Unit 1: Laboratory Values and Nursing Management

Basic Concepts Review

Important concepts from anatomy and physiology: osmosis, diffusion, filtration.
Osmosis: Movement of water from high to low concentration.
Diffusion: Movement of solutes from high to low concentration.
Filtration: Forced movement of water through a membrane due to pressure, not concentration gradient.
Electrochemical Gradient: Balance of sodium, calcium, magnesium, and potassium across cell membranes, maintaining cell function.
Sodium-Potassium Pump: Uses ATP to maintain high potassium inside cells and high sodium outside.
Resting Membrane Potential: Inside of the cell is more negative than the outside, essential for neurostimulus and muscle contraction.

Sodium (Na+):
- Normal range: 135-145 mEq/L
- Major cation in extracellular fluid (ECF)
- Contributes to electrochemical gradient, muscle contraction, nerve impulses.
- Regulated by diet, renal excretion, RAS system, and thirst sensation.
- Elderly may have reduced thirst sensation, affecting sodium balance.
Potassium (K+):
- Normal range: 3.5-5 mEq/L
- Major cation in intracellular fluid (ICF)
- Critical for cardiac function, narrow range.
- Regulates muscle contraction and nerve function.
- Related to diet, acid-base balance, and cellular communication.
Magnesium (Mg+):
- Normal range: 1.3-2.3 mg/dL
- Important for cardiac function and neuromuscular function.
- Seen in clinical settings frequently administered.
Calcium (Ca+):
- Normal range: 8.6-10.2 mg/dL
- Important for bone density, muscular contraction, and blood clotting.
- Major reservoir in bones and teeth.
- Critical in orthopedic patients and certain muscle functions.

Definition: Serum sodium < 135 mEq/L
**Causes: Fluid volume deficit, GI losses, diuretics, excessive sweating, hyperglycemia, poor intake, malabsorption, excessive fluid intake, renal/heart failure.
Symptoms: CNS changes (alt. mental status, headache, lethargy, confusion, seizures), GI symptoms (nausea, cramping), musculoskeletal symptoms (cramping, weakness), integumentary symptoms (poor skin turgor, dry mucosa).
Management: Increase monitoring, safety precautions, medication management, dietary sodium, fluid monitoring, possibly IV administration (correct slowly).

Definition: Serum sodium > 145 mEq/L
Causes: Fluid volume deficit, poor fluid intake, excessive sweating, watery diarrhea, burns, poor renal excretion, excessive sodium intake.
Symptoms: CNS changes (thirst, irritability, restlessness, seizures), cardiovascular symptoms (BP changes), integumentary symptoms (skin turgor).
Management: Increase monitoring, safety precautions, manage medications, dietary restrictions, fluid intake, possibly hypotonic IV solutions (correct slowly).

Definition: Serum potassium < 3.5 mEq/L
Causes: GI losses, poor intake, hormonal imbalances, alkalosis, certain medications (insulin, diuretics).
Symptoms: Cardiac changes (ECG changes, dysrhythmias), PNS changes (numbness, tingling, hypoactive reflexes), GI symptoms (decreased motility), musculoskeletal symptoms (weakness, cramps).
Management: Increase monitoring, safety precautions, medication management, dietary potassium, possibly IV potassium (never IV push).

Definition: Serum potassium > 5 mEq/L
Causes: Excessive intake, renal failure, tissue trauma, certain medications (potassium-sparing diuretics, ACE inhibitors).
Symptoms: Cardiac changes (ECG changes, dysrhythmias), CNS changes (anxiety, irritability), GI symptoms (cramping), musculoskeletal symptoms (weakness, paralysis).
Management: Increase monitoring, safety precautions, medication management, dietary restrictions, possibly kayexalate, insulin with glucose, or dialysis.

Definition: Serum magnesium < 1.3 mg/dL
Causes: GI losses, poor intake, malnutrition, alcoholism, certain medications (diuretics).
Symptoms: Cardiac changes (ECG changes), CNS changes (confusion, agitation), musculoskeletal symptoms (hyperreflexia, tetany), GI symptoms (nausea).
Management: Increase monitoring, safety precautions, medication management, dietary magnesium, possibly IV magnesium sulfate.

Definition: Serum magnesium > 3 mg/dL
Causes: Renal failure, excessive intake, tissue trauma.
Symptoms: Cardiac changes (hypotension), CNS changes (drowsiness, coma), musculoskeletal symptoms (weakness, hyporefexia), integumentary symptoms (flushing).
Management: Increase monitoring, safety precautions, medication management, dietary restrictions, possibly IV calcium gluconate, dialysis, diuretics.

Definition: Serum calcium < 8.5 mg/dL
Causes: Vitamin D deficiency, osteoporosis, malabsorption, certain medications (antacids, PPIs), thyroidectomy.
Symptoms: Cardiac changes (ECG changes, hypotension), CNS changes (anxiety, seizures), musculoskeletal symptoms (tetany, hyperreflexia), GI symptoms (diarrhea).
Management: Increase monitoring, safety precautions, medication management, dietary calcium, possibly IV calcium gluconate/chloride.

Definition: Serum calcium > 10.5 mg/dL
Causes: Vitamin D intoxication, excessive intake, bone trauma, cancer.
Symptoms: Cardiac changes (hypertension, ECG changes), CNS changes (lethargy, confusion), musculoskeletal symptoms (bone pain, fractures), GI symptoms (constipation).
Management: Increase monitoring, safety precautions, medication management, dietary restrictions, possibly IV calcitonin, dialysis, diuretics.

Electrolyte imbalances can cause significant clinical symptoms and require careful monitoring and management.
Understanding fluid and electrolyte balance is crucial for proper patient care.
Be aware of the interplay between different electrolytes and the body's compensatory mechanisms.
Always correct imbalances slowly to avoid further complications.