fluid/acid-base HYPO NA Flashcards
HypoNa. what normal serum osmol?
275-295
HypoNa. If osmolality increased, what released?
Incr. in osmolality -> incr. ADH -> incr. H2O resorption in distal tubules and collecting ducts.
HypoNa. If osmolality decreased, what supressed?
Osmolality is low -> low ADH -> less water absorbed.
ADH is secreted in response to hypovolemia and this stimulus will over-ride any response to serum osmolality.
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What is osmolality?
Osmolality = effective osmoles + ineffective osmoles
What is tonicity?
Tonicity = effective osmoles
Tonicity leads to driving force for water to move, since particles do not cross membrane and it leads to incr. tonicity.
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Effective osmoles how move?
Effective osmoles – does not move easily.
Ineffective osmoles how move?
Ineffective osmoles – moves easily through compartments.
Tonicity (effective osmoles) - what particles?
It is determined by endogenous (sodium and glucose) and exogenous (mannitol, raffinose) solutes with a reflection coefficient of 1.0 that are unable to pass through cell membranes.
ineffective osmoles - what particles?
Freely permeable substances that have a reflection coefficient of zero (such as urea, ethanol, and methanol) are named as “ineffective osmoles” and they can easily shift through fluid compartments.
Serum osml. formula?
Serum Osm = 2 x Na + Glucose + Urea (international units (all of which are in mmol/L)).
what is osmolal gap? calculation?
The osmol gap is the difference between the measured and calculated osmolality
(measured – calculated)
Inc. osmolality. 2 mechanisms?
1st mechanism: there may be an additional solute or solutes other than a sodium salt, glucose, or urea that is present at a concentration high enough to raise the osmolality.
2nd mechanism: Marked hyperlipidemia or hyperproteinemia.
normal osmolal gap?
Normal gap =< 10 mOsm/kg water.
Above 10 - incr. osmolal gap
Inc. osmolality. 1st mechanism - inc. solutes. it may be with or without anion gap acidosis.
WITH anion gap ACIDOSIS what particles contribute to LARGE anion gap?
Major causes of a large osmolal gap: ethylene glycol or methanol ingestion, propylene glycol infusion – it a diluent found in iv medications such lorazepam (Ativan), diazepam (valium), phenytoin, phenobarbital, nitroglycerin.
Inc. osmolality. 1st mechanism - inc. solutes. it may be with or without anion gap acidosis.
WITH anion gap ACIDOSIS what particles contribute to SMALL anion gap?
Causes of smaller osmolal gap: severe CKD without regular dialysis, ketoacidosis (diabetic or alcohol), lactic acidosis, paraldehyde ingestion or injection.
Inc. osmolality. 1st mechanism - inc. solutes. it may be with or without anion gap acidosis.
WITHOUT anion gap ACIDOSIS what particles contribute to anion gap?
Ethanol, isopropanol, diethyl ether ingestion; infusion of mannitol, infusion of nonconductive glycine (TURP syndrome), sorbitol; pseudohyponatremia (severe hyperlipidemia or hyperproteinemia)
Inc. osmolality. 2nd mechanism.
Marked hyperlipidemia or hyperproteinemia does not affect the concentration of sodium in serum water, and it is this concentration that determines the measured serum osmolality.
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HypoNa. UW. Low osmolality. What are fluid statuses?
Hypovolemic, euvolemic, hypervolemic.
HypoNa. UW. 1st step?
is there hyponatremia < 135?
HypoNa. UW. normal osmol and inc. osmol. what fluid statuses?
,,variable”
fantastika blet
HypoNa. UW. there is Na < 135. what next?
check osmolality - o
low < 275
normal,
high > 295 mOsm/kg
HypoNa. UW. if low Na + high osmol?
evaluate 2 things.
1st - glucose - it may be result of hyperglycemia
2nd - exogenous solutes eg mannitol, contrast agents, alsa was mentioned advanced renal failure.
HypoNa. UW. if Na low and there is no increase in serum osmol (it means osmol low or normal). what to evaluate then?
urine osmolality.
HypoNa. UW. urine osmolality range?
Urine osmolality varies between 50 and 1200 mmol/kg.
