Chapter 24: Principles of Electrolyte Homeostasis and Electrolytes

Question 1

Electrolytes

Answer 1

• ionized salts dissolved in water

- Most clinically important includes sodium, potassium, calcium, magnesium, chloride, bicarbonate, and phosphate

Question 2

Normal levels of electrolytes in the body

Answer 2

• Calcium: 9-11 mg/dl
• Magnesium: 1.5-2.5 mEq/L
• Phosphate (adult/older children): 2.5-4.5 mg/dl
• Phosphate (children): 4.5-6.5 mg/dl
• Phosphate (neonates): 4.3-9.3 mg/dl
• Potassium (normal): 3.5-5.0 mEq/L
• Potassium (neonates): 3.9-5.9 mEq/L
• Sodium (normal): 135-145 mEq/L
• Sodium (neonates): 135-162 mEq/L

Question 3

Dynamic Control

Answer 3

• 4 processes: electrolyte intake, electrolyte absorption, electrolyte distribution, and electrolyte excretion
• processes work together to maintain dynamic control of electrolyte within normal limits
• if intake of specific electrolyte increases, excretion of that electrolyte may increase to normalize plasma levels
• Similarly, if electrolyte intake decreases, electrolytes may be redistributed into the plasma to maintain normal plasma level

Question 4

Electrolyte Intake

Answer 4

• intake normally occurs orally, through food and drink
• other routes include oral medications, intravenous fluids (IV), nutritional solutions, blood trasfusions, administration of electrolytes, and tubes into body cavities (nasogastric and GI feeding tube)

Question 5

Electrolyte Absorption

Answer 5

• essential if electrolyte is to be useful metabolically
• Depends on other factors such as concentration gradients, binding proteins, contents of the GI tract, pH of intestinal content, Medications, and surgical removal of portions of the GI tract

Question 6

Electrolyte distribution

Answer 6

• electrolyte composition differs in various compartments
• concentrations of potassium, magnesium, and phosphate ions are high inside cells
• Extraacellular fluid contains higher concentrations of sodium, chloride, and bicarbonate ions
• influenced primarily by hormones such as epinephrine, insulin, and parathyroid hormone
• certain medications also influence electrolyte distribution

Question 7

Electrolyte Excretion

Answer 7

• occurs through urine, feces, and sweat
• influenced by hormones
• other factors that influence include rate of renal tubular fluid flow and medications

Question 8

Electrolyte loss through abnormal routes

Answer 8

• exit of electrolytes from the body through routes other than urine, feces, and sweat
• may be uncontrollable or may result from therapeutic procedures
• alters electrolyte homeostasis

Question 9

Electrolyte loss through abnormal routes

Answer 9

• exit of electrolytes from the body through routes other than urine, feces, and sweat
• may be uncontrollable or may result from therapeutic procedures
• alters electrolyte homeostasis

Question 10

Examples of Electrolyte loss through abnormal routes

Answer 10

• vomiting
• nasogastric suction
• paracentesis
• Hemodialysis
• wound drainage
• fistula drainage

Question 11

Causes of Electrolyte imbalances: Excess

Answer 11

• increased intake
• increased absorption
• shift into extracellular fluid
• decreased excretion

Question 12

Causes of Electrolyte Imbalances: Deficit

Answer 12

• decreased intake
• decreased absorption
• shift into electrolyte pools
• increased excretion
• Loss through abnormal route