Electrolytes Flashcards
What is the major extracellular fluid ion?
Sodium
How is sodium eliminated from cells?
Sodium pump
What is a major influence on osmolality?
Sodium
How is sodium regulated?
Through adequate intake
Renal tubular absorption
Intestinal absorption
Osmoreceptors that secrete ADH
What affects plasma volume of sodium?
Urine
GI Tract
Sweat
What are the 2 related and interdependent systems of sodium balance?
Osmoregulation
Volume regulation
What control osmoregulation of sodium?
Osmoreceptors in the hypothalamus sense increased osmolality and secrete ADH
What controls volume regulation of sodium?
Stretch receptors sense volume changes
What does ADH respond to?
Increases osmolality
Decreased Plasma volume
Where does ADH act?
on the collecting ducts to maximize water reabsorption
What system is the main regulator of sodium balance?
Renin-Angiotensin - Aldosterone system
What is Aldosterone secreted in response to?
Angiotensin
Hyperkalemia
ACTH
What does Aldosterone increase the secretion of?
Potassium
What are the four causes of Hyponatremia?
Loss of Sodium
Increase in extracellular water
decreased intake of sodium
shifts in plasma osmolality not due to sodium
What is the most common cause of Hyponatremia?
Excess sodium loss
What are the 4 causes of Excess sodium loss?
through the GI tract: Vomiting, diarrhea, and salive
Renal loss
Cutaneous: sweating and burns
3rd space: sequestration of fluid
What are examples of extracellular fluid sequestration?
Peritonitis Ascites Uroabdomen Chylothorax GI sequestration
What is a common cause of sodium osmotic shift from Intracellular to extracellular fluid?
Hyperglycemia
Mannitol adminstration
What are the three causes of increased extracellular water and hyponatremia?
Primary polydipsia
Excessive administration of sodium poor IVF
Edematous conditions
What is the most common cause of Hypernatremia?
Dehydration due to lack of intake or pure water loss
What is the less common cause of Hypernatremia?
Excess intake or retention through ingestion, IV administration, or increased aldosterone
What is the major extracellular fluid anion?
Chloride
What is chloride involved in?
transport of electrolytes and water
Acid base metabolism
If the changes in sodium and chloride are proportional consider …
abnormalities in sodium
If changes in chloride concentrations are greater than sodium consider…
acid-base abnormalities
When evaluating chloride look at….
Sodium concentrations
Total CO2
What regulates chloride?
electrochemical gradients
active transport of sodium
What interferes with chloride transport?
Furosemide
GI entertoxins
What is the most common cause of hypochloremia?
Hypochloremic metabolic alkalosis
What are the other causes of Hypochloremia?
All causes of hyponatremia Vomiting in monogastrics Abomasal disorders High GI obstructions Sweating in horses
Paradoxical aciduria requires what 2 things?
Volume depletion
Chloride depletion
What does the kidney do to compensate for Hypochloremia and Paradoxical aciduria?
Reabsorbs sodium to correct dehydration
Resorbs HCO3- instead of chloride (electroneutrality)
What is the cause of Hyperchloremia?
Parallels sodium increased
Hyperchloremic Metabolic acidosis: GI tract loss of Bicarb or Proximal and distal renal tubular acidoses
Alkalemia/Bicarb excess
What are the major functions of Potassium?
Major intracellular cation
Resting cell membrane potential
Carbohydrate metabolism
Electron transport
What is the major intracellular cation?
Potassium
How is potassium regulated?
Adequate intake
Renal excretion
Sweat
GI loss
What hormone promotes renal excretion of potassium?
Aldosterone
What is the most common cause of Hyperkalemia?
Failure of Renal Excretion
What are the causes of Hyperkalemia?
Failure of renal excretion
Redistribution
Increased intake through parenteral administration
What causes of Hyperkalemia pertain to the urinary system?
Oliguria/Anuria
Urethral obstruction
Rupture urinary bladder
What disease causes Hyperkalemia?
Hypoadrenocorticism (Addison’s) - decreased aldosterone
What diuretics cause Hyperkalemia?
Potassium sparing Diuretics - Spirolactone
What is the magic number for Sodium:Potassium ratio??
27
What is a major mechanism for Hyperkalemia?
Redistribution:
Inorganic Acidosis
Insulin deficiency
Severe muscle trauma: Rhabdomyolysis or Seizures
What causes Pseudohyperkalemia?
Generally in vivo: Marked Thrombocytosis: leakage of intracellular potassium
Hemolysis
What is characteristic of EDTA contamination?
Low levels of calcium
High levels of potassium
What are causes of Hypokalemia?
Decreased intake or low Potassium IV fluids
Loss
Horse Sweat
Redistribution: Alkalemia or Insulin injection
What are the consequences of Potassium
Weakness
Neurologic signs
EKG abnormalities
