Chapter 5 - Water, Electrolyte, Acid-Base, and Hemodynamic Disorders Flashcards
What are the major ECF and ICF cations?
Na+, K+: major ECF and ICF cations, respectively
Describe how water compartment sizes compare to one another.
Compartment sizes: ICF > ECF; interstitial > vascular
Describe how plasma osmolality differs between isotonic, hypotonic and hypertonic states.
Isotonic, hypotonic, hypertonic: normal POsm, ↓POsm, ↑POsm, respectively
What is the plasma osmolality equation?
POsm = 2 (serum Na+) + serum glucose/18 + serum BUN/2.8 = 275–295 mOsm/kg
What is the equation for effective osmolality? How does this equation differ from the plasma osmolality equation?
EOsm = 2 (serum Na+) + serum glucose/18; urea diffuses between ECF and ICF
Describe two features of osmosis.
Osmosis: H2O moves between ECF and ICF; Na+ controlled movement
Describe osmosis in hyponatremia.
Hyponatremia: H2O moves from ECF to ICF (expanded)
Describe osmosis in hypernatremia/hyperglycemia.
Hypernatremia/hyperglycemia: H2O moves from ICF (contracted) to ECF
What does the serum sodium concentration approximate?
Serum Na+ ~ TBNa+/TBW
List four clinical findings with decreased total body sodium.
↓TBNa+: ↓skin turgor, dry mucous membranes, ↓blood pressure, ↑pulse when sitting/standing up
List two clinical findings with increased total body sodium.
↑TBNa+: pitting edema, body cavity effusions
How does an increase in total body sodium affect Starling forces?
↑TBNa+: alteration of Starling forces (↑HP and/or ↓OP)
What do Starling forces do?
Starling forces: control fluid movements in ECF compartment
What is the most common cause of weight gain in a hospitalized person?
↑Patient weight in hospital: ↑TBNa+
How does an isotonic loss or gain affect serum sodium concentration?
Isotonic loss or gain: serum Na+ normal
If there is a gain in fluid, how does the ECF respond?
Gain in fluid: ECF always expands
If there is a loss of fluid, how does the ECF respond?
Loss in fluid: ECF always contracts
How does an isotonic loss of fluid affect TBNa+ and TBW? Provide an example.
Isotonic loss: ↓TBNa+/↓TBW; secretory diarrhea
What is the treatment for an isotonic loss of fluid?
Rx isotonic loss: normal saline
What results from a normal saline infusion?
Normal saline: ↑BP; equilibrates between vascular/interstitial space
How does an isotonic gain of fluid affect TBNa+ and TBW? Provide an example.
Isotonic gain: ↑TBNa+/↑TBW; ↑↑isotonic saline infusion
What is the treatment for an isotonic gain of fluid?
Rx isotonic gain: restrict water; loop diuretics
What is always present in hypotonic disorders? How does the ICF respond?
Hypotonic disorders: hyponatremia always present; ICF expansion
How does a hypertonic loss of fluid affect TBNa+ and TBW?
Hypertonic loss: ↓↓TBNa+/↓TBW
List three examples of a hypertonic loss of fluid.
Hypertonic loss: loop diuretics/thiazides (excessive), Addison, ↓21-hydroxylase
What is the treatment for a hypertonic loss of fluid?
Rx hypertonic loss: infuse normal saline or equivalent
What may result in central pontine myelinolysis?
Central pontine myelinolysis: rapid correction of hyponatremia with saline in alcoholic
How does a hypotonic gain of water affect TBNa+ and TBW? Give two examples.
Hypotonic gain water: TBNa+/↑↑TBW; SIADH, compulsive water drinker
What is the treatment for a hypotonic gain of water?
Rx hypotonic gain water: restrict water
How does a hypotonic gain of Na+ affect TBNa+ and TBW?
Hypotonic gain water + Na+: ↑TBNa+/↑↑TBW
List three different pitting edema states. How is cardiac output affected?
Pitting edema states: RHF, cirrhosis, nephrotic syndrome; ↓cardiac output
What is the treatment for pitting edema states?
Rx pitting edema states: restrict water/sodium; diuretics
Name two hypertonic disorders. How does the ICF respond?
Hypertonic disorder: hypernatremia/hyperglycemia; ICF contraction
How does the ICF always respond in hypertonic conditions?
Hypertonic conditions: ICF always contracted
How does a hypotonic loss of Na+ affect TBNa+ and TBW?
Hypotonic loss Na+ + water: ↓TBNa+/↓↓TBW
List four examples of hypotonic loss of Na+.
Hypotonic loss Na+ + water: osmotic diuresis/diarrhea, sweating, vomiting
How does loss of pure water affect TBNa+ and TBW?
Hypotonic loss water: TBNa+/↓↓TBW
List two examples of loss of pure water.
Hypotonic loss water: diabetes insipidus; insensible water loss
How does hypertonic gain of Na+ affect TBNa+ and TBW?
Hypertonic gain Na+: ↑↑TBNa+/↑TBW
Provide two examples of hypertonic gain of Na+.
Hypertonic gain: ↑NaHCO3, Na+-containing antibiotic infused
What is DKA and what does it cause?
DKA: hypertonic state with dilutional hyponatremia; osmotic diuresis
What occurs in the proximal tubule?
