CHLORIDE AND BICARBONATE Flashcards
- HYPOCHLOREMIA
- Salt-Losing Nephritis
- Addisonian Crisis
- Prolonged Vomiting
- Metabolic Alkalosis
- HYPERCHLOREMIA
- Dehydration
- Renal Tubular Acidosis
- Metabolic Acidosis
A decreased HCO3
- Metabolic acidosis
- Renal failure
- RTA w/ hypochloremia
- Diarrhea
- States of poor tissue perfusion
- Respiratory alkalosis
An increased HCO3
- Metabolic alkalosis due to severe vomiting with the loss of Na intake, hypokalemic states, excessive intake of alkali
: Plasma Cl Tends To Fall As HCO; Increases
Metabolic Alkalosis
- Assoc. W/ Prolonged Diarrhea & Loss Of Nahco3
Metabolic Acidosis
DETERMINATION OF CHLORIDE
Major extracellular anion (counterpart of na)
Major extracellular anion (counterpart of na)
Chloride
Chloride
Represents the largest fraction of the plasma total inorganic anion concentration
(~154 mmol/l)
In RBCs:
45 - 54 mmol/l
In tissue cells :
~1.0 mmol/l
Functions in the maintenance of:
- Water distribution (maintains osmolality)
- Osmotic pressure (and blood volume)
- Anion-cation balance in the ecf (electrical neutrality)
one of the most important
electrical neutrality
balance of the + and – charges in the system
electrical neutrality
proper/normal number and ratio of the + and – charges within and outside the cell
electrical neutrality
Chloride maintains electrical neutrality in two ways:
- Na+ is reabsorbed along w/ Cl- in the PCT & LH
- Chloride shift
CO2 generated by cellular metabolism w/in the tissue diffuses out into both the plasma & the rbc
Chloride shift
Chloride is filtered from the plasma by the.
glomerulus
passively absorbed along with sodium in the (?)
proximal convoluted tubules
active reabsorption through the chloride pump happens in the.
ascending loop of Henle
o – movement of Cl against a concentration gradient needing ezymes and energy
Active
active reabsorption by the so called
chloride pump
Excessive sweating triggers release of
Aldosterone
causes the sweat glands to reabsorb more Na+ and Chloride
Aldosterone
conserves or retains Na
Aldosterone
Reference ranges:
Plasma, serum:
Urine (24-hour) :
Plasma, serum: 98-110 mmol/l
Urine (24-hour) :110 - 250 mmol/l
Varies w/ diet
Same time in different days
Samples in the lab are submitted in a large gallon
100 to 150 mL
Urine (24-hour)
Decrease plasma concentration of Cl
HYPOCHLOREMIA
It uses diphenylcarbazone as the indicator and HgCl2 as the end product of the reaction
Mercumetric Titration or the Schales and Schaled method
It is done using spectrophotometric reading which uses diphenylcarbazone as the reagent with reddish complex end point product which is read spectrophotometrically.
Whitehorn Titration Method
When all Cl- in the sample is bound to Ag excess Ag is used to indicate the endpoint
Coulometric - Amperometric Titration
Uses an ion-exchange membrane
Ion-Selective Electrode
2nd most abundant anion in the ECF (following Cl)
Accounts for >90% of the total CO2
Total Carbon Dioxide (CTCO2) in plasma
- HCO3 or CO3 ions – bicarbonate or carbonic ions
- H2CO3 – carbonic acid
- CO2 in Physical Solution
- CO2 loosely bound to proteins (carbamino compounds)
About 85% of filtered bicarbonate is reabsorbed in the (?) and the rest (15%) in the (?)
proximal convoluted tubules
distal convoluted tubules
Tubules are known to be only slightly permeable to bicarbonate because bicarbonate after being filtered into the tubules combines with hydrogen to form (?).
carbonic acid
Bicarbonate do no as is enters the cell, but is reabsorbed back as
carbon dioxide
Little bicarbonate is loss in
urine
then dissociates into molecules of water and carbon dioxide where carbon dioxide readily diffuses back into the ECF.
Carbonic acid
Alterations of (?) in plasma are characteristic of acid-base imbalance.
HCO3 & CO2
: provide a definitive picture of the over-all pattern of imbalances.
