Sodium Flashcards
positively charged ion that binds at the active site of enzymes, playing a crucial role in substrate binding and transition state stabilization.
Monocovalent cation
Sodium
• most abundant____ in the____
cation
ECF
SODIUM
•____ of all ECF cations
• major determinant of______
90%
plasma osmolality
plasma osmolality
295 millimoles per liter
Sodium constitutes ______ of the plasma osmolality
270 millimoles per liter
Percent of sodium in ECF
90%
Which is greater in EXTRACELLULAR fluid?
Sodium or potassium?
Sodium
Which is greater in INTRACELLULAR fluid?
Sodium or potassium?
Potassium
POSSIBLE SPECIMENS for SODIUM
SERUM
PLASMA
URINE
WHOLE BLOOD
SWEAT
CSF
What TUBE to use for PLASMA spx
lithium heparin
ammonium heparin
lithium oxalate
SODIUM ION DETERMINATION
• Chemical methods
• FES
• AAS
• ISE (glass ion exchange membrane)
Reference Ranges
• Serum:
136-145 mmol/L
Urine RR
40 - 220 mmol/day (varies with diet)
CSF rr
136 - 150 mmol/L
Chemical Method
• Albanese Lein Method
• Magnesium-Uranyl Method
• Principle:
• Sodium is made to react with zinc uranyl acetate to produce a sodium uranyl acetate precipitate
• Precipitate is mixed with water and a yellow solution is formed which is then measured spectrophotometrically
Albanese Lein Method
Albanese Lein Method
• Principle:
• Sodium is made to react with_____ to produce a______
• Precipitate is mixed with water and a____(color) solution is formed which is then measured spectrophotometrically
zinc uranyl acetate; sodium uranyl acetate precipitate
yellow
Chemical Method
• Principle:
• Sodium is precipitated with magnesium-uranyl acetate; the uranyl ions remaining in suspension from a yellow-brown complex with thioglycolic acid
• The difference between reagent blank and analysis is proportional to the sodium concentration
• Protein precipitant: Uranyl acetate and magnesium acetate
Magnesium-Uranyl Method
Chemical Method
• Magnesium-Uranyl Method
• Principle:
• Sodium is precipitated with________; the uranyl ions remaining in suspension from a_____(color) complex with______
• The difference between reagent blank and analysis is proportional to the sodium concentration
• Protein precipitant: ______ and _____
magnesium-uranyl acetate; yellow-brown; thioglycolic acid
Uranyl acetate and magnesium acetate
2 electrodes in ISE (glass ion exchange membrane)
Constant potential
Measuring electrode
Internal reference electrode
Constant potential
Schematic diagram of the ion-selective electrode system for the potentiometric slide on the Vitros. (Courtesy of OCD, a Johnson & Johnson company, Rochester, NY.)
- Upper slide mount
- Paper bridge
- Ion-selective membrane
• Metnyl monensin - Reference layer
• NaCl
• Buffer at pH 5.6 - Silver, silver chloride layer
- Support layer
- Lower slide mount
SOURCES OF ASSAY ERROR in SODIUM
• SLIGHT HEMOLYSIS VS. MARKED HEMOLYSIS
• HYPERPROTEINEMIA
• HYPERLIPIDEMIA
• DIRECT ISE VS. INDIRECT ISE
Agappe RR
Serum Plasma :
128 - 160 mmol/L
Linearity
This reagent is linear upto
200 mmol/L
Factor
150
Hemolysis
Decrease
Precipitating reagent
R1
Coloring reagent
R2
Mode of Reaction
End point
Slope of Reaction
Slope of reaction
Wavelength
546
Temperature
30C
Standard Concentration
150 mmol/L
Linearity
200 mmol/L
Blank
Reagent
Incubation time
5 mins
Sample vol
10 uL