Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

X Clin Lab Med > Sodium Disorders > Flashcards

Sodium Disorders Flashcards

1
Q

What is total body water?

A 
60% of total body weight (2/3 is ICF and 1/3 is ECF)
TIE 60, 40, 20
Total body fluid is 60%
ICF is 40% body weight
ECF is 20% body weight
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What gender has more percent of weight being water?

A

Males (by 10%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What body type has more body water?

A

Lean (b/c fat will have no water in it)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Primary ions of ECF

A

Na (principle cation) and Cl

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Primary ions of ICF

A

K and PO4/organic anions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is osmolality?

A

Total solute concentration in a fluid compartment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What solutes determine calculated osmolality of ECF?

A

Sodium, glucose and urea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Normal osmolality range

A

280-295 mOSM/kg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How to calculate osmolality

A

(2xNa) + (glucose/18) + (BUN/2.8)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

When do sxs occur regarding osmolality?

A

> 320mmOsm/kg or <265 mOSM/kg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are other osmotically active substances that aren’t in the calculated osmolality?

A

Mannitol (and other proteins)
Ethanol, methanol and ethylene glycol
*will see an elevated osmolal gap over 10

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is tonicity?

A

Ability of the combined effect of all of the solutes to generate osmotic driving force that causes water movement from one compartment to another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How can a solute increase ECF tonicity?

A

That solute must be confined to the ECF (Na, glucose, mannitol)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Does urea contribute to osmolality or tonicity?

A

ONLY osmolality because it easily crosses cell membranes and can distribute evenly throughout total body water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What happens when there is decreased tonicity of the ECF due to decreased Na?

A

Shift of water from ECF to ICF and cells will swell with the extra water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the major determinant of the size of the extracellular fluid volume?

A

Total amount of Na in the ECF (so increase it and get hypervolemia)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does serum [Na+] refer to?

A

Amount of water relative to Na in the ECF (NOT total body amt of Na)
High Na: too little water relative to sodium etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is a marker of abnormal sodium control?

A

Abnormality with the size of the ECFV

High ECFV: too much sodium etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is clinical volume status proportional to?

A

Size of the ECFV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Causes of hypovolemia

A 
GI losses (bleed, vomit, diarrhea)
Renal losses (diuretics, diabetes insipidus)
Skin losses (sweat, burns)
Sequestration without loss (intestinal obstruction, pancreatitis, rhabdo)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Presentation of hypovolemia

A

Increased thirst/ decreased sweating
Decreased skin turgor and dry mucous membranes
Oliguria with increased urine concentration
CNS depression
Weakness and muscle cramps
Decreased BP (postural hypotension/dizziness)
Increased pulse, postural pulse increase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Main causes of hypervolemia

A

Heart failure
Liver disease
Acute/chronic renal failure
(nephrotic syndrome, primary hyperaldosteronism, pregnancy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Presentation of hypervolemia

A 
Edema
SOB
Orthopnea, PND
JVD
Hepatojugular reflux
Crackles on pulm exam
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is water retention influenced by?

