LAB 5 - MAGNESIUM Flashcards
the normal human body contains about ____ of magnesium
20-80 g
magnesium on our body is most stored in
what organs
bone and muscles
what will happen to organs if there’s deficiency in Mg
can be subjected to immobilization
magnesium is an essential component in many enzyme reactions either as a ___ or ____
metalloenzyme or an intermediary activator
It is the most important in those reactions involving PT and PS
what do they stand for?
phosphate transfer and protein synthesis
severe magnesium deficiency can result in impairment of __ function
neuromuscular
Symptoms usually do not occur until magnesium levels fall below _____ mEq/L
1 mEq/L ( mmol/l)
since renal clearance plays a large role in magnesium homeostasis, the _____ excretion of magnesium is also a useful index of magnesium deficiency or excess
urinary
On the lab test performed during our laboratory, what are the reagent we combine?
magnesium and xylidyl blue-1 under ALKALINE CONDITION
combining magnesium and xylidyl blue will give us water soluble _______
red-purple chelate
we perform the activity at what wavelength
520 mn
Interference from calcium is prevented by the presence of ____ which completely masks a similar colored calcium chelate
EGTA
the magnesium chelate color is STABLE, and the assay is not subject to interferences from other inorganic ions
true or false
true
magnesium reagent components
ethanolamine 750 mmol/l
EGTA 60 mmol/l
thiomalic acid 6.7 mmol/l
xylidyl blye 110 mmol/l
magnesium standard components
Aqueous solution of magnesium chloride with sodium aside as preservatives
Both reagent and standard are stable at _____*C until the expiration date on the labels
2-8*C
nm of MG determination we use in the lab
520 nm
what type of specimen is the preferred specimen
serum
can we use plasma here?
yes but avoid EDTA as anticoagulant
why do we need to avoid EDTA?
gives us lower test results
what type of urine smple is needed for Mg determination?
24 hr urine
24 hr urine must be preserved with ____
hydrochloric acid
24 hr urine’s pH must be adjusted to
3-4
24 hr urine must be diluted __ before analysis
1 part urine with 4 parts distilled water before analysis
stability of serum and plasma in 2-8*C
7 days
stability of serum and plasma in -20*C
1 month
stability of treated urine in 2-8*C
7 days as well same as plasma
interferences for Mg determination
use of EDTA
hemolysis
bilirubin up to 20 mg/dl
lipemic serum
contaminated glassware
why hemolysis is must be avoided
rbc contain higher levels of magnesium
is the greatest source of error
contaminated glassware
since contaminated is the greatest source of error in Mg Determination
it is recommended to employ ___ in the procedure
use disposable tubes and pipette tips
reagent blank
reagent -
standard-
sample
reagent blank
reagent - 1 ml
standard- 0
sample - 0
standard blank
reagent -
standard-
sample -
standard blank
reagent - 1 ml
standard- 0.01 ml
sample - 0
sample
reagent -
standard-
sample -
reagent - 1 ml
standard- 0
sample - 0.01 ml
what should we do if the instrument requires volumes greater than 1 ml
volumes may be doubled
step after preparing solutions needed
incubate the cuvettes at 37*C for 5 minutes
after incubating at 37*C we must run the test at 520 nm within _______
1 hr
formula for plasma or serum (mEq/L)
(Au / As) * 2
formula for urine magnesium (mEq/L)
(Au / As) * 2*5
(Au / As) * 10
samples having magnesium values greater than ____ are diluted 1:2 (1+1) with distilled water, the assay repeated and results multiplied factor of 2
4.3 mEq/L
serum or plasma ref range
1.3-2.1 mEq/L
24 hr urine ref range
6 - 10 - mEq/L
