Fluid & Electrolyte Imbalance Flashcards
What is the difference between aldosterone, antidiuretic hormone, and natriuretic peptides?
– aldosterone: secreted by the adrenal cortex when the ECF sodium level is low; it prevents the kidneys from secreting too much sodium
– antidiuretic hormone (ADH or vasopression): secreted by the brain under control of the hypothalmus in response to high sodium concentration in blood; acts on renal tubules to promote water reabsorption
– natriuretic peptides: secreted by atria and ventricles to make the kidneys secrete more sodium when sodium levels are too high
What are normal sodium levels? Where in the body is sodium the major solute?
– 135 - 145 mmol/L
– major solute in ECF
What can cause hyponatremia?
– sodium loss – diuretic therapy, burns, renal disease
– water gain – water overload
What are normal potassium levels? Where in the body is potassium the major solute? What does potassium regulate?
– 3.5 - 5.0 mEq/L
– dominant solute in the ICF
– regulates cellular excitability
- skeletal muscle contraction
- cardiac muscle contraction
- neuromuscular transmission
What is important to note about hypokalemia? What are the signs of hypokalemia (SUCTION)?
– can be life-threatening because every body system is affected
– SUCTION:
- Skeletal muscle weakness
- U wave, flattened T, depressed ST
- Constipation
- Toxicity of digoxin
- Irregular or weak pulse
- Orthostatic hypotension
- Numbness
What are the 3 P danger signs of hypokalemia?
- paralytic ileus
- paralysis of muscles – including respiratory
- pulse craziness – including cardiac arrest
What are the 2 administration methods of potassium?
- PO
- IV infusion
- only in 20 - 40 mEq/L doses
- can give lidocaine in infusion since it burns
– only lethal injections are potassium IV push
Which patients often exhibit hyperkalemia?
pts with renal failure
What is the most severe problem in hyperkalemia? What is another symptom of hyperkalemia?
– most severe problem: cardiovascular changes (cardiac arrest) – due to hyperactivity of muscles
– increased GI motility (diarrhea)
What are 2 drugs that can be used for hyperkalemia? Describe generally how they work.
- Kayexalate – PO or rectally inserted to help pt excrete excess K+
- insulin – binds to circulating K+ and pulls it from the ECF into the ICF
- must have glucose (dextrose) with insulin for reducing K+ in order to prevent low blood sugars
What are normal calcium levels? Where is calcium mainly found in the body? What are 3 major functions of calcium?
– 9.0 - 10.5 mg/dL
– mainly found in teeth and bones
– functions of calcium:
- cell membrane permeability
- enzyme activator in cells
- coagulation
What are the 2 hormones that regulate calcium?
- parathyroid hormone – pulls Ca2+ from bones, stimulating vitamin D to help intestinal absorption of dietary Ca2+
- stimulated when Ca2+ is low
- calcitonin – keeps Ca2+ in the bones, decreasing the amount that is available
- stimulated when Ca2+ is high
What are 2 reflexes that pts demonstrate if they have hypocalcemia?
- Trousseau’s sign: palmar flexion that is stimulated when a BP cuff is placed on the pt’s arm and inflated for 1 - 2 minutes
- Chvostek’s sign: wink on the side of and mouth movement towards where the pt’s facial nerve is tapped
Where is the first location that demonstrates effects of hypercalcemia? Which systems are affected by hypercalcemia? Which pts demonstrate hypercalcemia?
– first demonstrated in excitable tissues
– all systems are affected
– often tied to cancer pts, especially when the cancer has metastasized to the bone
What is the most serious and life-threatening problem of hypercalcemia?
cardiovascular changes – slower HR and conductions in the heart