Evaluation of blood gases & pH
A decreased HCO3
- Metabolic acidosis
- Renal failure
- RTA w/ hypochloremia
- Diarrhea
- States of poor tissue perfusion
- Respiratory alkalosis
An increased HCO3
- Metabolic alkalosis
may occur from metabolic acidosis as HCO3- combines with H to produce CO2, which is exhaled by the lungs
Metabolic acidosis
– great reduction in the normally functioning nephrons
Renal failure
– exchange of fluid, ions, and gasses are disrupted
States of poor tissue perfusion
CO2 in the blood decreases
Respiratory alkalosis
ex. Hyperventilation – rapid inhalation; removing high amount of CO2 =
Respiratory alkalosis
Management: paper bag
Respiratory alkalosis
Metabolic alkalosis due to
severe vomiting with the loss of Na intake, hypokalemic states, excessive intake of alkali
(antacids like Kremil-S for hyperacidity/heartburn containing bicarbonate supplements: only 7 tablets per day)
Alkali
HCO3 specimen
Serum or Lithium heparinized plasma (from venous or capillary blood)
Specimen drawn in (?): unopened & centrifuged ASAP
evacuated tube
Analyzed promptly after the tube is
opened
Note: Exposure to air = CO2 loss; decrease by (?) within an hour
6 mmol/L
Ideal collection
Arterial Blood Collection
Collection from the artery
Arterial Blood Collection
Complex procedure performed by trained personnel
Arterial Blood Collection
Arterial Blood Collection
To determine
arterial blood gasses
Sample is collected via catheter placed in artery or direct syringe puncture (pre-heparinized)
Arterial Blood Collection
Handled to minimize air exposure
Arterial Blood Collection
Arterial Blood Collection
Primary site of collection:
radial artery (thumb site)
Arterial Blood Collection
Other sites:
brachial, femoral (inguinal)
Arterial Blood Collection
Ideal gauge:
20, 23, 25
Use of syringe w/ cover is used to prevent excess O2 entering the sample
Arterial Blood Collection
hold the syringe like a dart
Arterial Blood Collection
Arterial Blood Collection
Angle:
45o
When advancing the needle, allow the flush back to appear
Arterial Blood Collection
Ideal to not to pull the plunger • Let the pressure push the plunger up
Arterial Blood Collection
Performed to check for collateral circulation
Allen’s Test
Inflammation test
1. Pressing the radial and ulnar to block the access of blood
2. Release the hand pressing the ulnar artery
• Collateral: flushing red – can be used
• Remains white: cannot be used for the procedure
Allen’s Test
Cl acts a
rate-limiting component
Na absorption will depend on the number on the amount of[?] available for reabsorption
Cl
Ex. 20 Cl ions and 50 Na ions in the PCT: [?] Na ions will be reabsorbed back
20
Both are reabsorbed back in the circulation but the number varies
Na and Cl
The number of Na that will be reabsorbed will depend on the[?] available for reabsorption
Cl
Carbon dioxide will form a complex with water forming a complex, [?] by the catalytic activity of [?].
carbonic acid
carbonic anhydrase
will split into water and bicarbonate.
Carbonic acid
Inside the RBC, hydrogen will be buffered by the oxyhemoglobin, while [?] will diffuse out into the plasma.
bicarbonate
– (-) charge ion that diffuses out of the plasma, causing imbalance
Bicarbonate
Shifting of Cl from extracellular to intracellular in exchange of[?] moving out of the cell
bicarbonate
almost the same cause of Na disturbance; Na follows both water and Cl
HYPOCHLOREMIA
tubular or medullary condition affecting Na and Cl transportation or reabsorption
Salt-Losing Nephritis
problem in the tubule causing excessive loss of Na and Cl
Salt-Losing Nephritis
adrenal insufficiency – body cannot produce enough aldosterone
Addisonian Crisis
causing loss of Na
excretion of Na and Cl in inc amount
aldosterone
Addisonian Crisis
triggered by
traumatic events, severe and viral infection
Excessive GIT loss
Prolonged Vomiting
When bicarbonate moves out of the plasma, bicarbonate increase the pH of blood causing alkalosis
Caused by increase movement of bicarbonate from intracellular fluid extracellularly
bicarbonate moving out of the cell = Cl entering the cell = Cl conc in the plasma
↑
↑
↓
Always measure conc in the plasma
extracellularly
kidneys are unable to appropriately excrete acid
Renal Tubular Acidosis
Problems w/ Na and Cl reabsorption
Renal Tubular Acidosis
[?] is secreted out of the urine in exchange of the reabsorption of [?]
H
Na
[?] filtered must go back to the circulation
Na
– passageway of filtered ions and chemicals filtered by the glomeruli; electrolytes filtered by the glomerulus
Lumen of PCT
– division between the lumen and the blood circulation
PCT cell
PCT cell
[?]is present
[?] will form a complex in the presence of [?] forming [?], which splits into [?]
Water
CO2; CA; carbonic acid; hydrogen and bicarbonate
[?] diffuses out of the tubular cell in exchange for[?]
H; Na
[?] will return back to the circulation in exchange for more [?]
