Monovalent Electrolytes, Anion Gap, and Osmolality Flashcards
What are the monovalent electrolytes?
Na K Cl HCO3 Lactate Ketones
What is the role of Na, K, and Cl in metabolism?
Responsible for shifts between ICF and ECF
What is the concentration of Na, K, and Cl like in ECF?
Na and Cl rich and K poor
What will changes in the ECF electrolyte concentration change?
Plasma electrolytes concentration
What electrolyte do platelets release?
K
When platelets release K, does the serum or plasma have a higher concentration?
Serum
How are electrolytes and H2O excreted or lost?
Via kidneys, skin, or respiration
How is the [HCO3] altered?
By changing other [electrolytes] or acid-base balance
What does abnormal [electrolyre] in plasma cause?
Decreased or increased intake
Shifts between ICF and ECF
Increased renal retention
Increased loss
What is [Na] in plasma equivalent to?
[Na] in ECF
What is important for [Na] interpretation?
Hydration
How does [K] affect [Na]?
If [K] decreases, [Na] also decreases since it enters cells to keep the electrical balance
A severe [K] increase would be necessary for [Na] to increase, but severe [K] is not compatible with life
What does H2O follow?
Na, but not in the distal nephron because there is an absence of ADH
What is the Na concentration regulated by?
Blood volume and palsma osmolality regulation
How does blood volume regulate [Na]?
Hypovolemia –> RAS –> angiotensin II and aldosterone: Angiotensin II increases Na, K, Cl resorption in proximal tubules; Aldosterone increases Na resorption in collecting ducts
Hypovolemia –> carotid sinus baroreceptors –> ADH release –> increased H2O resorption
Hypervolemia –> atrial baroreceptors –> atrial natriuretic peptide –> decreased Na resorption
How does plasma osmolality regulate [Na]?
Hyperosmolality –> hypothalamic osmoreceptors –> promotion of water intake and release of ADH –> H2O resorption and Na, K, Cl in ascending loop of henle
Hypoosmolality –> decreased water intake
How is [Na] self regulated?
Decreased [Na] –> aldosterone release, increased retention
Increased [Na] –> decreased aldosterone release, decreased retention
What is the most important regulator of aldosterone release?
[K]
What is dehydration the equivalent of?
Decreased tb-H2O
What happens if you have only H2O loss?
Decreased intake or loss of free H2O
What happens if you lose H2O and Na?
Alimentary, renal, or cutaneous loss
What are hypernatremic, hyperosmolar, and hypertonic dehydrations caused by?
Net hypoosmolar or hypotonic fluid loss –> H2O loss > Na loss
What are normonatremic, isoomolar, or isotonic dehydrations caused by?
Net isoosmolar or isotnoic fluid loss –> H2O loss = Na loss
What are hyponatremic, hypoosmolar, and hypotnoic dehydrations caused by?
Net hyperosmolar of hypertonic fluid loss –> H2O loss < Na loss
What are the disorders associated with hypernatremia?
Inadequate water intake
Pure water loss
Loss of water > loss of Na
Na excess group
What is the pathogenesis of loss of water > loss of Na?
Alimentary or renal osmotic loss
What is the pathogenesis of Na excess group?
Decreased renal excretion of Na
Excess Na intake with concurrent restricted H2O intake
What are symptoms of dehydration with net loss of isotonic fluids in the alimentary system?
Vomit
Diarrhea
Sequestration
What are symptoms of dehydration with net loss of isotonic fluids in the renal system?
Polyuric renal diseases with defective tubular functions
Osmotic diuresis
Increased diuresis
What are symptoms of dehydration with net loss of isotonic fluids cutaneously?
Profuse sweating in horses
What can create either normonatremia or hyponotremia?
Edema or transudation with net retention of isotonic fluids
What are causes of edema or transudation with net retention of isotonic fluids?
Congestive heart failure
Hepatic cirrhoses
Nephrotic syndrome (PLN)
What are the 2 theories associated with hepatic cirrhosis?
Underfilling theory
Overflow theory
What are the disorders associated with hyponatremia?
Na deficit H2O excess Shifting water ICF --> ECF Shifting of Na from ECF to ICF Shift of Na from IV to EV K depletion
What are the causes of Na deficit with hyponatremia?
Alimentary, renal, cutaneous, or third space loss
What causes H2O excess with hyponatremia?
Water retention > Na retention (edematous disorders)
Where does shifting of water from ICF to ECF that causes hyponatremia occur?
Osmotic draw
Where does shifting of Na from ECF to ICF that causes hyponatremia occur?