For diagnostic - 100 mOsm/kg
HypoNa. UW.
Na low and there is no increase in serum osmol. evaluated urine osmol > 100 mOsm/kg.
what that means? causes
Indicates impaired ability to dilute the urine. Urine is concentrated, it means that water is lack in urine. It means ADH is released.
Causes: SIADH (also U Na > 40), hypothyroidism, glucocorticoid deficiency (aka secondary adrenal insufficiency).
HypoNa. UW.
Na low and there is no increase in serum osmol. evaluated urine osmol < 100 mOsm/kg.
What that means? causes
It indicates diluted urine. Urine is dilated, it means there is too much water, that need to excrete. It means ADH is suppressed.
Primary polydipsia, beer drinkers potomania.
what is beer potomania?
Beer potomania, a unique syndrome of hyponatremia (5 or more drinks/day). It is described as the excessive intake of alcohol, particularly beer, together with poor dietary solute intake that leads to fatigue, dizziness, and muscular weakness.
The low solute content of beer, and suppressive effect of alcohol on proteolysis result in reduced solute delivery to the kidney. The presence of inadequate solute in the kidney eventually causes dilutional hyponatremia secondary to reduced clearance of excess fluid from the body.
HypoNa. UW.
Na low and there is no increase in serum osmol. evaluated urine osmol > 100 mOsm/kg. what evaluate next?
Urine sodium
HypoNa. UW.
Na low and there is no increase in serum osmol. evaluated urine osmol > 100 mOsm/kg. esant >100 toliau tesiasi algoritmas siekiant ivertinti (pagal U Na) kokia yra priezastis - renal or extrarenal. cia jau priklauso prie hypovolemic. nes jeigu <100 - tai normovolemija, bet jeigu > 100, tai reikia issdifernecijuoti ar tai nera hypovolemine bukle.
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HypoNa. UW.
Na low and there is no increase in serum osmol. evaluated urine osmol > 100 mOsm/kg.
pagal UW algo yra rodiklis U Na 25.
U Na < 25? causes
Volume depletion
CHF, cirrhosis (decr. effective circulating volume) - siaip schemoj yra prie hypervolemia, nes bendrai paemus skysciu yra daug, bet tas efektyvus turis yra sumazejes, todel pvz U Na yra zemas, nes bando kunas issaugoti natri, nes neva ,,hipovolemija”
HypoNa. UW.
Na low and there is no increase in serum osmol. evaluated urine osmol > 100 mOsm/kg.
pagal UW algo yra rodiklis U Na 25.
what means if U Na > 25? causes
SIADH, adrenal insuffieciency, hypothyroidism.
Hypovolemic hypoNa. symptoms?
decr. intake and decr. output of water, orthostatic lightheadness, dry mucous membranes, poor skin turgor, tachycardia, orthostatic hypotension.
Hypovolemic hypoNa. Extrarenal loses U Na =< 20?
burns, diarrhea, vomiting, pancreatitis
Hypovolemic hypoNa. Renal loses U Na > 20?
Diuretics, mineralcorticoid deficiency
Hypovolemic hypoNa. decreased effective circulating volume? nu cia bendrai yra hypervolemia, bet del sumazejusio efektyvaus turio organizas galvoja kad yra hipovolemija
CHF, cirrhosis
Mechanism of hypovolemic hyponatremia.
Solute and water loss –> 3 results?
- decr. renal perfusion
- hypotension
- hypovolemia
Mechanism of hypovolemic hyponatremia.
Solute and water loss –> 1. decr. renal perfusion –?
Activation or RAAS –> AT II –>
- Incr. aldosterone -> incr. Na absorb.
- Incr. THIRST –> Incr. water intake –> decr. serum Na
- Incr. ADH (non-osmotic stimulation) –> incr. water reabs. –> decr. serum Na
Mechanism of hypovolemic hyponatremia.
Solute and water loss –> hypotension –>?
BARORECEPTORS –> Incr. ADH (non-osmotic stimulation) –> incr. water reabs. –> decr. serum Na
Mechanism of hypovolemic hyponatremia.
Solute and water loss –> hypovolemia –> ?
