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40 Cards in this Set

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(3) major toxins that increase the serum's osmolarity
EtOH

Methanol

Ethylene glycol
ICF is what fraction of TBW?

Major cations of ICF? (2)

Major anions? (2)
ICF = 2/3 of TBW

Cations:
K
Mg

Anions:
Proteins
Oranic Phosphates (ATP, ADP, AMP)
ECF is what fraction of TBW?

Major cation of ECF?

Major anions? (2)
ECF = 1/3 of TBW

Cation:
Na

Anions:
Cl
HCO3
What composition does interstitial fluid resemble?
What is different?
resembles Plasma

Interstitial fluid contains little protein (ultrafiltrate)
What (2) compartments does water shift between?

If solutes (glucose, sodium, mannitol) dont cross the cell membrane, what osmolarity do they contribute to?
ECF + ICF

ECF
Formula for Serum Osmolarity

Normal Serum Osmolarity?
SO = 2(Na+K) + Glucose/18 + BUN/2.8

300 mOsm/kg
Define:

HypoN
plasma sodium < 134mEq/L
What are the (3) categories of HypoN?
Hypovolemic

Isovolemic

Hypervolemic
How can you distinguish b/t renal and extrarenal causes of hypovolemic hypoN?
Urine Sodium:

U-Na > 20 = Renal

U-Na < 10 = Non-renal
Extra-renal causes of hypovolemic hypoN
(5)
GI loss (Vomiting/Diarrhea)

Extensive burns

Dehydration

3rd spacing (pancreatitis, peritonitis)
GED 3
Renal causes of Hypotonic Hypovolemic HypoN
(5)
TANAS:
Thiazides (diuretics);
ACEi;
Nephropathies;
Addisons Dz (Mineralcorticoid deficiency);
Salt-wasting nephropathies
TANAS
Etiology of Hypotonic Euvolemic HypoN
(separate into 2 categories - 8 total)
Less dilute urine (SHiT):
SIADH
Hypothyroidism
Idiosyncratic drug rxn (Thiazides, ACEi)

More dilute urine (Huge PEPE):
HypoK
Post-op HypoN
EtOH addiction
Psychogenic polydipsia
Exercise
SHiT
Huge PEPE
"tonic" as in hypertonic refers to what?
serum osmolality
Serum osmolality level for:

HypoN

HyperN
HypoN: < 280 mOsm/kg

HyperN: > 300 mOsm/kg
Etiology of Hypotonic Hypervolemic HypoN
(4)
CLAN:
CHF
Liver disease
Advanced Renal Failure
Nephrotic syndrome
CLAN
Etiology of Isotonic HypoN
(2)
Hyperproteinemia

Hyperlipidemia
Etiology of Hypertonic HypoN
(2)
Facticious HypoN:

Hyperglycemia

Hypertonic infusions
(mannitol, glucose, contrast)
How does each 100 mL/dL increase in serum glucose above normal cause sodium to decrease?
Sodium decreases by 1.6 mEq/L
Signs/Sx of moderate hypoN or gradual onset
(4)
Confusion
Muscle cramps
Anorexia
Nausea
C-MAN
Signs/Sx of severe hypoN or rapid onset
(2)

At what level is considered severe?
Seziures or Coma

Severe: < 115 mEq/L
With low serum osmolarity (< 280), what signs should be observed to differentiate b/t Hypovolemia, Isovolemia, & Hypervolemia?
Hypovolemia:
Tachycardia; Hypotension; poor skin turgor

Isovolemia:
Normal vital signs w/o edema

Hypervolemia:
peripheral Edema
Dx:
measured & calculated serum osmolarities are different

What (2) problems is it seen in?
Pseudohyponatremia

Seen in:
Multiple myeloma
Hyperlipidemia
Tx of Hypovolemic HypoN
(2)
1. address underlying disorder

2. replace volume w/ NS
(monitor Na to prevent CPM)
Tx of Isovolemic or Hypervolemic HypoN
(2)
1. address underlying disorder

2. Sodium + water restriction
What is Tx for CHF-induced Hypervolemic HypoN?
(2)
1. Sodium + water restriction

2. Combination of Captopril & Furosemide
Rules for correcting HypoN by increasing serum sodium
(2)

Why?
1. only go into low-normal range in forst 24 hours

2. never correct sodium faster then 1 mEq/L/hr

Can lead to Central Pontine Myelinolysis (CPM), seizures, coma
What are pre-menopausal women at high risk for during an acute episode of HypoN?
Cerebral edema
Dx:
Osmotic demyelination syndrome occurring as a treatment complication of severe or chronic hypoN
Central Pontine Myelinolysis
(CPM)
Serum sodium level that is considered HyperN
Serum Na > 145 mEq/L
Type of HyperN:
Loss of both water + sodium
(water loss >> sodium loss)
Hypovolemic HyperN
Type of HyperN:
Decreased TBW, normal body sodium, decreased ECF
Isovolemic HyperN
Type of HyperN:
Increased TBW, markedly Inc total body Na, Inc ECF
Hypervolemic HyperN
Etiology of Hypervolemic HyperN
(3)
Hypertonic fluid administration;

Mineralcorticoid excess (Cushing's, Conn's);

Excess salt ingestion
Etiology of Isovolemic HyperN
(2)
Diabetes Insipidus;

Skin losses (due to hyperthermia)
Etiology of Renal-related Hypovolemic HyperN
(3)
Diuretics;

Acute/chronic Renal failure;

Partial obstruction
Etiology of Extra-renal-related Hypovolemic HyperN
(5)
Hyperpnea;

Excessive sweating;

Diarrhea;

Burns;

Dialysis
formula for Water Deficit in HyperN patient
WD (liters) = 0.6 x body wt (kg) x (measured Na/140) -1
Tx for Hypovolemic HyperN
Fluid replacement w/ NS

(correct plasma osmolarity no faster then 2 mOsm/kg/hr)
Tx for Isovolemic HyperN

What additionally should you do if Dx is Central Diabetes Insipidus?
Fluid replacement w/ 1/2 NS
(correct only half of the deficit in first 24 hrs)

C-DI: Vasopressin
Tx for Hypervolemic HyperN
(2)
1. Fluid replacement w/ 1/2 NS (for hypertonicity)

2. Loop diuretic (furosemide) to inc Na excretion