Electrolytes Flashcards
(128 cards)
1
Q
7 functions of electrolytes
A
Hydration Enzyme activation pH maintenance blood coagulation electron transfer Neuromuscular activity Bone stability
2
Q
Definition of osmolality
A
a physical property of a solution which os based on concentration of a solute (millimoles per Kg solvent).
Concentration of dissolved ions.
3
Q
___ accounts for 90% of human serum and urine osmolality
A
Sodium (and its associated anions)
4
Q
Osmolality reference range
A
280-300 mOsm/kg
5
Q
AVP
A
Arganine vasopressin hormone
6
Q
AVP secreted by…
A
pituitary gland
7
Q
AVP causes…
A
increased water reabsorption in renal tubules and increased thirst
8
Q
AVP excretion regulated by…
A
osmoreceptors in hypothalamus
9
Q
How does Natriuretic peptide affect osmol?
A
decreased blood volume by excreting Na and water
10
Q
What triggers release of renin?
A
Juxtaglomerular apparatus in kidney senses change in blood volume
11
Q
What does renin do?
A
Converts angiotensinogen to angiotensin I
12
Q
Angiotensin I is converted to angiotensin II in the…
A
lungs
13
Q
What does Angiotensin II do? (2 functions)
A
increases renal blood flow
(vasoconstrictor)
stimulates aldosterone from adrenal gland
14
Q
Aldosterone causes __ ___ and is the primary _____
A
Na retention
mineralocorticoid
15
Q
Natriuretic peptides cause…
A
Na and H2O excretion
16
Q
Natriuretic peptides released by heart due to (3 things)
A
Increase in volume
Increased Na
Stretching of vessel walls
17
Q
GFR will _____ rate with increased ____
A
increase
volume
18
Q
Causes of hyperosmolality
A
H2O loss Hyperglycemia Diabetes insipidus Alcohol intoxication IV osmotically active drugs Renal failure
19
Q
Causes of hypo-osmolality
A
Loss of Na+ due to diuretics
SIAD
20
Q
Urine osmol reference range
A
200-1000 mOsm/kg
21
Q
Urine osmol used as a reflection of ____ ____ and as a measure of body ____
A
serum osmol
hydration
22
Q
Urine:plasma osmol Ref range
A
1.0 to 3.0
23
Q
Calculated osmol equation
A
2(Na) + (gluc/20) + (BUN/3)
24
Q
Osmol gap is…
A
difference between measured and calculated osmol. Determines if osmotically active substances are present (ketones, etc)
25
Osmol measurement is based on _____ ____ of a solution. Not affected by ___ or ___ ___.
colligative properties
| size, molecular weight
26
2 methods of measuring osmol.
Freezing point depression
| Vapor pressure
27
Anion gap is...
the difference between measured anions and measured cations
| there is never really a real gap
28
Anion gap equation
AG = (Na + K) - (Cl + HCO3)
29
Anion gap reference range
10-20 mmol/L
30
Patient reasons for a low anion gap
cancer patient, multiple myeloma
31
patient reasons for a high anion gap
ketoacidosis, alcohol, salicylates, lactic acidosis, high levels of urea
32
Sodium reference range
133-145 mEq/L
33
Sodium maintains osmotic pressure by...
being pumped out of cells. water follows. Prevents cells from swelling.
34
Sodium maintains acid-base balance by...
exchanging with H+ ions in kidneys
35
Na used in transmission of ____
nerve impulses
36
The kidney is able to excrete or conserve large amounts of Na as needed by responding to ____ ____ or _____
blood volume
| aldosterone
37
How does sodium respond to low blood volume?
As blood volume decreases, GFR decreases, stimulating secretion of renin. Renin stimulates production and release of aldosterone, which causes retention of Na. Net effect = increased blood pressure.
38
3 factors that stimulate aldosterone secresion
Decreased blood volume
Decreased extracellular fluid Na
Increased extracellular K
39
Na and Cl levels are ____ with loss of renal function
decreased
40
2 main causes of hyponatremia
Excess loss of Na (depletional)
| Excessive intake of H2O
41
Conditions/factors leading to loss of Na
```
Diuretics
renal tubular disorder
loss of renal fx
GI loss
loss via skin
diabetic ketoacidosis
SIADH
K deficiency
Addison's
edema from nephrotic symdrome or cardiac failure
```
42
S/S of hyponatremia
```
May go into shock if extreme rapid loss of Na
hypotension
weakness, fatigue, lethargy, nausea, HA
muscle cramps
Neurologic symptoms!!
```
43
The ____ __ ____ is most important for hyponatremia, because...
rate of decline
| brain swells when hyponatremia occurs quickly
44
Must increase Na conc. ____ to prevent....
slowly
| cerebral demyelination
45
2 main causes of hypernatremia
Loss of H2O
| Excess Na
46
Reasons for loss of H2O leading to hypernatremia
H2O loss disproportionate to Na loss- sweating, vomiting, diarrhea, polyuria
Decreased production of AVP
Hypothalamic disorder that affects thirst mechanism
47
Reasons for excess Na leading to hypernatremia
Cushing's (secondary)
Conns syndrome (primary- tumor on adrenal gland)
Brain injury causing impairment of adrenocorticoid production
Response to insulin in an uncontrolled diabetic (Na replaces glucose in plasma when glucose pushed into cells)
48
S/S of hypernatremia
```
Primary problems associated with CNS
Weakness, nausea, HA, lethargy
Seizures, coma
blood volume expansion, HTN
Hypokalemia (usually)
```
49
Need to correct hypernatremia ____ or will lead to ____ ____
slowly
| cerebral edema
50
2 ways to measure Na
Flame photometry
| ISE
51
Na ISE uses a ___ membrane
glass
52
Direct ISE uses a ____ specimen
nondiluted
53
Indirect ISE uses a _____ specimen. One problem with it is the possibility of ______ if patient has a certain condition.
diluted
| pseudohyponatremia
54
Pseudohyponatremia occurs when...
Patient has high lipid or monoclonal Ab content in plasma. Specimen for Indirect ISE test does not dilute correctly. H2O dispersement causes sample to be overdiluted and have falsely low Na.
55
Potassium reference range
3.5-5.0 mEq/L
56
K ions exchanged for __ in the ____ ___ ____. This causes ___ to remain in body and __ to be excreted.
Na
Distal Convoluted tubule
Na remains; K lost
57
Electric neutrality is maintained by the kidneys...
retaining Na and excreting K
58
4 main purposes of K
Nerve impulse conduction
Muscle contraction
Maintains acid-base balance
Maintains osmotic pressure
59
3 ways potassium is regulated
1. Dietary intake of K
2. Kidney fx (no renal threshold): A/B balance, exchange H for K
3. Cellular regulation w/ Na/K pump (needs ATP)
60
Renal disease typically causes ___ K
increased
61
4 causes of hypokalemia
Renal loss
Decreased dietary intake
IV fluids without K+
Insulin therapy (causes K to go into cells)
62
Renal loss of K (4 ways)
1. renal tubular acidosis
2. K+ losing nephropathy
3. diuretics
4. primary aldosteronism
63
Symptoms of hypokalemia
Cardiac arrhythmias leading to circulatory failure and HTN
Muscular cramps, weakness, confusion
Absence of peristalsis
64
4 main causes of hyperkalemia
1. Rapid infusion of K+ rich fluids
2. Decreased excretion of K+ by kidney
3. Redistribution of K+ into ECF
4. Massive transfusion
65
Causes of decreased K+ via kidney
Acute or end stage renal failure ass. w/ oligura or anuria
Acidosis: H+ leaves body in exchange for K+ being retained
Addison's: Excrete Na and retain K
66
dialysis patients always have high ___
potassium
67
Causes for K+ to be redistributed into ECF
dehydration, shock, exercise
DKA
intravascular hemolysis
68
Symptoms of hyperkalemia (4 main)
Mental confusion
weakness
myocardial irregularities (EKG changes)
Cardiac standstill and peripheral vascular collapse (K+ >7.0 mEq/L)
69
Treatment of hyperkalemia
Ca++ infusion (antagonist of effects of K on heart)
Move K back into cells with NaHCO3, insulin
Kidney dialysis
70
Serum K+ ____ than plasma K because...