Left atrial stretch receptor stimulation –> Incr. ADH (non-osmotic stimulation) –> incr. water reabs. –> decr. serum Na.
Mechanism of hypovolemic hyponatremia. short.
Solute and water loss –> decr. renal perfusion –> general result?
activation of RAAS –> incr. ATII
Mechanism of hypovolemic hyponatremia. short.
Solute and water loss –> hypotension –> general result?
baroreceptors activated
Mechanism of hypovolemic hyponatremia. short.
Solute and water loss –> hypovolemia–> general result?
Left atrial stretch receptor stimulation
hypoNa. treatment. what first evaluate?
onset - 48h
hypoNa. treatment.
acute < 48
chronic or unknown >48
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hypoNa. treatment.
acute –> what evaluate?
whether symptoms (mild, moderate, severe) are present?
hypoNa. treatment.
Acute + yes symptoms –>?
100 ml 3 proc. saline and repeat twice as needed.
monitor Na hourly until serum Na has increased by 4 to 6 mmol/l after which monitoring can be reduced
recurrent hypoNa may require repeat treatment as above
hypoNa. treatment.
Acute + no symptoms –> what evaluate?
Is the hyponatremia already autocorrecting due to a water diuresis?
hypoNa. treatment.
Acute + no symptoms –> already autocorrects due to water diuresis –> ?
Monitor Na hourly until serum Na has increased by 4 to 6 mmol/l above nadir (lowest value)
Further decline of Na means no autocorrection or delayed absorption of ingested water
If declines –> give 50 ml bolus 3 proc saline
hypoNa. treatment.
Acute + no symptoms –> DOES NOT already autocorrects due to water diuresis –> ?
50 ml 3 proc. saline bolus to prevent decline
Monitor Na hourly to determine the need for repeated bolus
hypoNa. treatment.
Acute + no symptoms –> autocorrect pathway due to water diuresis –> further decline of Na. What 2 reasons?
Decline means there is no autocorrection OR occurs delayed absorption of ingested water
hypoNa. treatment.
Chronic –> evaluate for SEVERE symptoms.
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hypoNa. treatment.
Chronic + SEVERE symptoms –>
100 ml 3 proc. saline and repeat twice as needed.
monitor Na hourly until serum Na has increased by 4 to 6 mmol/l after which monitoring can be reduced.
recurrent hypoNa may require repeat treatment as above
hypoNa. treatment
Chronic + No SEVERE symptoms –> EVALUATE wether has intracranial pathology - recent TBI, brain surgery or hemorrhage, or neoplasm.
If yes and no?
if yes: manage same ar with severe symptoms (100 ml 3 proc saline)
if no: evaluate wether Na < 120?
hypoNa. treatment
Chronic + No SEVERE symptoms –>no brain pathology –> Na < 120 mmol/l –> what evaluate?
evaluate wether hyponatremia is due to self-induced intoxication? (extreme polydipsia?).
hypoNa. treatment
Chronic + No SEVERE symptoms –>no brain pathology –> Na < 120 mmol/l –> YES water intoxication –> monitoring of sodium, general measures. no question
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hypoNa. treatment
Chronic + No SEVERE symptoms –>no brain pathology –> Na < 120 mmol/l –> NO water intoxication –> what evaluate?
Is patient is edematous? (CHF, cirrhosis)
hypoNa. treatment
! Chronic + No SEVERE symptoms –>no brain pathology –> Na < 120 mmol/l –> NO water intoxication –> YES edematous state –> ? treatment
Infusion of 3 proc. saline at 15 to 30 ml/h PLUS iv furosemide (40 mg or higher) TWICE DAILY.
Monitor Na frequently (eg 2-4h) and adjust rate of 3 proc. saline to ACHIEVE a 24h increase in serum sodium of 4-6 mmol/l.
Titrate furosemide to prevent severe hypervolemia
Discontinue regimen when serum Na has increased at least 125.
hypoNa. treatment
Chronic + No SEVERE symptoms –>no brain pathology –> Na < 120 mmol/l –> NO water intoxication –> No edematous state –> ? evaluate rapid reversible causes of hypoNa: 3?
