1. Electrolyte
“Chlorides”
Prepared by:
PRINCESS ALEN I. AGUILAR
Characteristics:
 The major extracellular anion.
 Function: involve in maintaining osmolality, blood volume, and electrical neutrality.
 Median plasma and interstitial fluid concentrations of 103mmol/L
 Represents the largest fraction of the total inorganic anion concentration of 154mmol/L
 Represent the majority of osmotically active constituents of plasma
 45-54mmol/L- concentration of Cl-
in intracellular fluid of RBCs whereas on other tissues only
1mmol/L
 Most abundant anion in gastric and intestines
 In most process, it shifts secondarily to a movement of Na+
or HCO3
 It is almost completely absorbed by the intestinal tract then filtered out by the glomerulus and
passively reabsorbed, in conjunction w/ Na+
, by the proximal tubules.
 Excess is excreted in urine and sweat.
 Aldosterone is stimulated by excessive sweating making the sodium and chloride to be conserved.
Cl-
maintains electrical neutrality in two ways:
1. Na+
is reabsorbed along with Cl-
acts as the rate-limiting component so Na reabsorbtion is limited
by the amount of Cl-
available.
2. Chloride shift:
CO2 of plasma and RBC forms
> carbonic acid which then splits to
> H+HCO3
-
(bicarbonate)
*DeoxyHgb buffers H+
whereas the HCO3
-
diffuses out into the plasma
*consequently, Cl-
diffuses into the red cell to maintain the electric balance of the cell
CLINICAL SIGNIFICANCE
*chloride disorders are often a result of the same causes that disturb Na+
levels because Cl-
passively
follows Na+
. There are few exceptions:
1. Hyperchloremia
I. May occur when there is an excess loss of HCO3 as a result of GI losses, RTA, or
metabolic acidosis.
II. Dehydration
III. Conditions causing decrease renal blood flow as in Congestive Heart Failure (CHF)
IV. Hyperchloremic acidosis
V. Cystic fibrosis
VI. Hypercalcemia due to parathyroid hyperfunction
2. Hypochloremia
I. May occur with excessive loss of Cl-
from prolonged vomiting, diabetic ketoacidosis,
Aldosterone deficiency, or salt losing renal diseases such as pyelonephritis.
II. In diarrhea, profuse sweating and certain endocrine disturbances wherein sodium loses
are excessive will also deplete Cl- in blood

2. Electrolyte
“Chlorides”
Prepared by:
PRINCESS ALEN I. AGUILAR
III. Hypochloremia alkalosis due to gastric juice secretion inhibition.
IV. Salt-losing nephritis associated with chronic pyelonephritis
*Low serum levels of Cl-
due to high serum HCO3
-
:
I. Compensated respiratory acidosis
II. Metabolic alkalosis
DETERMINATION OF CHLORIDE
Methods:
1. ISEs (Ion-Selective Electrode)- most commonly used
Principle: Ion-exchange membrane is used to selectively bind Cl-
ions
-Solvent polymeric membranes that incorporate quaternary ammonium salt anion-
exchangers, such as tri-n-octylpropylammonium chloride decanol, are used to construct Cl-
selective electrodes in clinical analyzers
-These electrodes have been described to suffer from membrane instability and lot-to-lot
inconsistency in selectivity to other anions.
-Anions that tend to be problematic are other halides and organic anions, such as SCN-
,
which can be particularly problematic because of their ability to solubilize in the polymeric
organic membrane of these electrodes.
2. Amperometric-coulometric titration -are the most precise methods for measuring CI- over
the entire range of concentrations displayed in body fluids.
Principle: Method using coulometric generation of silver ions (Ag+
) which combine with Cl-
to
quantitate chloride concentration
Reaction: Ag2+
+ 2Cl-
 AgCl2
-When all Cl-
is bound to Ag+
, excess or free Ag+
is used to indicate the endpoint. A
timing device records the elapsed time between the start and stop of the Ag+ generation.
*DIGITAL (COTLOVECHLORIDOMETER) (Labconco Corporation) uses this
principle in Cl-
analysis
REAGENTS:
A. Nitric acid-Acetic acid Solution -serves as diluent and prevents reduction of precipitated
AgCl2 at the sensing electrode
a. Nitric acid-provides good electrolyte conductivity
b. Acetic acid-makes the solution less polar, reducing the solubility of Silver Chloride.
B. Gelatine- equalizes the reaction rate over the entire electrode surface.