0.2 higher
| platelets are activated to make clot
71
K+ ISE uses _____ membrane
valinomycin
72
#1 analyte affected by phlebotomy and specimen handling
Potassium
73
Chloride reference range
98-107 mEq/L
74
Cl- follows ___ and helps maintain ___ and ___ ___
Na+
pressure
electo-neutrality
75
Chloride regulation (3 ways)
1. Dietary Cl- almost entirely absorbed into GI tract
2. Cl- filtered by glomerulus and reabsorbed in conjunction with Na in PCT
3. If serum Cl <100 mEq/L = little urinary excretion
76
Chloride ISE uses ____ membrane
Anion exchanger with ammonium salts
Not specific for chloride- other dissolved anions may interfere (ex. salicylates)
77
Purpose of chloride shift
To maintain electrically neutral environment, Cl may shift with HCO3
CO2 created inside cells
As HCO3 builds up in RBCs, it diffuses out into plasma. Cl goes into cells to maintain neutrality.
78
Causes of hyper and hypochloremia
Mineralcorticoid or adrenocorticoid disorders
Renal tubular disorders
Na disorders
Vomiting, diarrhea, burns, dehydration
79
Reference measurement of Cl-
Amperometric-Coulometric Titration
80
Total CO2 or Bicarb reference range
19-30 mEq/L
81
Bicarb's major function
component in blood buffer system (maintains pH)
Toxic CO2 in plasma converted to HCO3 which can be eliminated
82
Total CO2 = ___ HCO3
90%
| small amt carbonic acid, small amt CO2
83
Major regulator of bicarb is ____
kidney
kidney exchanges bicarb for H+ to maintain pH balance
84
Causes of high TCO2
Metabolic alkalosis (vomiting, antacids, aldosteronism)
Compensated respiratory acidosis (Emphysema, COPD), can cause negative anion cap due to increased CO2
85
Causes of low CO2
Metabolic acidosis (DKA, severe diarrhea, dehydration, salicylate poisoning)
Compensated respiratory alkalosis
86
3 ways to measure TCO2
1. Calculated HCO3-, after pCO2 measurement (ABL analyzer)
2. ISE- glass
3. Enzymatic- Roche
87
TCO2 will ____ if sample left uncapped
decrease
88
Calcium reference range
8.5-10.5 mg/dL
89
Adult iCal range
4.6-5.3 mg/dL
90
___ of calcium id found in blood and tissues, with about ___ ionized and ___ bound to protein. ___ is bound to anions.
1%
45% ionized
40% protein-bound
15% anion-bound
91
6 ways calcium is significant
1. Contraction of (cardiac) muscle fibers
2. Secretion of fluids, hormones, etc.
3. Activation of anzymes
4. Transfer of ions across membranes
5. Blood coag
6. Neuromuscular activity
92
Decreasing the pH by 0.1 unit will ____ the ionized Ca by ____.
increase
| 0.05 mmol/L
93
Effect of uncapped tube on iCal
Decreased (pH up from loss of CO2)
94
3 things that regulate calcium
1. Calcitonin
2. PTH
3. Vitamin D
95
Effect of calcitonin on Calcium, PTH and Vit D.
Decreases calcium levels by causing bone building.
| Inhibits PTH and vit D.
96
Calcitonin originates in _____ in response to _____ _____.
medulla cells of thyroid
| Increased calcium
97
PTH is released in response to ___ calcium
decreased
98
effect of PTH on calcium
Acts on kidneys and bones to increase calcium levels (bones break down, kidneys retain)
99
Effect of vit D on calcium
Increases absorption in intestine and kidneys.
| Increases calcium levels.
