Electrolytes Flashcards
(64 cards)
1
Q
Anions move toward anode or cathode?
A
Anode
2
Q
Cations move toward anode or cathode?
A
Cathode
3
Q
Na, Cl, K are important for which processes?
A
Volume + osmotic regulation
4
Q
K, Mg, and Ca are important for which processes?
A
Mycocardial rhythm and contractility
5
Q
Mg, Ca, and Zn are important cofactors for what?
A
Enzyme activation
6
Q
Ca and Mg are important for which process?
A
Blood coagulation
7
Q
Water
Percent body wt?
How much in intra/extracellular compartments?
How is it controlled?
A
- 40-75% of human body wt
- 2/3 intracellular and 1/3 extracellular
- Controlled by maintaining electrolyte/protein concentration in compartments
8
Q
Osmolality
Definition?
A
- Physical property of solution based on concentration of solute (mmol) per kg solvent (w/w)
- Related to changes in properties of solution relative to pure water (decrease in fp and vapor pressure)
9
Q
Osmolality
Clinical significance?
A
- Hypothalamus responds to it
- Affects plasma sodium conc.
- Regulation of sodium + water controls blood volume
10
Q
From which specimen(s) do we measure osmolality?
A
Serum or urine
11
Q
Anti-diuretic hormone (ADH) is now called _____
Function?
A
- Arginine vasopressin (AVP) hormone
- Functions to promote water reabsorption in renal tubule of kidneys (aka stimulates thirst)
12
Q
Diabetes insipidus
General mechanism?
Symptom?
A
- Pituitary gland produces insufficient AVP, meaning body can’t reabsorb water, so that water gets excreted into lots of urine
- Symptom: constant thirst
13
Q
Function of Renin-Angiotensin-Aldostorone System?
A
Helps control blood pressure
14
Q
Other factors affecting blood volume
A
- Atrial natriuretic peptide released by myocardial atria in response to vol expansion->promotes Na and water excretion
- Volume receptors independent of osmolality stimulate AVP release
- GFR increases with overhydration (vol expansion) and decreases with dehydration (vol depletion)
- Increase in plasma sodium increases urine sodium and water excretion, and vice versa (ceterus paribus)
15
Q
How to calculate osmolality?
A
- Uses glucose, BUN, and Na values
- (2 X Na) + (glucose/20) + (BUN/3)
16
Q
How to calculate osmolal gap?
A
- Gap= Measured osmolality - calculated osmolality
- Gap should be less than 5-10
17
Q
Define osmolal gap
A
Difference between calculated and lab-determined osmolality
18
Q
Sodium ion
Percent of extracellular fluid (ECF)?
Determines what parameter of plasma?
Conc. in ECF compared to intracellular?
How to prevent sodium equilibrium?
A
- 90% ECF
- Largely determines plasma osmolality
- ECF Na+ > Intracellular Na+
- ATPase ion pumps (active transport) prevents sodium equilibrium
19
Q
How is sodium ion regulated?
A
- Intake of water in response to thirst
- Water excretion
- Blood volume status
20
Q
Sodium Reference Range
A
135-145 mmol/L
21
Q
Serum sodium levels in hyponatremia
A
Sodium < 135 mmol/L
Sodium < 120 mmol/L clinicaly sig
22
Q
Serum sodium levels in hypernatremia
A
Sodium > 145 mmol/L
Sodium > 160 mmol/L leads to death
23
Q
Specimens for sodium measurment?
A
- Serum
- Plasma
- Whole blood
- Urine
- Sweat
24
Q
Common symptoms in hyponatremia Na+ btwn 120-135 mmol/L?
A
- Headache
- Nausea
- Vomiting
- Fatigue
- Confusion
- Muscle cramps
25
Symptoms in hyponatremia Na+ < 120 mmol/L?
- Headache
- Restlessness
- Lethargy
- Seizures
- Brain-stem herniation
- Respiratory arrest
- Death
26
Causes of hypernatremia?
- Excess water loss
- Decreased water intake
- Increased intake or retention
27
Hypernatremia symptoms?
**FRIED SALT**
Fever
Restlessness (irritable)
Increased fluid retention/BP
Edema
Decreased urinary output/dry mouth
Skin flushed
Agitation
Low-grade fever
Thirst
28
**Potassium**
Conc intracellular fluid (ICF) vs ECF?
Functions?
- Intracellular K+ 20 times greater than ECF
- Functions: regulate neuromuscular excitability, heart contraction, ICF volume, H+ conc
29
Potassium regulation
- Kidneys regulate potassium balance
- Potassium uptake from ECF into cells normalizes: acute rise in plasma potassium due to increased intake
- Exercise increases plasma potassium
- Hyperosmolality decreases plasma potassium
- Cellular breakdown releases potassium into ECF so avoid hemolysis of samples
30
Factors that influence potassium distribution
1. Inhibition of **Na+ K+ ATPase** pump
2. **Insulin** promotes potassium ions entering muscle and liver
3. **Catecholamines** promote cellular entry of potassium
31
High WBC manifests as which condition?