A

Thirst and ADH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What is salt retention influenced by?
RAAS, ANP and catecholamines | GFR, RBF etc
26
Actions of aldosterone
Increase renal Na reabsorption | Increase renal K secretion
27
What is the most common electrolyte abnormality in hospitalized pts?
Hyponatremia
28
When is hyponatremia severe?
Serum sodium <120 (sometimes below 125 is when you see sxs) | *faster the decrease, the more severe the sxs
29
What diseases are associated with hyponatremia?
Pulmonary or CNS disorders
30
Manifestations of hyponatremia
``` HA/dizzy N/v Lethargy Weakness Confusion Hypoventilation/ respiratory arrest Seizures (frequent when severe) Coma, death **sxs depend on level of cerebral edema ```
31
Causes of hyponatremia
Pseudohyponatremia Redistributive hyponatremia Hypo/hyper/euvolemic hyponatremia (must determine their volume status)
32
What is pseudohyponatremia?
Falsely low serum sodium (serum Na<135 but normal osmolality--isoosmolar)
33
What does pseudohyponatremia occur with?
Hyperlipidemia and hyperproteinemia (also with obstructive jaundice and multiple myeloma)
34
How is pseudohyponatremia classified?
As a laboratory artifact (relative % of water reduced and flame photometry reports artificially low sodium) *if suspected then there are more specialized tests that can be done
35
What causes redistributive or hyperosmolar hyponatremia?
Osmotically active solutes in extracellular space that draw H2O from cell diluting serum sodium concentration (increased glucose in ECF causes shift of water from ICF to ECF thus lowering serum Na)
36
Common metabolic cause of hyperosmolar hyponatremia
Hyperglycemia
37
Causes of hypervolemia hyponatremia
Hepatic cirrhosis CHF Renal failure
38
Tx of hypervolemia hyponatremia
Diuretics, dialysis, fluid restriction
39
Causes of hypovolemia hyponatremia
``` Renal losses (diuretics, osmotic diuresis, Addisons) Non renal losses (external GI like vomiting or diarrhea, internal GI like pancreatitis or peritonitis, burns) ```
40
Tx for hypovolemic hyponatremia
Replace fluid losses (with isotonic fluid) and treat underlying cause
41
Causes of euvolemic hyponatremia
SIADH Psychogenic polydipsia (urine maximally dilute) Hypothyroidism Adrenal insufficiency
42
Tx for euvolemic hyponatremia
Fluid restriction, treat underlying cause
43
What is SIADH?
High levels of ADH that impairs free water excretion but sodium continues to be excreted normally
44
Hallmark lab findings of SIADH
Concentrated urine (>100mOsm/kg) with low serum osmolality and euvolemia
45
Causes of SIADH
``` CNS disease-MRI/CT r/o Pulmonary disease (small cell lung CA)-CXR Meds Major surgery Stress Psych Pain Good amount of hospitalized pts get it ```
46
Tx for SIADH
``` Fluid restriction Treat underlying pathology Refractory cases (hypertonic saline, democlycline, urea, lithium, vaptan) ```
47
Labs for nyponatremia
First look: UAna, UAosm, serum osm, CMP | Second look: TSH, serum cortisol
48
When should you hospitalize a pt with hyponatremia?
Na<125 or symptomatic
49
What can a rapid increase in serum sodium lead to?
Cerebral pontine myelinolysis (osmotic demyelination syndrome)
50
When do you use hypertonic solutions for hyponatremic pts?
Severe symptomatic cases
51
Traditional tx of chronic hyponatremia
Demeclocycline to induce nephrogenic DI | vaptans are newer and are vasopression receptor antagonists
52
What is the rate of correction for pts with severe symptomatic hyponatremia vs chronic hyponatremia?
Severe: 6-12 mEq/L in first 24 hrs and <18mEq/L in 48 hrs Chronic: <8 mEq/L in first 24 hrs--don't overcorrect *check serum Na q2h
53
What is central pontine myelinolysis?
Poorly understood but characterized by focal demyelination in pons and extra pontine areas (irreversible!)
54
Presentation of central pontine myelinolysis
Dysarthria, dysphagia, seizures, altered mental status, quadriparesis, hypotension etc-- usually 1-3 days after over correction
55
What is hypernatremia?
Hypertonic disorder due to serum sodium>145mEq/L "too little water relative to salt" Due to brain shrinkage secondary to increased ECF osmolality
56
Causes of hypernatremia
Too little dietary water Too much dietary salt Excessive water loss from body -GI losses, skin loss, renal loss, drug related, osmotic diuresis (hyperglycemia, increased mannitol)
57
Presentation of hypernatremia
``` Often asymptomatic Thirst, signs of volume depletion AMS, weakness Neuromuscular irritability Focal neurologic deficits Seizures or coma *sxs related to rate of onset ```
58
What is bodys normal response to hypernatremia?
Create thirst and increase fluid intake | Maximally concentrate urine to prevent further water loss (vast majority are due to water loss)
59
One of most common causes of hypernatremia
Diabetes insipidus
60
What is diabetes insipidus?
Nonosmotic urinary water loss in setting of elevated serum sodium (urine is dilute when it should be concentrated--collecting ducts are impermeable to water and it is not reabsorbed)
61
What is central DI?
Due to impaired secretion of ADH (neurogenic DI) | Typically treated with desmopression (inhaled dDAVP nasal spray or IV)--ADH analog
62
What is nephrogenic DI?
Lack of kidney response to ADH, causing continued water loss even though pt is low on water *adequate ADH present
63
Cause of nephrogeneic DI
Can be genetic or acquired (from chronic renal insufficiency, tubulointerstitial renal disease, amyloidosis, lithium toxicity)
64
Tx for nephrogenic DI
Thiazide diuretic Amiloride (K sparing diuretic) Chlorpropamide (antidiabetic oral agent) NSAIDs have been tried (indomethacin)
65
Tx of hypernatremia
Hospitalize if severe Stop water loss Replace water deficit (oral, NG tube or IV hypotonic fluid)
66
Why should you not replace fluids too rapidly in hypernatremia?
*especially if it has been there for several days | Can cause seizures, brain damage and CPM (if acute then can correct rapidly)
67
What is the importance of water deficit?
Must be calculated in order to replace free water in hypernatremia -how much pt will need to drink etc to correct
68
How to calculate water deficit
Water deficit=normal TBW-current TBW Normal=.6 X body weight in kg Current=(normal serum Na x normal TBW)/measured serum Na

X Clin Lab Med (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions