Electrolytes 1 Flashcards
1
Q
What labs need to be ordered separately?
A
Magnesium & Phosphate
2
Q
- Total body water is __% of total body weight.
- Intracellular Fluid Compartment (ICF) is ___ of body water
- Extracellular Fluid Compartment (ECF) is ___ of body water.
A
- TBW: 60%
- ICF: 2/3
- ECF: 1/3
3
Q
- Total body water for infants is ___% of total body weight.
- Total body water for elderly is ___% of total body weight.
A
- 80%
- 45%
4
Q
Does a lean or an obese individual have a higher percentage of total body water?
A
Lean = 60%
Obese = 30%
5
Q
TIE : 60/40/20
A
- Total body fluid = 60% total body weight
- Intracellular = 40% of total body weight
- Extracellular = 20% of total body weight
6
Q
Definition:
- Total solute concentration in a fluid compartment
- What 3 solutes determine the calculated value of the ECF?
- Which solute is most important?
A
Osmolality
- Sodium (most important)
- Glucose
- Urea
7
Q
- Normal range for Osmolality is 280-295mOsm/kg
- Symptoms occur if >____ mmOsm/kg
A
>320
8
Q
What are 4 other “osmotically active” substances that aren’t included in the calculated osmolality?
A
- Mannitol (& other proteins)
- Ethanol
- Methanol
- Ethylene glycol (antifreeze)
9
Q
- A normal osmolal gap is <__
- A high osmolal gap is >___
A
- 10
- 10
10
Q
Definition:
- the ability of the combined effect of all of the solutes to generate an osmotic driving force that causes water movement from one compartment to another
A
Tonicity
11
Q
- To increase ECF tonicity, a solute must be confined to the _____ (unable to cross from ECF to ICF).
- ____ easily crosses cell membranes and therefore distributes evenly throughout total body water (so it contributes to ____, but NOT ____)
A
- ECF compartment
- Urea (contributes to osmolality, but NOT tonicity)
12
Q
- The reason why we care about tonicity is because it affects ____
- Decreased ___, leads to decreased tonicity of ECF, which causes a shift of water from ECF to ICF, which leads to _________.
A
- the size of cells
- Na / cells swelling w/ extra water (including brain cells)
13
Q
- The total amount of ___ in the ECF is the major determinant of the size of ECFV (extracellular fluid volume)
A
Na
14
Q
- Increased Na & increased ECFV
A
Hypervolemia
15
Q
- Decreased Na & Decreased ECFV
A
Hypovolemia
16
Q
Serum ___ is the principle cation in the ___ where 90-95% of total body __ is located.
A
Na / sodium
17
Q
Serum ___ (lab value) primarily refers to the amount of water relative to __ in the ECF.
(NOT the total body __ amount)
A
Na
18
Q
- Abnormal serum Na is a sign of ______.
- If Na is high, water is ___. (relative)
- If Na is low, water is ____. (relative)
A
- A disorder of water regulation
- too little
- too much
19
Q
With any sodium disorder, it is REALLY important to determine _____.
A
the patient’s volume status
20
Q
Clinical volume status is proportional to the size of ____.
A
the ECFV (extracellular fluid volume)
21
Q
5 causes of Hypovolemia
A
- GI losses (bleed, NG suction, V/D)
-
Renal losses
- (diuretics cause salt & water loss)
- (diabetes insipidus causes water loss)
- Skin losses (sweat, burns)
-
Sequestration w/o loss
- intestinal obstruction, pancreatitis, rhabdomyolysis
- Hemorrhage/bleeding
22
Q
Signs of what?
- CNS depression
- Weakness / muscle cramps
- Decreased BP / postural hypotension
- Dizziness
- Increased pulse / postural pulse increase
A
Hypovolemia
23
Q
What are the top 2 causes of Hypervolemia?
A
Liver disease & Heart failure
24
Q
The following are causes of what?
- Acute/Chronic renal failure
- Nephrotic syndrome
- Primary hyperaldosteronism
- Cushing’s syndrome
- Pregnancy
A
Hypervolemia
25
**Clinical Features of what?**
* Edema
* SOB
* Orthopnea
* Paroxysmal nocturnal dyspnea (PND)
* Jugular venous distension
* Hepatojugular reflux
* Crackles on pulmonary exam
Hypervolemia
26
Water retention is influenced by what 2 things?
