electrolytes Flashcards
processes electrolytes involved in
Volume and osmotic regulation
Acid base balance Cofactors for enzyme activation
Blood coagulation
Neuromuscular activity
Hydration
movement of ions happens either
active transport
passive transport
if sample is intracellular what is will affect the it
hemolysis
sodium is
-extracellular
-abundant cation in extracellular fluid 90%
main ion that determines osmolality
sodium
sodium reference range
135-145
sodium renal threshold
110-130
sodium potassium pump
3 sodium out and 2 potassium in
main regulator of sodium
kidneys
-absorbed proximal tubules
ADH- antidiuretic hormones released by
pituitary gland
aka vasopressin
ADH directly related to
thirst
when sodium values increased, plasma osmolality increased = ADH turned on to dilute sodium
renin produced by
kidneys
RAAS system
renin aldosterone angiotensin system
how does RAAS start
BP decreased, when sodium decreased— renin released into bloodstream
renin converts angiotensin to angiotensin 1
angiotensin 1 to angiotensin 2 by ACE
-causes blood vessels to narrow
aldosterone produced by
adernal glands
main goal: keep sodium at expense of potassium
sodium follows
aldosterone
BTNP- brain type natriuretic peptide released in response
to increased fluid and blood pressure
main job: help body get rid of sodium so we can reduce fluid volume and decrease BP
marker of congestive heart failure
BTNP
hypernatremia causes
hyperaldosteronism
vomiting/ diarrhea
sweating
too much NaCl
diabetes insipidus
dehydration
hyperaldosteronism also called
Conn’s syndrome
hyponatremia causes
Vomiting and diarrhea
Hypo aldosterone
Severe burns -deletional
Kidney loss of sodium
Water excess
Syndrome of SIADH
diabetes
hyponatremia osmolality
hypo osmolality
increase or decrease of sodium depends on
how much sodium you lose compared to water
SIADH
syndrome inappropriate anti-diuretic hormone
-too much ADH
loss of sodium in kidney specimen
urine
if Na >20
sodium being loss via the kidneys
-kidney disfunction
if Na < 20
something else is going on
specimen collection for sodium levels
serum or plasma (heparin)
no sodium heparin
sodium values detected via
glass ISE
direct ISE: no dilution required
indirect ISE: need dilution
-affected by increased lipids (centrifuge specimen first to clear them)
what is it called when sodium values affected by lipids
electrolyte exclusion effect
potassium found
intracellular -affect on specimen collection
quantity is 20x greater in RBC than ex.
where is potassium important
skeletal and cardiac muscle
range of potassium
3.5-5.3
> 7 panic value
how is potassium regulated
kidneys
hyperkalemia causes
kidney issues
hypoaldosteronism - opposite
metabolic acidosis
bleed injury
drawing EDTA tube
K IV
hyperkalemia metabolic acidosis b/c
too much hydrogen and trys to pull hydrogen in and potassium also comes out
+ for +
water comes out and potassium also comes out when diluting glucose
hypokalemia causes
too much insulin- driving too much insulin into cell
hyperaldosteronism
increased GI or urinary loss
metabolic alkalosis
specimen integrity for potassium
NO hemolysis -false increase
no potassium draw after exercise- will leak out of cell
serum for potassium
serum has higher potassium
platlets give off small amount of potassium when they clot
increase in platelets– slightly increase level of K
to correct draw plasma with heparin
can potassium specimen sit around for 5-6 hours
no
cells and serum have not been separated
RBC’s will start to lyse
how is potassium measured
ISE with valamycin coated membrane
chloride found where
extracellular anion
hemolysis will not affect
chloride range
99-109
-helps maintain electroneutrality
chloride shift exchanges
bicarb in RBCs
passice
hypochloremia causes
same as sodium
but
metabolic alkalosis
-excess bicarb, so get rid of chloride
hyperchloremia causes
same as sodium
except
metabolic acidosis
-using bicarb to get back into balance, so keep chloride
increased in bromide concentration in blood- psycharatic meds
specimen collection for chloride
serum or plasma
ISE -silver chloride silver electrode
chlordie sweat test
no longer done
used to be done to test for cystic fibrosis (don’t reabsorb chloride back into the skin)
only done on children
2nd most abundant cation in extracellular fluid
bicarb
-total CO2 made up mainly of bicarb
bicarb is a major
buffering system
-helps in acidosis by taking in hydrogen and making it into carbonic acid and eventually CO2 to get rid of it
bicarb normal value
22-26
how is bicarb regulated
kidneys
-either excreted or reabsorbed depending on body
increases or decreased related to metabolic acid base imbalance
calcium is needed for
bone development, muscle contractions, and coag cascade
98% found in bone
2 forms of calcium
bound
ionized- free form metabolically active
what is bound calcium too
albumin
dependent upon albumin levels
most responsible for control over calcium values
ionized
does not change day to day
-not dependent on albumin levels
parathyroid hormone -PTH
secreted by parathyroid
-behind thyroid
-regulated calcium via feedback loop- ionized calcium
when ionized Ca is low
PTH turned on
when ionized Ca is high
PTH turned off
3 effects on PTH regulated Ca
- Activates bone resorption - osteoblast breaks down to released calcium
- Helps kidneys keep calcium through reabsorption
- Helps convert renal conversion of vitamin D to active form
where is vitamin D activated
kidney
what is the active form of vitamin D
1,25 dihydroxy vitamin D
PTH indirectly affects
phosphorus
Calcium and phosphorus inverse relationship
calcitonin
lowers calcium by inhibiting vitamin D with PTH???
