Chloride Cl- Flashcards
1
Q
Chloride [Cl−]
A
- Major extracellular anion.
- Chloride concentration in ECF is about 103 mmol/L, intracellular fluids of
RBCs is 45 to 54 mmol/
2
Q
how are Cl ions absorbed
A
- Chloride ions are almost completely absorbed from the intestinal tract.,
- passively reabsorbed, along with Na+, in the proximal tubules
3
Q
Chloride [Cl−] is involved in:
A
maintenance of blood volume
maintenance osmotic pressure
maintenance anion-cation balance in the ECF (electric neutrality)
3
Q
How are Cl- excreted
A
excreted in the urine and sweat.
4
Q
Mercuric titration principle
A
- The earliest methods for determining Cl− in biological fluids
- A protein free sample is titrated with mercuric nitrate solution in the
presence of diphenylcarbazone as an indicator - Free Hg2 + combines with Cl− to form soluble mercuric chloride (HgCl2).
- Excess Hg2 + reacts with diphenylcarbazone to form a blue-violet color
complex
4
Q
Specimen for chloride determination
A
- Chloride most often is measured in serum or plasma, urine and sweat
- Serum chloride is stable, gross hemolysis does not affect plasma chloride
concentrations - Erythrocyte concentration of Cl− is approximately half of that in plasma.
- Very little Cl− is protein bound, change in posture or stasis, or the use of
tourniquets, has little effect on its plasma concentration
5
Q
Determination of chloride
A
- Generally chloride is determined using methods including:
ISE
Mercurimetric titration,
Spectrophotometry,
Coulometric-amperometric titration
Colorimetry
6
Q
A
7
Q
Spectrophotometric methods
A
- Based on the reaction of Cl− with mercuric thiocyanate
- Chloride ions react with undissociated mercuric thiocyanate to form undissociated
mercuric chloride and free thiocyanate ions. - In the presence of perchloric acid, thiocyanate reacts with ferric ions forming ferric
thiocyanate - Ferrric thiocyanate [Fe(SCN)3] is a reddish colored compound that absorb light at
480nm - High concentrations of globulins in the serum interfere in these methods through
turbidity
8
Q
Calorimetric-amperometric titration
A
- Based on the generation of Ag+ from a silver electrode at a constant rate
and on the reaction of Ag+ with Cl− in the sample to form insoluble silver
chloride (AgCl) - Excess Ag+ in the mixture triggers shutdown of the Ag+ generation system
- A device records elapsed time between the start and stop of Ag+
generation. - The time interval is proportional to the amount of Cl− in the sample,
9
Q
Ion-Selective Electrode Methods
A
- In clinical analyzers tri-n-octylpropylammonium chloride decanol, are used
to construct Cl− selective electrodes - These electrodes have been reported to suffer from membrane instability
and lot-to-lot inconsistency in selectivity
10
Q
Reference intervals
A
plasma or serum = 98- 107 mmol/L
Urine( 24h) = 110-250 mmol/L varies with diet
10
Q
Clinical significance or conditions
A
- Hypochlorinaemia is associated with respiratory acidosis
- Hyperchlorinaemia occurs in dehydration prolonged diarrhea and
overtreatment with normal saline - Hyperchlorinamia may also be seen in respiratory alkalosis
11
Q
Sweat chloride (clinical significance) Used to confirm wnat
A
Used to confirm diagnosis of cystic fibrosis (CF), conducted in conjunction
with newborn screening
11
Q
Sweat chloride (clinical significance)
A
- Used to confirm diagnosis of cystic fibrosis (CF), conducted in conjunction
with newborn screening - Sweat test involves sweat stimulation, sweat collection and qualitative or
quantitative analysis - Qualitatively sweat chloride concentration is determined (positive or
negative results are obtained) - Quantitatively sweat chloride concentration is determined using
colorimetric titration with chloridometer and ISE - Sweat is collected onto preweighed gauze pad, filter paper, macroduct
coils - Infants, greater or equal to 60mmol/L is indicative of CF
