Chloride and Bicarbonate (RVSP) Flashcards
3 functions of chloride
- maintains osmolality
- maintains blood volume
- maintains electric neutrality
Major extracellular anion
Chloride (Cl-)
Cl- shifts secondarily to a movement of ___ and ___
Na+
HCO3-
Organ that absorbs Cl-
Small intestine
Passively reabsorbs Cl-
Proximal tubules
Excess Cl- is excreted in the _____ and ______
Urine
Sweat
Stimulates aldosterone secretion; Cl-
Excessive sweating
Effect of aldosterone on serum Cl- levels
Increased Cl- levels
Effect of aldosterone on sweat Cl- levels
Decreased Cl- levels
Electrolyte that is the partner of Na+
Cl-
2 ways in which Cl- maintains electric neutrality
- Cl- acts as a rate-limiting component in Na+ reabsorption
- Chloride shift
Buffers H+ inside the red cell
Deoxyhemoglobin
Process of maintaining electric neutrality where Cl- diffuses into the red cell as HCO3- didfuses out into the plasma
Chloride shift
True/False. Cl- passively follows Na+
True
Excessive loss of HCO3-; increased serum Cl-
Hyperchloremia
Excessive loss of Cl-
Hypochloremia
Causes of hyperchloremia
- GI losses
- RTA
- metabolic acidosis
Causes of hypochloremia
- prolnged vomiting
- diabetic ketoacidosis
- aldosterone deficiency
- salt-losing renal diseases (ex: pyelonephritis)
- metabolic alkalosis
- compensatory respiratory acidosis
Specimens for Cl-
- serum
- plasma (lithium heparin)
- whole blood
- urine (24 hr)
- sweat
Effect of hemolysis on Cl- levels
Decreased (because of dilutional effect)
Most commonly used method for Cl-
ISE
Mts for Cl-; uses silver wire coated with AgCl as electrode
ISE
Reaction for Colorimetric determination of Cl-
Cl- + Hg(SCN)2 —> HgCl2 + SCN-
SCN- + Fe3+ —> Fe(SCN)3
Cl- mtd; Ag+ combines with Cl-; excess/free Ag+ indicates endpoint
Cotlove Chloridometer/Whitehorn/Sendroy Stiff/Amperometric-Coulometric
Cl- mtd; excess amount of Hg measured by titrating diphenylcarbazone
Schales and Schales / Mercurimetric titration
Endpoint of Schales and Schales mtd for Cl-
Blue violet color
Reaction for Schales and Schales / Mercurimetric titration for Cl-
Cl- + Hg(NO3)2 —> HgCl2 + NO3-
Titrated in the mercurimetric titration/Schales and Schales method for Cl-
Diphenylcarbazone
RR for Cl- (Serum/plasma and urine)
Serum/plasma: 98-107 mmol/L
Urine: 110-250 mmol/day, varies with diet
Indicator if Cl- movement
Na+
Second most abundant anion in the ECF
Bicarbonate (HCO3-)
Composition of Total CO2
- Bicarbonate ion (HCO3-): 90%
- carbonic acid (H2CO3)
- dissolved CO2
Indicative of Total CO2 measurement
HCO3- measurement
Major component of the buffering system of blood
HCO3-
Reaction in the production of HCO3-
CO2 + H2O H2CO3 H+ + HCO3-
Is CO2 acidic or basic?
Acidic
Reabsorbs 85% of HCO3-
Proximal tubules
Reabsorbs 15% of HCO3-
Distal tubules
HCO3- is reabsorbed in the tubules as _______
CO2
Problem in alkalosis
Too much HCO3-
Remedy for alkalosis
Excrete HCO3-
Problem in Acidosis
Too much H+
Remedy for Acidosis
- excrete H+
- reabsorb HCO3-
HCO3- level in metabolic acidosis
Decreased
Response for metabolic acidosis
Hyperventilation
Total CO2 level in metabolic alkalosis
Increased
Response for metabolic alkalosis
Hypoventilation
3 causes of metabolic alkalosis
- severe vomiting
- hypokalemia
- excessive alkali intake
Specimens for HCO3- determnation
Serum
Plasma (lithium heparin)
ANAEROBIC (specimens should be capped)
Rate of decrease in CO2 if specimen is left uncapped
6 mmol/L/hr
HCO3- mtd; uses an acid reagent to convert all forms of CO2 to CO2 gas; uses pCO2 electrode
ISE
In the ISE mtd for HCO3-, all forms of CO2 is converted to _______
CO2 gas
Electrode used in ISE for HCO3-
pCO2 electrode
Reagent used in ISE for HCO3-
Acid reagent
HCO3- mtd; Sx is alkalinized to convert all forms of CO2 to HCO3-
Enzymatic mtd
In enzymatic mtd for HCO3-, all forms of CO2 is converted to ______
HCO3-
Reaction for Enzymatic mtd for HCO3-
- Phosphoenolpyruvate (PEP) + HCO3- –PEP Carboxylase–> Oxaloacetate + H2PO4-
- Oxaloacetate + NADH + H+ –MDH–> malate + NAD+
MDH: malate dehydrogenase
RR for HCO3- (plasma, serum)
CO2, venous 23-29 mmol/L