Proximal tubule: reabsorb Na+, reclaim HCO3−
How does decreased EABV affect FF, PO and PA?
↓EABV → ↑FF → PO > PH
How does increased EABV affect FF, PH and PO?
↑EABV → ↓FF → PH > PO
What is reclaiming HCO3-?
Reclaiming HCO3−: retrieving filtered HCO3−
What is the effect of decreasing the threshold for reclaiming HCO3-? Provide an example.
↓Threshold for reclaiming HCO3− (carbonic anhydrase inhibitor): lose HCO3− in urine, ↓HCO3− in blood (metabolic acidosis)
What is the effect of increasing the threshold for HCO3-? Provide an example.
↑Threshold for reclaiming HCO3− (vomiting): reclaim more HCO3− from urine, ↑HCO3− in blood (metabolic alkalosis)
Heavy metal poisoning results in what?
Heavy metal poisoning: Fanconi syndrome
What are the functions of Na+-K+- 2Cl− symporter?
Na+-K+- 2Cl− symporter: generates fH2O, reabsorbs Ca2+
What type of water does ADH reabsorbs?
ADH: only reabsorbs fH2O not oH2O
What do loop diuretics do?
Cl− binding site in Na+-K+-Cl− symporter: inhibited by loop diuretics
What electrolyte abnormalities may loop diuretics produce?
Loop diuretic: hyponatremia, hypokalemia, metabolic alkalosis
What do thiazides do?
Thiazide: inhibits Cl− site Na+-Cl− symporter; ↑Ca2+ reabsorption
How do thiazides affect electrolytes?
Thiazide: ↓serum Na+, ↓K+; ↑HCO3− (metabolic alkalosis), ↑Ca2+ (if ↑PTH)
How do thiazides affect Na+ and K+? What is there danger of?
Thiazides: ↑Na+ reabsorption, ↑K+ excretion (danger of hypokalemia)
How does hypokalemia affect H+ and HCO3-? What is there risk for?
Hypokalemia: ↑H+ excretion → ↑HCO3− in blood; risk for metabolic alkalosis
Name two potassium-sparing diuretics.
Amiloride, triamterene: K+-sparing diuretics
How do proximally-acting diuretics affect distal delivery of Na+? What results from this effect?
↑Distal delivery Na+ (proximally-acting diuretics): ↓K+, metabolic alkalosis
Give an example of a titratable acid.
Titratable acid: NaH2PO4
What is the most effective way of removing H+?
NH4Cl: most effective way of removing H+
What does the H+-K+-ATPase pump excrete and regenerate?
H+-K+-ATPase pump: excretes excess H+; regenerates HCO3−
What is spironolactone and what does it do?
Spironolactone: aldosterone inhibitor; spares K+
How does an ACE inhibitor affect afterload and preload?
ACE inhibitor: ↓afterload (↓ATII), ↓preload (↓aldosterone)
How does Addison disease affect electrolyte levels?
Addison disease: hyponatremia, hyperkalemia, metabolic acidosis
What is primary aldosteronism most frequently caused by?
1° Aldosteronism: adenoma in zona glomerulosa
What electrolyte abnormalities are present in primary aldosteronism?
1° Aldosteronism: hypernatremia, hypokalemia, metabolic alkalosis
How does primary aldosteronism affect renin levels and blood pressure?
1° Aldosteronism: low renin hypertension
Why is pitting edema absent in mineralocorticoid excess states?
Absence pitting edema: escape phenomenon (PH > PO; lose Na+ in urine) + ↑ANP/BNP
What results from the absence of ADH?
Absence of ADH → dilution → loss of fH2O
How does CDI/NDI affect urine concentration?
CDI/NDI: always diluting, never concentrating
In CDI/NDI, how do UOsm and POsm compare?
CDI/NDI: UOsm < POsm
List one lab finding and two clinical findings in CDI/NDI.
CDI/NDI: hypernatremia, polyuria, polydipsia
Describe the results of water deprivation studies in CDI and NDI.
CDI: desmopressin ↑UOsm (concentration); NDI: desmopressin no change in UOsm
What is the treatment for CDI?
Rx CDI: desmopressin acetate
What is the treatment for NDI? How does the treatment work?
Rx NDI: thiazides; volume depletion decreases polyuria
How is the normal concentration of urine affected in CRF?
CRF: loss of concentration and dilution
What is a common cause of hyponatremia in a hospitalized patient?
SIADH: common cause of hyponatremia in hospitalized patient
What is the most common neoplasm ectopically producing SIADH?
SIADH: MCC small cell carcinoma of lung
How does SIADH affect the normal concentration of urine?
SIADH: always concentrating never diluting
In SIADH, how do UOsm and POsm compare?
SIADH: UOsm greater than POsm
What is diagnostic of SIADH? How are TBNa+ and TBW affected?
SIADH: serum Na+ <120 mEq/L; TBNa+/↑↑TBW
How are UOsm and random UNa+ affected in SIADH?
UOsm and random UNa+ increased in SIADH
How is mild SIADH treated?
Rx SIADH: restrict water
What does demeclocycline do and produce?
Demeclocycline: inhibits ADH; produces NDI
How does hypokalemia affect insulin secretion?
Hypokalemia inhibits insulin secretion