Is the case of hypoNa rapidly reversible? Specifically:
- Due to true hypovolemia?
- due to adrenal insufficiency?
- transient SIADH (eg from surgery, pain, drug induced)
hypoNa. treatment
Chronic + No SEVERE symptoms –>no brain pathology –> Na < 120 mmol/l –> NO water intoxication –> No edematous state –> ? evaluate rapid reversible causes of hypoNa –> present. what treatment?
Infusion of 3 proc. saline at 15 to 30 ml/h PLUS iv or s/c desmopresin 1-2 mcg every 6-8h.
Monitor Na frequently
(eg 2-3h initially, and then, after water losses have been controlled with desmopressin, every 4-6h); adjust 3proc. saline rate to ACHIEVE a 24h increase in serum sodium of 4-6 mmol/l.
Discontinue regimen when serum Na has increased at least 125.
hypoNa. treatment
Chronic + No SEVERE symptoms –>no brain pathology –> Na < 120 mmol/l –> NO water intoxication –> No edematous state –> ? evaluate rapid reversible causes of hypoNa –> not present –> what evaluate then? 5
Is the patient at high risk for osmotic demyelination syndrome?
1. Serum sodium =< 105
2. Concurrent hypokalemia
3. Patient with alcohol use disorder
4. Malnourished patient
5. Concurrent liver disease
hypoNa. treatment
Chronic + No SEVERE symptoms –>no brain pathology –> Na < 120 mmol/l –> NO water intoxication –> No edematous state –> ? evaluate rapid reversible causes of hypoNa –> not present –> if patient is at high risk for demielination syndrome –> treatment?
same as with rapidly reversible (saline and desmopresin)
hypoNa. treatment
Chronic + No SEVERE symptoms –>no brain pathology –> Na < 120 mmol/l –> NO water intoxication –> No edematous state –> ? evaluate rapid reversible causes of hypoNa –> not present –> if patient is NOT at high risk for demielination syndrome –> treatment?
Standartinis letas.
Infusion of 3 proc. saline at 15 to 30 ml/h
Monitor Na frequently (eg 4-6h) and adjust rate of 3 proc. saline to ACHIEVE a 24h increase in serum sodium of 4-6 mmol/l.
hypervolemia
Discontinue regimen when serum Na has increased at least 125.
Hyperglycemia, exogenous solutes, advanced renal failure. status?
Osm > 295
Fluid status - variable
Pseudohyponatremia (eg. paraproteinemia, hyperlipidemia). status?
osm normal, fluid status variable
primary polydipsia, malnutrition (beer potomania). status?
osm < 275
euvolemia
U Osm < 100
SIADH, hypothyroidism, secondary adrenal insufficiency. status?
osm < 275
euvolemia
U Osm > 100
FA. HypoNa most common cause?
Increased ADH.
Causes: physiologic - eg dec. effective circulating volume
or
pathologic - SIADH
FA. HypoNa ADH independent causes?
primary polydipsia, starvation (solute deficiency), presence of a non-sodium effective osmole in the ECF (eg glucose in hyperglycemia)
FA. HypoNa. treatment.
treat underlying cause.
If hypervolemic or euvolemic?
water restriction +/- diuretics
FA. HypoNa. treatment.
hypovolemic?
replete volume with NaCl.
FA. HypoNa. treatment.
If severe hypoNa < 120?
consider 3 proc. hypertonic saline, particularly if symptomatic (eg seizures)
FA. HypoNa. treatment.
Chronic. rate of treatment?
slowly < 10 mmol/l day to prevent osmotic demyelination syndrome (symptoms include paraparesis/quadriparesis, dysarthria, coma)
UW. Iatrogenic HypoNa.
4 risk factors?
Hypotonic fluid hydration
Children, postmenopause, elderly
Hypoxia
Central nervous system disorders
UW. Iatrogenic HypoNa. clinical? 3
Headache
Nausea/vomiting
Encephalopathy (mental status changes, seizures)
UW. Iatrogenic HypoNa. treatment 3.
Hypertonic 3 proc. saline
Serial measurement of electrolytes
Incr. in serum sodium 6-8mmol/l in first 24h.