Muscle
Where does shifting of Na from IV to EV that causes hyponatremia occur?
Uroperitoneum
What is potassium concentration dependent on?
Mostly on tbK and movement into and out of the cell in response to changes in acid-base status
Why are most cells K rich?
Na/K ATPase pump
What is plasma K regulated through?
ECF ICF
Renal excretion
What should be considered when interpreting [K+]?
Acid base status
What may cause hyperkalemia to shift ICF to ECF?
An inorganic acidosis
Does an organic acidosis cause hyperkalemia?
Not typically
What may cause hypokalemia?
Treatment of acidosis
Metabolic alkalosis
What promotes K uptake?
Epinephrine and insulin
Hyperkalemia causes cellular uptake of K
Where is K resorbed?
Before the distal nephron
What is K secreted by?
Principal cells of collecting tubules, promoted by aldosterone
What are the major stimulants of aldosterone secretion?
Hyperkalemia and angiotensin II
What happens to K in hypochloremic states?
Resorption of Na without Cl establishes electrochemical gradients that promotes K secretion
When does hyperkalemia typically occur?
In decreased K renal excretion or shifts from ICF to ECF
What are the disorders associated with hyperkalemia?
Shifting of K from ICF to ECF
Increased total body K
Repeated chylous effusion drainage
What are causes of shifting of K from ICF to ECF?
Metabolic inorganic acidosis From muscle Massive intravascular hemolysis, massive tissue necrosis Hypertonicity: diabetes mellitus Pseud-hyperkalemia
What are causes of increased total body K?
Renal insufficiency: oliguric, anuric
Urinary tract obstruction or leakage
Hypoaldosteronism, hypoadrenocorticism
When do you have hypokalemia?
ECF —> ICF
Decreased intake
Increased loss
What are the disorders associated with hypokalemia?
ECF —> ICF
Decreased total body K
Hypokalemic renal failure in cats
What are causes of ECF —> ICF associated with hypokalemia?
Metabolic alkalosis
Increased insulin activity
What are causes of decreased total body K?
Decreased intake
Increased renal loss: increased fluid flow, ketonuria, lacturia, bicarbonaturia, and hypochloremic metabolic alkalosis
Vomiting, diarrhea, excessive salivation
Sweating in horses
What are causes of a decreased Na:K ratio?
Hypoadrenocorticism Diarrhea Renal failure Urinary tract obstruction or uroperitoneum Diabetes mellitus with ketonuria Third space loss
What is serum [Cl] equal to?
ECF [Cl]
What is [Cl] influenced by?
Na and HCO3
What controls [Cl]?
Renal resorption and secretion
Alimentary tract functions
What does hyperchloremia typically occur with?
Hypernatremia: increased [Na] –> increased [Cl]
Occasionally with low bicarb: decreased [HCO3] –> increased [Cl]
What are diseases and conditions associated with hyperchloremia?
Water deficit (inadequate water intake, pure water loss)
Excess Cl
Hyperchloremic metabolic acidosis: alimentary, renal
Chronic respiratory alkalosis
What does hypochloremia typically occur with?
Hyponatremia or increased serum bicarb
Also metabolic acidosis with increased anion gap
What are conditions assoicated with Hypochloremia?
Cl deficit
H2O excess (water retention > Cl retention)
Shifting water ICF to ECF (osmotic draw)
Shift of Cl from IV to EV (uroperitoneum)
What are causes of Cl deficit?
Hyponatremic dehydration: Alimentary, renal, cutaneous or third space loss
Acid base disturbances: metabolic alkaloses, metabolic acidoses with increased anion gap
What is bicarb?
A major buffer that helps maintain the blood pH
What is bicarb produced from?
H2O and CO2 by carbonic anhydrase
What does total CO2 reflect?
Total amount of CO2 gas that can be liberated from serum
What percent of the potential CO2 gas is in the form of HCO3?
95% (5% is dissolved)
What is [tCO2] nearly equal to?
[HCO3]
What causes increased [HCO3] or [tCO2]?
Metabolic alkalosis, primary or compensating
What are conditions associated with increased [HCO3] or [tCO2]?
Loss of H from the body
Shift of H from ECF to ICF due to hypokalemia
Administration
Contraction alkalosis
What are causes of loss of H+ from the body?
Gastric loss (vomiting, pyloric obstruction) Renal loss of H+ (loop of Henle diuretics, thiazide diuretics, secondary to respiratory acidosis, hypokalemia)
What causes decreased [HCO3] or [tCO2]?
Metabolic acidosis, primary or compensating
What are conditions associated with decreased [HCO3] or [tCO2]?