100
6 causes of hypercalcemia
1. hyperparathyroidism (increased PTH - increased Ca)
2. Paget's disease (bone disease)
3. Malignancies
4. Chronic renal disease (retains Ca)
5. Sepsis
6. Cardiopulmonary insufficiency
101
Corrected calcium
takes albumin into account when less than 3.5 g/dL. Low albumin causes low plasma calcium
102
9 causes of hypocalcemia
Hypoparathyroidism
Decreased vit D
GI disease causing decreased absorption of vit D or Ca
Nephrotic symdrome, decreased plasma protein
Magnesium deficiency
Chronic renal disease (cant make active vit D)
Alkalosis
Massively transfused pts
Neonates
103
Only way to measure iCal
ISE
104
Ways to measure Ca (not iCal)
```
Atomic absorption
Color complex (arsenazo III or orthocresolphthalein complexone)
```
105
Only 2 ions where hemolysis not a problem
Na and Cl
106
Magnesium RR
1.8 - 2.4 mg/dL
107
50% of magnesium stored in ____, 49% stored in...
bone
| skeletal muscle, liver, myocardium
108
Regulation of magnesium
Obtained via diet
Regulated by kidneys
Relationship with Ca
109
PTH causes ____ reabsorption of Mag
increased
110
Mag relationship to Ca
compete for renal tubular absorption
| Mag needed for release of PTH and action of hormone on target tissues
111
Causes of hypermagnesemia
```
Antacids
Chronic renal disease
Severe dehydration
Adrenal insufficiency (aldosterone deficiency)
Stopping premature labor
Bone carcinoma
```
112
Symptoms of hypermagnesemia
```
CNS depression
Decreased reflexes
slow heartbeat
hypotension
abnormal hemostasis
lethargy
hyperkalemia, hypercalcemia
```
113
Causes of hypomagnesemia
```
Decreased absorption
Increased GI loss via vomiting, diarrhea
Chronic IV fluid therapy, diuretics (diluted)
PO4 depletion
Metabolic acidosis
Primary aldosteronism
vit D deficiency
AMI
```
114
Symptoms of hypomagnesemia
```
Neuromuscular- lethargy, weakness, tetany
Arrhythmia and cardiac problems
GI- n/v
Hypocalcemia (decreased PTH)
Hypokalemia (renal issues)
pre-term labor
```
115
Renal issues usually cause ___ magnesium
increased
116
2 ways to measure Mag
```
Atomic absorption
Chlorophosphonazo III (binds, abs increase at 659)
```
117
PO4 RR
2.5-4.6 mg/dL
118
80-85% of PO4 is combined with ___ in ___ in the compound ____
calcium
bone
hydroxyapatite
119
PO4 levels are ____ in morning
highest
120
Uses for PO4
```
storage and transfer of energy- ATP
Metabolism of glucose and lipids
Maintenance of acid-base balance
generation of bone
O2 carrying capacity of Hgb
Constituent in DNA and RNA
```
121
PO4 regulation
Dietary PO4 absorbed in intestine
Control linked closely to Ca regulation
Kidneys
122
PO4 has ___ relationship with calcium
inverse
123
PTH causes ___ PO4
decreased
124
kidney disease ___ phosphate
increases
125
causes of hyperphosphatemia
```
kidney dysfunction
hypoparathyroidism
Chemo- esp ALL
Acidosis
High vit D levels
```
126
Causes of hypophosphatemia
```
malnourishment- alcoholics, nutritional recovery symdrome
Hyperparathyroidism
Ricketts or ostermalacia
diabetic coma
Hyperinsulinism
antacids that bind PO4
```
127
symptoms of hypophosphatemia
Respiratory and cardiac insufficiency
Hematologic disorders
Muscular weakness- rhabdomyelosis, myocardial dysfunction
Kidney- metabolic acidosis
RBC formation of 2,3-DPG affected, impaired O2 delivery
CNS dysfunction
128
Measurement of PO4
forms an ammonium phosphomolybdate complex with ammonium molybdate in presence of sulfuric acid