magnesium is needed to release
PTH
-low magnesium = low PTH
hypercalcemia causes
hyperparathyroidism -remove gland
bone tumor -Ca in bones
paget’s disease -abnormal breakdown
multiple myeloma
neonates -first 6 months increased Ca
if mom is hypercalcemia baby will
not have normal development of PTH
consequences of increased Ca
irregular heartbeat
mental confusion
formation of kidney stones
tetany
what enzyme is affect in increased Ca
ALP increased; bones
hypocalcemia causes
hypoalbuminemia
Low PTH
low vitamin D
low magnesium
menopause
hypoalbuinemia why in low Ca
much Ca is bound to albumin so total Ca are dependent on bound albumin
seen in decreased albumin
cause pseudo low values
-this is why to ionized Ca just bound
correction for low calcium
Corrected Ca= measured Ca + 0.8(4-serum albumin)
best measurement of calcium
ionized Ca
-collect anaerobically
sensitive to pH and temp
serum or heparin (can’t use most anticoag)
normal calcium
8.5-10
where is Mg found
bone, some in cells, and small amount in the blood
ionized and bound form
cofactor for over 300 enzymatic reactions in body
magnesium
-helps in metabolism of CHO, lipids, and proteins
how is magnesium regulated
aldosterone and PTH
PTH helps in reabsorption
aldosterone acts the same way as it does on potassium
(aldosterone high, mg low)
normal mag levels
1.5-2.5
causes of hypo magnesium
long term diuretics
-cancer patients, alc. cirr
increased aldosterone
how to correlate Mg and Ca
if person has tetany and Ca look normal go to Mg
what is Mg associated with
vasospasms and sudden cardiac death
hyper magnesium causes
intake of laxatives and antacids
end stage liver disease- lead to cardiac arrest
specimen collection Mg
NO anticoag; block Mg
no hemolysis
in preg decreased levels of mg can lead to
pre-elcampsia
high bp, protein in urine , swelling in legs
giving mg can prevent the from going to eclampsia (seizures)
main buffering system for acid base balance in urine
phosphate
under control of PTH
if phosphate is too low
Hgb increased affinity to oxygen, won’t want to give it up
-can affect hemoglobin affinity to oxygen
does phosphorus vary in the body
no!
diurnal variation
-high in morning and low at night
under the control of the kidney
collection for phosphate
serum or heparin
no anticoag
if taking growth hormones can’t measure levels
why do we look at lactate levels
O2 deprivation, septic, or acidosis
what is lactate
by product that produces small amount of ATP when oxygen is low
lactate in normal glucose metabolism
glucose first goes to pyruvate then goes to acetyl Coa (under aerobic conditions)
(anerobic) pyruvate to lactate and leads to increases in NADPH
when there is too much lactate for the liver to handle – you get a build up which is an indicator of
oxygen deprivation or sepsis
(think of anything that can cause hypoxia, no breathing, massive bleeding)
why in bacterial sepsis is there increased lactate
bacteria uses oxygen
buildup in metabolic acidosis and alcohol poisoning
normal lactate value
0.5-2
specimen collection lactate
no tourniquet - not longer than 2 minutes
gray tube on ice - prevent breakdown of glucose for 72 hours
anion gap
cations should = anions
(Na + K) - (Cl+ Bicarb)
w/o K= 8-16
with K= 10-20
don’t do potassium anymore– highest correlation with preanalytical error
increases in anion gap
DKA
OH- alcohol (alcohol breaks down to acids)
Instrument QC
-anion gap is qc for instrument error
-if screwed anion gap for lost for patients - instrument error
decreases in anion gap
low albumin
kidney/ liver failure
multiple myeloma- decrease in albumin, increase gamma globulin
osmolality
number of dissolved particles in solution
main particles for hypothalamus on and off
can turn on or off ADH
regulated aldosterone
normal osmol value
275-295
main drivers of osmolality
sodium
glucose
how to measure osmolality
freezing point depression
-also vapor pressure
use serum or urine
osmolality formula
2Na + (glucose/20) + (BUN/3 )
what is osmol gap
difference between measured and calculated
want it to be less than 10
when in osmol gap increased
1 reason is alcohol
acidosis and alcohol
leads to alcohol testing on patient
ISE stands for
ion selective electrode
membrane makes it selective
ISE measures
free electrolytes
ISE type of analysis
potenime
internal solution in ISE
KCl
changes in voltage in zero current