Generation of excess H+
Decreased renal excretion of H+
Increased HCO3 loss
Dilutional acidosis
What are causes of generation of excess H?
Tirational acidoses
Lactic acidosis
Ketoacidosis
Ingestion of certain compounds (ethylene glycol, methanol)
What are causes of decreased renal excretion of H?
Renal failure
Urinary tract obstruction and uroperitoneum
Distal renal tubular acidosis
Hypoaldosteronism in hypoadrenocorticism
What are causes of increased HCO3 loss?
Alimentary (intestinal and pacreatic secretions are HCO3 rich)
Renal (proximal renal tubular acidosis: defect in HCO3 conservation)
What is a cation?
Atom or molecule with positive charge
Monovalents, divalents
What is measured cation charge?
Na and K
Monovalents measured as free ions
[ion] = [charge]
What is unmeasured cation charge?
[Charge] of all other cations of blood
fCA, fMg, and cationic globulins
[charge] > [ion]
What is an anion?
Atom or molecule with negative charge
Monovalent, divalent, trivalent
What is measured anion charge?
Cl and HCO3
Monovalents and measured as free ions
[ion] = [charge]
What is unmeasured anion charge?
[Charge] of all other anions of blood
PO4, albumin, anions or organic acids, and SO4
[charge] > [ion]
What is total cation or anion charges?
Total [charge]
Measured and unmeasured
What is the anion gap?
Difference in the [charge] between uA and uC
What is the charge of serum?
Neutral
What are the major contributors to anion gap?
Cations: Na and K (95%)
Anions: Cl and HCO3
What is the major purpose of calculating anion gap?
Identify increase uA, thus detect increased circulating anionic molecules
What is the anion gap of a healthy animal?
uA are greater than uC
What is the anion gap almost equivalent to in a health animal?
[Anions] from organic acids and proteins, PO4, and SO4
What is the anion gap of normochloremic and hypochloremic metabolic acidosis?
Increased AG due to increased uA
What is the anion gap of hypochloremic metabolic alkalosis?
No change in AG
What is the AG of an animal with hyponatremia and hypochloremia?
No change in AG
What is the anion gap on an animal with hypoproteinemia?
Decreased AG
What are causes of increased AG?
Metabolic acidosis
Hyperalbuminemia
What is decreased AG often due to?
Hypoalbuminemia
What is the glycolytic pathway?
Anaerobically converts glucose into ATP and generate pyruvate
What is the major tissue source of lactate?
Skeltal muscle
What is gluconeogenesis?
L-lactate –> glucose (Cori cycle)
L-lactate –> ATP (Krebs)
What is the primary reason for hyperlactemia?
Hypoxia
May also be due to defective metabolic pathways
What are disorders associated with hyperlactemia?
Inadequate delivery of O2 to tissues (stagnant hypoxia, demand hypoxia)
Increased production by metabolic pathways
Sepsis
Canine babesiosis
Liver disease
Transfusion of stored erythrocytes
What is the relationship between lactate and AG?
Both L-lactate and D-lactate will contribute to an anion gap
What is ketogenesis in hepatocytes promoted by?
Glucagon
What is ketogenesis in hepatocytes inhibited by?
Insulin
What is increased ketine body concentration in blood called?
Ketonemia
What is the clinical disorder of increased ketone body concentration?
Ketosis
Why does ketosis occur?
Excess glucagon or insulin deficiency
In negative energy status: oxidation of lipids with inadequate amount of oxaloacetate
What are causes of ketonemia in all mammals?
Starvation
Prolonged anorexia
Diabetes mellitus
What are causes of ketonemia in cattle?
Bovine ketosis in lactation
Displaced abomasum
Hepatic lipidosis
What are causes of ketonemia in dogs?
Starvation
Lactation
Endurance racing
What are causes of ketonemia in horses?
Endurance racing
What is osmolality?
Concentation of a solute in moles/kg
What is osmolarity?
Concentration of a solute in moles/L
What is osmotic pressure?
Force required to counterbalance the force of osmotic solvent flow through
What is osmosis?
Passage of solvent from a solution of lower concentration to a solution of higher concentration through a semipermeable membrane
What is tonicity?
Effective osmolality of a solution
What is a solute?
Substance dissolved in a solvent
What is colloidal osmotic pressure?
Osmotic pressure exerted by colloidal particles
What are colloidal particles?
Macromolecules too small to settle out by gravity
What is the major solute in serum?
Na
Cl is second
What are causes of increased osmolality?
Increased Na, urea, glucose
Increased concentration of nonanionic compound
What are causes of decreased osmolality?
Hyponatremia
