Electrolytes (1) (M) Flashcards
What are electrolytes?
These are ions (minerals) w/c are capable of carrying an electric charge
Where are electrolytes found?
1) Blood
2) Urine
3) Tissues
4) Other body fluids
What is electroneutrality?
It is the balance of charges
What is the principle of electroneutrality?
Fluid always contains equal # of cations and anions
The dissociation of solutes into charged particles depends on what?
1) Chemical composition of the compound
2) Concentration of other charged particles in the medium
What are charged particles?
Ions
What is the main source of electrolytes?
Food sources
*What is the concentration of potassium (K^+)?
20 mEq
*What is the concentration of sodium (Na^+)?
45 mEq
*What is the concentration of chloride (Cl^-)?
35 mEq
What are the food sources where Na can be obtained?
1) Processed and canned foods
2) Cheese
3) Breads
4) Cereals
5) Sauces
6) Pickled foods
7) Commercial rice or pasta mixes
8) Condiments
What are the food sources where K can be obtained?
1) Green leafy vegetables (such as spinach and kale)
2) Tomatoes
3) Cucumbers
4) Pumpkin
5) Carrots
6) Potatoes and sweet potatoes
7) Bananas
8) Avocado
9) Beans and peas
10) Milk
11) Yoghurt
12) Meat
What are the food sources where Cl can be obtained?
1) Seafood
2) Seaweeds
3) Rye
4) Tomatoes
5) Lettuce
6) Celery
7) Olives
What are the food sources where calcium (Ca) can be obtained?
1) Milk
2) Milk alternatives
3) Soya
4) Nuts
5) Green leafy vegetables (such as broccoli, cabbage, and okra)
What are the food sources where magnesium (Mg) can be obtained?
1) Legumes
2) Nuts
3) Seeds
4) Fish
5) Whole grains
What are the food sources where phosphorus (P) can be obtained?
1) Milk
2) Milk products
3) Meat alternatives (such as beans, lentils, and nuts)
4) Grains
What are the electrolytes that fxns for volume and osmotic regulation?
1) Na
2) Cl
3) K
What are the electrolytes that fxns for myocardial rhythm and contractility?
1) K
2) Ca
3) Mg
What are the electrolytes w/c are impt cofactors in enzyme activation?
1) Ca
2) Mg
3) Zn
4) K
5) Cl
What is the electrolyte that fxns for the regulation of ATPase ion pumps?
Mg
What are the electrolytes that fxns for neuromuscular excitability?
1) K
2) Ca
3) Mg
What are the electrolytes that fxns for the production and use of ATP from glucose?
1) Mg
2) PO4
What are the electrolytes that fxns for the maintenance of acid-base balance?
1) HCO3
2) K
3) Cl
4) PO4
What is the electrolyte that fxns for the replication of DNA and the translation of mRNA?
Mg
What is osmolality?
It is a physical property of a solution that is based in the concentration of solutes per kilogram of solvent (w/w)
The concentration of solutes in osmolality is expressed as what?
Millimoles
Why is osmolality in plasma impt?
Because it is the parameter to w/c the hypothalamus responds
The regulation of osmolality also affects what?
Na^+ concentration in plasma
Why is Na^+ concentration in plasma also affected by the regulation of osmolality?
Largely because Na+ and its associated anions account for approx 90% of the osmotic activity in plasma
What is the normal plasma osmolality?
275 - 295 mOsm/kg of plasma H2O
How to maintain a normal plasma osmolality?
The osmoreceptors present in the hypothalamus respond quickly to small changes in osmolality
A 1% - 2% increase in osmolality causes what?
Causes a fourfold increase in the circulating concentration of AVP (arginine vasopressin)
What is the result of 1% - 2% decrease in osmolality?
The AVP production is shut off
What is the normal reference range for osmolality in the serum?
275 - 295 mOsm/kg
What is the normal reference range for osmolality in the urine (24 hr urine sx)?
300 - 900 mOsm/kg
What is the normal reference range for osmolality in the urine/serum ratio?
1.0 - 3.0
What is the normal reference range for osmolality in the random urine?