3. Electrolyte
“Chlorides”
Prepared by:
PRINCESS ALEN I. AGUILAR
Considerations when using this method:
1. The method is subject to interferences by other halide ions, by CN-
and SCN-
ions, by sulfhydryl groups, and by heavy metal contamination. Because samples
are pre-diluted before analysis, these methods are also subject to the electrolyte
exclusion effect.
2. Maintenance of the systems is crucial to proper operation; electrodes and reaction
vials or chambers must be kept scrupulously clean and the proper shape and size
of the Ag+ generating electrodes must be maintained.
3. Mercurimetric titration- one of the earliest method
Principle: A protein-free filtrate of specimen is titrated with mercuric nitrate solution in the
presence of diphenylcarbazone as an indicator. Free Hg2+
combines with CI-
to form soluble
but essentially nonionized mercuric chloride:
Reaction: 2Cl + Hg(N03)2
-> HgCl2 + 2NO3
-
-Excess Hg2+ reacts with diphenylcarbazone to form a blue-violet color complex
REAGENTS & RESULTS:
1. s-diphenylcarbazone- indicator
2. Mercuric nitrate-titrating agent
3. Mercuric chloride-end product
4. Blue violet-end color
4. Spectrophotometric methods/ Whitethorne Titration/ Zall Color Reaction/Fisher and
Gerarl
Principle: Chloride ions react with undissociated mercuric thiocyanate to form
undissociated mercuric chloride and free thiocyanate ions. The thiocyanate ions react with
ferric ion (Fe3*) to form the highly colored, reddish-brown complex of ferric thiocyanate
with an absorption peak at 480 nm. Perchloric add increases the intensity of the red color.
Reaction:
Considerations in using this method:
 High concentrations of globulins in the serum interfere in these
methods because turbidity develops.
 This reaction is also very temperature sensitive.
5. Sweat Chloride
Principle: the analysis of sweat for increased electrolyte concentration is used to
confirm the diagnosis of cystic fibrosis (CF). It is caused by a defect in the cystic fibrosis
transmembrane conductance regulator protein (CFTR), a protein that normally regulates
electrolytes transport across epithelial membranes.

4. Electrolyte
“Chlorides”
Prepared by:
PRINCESS ALEN I. AGUILAR
Performed in three phases:
1. Sweat stimulation by pilocarpine iontophoresis
2. Collection of sweat
3. Quali or quanti analysis of sweat Cl-, Na+, conductivity or osmolality
Reference range:
>60mmol/L = consistent with CF
40-60mmol/L = borderline
<40mmol/L = normal
Newborn = upto < 30mmol/L
6. Furic perchlorate (Fingerhut Method)
Principle: based on the formation of complex between ferric perchlorate and chloride. The
complex formed is thought to be a chloro-complex of ferric ions which has a maximum
absorbance at 340nm.
7. Colorimetry
PRACTICAL CONSIDERATIONS
Specimen:
 Serum or plasma maybe used, w/ lithium heparin being the anticoagulant of
choice
 Hemolysis does not significantly affect the serum or plasma Cl-
value
 Whole blood can be used with some analyzers
 In urine Cl-
, 24 hour collection is the specimen of choice
 Fecal Cl-
determination may be useful in diagnosis of congenital hypochloremic
alkalosis with hyperchloridorrhea (Increased excretion of Cl-
in stool)
o [Feces Cl-
]= 180mmol/L with almost no Cl-
being found in urine
 Sweat is also suitable for analysis
Interferences:
 Dirty pipette due to contamination
 Bromide and other halogens-react also in the procedure
 Hemolyzed sample will obscure to the end point giving as much as 15mmol/L
increase in the value
 Utilizing with the direct se of serum will five 2% increase because of protein
interferences.
 Sensitivity w/ pH of about 3-4.5
 End point is not so stable (diphenylcarbazone- orange red will change to dark
cherry red)
 Should be kept in dark colored bottles otherwise it will deionized.
REFERENCE RANGES

5. Electrolyte
“Chlorides”
Prepared by:
PRINCESS ALEN I. AGUILAR
Plasma/Serum: 98-107mmol/L (580-630 mg/dL)
*for neonates: 110mmol/L
*The spinal fluid Cl-
concentrations are 15% higher than in serum
Urine: 110-250mmol/day, varies w/ diet
Feces: 3.2 + 0.7mmol/L