Pseudo-hyperkalemia (false increase in potassium levels)
32
Serum potassium ref range
3.5-5.1 mmol/L
33
Urine 24 hr potassium reference range
33-86 mmol/d
34
Causes of hypokalemia
- GI loss (vomiting, malabsorption)
- Renal loss (diuretics, nephritis, acute leukemia)
- Cellular shift (alkalosis or insulin overdose)
- Reduced intake
35
Hypokalemia signs and symptoms
**A SIC WALT**
Alkalosis
Shallow respirations
Irritability
Confusion/drowsiness
Weakness/fatigue
Arrhythmias
Lethargy
Thready pulse
36
Causes of hyperkalemia
- Decreased renal excretion (renal failure, diuretics)
- Cellular shift (acidosis, muscle/cell injury, chemo, leukemia, hemolysis)
- Increased intake
- Artifactual (sample hemolysis, thrombocytosis, prolonged tourniquet use or excessive fist clenching)
37
Hyperkalemia sign and symptoms
**MURDER**
Muscle cramps
Urine abnormalities
Respiratory distressed
Decreased cardiac contractility
EKG changes
REflexes
38
**Chloride ion**
Majority conc. found where?
Functions?
Absorbed by?
- Major extracellular ion
- Functions: maintains osmolality, blood volume, and electric neutrality
Ingested in diet and almost completely absorbed by intestinal tract
39
Chloride clinical applications
- Hyperchloremia
- Hypochloremia
40
Specimens for measuring chloride
Serum
Plasma
Urine
Sweat
41
Ref range for chloride in plasma/serum
98-107 mmol/L
42
Ref range for urine chloride (24 hr)
110-250 mmol/d
43
Bicarbonate (HCO3-) makes up what percent of CO2? What about this percentage makes it "special?"
90% of CO2, which is special because it means that it can correlate closely with total CO2 on metabolic panel
44
**Bicarb**
Abundance? Where?
Function?
Regulation?
Clinical applications?
- Second most abundant anion in ECF
- Functions to buffer blood
- Regulation: reabsorbed by proximal (85%) and distal (15%) tubules in kidneys
- Metabolic acidosis may reduce bicarb
45
Determinations of CO2
- Serum or plasma specimens
- ISE and enzymatic methods
46
Total CO2 equation
Total CO2 = CO2 (g) + HCO3- + H2CO3
47
Reference range for venous CO2 in plasma or serum?
22-29 mmol/L
48
Describe chloride-bicarbonate exchange
Chloride in
Bicarb out
Mediated by one exchange protein
49
**Magnesium**
Abundance? Where?
Functions?
Regulation?
- Fourth most abundant cation in body, second intracellularly
- Functions: glycolysis, transcellular ion transport, neuromuscular transmission, synthesis of carbs/proteins/lipids/nucleic acids, and release of/response to certain hormones **(cofactor for 300+ enzymes)**
- Regulation: controlled mainly by kidneys (reabsorb in deficiency/excrete excess
50
Magnesium reference range in serum?
0.66-1.07 mmol/L
51
General causes of hypomagnesemia?
- Increased renal excretion (glomerulonephritis)
- Increased endocrine excretion (hyperthyroidism)
- Increased drug-induced excretion (diuretics, Abx)
- Reduced absorption
- Reduced intake
- Misc (pregnancy, excess lactation)
52
General causes of hypermagnesemia?
- Decreased excretion (hypothyroidism)
- Increased intake (enema)
- Misc (dehydration, bone carcinoma)
53
What conc of Mg2+ causes death?
Mg2+ > 5.0 mmol/L
54
**Calcium**
Distribution?
Functions?
Regulation?
- Distribution: 99% body Ca2+ in bone, 1% in blood/other ECF
- Functions: **Essential for myocardial contraction**, maintaining normal ionized levels during surgery, and in critically ill patients
- Regulation: by PTH, **Vit D**, and calcitonin. Blood-ionized Ca2+ closely regulated with mean conc 1.18 mmol/L
55
Causes of hypocalcemia
- Primary hypoparathyroidism
- Vit D deficiency
- Hypomagnesemia
- Hypermagnesemia
- Hypoalbuminemia
- Acute pancreatitis
- Renal disease
- Rhabdomyolysis
56
Causes of hypercalcemia
- Primary hyperparathyroidism
- Hyperthryoidism
- Increased Vit D
- Benign familial hypocalciuria
- Malignancy
- Multiple myeloma
- Milk alkali syndrome
- Thiazide diuretics
- Prolonged immobilization
57
**Phosphorus/Phosphate**
Found where?
Functions?
Regulation?
- Found everywhere in living cells, 80% found in bone/20% in soft tissues/serum plasma <1%
- Functions in lots of biochem processes
- Regulation: may be absorbed in intestine from dietary sources, released from cells into blood, and lost from bone
58
**Lactate**
Found where?
Clinical applications?
Regulation?
- By-product of emergency mechanism that makes small amount of ATP when hypoxic
- Clinical apps: metabolic monitoring of critically ill pts
- Regulation non-specific; Rapid rise when O2 delivery decreases below critical level
59
Type A (anaerobic) causes of lactic acidosis?
- Shock
- Heart failure
- Asphyxia
- Carbon monoxide poisoning
60
Type B (aerobic) causes of lactic acidosis
- Systemic disease (diabetes, neoplasia, hepatic failure, renal failure)
- Drugs (ethanol/methanol, salicylate overdose, inborn errors of metabolism)
61
Explain metabolic effects of hypoxia and cellular consequence
Lactic acid accumulation -> cell death
62
Anion gap definition + equation
Difference between **unmeasured anions** and **unmeasured cations**
AG = [Na + K] - [Cl + HCO3]
63
Anion gap reference range
10-20 mmol/L
64
Anion gap usefulness
- Indicate increase in 1+ anions in serum
- QC for analyzer used to measure electrolytes