50 - 1,200 mOsm/kg
What is the normal reference range for osmolality in the osmolal gap?
5 - 10 mOsm/kg
What is the other term for sodium?
Natrium
Where can sodium (Na) be found?
It is present in all body fluids
Where can the highest concentration of Na be found?
1) In the blood
2) In the extracellular fluid (ECF)
What is the major extracellular cation?
Na
Since Na is the major extracellular cation, hence, it is considered as what?
Major contributor of osmolality
What are the fxns of Na?
1) It has a central role in maintaining the normal distribution of H2O in the body
2) It has a central role in maintaining the osmotic pressure in the ECF compartments
3) It helps in controlling BP
4) It helps in proper fxning of muscles and nerves
What is the normal reference range of Na in serum and/or plasma?
135 - 145 mmol/L
What is the normal reference range of Na in 24 hr urine?
40 - 220 mmol/d (varies w/ diet)
What is the normal reference range of Na in the cerebrospinal fluid (CSF)?
135 - 150 mmol/L
What are the sxs that can be used for determination of Na lvls?
1) Serum
2) Plasma
3) 24 hr urine
4) CSF
The plasma concentration of Na depends on greatly on what?
Intake and excretion of H2O
Where can Na be obtained?
1) Food
2) Drink
Where is Na primarily lost?
1) Sweat
2) Urine
What is responsible for the regulation of Na lvl in the body?
Kidneys
What are the mechanisms on maintaining Na lvls?
1) Intake of H2O in response to thirst (as response to plasma osmolality)
2) Excretion of H2O (affected by AVP)
3) Blood volume status
How can healthy kidneys maintain a consistent lvl of Na in the body?
By adjusting the amt excreted in the urine
What are the mechanisms on how healthy kidneys maintain a consistent lvl of Na in the body?
1) By producing hormones that can increase or decrease the amt of Na eliminated in urine
2) By producing a hormone that prevents H2O losses
3) By controlling thirst
What is the hormone responsible for increasing the amt of Na eliminated in the urine?
Natriuretic peptides
What is the hormone responsible for decreasing the amt of Na eliminated in the urine?
Aldosterone
What are the hormones that are responsible for preventing H2O losses?
1) ADH or
2) Vasopressin (AVP)
What is the effect / mechanism present as a result of even a 1% increase in blood Na?
It will make the pt thirsty and cause the pt to drink H2O, hence, the pt’s Na lvl is returned to normal
What are the systems where abnormal blood Na can occur is some problem w/ 1 of these systems is present?
1) When the lvl of Na in the blood changes, the H2O content in the body also changes
2) There could be too little fluid or w/ too much fluid
What is the condition where there is too little fluid?
Dehydration
What is the condition where there is too much fluid?
Edema
What is hyponatremia?
There is a low lvl of Na in the blood (< 135 mmol/L)
What decreased Na lvl is considered as clinically significant?
< 130 mmol/L
What is the most common electrolyte disorder?
Hyponatremia
What are the causes of hyponatremia?
1) Increased Na^+ loss
2) Increased H2O retention
3) H2O imbalance
Na can also be classified accdg to what?
Accdg to serum / plasma osmolality
What are the classifications of Na according to serum / plasma osmolality?
1) Low osmolality
2) Normal osmolality
3) High osmolality
The symptoms of a pt w/ hyponatremia depends on what?
Serum lvl
What are the symptoms that a pt w/ Na lvl of 125 - 130 mmol/L possess?
Primary GI symptoms
What are the symptoms that a pt w/ Na lvl of < 125 mmol/L possess?
1) Nausea
2) Vomiting
3) Muscular weakness
4) Headache
5) Lethargy
6) Ataxia
What are the symptoms if a pt has severe hyponatremia?
1) Muscle twitching
2) Seizures
3) Coma
4) Death
What is it called if a pt has Na lvl of < 120 mmol/L for 48 hrs or less?
Acute hyponatremia
A pt having Na lvl of < 120 mmol/L is considered as what?
Medical emergency
What is the treatment for hyponatremia?
