muscles and nerve impulses.
What is the main source of sodium?
Main source is dietary intake.
Where is sodium excreted?
Excreted through the kidneys and gastrointestinal tract.
What is hyponatremia?
Sodium < 135 mEq/L
Serum osmolarity decreases
What is hypertramia?
Sodium > 145 mEq/L
Serum osmolarity increases
What are the causes of hypernatremia due to excessive sodium?
-Excessive sodium ingestion
-Hypertonic IV saline
administration
-Oversecretion of
aldosterone
What are the causes of hypernatremia due to deficient water?
- Decreased water ingestion
- Loss of thirst sensation
- Inability to drink water
- Third spacing
- Vomiting
- Diarrhea
- Excessive sweating
- Diuretic use
- Diabetes insipidus
What are the manifestations of hypernatremia?
increased temperature, warm and flushed skin, dysphagia, increased thirst, agitation, weakness, headache, seizures, lethargy, coma, hypotension, tachycardia, weak pulse, edema, and decreased urine output
What is the treatment for hypernatremia?
fluid replacement
What are the causes of hyponatremia due to deficient sodium?
- Diuretic use
- Gastrointestinal losses
- Excessive sweating
- Dietary sodium restrictions: rare
What are the causes of hyponatremia due to excessive water?
- Hyperglycemia
- Excessive water ingestion
- Syndrome of inappropriate antidiuretic hormone
What are the manifestations of hyponatremia?
gastrointestinal upset, blood pressure changes, pulse changes, edema, headache, lethargy, confusion, diminished deep tendon reflexes, muscle weakness, seizures, and coma
What happens with sodium and ECF loss?
hypotension, tachycardia, decreased urine output, poor skin turgor, dry mucous membranes
Dilutional hyponatremia
What is dilutional hyponatremia?
weight gain and edema
What is the treatment for hyponatremia?
treat the cause
What is the normal range of potassium?
3.5–5 mEq/L.
fact about potassium
The primary intracellular cation.
What does potassium play a role in?
Plays a role in electrical conduction, acid–base balance, and metabolism.
What is the main source of potassium?
Main source is dietary intake.
Where is potassium excreted?
Excreted through the kidneys and gastrointestinal tract.
What happens with potassium fluctuation?
Serum potassium cannot fluctuate much without causing serious issue.
What is hyperkalemia?
Potassium > 5 mEq/L
What are the causes of hyperkalemia?
Deficient excretion: renal failure, Addison’s disease, certain medications
Excessive intake: oral potassium supplements, salt substitutes, and rapid intravenous administration of diluted potassium
Increased release from cells: acidosis, blood transfusions, and burns or any other cellular injuries
Insulin deficit
What are the manifestations of hyperkalemia?
paresthesia, muscle weakness, dysrhythmias, cardiac arrest, abdominal cramping, nausea, and diarrhea
What is the treatment for hyperkalemia?
treat the cause. Calcium gluconate, insulin, cation exchange resins (oral or rectal).
What is hypokalemia?
Potassium < 3.5 mEq/L
What are the causes of hypokalemia?
Excessive loss: vomiting, diarrhea, nasogastric suctioning, fistulas, laxatives, potassium-losing diuretics, increased mineralcorticoids
Deficient intake: malnutrition, extreme dieting, and alcoholism
Increased shift into the cell: alkalosis and insulin excess
What are the manifestations of hypokalemia?
muscle weakness, paresthesia, hyporeflexia, leg cramps, weak and irregular pulse, hypotension, dysrhythmias, decreased bowel sounds, abdominal distension, constipation, and cardiac arrest
What are the treatments for hypokalemia?
identify and manage underlying cause along with potassium replacement
What is the normal range of calcium?
Normal range: 8.5 -10.5 mg/dL
Where is calcium mostly found?
Mostly found in the bone and teeth
What does calcium play a role in?
Plays a role in blood clotting, hormone secretion, receptor functions, nerve transmission, and muscular contraction
What does calcium have an inverse relationship with?
Has inverse relationship with phosphorus
What is the main source of calcium?
Main source is dietary intake.
What aids absorption of calcium?
Vitamin D aids absorption.
Where is calcium absorbed?
Absorbed through the gastrointestinal tract (small intestine).
Where is calcium excreted?
