Monovalent Electrolytes, Anion Gap and Osmolality Flashcards
Na, K, Cl from food/fluid
- metabolism is responsible for ICF ECF
- ECF is Na/Cl rich and K poor
- changes in ECF will change plasma electrolyte concentration
Platelets release _____
K+
- [K] serum > plasma
Electrolytes and H2O is excreted or lost via
Kidneys, skin or respiration
Abnormal [electrolyte] in plasma
- decreased or increased intake
- ICF ECF
- increased renal retention
- increased loss via kidney, skin, alimentary tract, respiration
[Na] in plasma is equivalent to ______
[Na] in ECF
- dependent of total body Na and total body H2O
- hydration is important for [Na] interpretation! –> H2O follows Na (except in distal nephron without ADH)
How does [K] affect [Na]
- if [K] decreases, [Na] decreases since it enters the cells to keep electrical balance
- a severe [K] increase would be necessary for [Na] to increase, but severe [K] is not compatible with life
Na concentration is regulated by ______
Blood volume and plasma osmolality regulation
Hypovolemia stimulates RAS –> angiotensin 2 and aldosterone
- angiotensin 2 increases Na, K, Cl resorption in proximal tubules
- aldosterone increases Na resorption in collecting ducts
How does hypovolemia stimulate ADH release?
Hypovolemia –> carotid sinus –> baroreceptors –> ADH release –> increased water resorption
How does hypervolemia stimulate ANP release?
Hypervolemia –> atrial baroreceptors –> atrial natriuretic peptide –> decreased Na resorption
Hyperosmolality
Hyperosmolality –> hypothalamic osmoreceptors –> promotion of water intake and release of ADH –> H2O resorption and Na, K, Cl in ascending loop of Henle
Hypoosmolality
Leads to decreased water intake
[Na] self regulation
- decreased –> aldosterone release, increased retention
- increased –> decreased aldosterone release, decreased retention
What is the most important regulator of aldosterone release?
[K]!!
Dehydration is equivalent to _____
Decreased total body H2O
- only H2O: decreased intake or loss of free H2O
- H2O + Na loss: alimentary, renal or cutaneous loss
Hypernatremic, hyperosmolar, or hypertonic dehydration
Caused by net hypoosmolar or hypotonic fluid loss
- H2O loss > Na loss
Normonatremic, isoosmolar, or isotonic dehydration
Caused by net isoosmolar or isotonic fluid loss
- H2O loss = Na loss
Hyponatremic, hypoosmolar, or hypotonic dehydration
Caused by net hyperosmolar or hypertonic fluid loss
- H2O loss < Na loss
Inadequate H2O intake
Hypernatremia!!
- H2O deprivation due to restricted access
- defective thirst response: hypothalamic dz may damage the osmoreceptor
- thirst center may be damaged
Pure H2O loss without H2O replacement
Hypernatremia!!
- insensible loss of H2O by panting, hyperventilation, or fever
- diabetes insipidus (central or nephrgenic) –> unrestricted access to H2O may drink sufficiently to prevetn the hypernatremia
H2O loss > Na loss
Osmotic diuretic agents (glucose and mannitol) –> inhibit passive H2O resorption = hypernatremia
Hypernatremia due to the alimentary system
- accumulation of osmotic agents will inhibit H2O absorption
- phosphate enema will pull H2O from ECF to the colon
- rumen acidosis causes accumulation of solutes in the rumen –> osmotic movement of H2O into the rumen –> hypernatremia
- dogs with paintball toxicosis
Na excess with concurrent restricted H2O intake
- salt poisoning: cattle with excessive Na and with concurrent restricted access to H2O –> increased tb-Na = hypernatremia
- administration of hypertonic saline or Na bicarbonate –> increased tb-Na and hypernatremia
Decreased renal excretion of Na
Hyperaldosteronism
- excessive aldosterone promotes excessive renal Na retention –> hypernatremia (and hyperchloremia) may occur if H2O is restricted or defective ADH activity