Treatment is directed at the correction of the condition that caused either H2O loss or Na^+ loss in excess of H2O loss
What are the causes of hyponatremia?
1) Increased Na loss
2) Increased H2O retention
3) H2O imbalance
What are the causes of increased Na loss?
1) Hypoadrenalism
2) K deficiency
3) Diuretic use
4) Ketonuria
5) Salt-losing nephropathy
6) Prolong vomiting or diarrhea
7) Severe burns
What are the causes of increased H2O retention?
1) Renal failure
2) Nephrotic syndrome
3) Hepatic cirrhosis
4) Congestive heart failure (CHF)
What are the causes of H2O imbalance?
1) Excess H2O intake
2) Syndrome of inappropriate arginine vasopressin hormone secretion (/ syndrome of inappropriate antidiuretic hormone) (SIADH)
3) Pseudohyponatremia
What are the classifications of hyponatremia by osmolality?
1) W/ low osmolality
2) W/ normal osmolality
3) W/ high osmolality
What are the causes of w/ low osmolality (as a classification of hyponatremia by osmolality)?
1) Increased Na loss
2) Increased H2O retention
What are the causes of w/ normal osmolality (as a classification of hyponatremia by osmolality)?
1) Increased nonsodium cations
2) Lithium excess
3) Increased gamma globulins- cationic (present in cases of multiple myeloma)
4) Severe hyperkalemia
5) Severe hypermagnesemia
6) Severe hypercalcemia
7) Pseudohyponatremia
8) Hyperlipidemia
9) Hyperproteinemia
10) Pseudohyperkalemia (due to in-vitro hemolysis)
What are the causes of w/ high osmolality (as a classification of hyponatremia by osmolality)?
1) Hyperglycemia
2) Mannitol infusion
What is pseudohyponatremia?
It is the reduction of serum Na concentration caused by a systematic error in measurement
Pseudohyponatremia is usually caused by what?
By the presence of excess lipids in serum
Are there Na ions dissolved in lipids?
None
How to get the concentration of Na via the application of flame photometry?
If the absolute amt of Na in a given volume of serum is determined via flame photometry, this value is divided by the sx volume to get the concentration
What is the consideration that should be observed if flame photometry is done in connection to pseudohyponatremia?
A part of the sx volume is lipid that has no Na, hence, a falsely low volume of Na can be obtained
What is hypernatremia?
High lvl of Na in the blood (145 mmol/L >)
Hypernatremia is from what?
Excess loss of H2O
The origin of hypernatremia w/c is excess loss of H2O is relative to what?
1) Na^+ loss
2) Decreased H2O intake, or
3) Increased Na^+ intake or retention
True or False
In terms of occurrence, hypernatremia is less commonly seen in hospital pt compared to hyponatremia
True
Hypernatremia commonly occurs in pts who are what?
In pts who may be thirsty but who are unable to ask for or obtain H2O (ex. adults w/ altered mental status and infants)
Chronic hypernatremia in an alert pt is indicative of what?
Hypothalamic disease
What are the causes of hypernatremia?
1) Dehydration from not drinking enough fluids
2) Diarrhea
3) Kidney dysfunction
4) Diuretics
5) Excessive sweating
6) Hormonal imbalance (ADH and aldosterone)
7) Diabetes insipidus (DI) (copious production of dilute urine: 3 - 20 L/day)
8) Excess ingestion of Na
9) Administration of hypertonic solutions of Na^+
What is necessary and should be done to evaluate the cause of hypernatremia?
Measurement of urine osmolality
What is the Na lvl of the pt if the pt has hypernatremia (if urine is used as sx; in relation to urine osmolality)?
150 mmol/L
What are the classifications of hypernatremia (150 mmol/L) related to urine osmolality?
1) Urine osmolality (< 300 mOsm/kg)
2) Urine osmolality (300 - 700 mOsm/kg)
3) Urine osmolality (700 mOsm/kg >)
What is the cause of urine osmolality being < 300 mOsm/kg?
DI (whereas there is impaired secretion of AVP or kidneys cannot respond to AVP)
What are the causes of urine osmolality being 300 - 700 mOsm/kg?