* Thirst
* ADH (antidiuretic hormone) (vasopressin)
27
Salt retention is influenced by what?
Renin-Angiotensin system
* Atrial Natriuretic Peptide
* Catecholamines
* Renal function (GFR), renal blood flow
28
ADH is produced by the \_\_\_\_\_, then transported to the \_\_\_\_\_, from which it is released into the bloodstream.
hypothalamus / posterior pituitary
29
**Renin-Angiotensin Aldosterone System (RAAS)**
* Aldosterone has what 2 actions?
* Increase renal **sodium reabsorption** (Na retention)
* Increase renal **potassium secretion** (K excretion)
## Footnote
**(Keeps Na and gets rid of K)**
30
* What is the most common electrolyte abnormality in hospitalized patients
* Can be acute or chronic
* Hyponatremia
31
**Hyponatremia**
* Most common in what age groups?
* Can be seen in associated with which 2 conditions?
* What should you always look up if pt has this?
* The faster the Na decreases, the \_\_\_\_\_.
* Very young / very old
* Pulmonary Disease or CNS disorders
* Baseline sodium
* more severe the sxs
32
**What condition would have "neuro" or vague sxs?**
* HA / dizziness
* N/V
* Lethargy
* Weakness
* Confusion
* Hypoventilation, respiratory arrest
* Seizures\*\*\*\*\*\*\*
* Coma
Hyponatremia
33
With treating hyponatremia, the goal is to prevent what 2 outcomes?
Seizures & Coma
34
What are the 5 types of Hyponatremia?
* **Causes:**
* Pseudohyponatremia
* Redistributive hyponatremia
* **Determining volume status is important:**
* Hypovolemic hyponatremia
* Hypervolemic hyponatremia
* Euvolemic hyponatremia
35
* Falsely low serum sodium
* Serum Na \<135, but with NORMAL osmolality (isoosmolar)
* Occurs w/ what 2 conditions?
* It is a laboratory artifact
* If this is suspected, speak to lab about more specialized tests to confirm true sodium level....
Pseudohyponatremia
36
What is the most common cause of Redistributive Hyponatremia?
Hyperglycemia
37
**What condition?**
* Hyperosmolar state
* Caused by osmotically active solutes in extracellular space that draw H20 from cell diluting serum sodium concentration
* Increased glucose in ECF causes shift of water from ICF to ECF thus lowering serum Na
Redistributive Hyponatremia
"relative hyponatremia"
38
What are the 4 renal losses which lead to Hypovolemic Hyponatremia?
* Diuretics
* Osmotic diuresis
* Addison's disease
* Hyperaldosteronism
39
3 causes of non-renal losses for Hypovolemic Hypnatremia
* **External GI:** V/D, NG suction, fistula
* **Internal GI:** pancreatitis, peritonitis
* **Burns**
40
Treatment of Hypovolemic Hyponatremia
* Replace fluid losses w/ isotonic fluid (normal saline)
* Treat underlying cause
41
3 causes of Hypervolemic Hyponatremia
* Hepatic cirrhosis
* CHF
* Renal failure
42
Treatment for Hypervolemic Hyponatremia
* Diuretics
* Dialysis
* Fluid restriction
43
4 causes of Euvolemic Hyponatremia
* SIADH (Syndrome of inappropriate antidiuretic hormone secretion)
* Psychogenic polydipsia (urine maximally dilute)
* Hypothyroidism
* Adrenal Insufficiency
44
Treatment for Euvolemic Hyponatremia
* Fluid restriction
* Treat underlying cause
45
**What condition?**
* Impairs free water excretion, but Na continues to be excreted normally
* **Hallmark finding:** Concentrated urine w/ low serum osmolality & euvolemia\*\*
* Often occurs in hospital setting
* Associated w/ what? \*\*
SIADH (Syndrome of inappropriate antidiuretic hormone secretion)
* Small cell lung cancer
46
How is SIADH diagnosed?
* Check urine (high osmolality)
* Check serum (low osmolality)
* Get CT / MRI of head to check for CNS disorder
* Get CXR to check for lung tumor/infection
* Review all pts meds
47
Treatment of SIADH
* Fluid restriction
* Tx of underlying pathology
* **If refractory case:**
* Hypertonic saline
* Demeclocycline
* Urea
* Lithium
* Vaptan
48
