JH IM Board Review - SOS I Flashcards
(99 cards)
Insensible losses:
500-1000ml/day lost through skin and respiratory tract.
Increases in plasma osmolality as small as …% can release ADH:
1%.
How great hypovolemia causes ADH release?
10% or greater.
What else causes incr. in ADH?
- Pain.
- Nausea.
- Dx: antidepressants, antipsychotics, nsaids, opioids, barbs.
Hyponatremia can occur with what total body Na?
- Low.
- Normal.
- High.
==> Hyponatremia requires the presence of too much water relative to the quantity of total body Na.
Asymptomatic hyponatremia is …?
Isosmolar.
Hypoosmolar hyponatremia causes symptoms by …?
SWELLING of the cns.
Hyperosmolar hyponatremia causes symptoms by …?
DEHYDRATION of the cns.
Hyponatremia 125-135 - Symptoms:
- Anorexia.
- Apathy.
- Restlessness.
- Nausea.
- Lethargy.
- Muscle cramps.
Hyponatremia 120-125 - Symptoms:
- Agitation.
- Disorientation.
- Headache.
Hyponatremia <120 - Symptoms:
- Seizures.
- Coma.
- Areflexia.
- Cheyne-Stokes.
- Incontinence.
- Death.
Rare causes of SIADH:
- HIV.
- Prolactinoma.
- Waldenstorm.
- Shy-Drager.
- Delirium tremens.
- Exercise-induced (eg marathon).
Hyponatremia - Deal with severe CNS symptoms:
- Raise Na concentration with 3% saline until symptoms abate.
- 4-6mmol/L increase in Na concentration should suffice.
- 100mL bolus of 3% saline infused over 10min. Can be repeated twice if necessary.
Mild to moderate symptoms - Hyponatremia - Manage:
Raise Na concentration with 3% saline at 1 mL/kg/h.
Effect of 1L of infused solution on Na concentration can be estimated by:
ΔNa = (Na (infused) - Na (serum))/(TBW +1).
Classic outpatient presentation of HYPERnatremia:
Elderly nursing home resident with underlying infection.
Hypernatremia - Patients may experience:
- Restlessness.
- Irritability.
- Lethargy.
- Muscle twitching.
- Hyperreflexia.
- Spasticity.
- Intracranial hemorrhage.
DI in pregnancy:
Placental production of vasopressinase.
Free water deficit equation:
FWD = TBW x [(Serum sodium concentration/140) - 1].
Hypokalemia - <2.5 and <2?
May result in fatigue progressing to muscle weakness and arrhythmia, followed by tetany or rhabdomyolysis at K less than 2.5, and then paralysis when less than 2.
Hypokalemia and osmotic demyelination syndrome?
Hypokalemia may increase the risk of osmotic demyelination syndrome when correcting hyponatremia.
==> If neurologically stable, correct hypokalemia before correcting hyponatremia.
Classic example of intracellular shifting is …?
Hypokalemic periodic paralysis.
What should be addressed before K repletion in hypokalemia?
Hypomagnesemia and hypocalcemia.
Degrees of hyperkalemia:
MILD ==> 5.5-6 ==> USUALLY asymptomatic.
> 6.5 ==> PROGRESSIVE weakness, muscle aches, areflexia, paresthesias, ECG changes.
> 7 ==> Paralysis, respiratory failure, life-threatening arrhythmias.