1) Partial defect in AVP release or response to AVP
2) Osmotic diuresis
What are the causes of urine osmolality being 700 > mOsm/kg?
1) Loss of thirst
* 2) Insensible loss of H2O (breathing, skin)
3) GI loss of hypotonic fluid
4) Excess intake of Na
What is the meaning of AVP?
Arginine vasopressin hormone
What is the other term for AVP?
Antidiuretic hormone (ADH)
What are the symptoms if pt has hypernatremia?
Commonly involve the CNS:
1) Altered mental status
2) Lethargy
3) Irritability
4) Restlessness
5) Seizures
6) Muscle twitching
7) Hyperreflexes
8) Fever
9) Nausea
10) Vomiting
11) Difficult respirations
12) Increased thirst
Serum Na^+ of 160 mmol/L > is associated w/ a mortality of what percentage?
60 - 75%
What is the treatment for hypernatremia?
Treatment is directed at correction of the underlying condition that caused the H2O depletion of Na^+ retention
What must be the way of correcting hypernatremia?
It must be corrected gradually
Why must hypernatremia be corrected gradually?
Because if correction of hypernatremia is done too rapidly, it can induce cerebral edema and death
What are the sxs that can be used for determination of Na lvls?
1) Serum
2) Plasma
3) 24 hr urine
4) Sweat
What are the suitable anticoagulants that should be used if plasma is the sx that will be used for determination of Na lvls?
1) Lithium heparin
2) Ammonium heparin
3) Lithium oxalate
What are the methods for determination of Na lvls?
1) Ion-Selective Electrode (ISE)
2) Atomic Absorption Spectrophotometry (AAS)
3) Flame Emission Spectrophotometry (FES)
What is the most routinely used method in terms of determination of Na lvls?
ISE
What is the major intracellular cation?
K
What are the fxns of K?
1) For regulation of neuromuscular excitability
2) For the contraction of the heart
3) Intracellular fluid (ICF) volume
4) H^+ concentration
Plasma K^+ affects what?
Affects the resting membrane potential (RMP) of the cell (RM is closer to zero)
Since plasma K affects the RMP of the cell, thereby it affects what?
Cell excitability
Where can K be obtained?
1) Food
2) Drink
K is lost primarily in what?
Urine
Some of the K are lost in what?
1) Digestive tract
2) Sweat
What is the primary cause of hypokalemia / hyperkalemia?
Dietary deficiency or excess (in rare conditions)
What is the result if a pt has preexisting condition?
It only enhances the degree of hypokalemia / hyperkalemia
What is the normal reference range of K in the serum?
3.5 - 5.1 mmol/L
What is the normal reference range of K in the plasma for males?
3.5 - 4.5 mmol/L
What is the normal reference range of K in the plasma for females?
3.4 - 4.4 mmol/L
What is the normal reference range of K in the 24 hr urine?
25 - 125 mmol/d
K is impt to what?
1) Heart
2) Digestive fxns
3) Muscle fxns
K lvls are mainly controlled by what?
Aldosterone
What is aldosterone?
It is a hormone produced by the adrenal glands in the kidneys
What are the 3 factors that influence the distribution of K^+ between cells and ECF?
1) K^+ loss frequently occurs whenever the Na^+, K^+-ATPase pump is inhibited by conditions (such as hypoxia, hypomagnesemia, or digoxin overdose)
2) Insulin promotes acute entry of K^+ into skeletal muscle and liver by increasing Na^+, K^+-ATPase activity
3) Catecholamines (such as epinephrine) promote cellular entry of K^+, whereas propanolol impairs cellular entry of K^+
What is the fxn of epinephrine?
It is a β2- stimulator
What is the fxn of propanolol?
It is a β- blocker
In connection to K, exercise causes what?
It causes K^+ release from the muscle cells
Is the effect of exercise whereas it causes K^+ release from the muscle cells reversible or irreversible? When is the effect reversible / irreversible?
It is reversible after several mins of rest
Forearm exercise during venipuncture can cause what?
Erroneous high plasma K^+ concentration