Excreted in urine and stool
What is calcium regulated bY?
Vitamin K
Parathyroid hormone
Calcitonin
What is hypercalcemia?
Calcium > 10.5 mg/dL
What are the causes of hypercalcemia?
- Increased intake or release: calcium supplements, cancer, immobilization, corticosteroids, vitamin D excess
- Deficient excretion: thiazide diuretics, and hyperparathyroidism
What are the manifestations of hypercalcemia?
dysrhythmias, headache, fatigue, muscle weakness, decreased deep tendon reflexes, anorexia, nausea, vomiting, constipation, high blood pressure, bone resorption
What is the treatment for hypercalcemia?
treat cause, increase excretion or mobility
What is hypocalcemia?
Calcium < 8.5 mg/dL
What are the causes of hypocalcemia?
Excessive losses: hypoparathyroidism, alkalosis, laxatives, diarrhea
Deficient intake: decreased dietary intake, alcoholism, absorption disorders
What are the manifestations of hypocalcemia?
dysrhythmias, increased bleeding tendencies, confusion, fatigue, increased deep tendon reflexes, increased bowel sounds, abdominal cramping, and positive Trousseau’s and Chvostek’s signs
What is the treatment for hypocalcemia?
- Identify and manage underlying cause
- Calcium replacement (oral or intravenous)
- Vitamin D
- Decrease phosphorus
What is the normal range of phosporus?
Normal range: 2.5–4.5 mg/dL.
Where is phosphorus mainly found?
Mostly found in the bones; small amounts are in the bloodstream.
What does phosphorus play a role in?
Plays a role in bone and tooth mineralization, cellular metabolism, acid–base balance, and cell membrane formation.
What is the main source of phosphorus?
Main source is dietary intake.
Where is phosphorus excreted?
Excreted through the kidneys.
What is hyperphosphatemia?
Phosphorus > 4.5 mg/dL
What are the causes of hyperphosphatemia?
Deficient excretion: hypoparathyroidism and phosphate containing laxatives
Excessive intake or cellular exchange: cellular damage, hypocalcemia, and cell destruction
What are the manifestations of hyperphosphatemia?
rarely seen alone, related to low calcium levels
What is the treatment for hyperphosphatemia?
Identify and manage underlying cause
Aluminum hydroxide binds with phosphate
Treat hypocalcemia
What is hypophosphatemia?
Phosphorus < 2.5 mg/dL
What are the causes of hypophosphatemia?
Excessive excretion or cellular exchange: hyperparathyroidism, and alkalosis
Deficient intake: malabsorption, vitamin D deficiency, magnesium and aluminum antacids, alcoholism, and decreased dietary intake
What are the manifestations of hypophosphatemia?
similar to hypercalcemia. Muscle weakness, irritability, confusion, bone resorption.
Treatment:
What is the treatment for hypophosphatemia?
Identify and manage the underlying cause Phosphorus replacement (oral or intravenous)
What is the normal range of magnesium?
Normal range: 1.8–2.4 mEq/L.
What kind of cation is magnesium?
An intracellular cation.
Where is magnesium mainly stored?
Mostly stored in the bone and muscle.
What does magnesium play a role in?
Plays a role in muscle and nerve function, cardiac rhythm, immune function, bone strength, blood glucose management, blood pressure, energy metabolism, and protein synthesis.
What is the main source of magnesium?
Main source is dietary intake.
Where is magnesium excreted?
Excreted through the kidneys.
What is hypermagnesemia?
Magnesium > 2.5 mEq/L (rare)
What are the causes of hypermagnesemia?
Causes: renal failure, excessive laxative and antacid use
What are the manifestations of hypermagnesemia?
muscle weakness, fatigue, dysrhythmias, hypotension, nausea
What is the treatment for hypermagnesemia?
diuretics and intravenous calcium
What is hypomagnesemia?
Magnesium < 1.8 mEq/L
What are the causes of hypomagnesemia?
inadequate intake, chronic alcoholism, malnutrition, pregnancy, diarrhea, diuretics, and stress
What are the manifestations of hypomagnesemia?
similar to hypocalcemia, confusion, increased reflexes, hypertension
What is the treatment for hypomagnesemia?
magnesium replacement (oral or intravenous)