Bicarbonate and Na; hydrogen
[?]is reabsorbed back first in the cell, but in exchange of [?] (electrical neutrality of + charges)
Na; hydrogen
With the movement of the cell from the lumen,[?] will form a complex
bicarbonate
Bicarbonate + Hydrogen = Carbonic Acid (dissociates into water and CO2) by the catalytic activity if
carbonic anhydrase
diffuses back in the tubular cell
CO2
Accumulation of hydrogen in the case of RTA, preventing Na reabsorption
RTA
Cl in the sample is determined by direct titration with (?) (standard)
mercuric nitrate solution
Cl binds to mercury liberating
nitrate
Excess mercury is made to react w/ diphemylcarbazone (indicator) forming a
blue-violet color
Intensity of color is [?] to the conc of Cl
inversely proportional
Cl is made to react w/ mercuric thiocyanate, yielding
mercuric chloride and thiocyanate
Cl is made to react w/ mercuric thiocyanate, yielding
mercuric chloride and thiocyanate
Liberated thiocyanate is made to react w/ iron = ferric thiocyanate ([?]@ 480 nm)
reddish color
: used as a substitute for mercuric thiocyanate (intense blue)
Tripyridyl triazine
Cl reacts w/ [?] forming a colored complex
ferric perchlorate
Intensity of color is directly proportional to the conc of Cl
Whitehorn Titration Method
Because HCO3 - composes the largest fraction of total CO2,[?] is indicative of HCO3- measurement
total CO2 measurement
Bicarbonate do no as is enters the cell, but is reabsorbed back as [?]
carbon dioxide
Little [?] is loss in urine
bicarbonate
– great reduction in the normally functioning nephrons
Renal failure
– exchange of fluid, ions, and gasses are disrupted
States of poor tissue perfusion
Analysis of an arterial sample collected anaerobically for BGA preserves
dissolved CO2
Content of the sample
(CTCO2)
HISTORICAL METHODS
Used prior to automated methods used in the lab
HISTORICAL METHODS
SMAC, TECHNICON INSTRUMENTS
Continuousflow analysis
gaseous CO2 diffuses across a silicone membrane into a recipient solution (w/ phenolphthalein) buffered at ph 9.2
Continuousflow analysis
decrease in ph: reduction in the red color (determined spectrophotometrically)
Continuousflow analysis
sample is acidified: converts CO2 in plasma into gaseous form
Manometric method
alkalinize: converts gaseous CO2 to H2CO3 then to HCO3
Manometric method
Change in pH: measured with phenolphthalein indicator
Manometric method
Mostly used in research
Manometric method
(NATELSON MICROGASOMETER)
Manometric method
– brand or automated machines
BECKMAN INSTRUMENTS
BECKMAN INSTRUMENTS
INDIRECT ELECTRODE: ASTRA METHOD
Gaseous CO2 is determined by a PCO2 electrode
INDIRECT ELECTRODE: ASTRA METHOD
The relationship between the sample and the signal generated by the internal pH is logarithmic and governed by nernst equation
INDIRECT ELECTRODE: ASTRA METHOD
Reference range:
Total CO2 (venous):
HCO3:
23 - 29 mEq/L or mmol/l
22 - 26 mEq/L or mmol/l
(ACA DUPONT)
Enzymatic method
Total CO2 (venous) includes
bicarbonate, dissolved undissociated H2CO3
Bicarbonate is made to react with
phosphoenol pyruvate
Reaction is catalysed by [?]
phosphoeneol pyruvate carboxylase
Like the coupled-enzymatic reaction; only 1 enzyme is involved in the reaction
Enzymatic method
2nd enzyme:[?] – converts oxaloacetate to malate with the subsequent conversion of NADH to NAD
MDH
Measurement of rate of conversion from NADH to NAD that will give a linear equivalent of the conc of bicarbonate
Enzymatic method
catalyses the formation of oxaloacetate at liberation of inorganic phosphates from the reaction that will take place
phosphoeneol pyruvate carboxylase
• Mathematical formula used to demonstrate electroneutrality of body
Anion Gap
• Difference between cations and anions that are not actually measured analytically when serum “electrolytes” are quantified
Anion Gap
Two calculations
• Na - (Cl + HCO3) = Anion gap
• (Na + K) - (Cl + HCO3) = Anion gap
• Na - (Cl + HCO3) = Anion gap
Expected anion gap:
7 – 16 mmol/l
• (Na + K) - (Cl + HCO3) = Anion gap
Expected anion gap: 10 – 20 mmol/l
DIAGNOSTIC SIGNIFICANCE OF ANION GAP
Increased
• Uremia
• Lactic acidosis
• Ketoacidosis
• Hypernatremia
• Ingestion of methanol, ethylene glycol, or salicylate.
DIAGNOSTIC SIGNIFICANCE OF ANION GAP
Decreased
• Hypoalbuminemia
• Hypercalcemia
