Lab Exam 2 Clin Chem

Front 1

State Formular of Anion Gap and its reference range

Back 1

Anion Gap = (Na+ + K+) - (Cl- + HC03-)
10-20 mmol/L

Front 2

What are the Causes of increased AG ? Cause 1

Back 2

Metabolic acidosis
↑ production of acids --> ↓ amount of + HCO3- in plasma --> ↑ AG

ex: DKA -->- ↑ ketoacids --->↓ HCO3-
Hypoxia-->- ↑ lactic acid --->↓ HCO3-
Renal failure -->- ↑ retention of normal acids --->↓ HCO3-

Front 3

What are the Causes of increased AG ? Cause 2

Back 3

Abnormal concentration of Na
ex: in renal disease, it is not reabsorbed from proximal convoluted tubules back into plasma.
ex: abnormal secretion of aldosterone  abnormal reabsorption from distal convoluted tubules back into plasma.
Increased K+ does not usually cause an increased anion gap b/c it is not compatible with life.
Chloride usually does not alter anion gap b/c it crosses cell membrane easily and never accumulates or gets used up in reactions.

Front 4

what are the clinical significance of SODIUM?

Back 4

Detect f aldosteronism (excessive secretion of hormone aldosterone), diabetes insipidus, adrenal hypertension, Addison`s disease, dehydration, inappropriate antidiuretic hormone secretion, or other diseases involving electrolyte imbalance.

Front 5

What type of membrane ISE’s used to measure Na+ ?

Back 5

Incorporate a silicate glass membrane that is permeable to Na ions and excludes other cations.
“Glass Membrane” = ionophore = ion-exchange resin that changes voltage when the sample’s ion replaces the native ion in the resin

Front 6

When the sample/buffer mixture contacts the electrode, sodium ions undergo an ion exchange in the hydrated outer layer of the glass electrode. As the ion exchange takes place, a change in potential (voltage) is developed at the face of the electrode.

Back 6

This potential is referenced to a sodium reference electrode in which small temperature variations and electrical noise are compensated through the use of common mode rejection techniques.

Front 7

The potential follows the Nernst equation and allows the calculation of sodium concentration in a solution.

Back 7

Under ideal conditions, the electrode imparts a selectivity of 300:1 over potassium and is insensitive to hydrogen ions in solutions buffered from pH 6 to 10.

Front 8

what are the clinical significance of POTASSIUM ?

Back 8

Detect hypokalemia, renal failure, Addison`s disease or other diseases involving electrolyte imbalance.

Front 9

What type of membrane the potassium electro consist?

Back 9

The potassium electrode consists of a valinomycin membrane. The physical structure of the valinomycin membrane is such that the complexing sites in the membrane nearly equal the diameter of the potassium ion.

Front 10

When complexing occurs, a voltage (potential) change takes place within the membrane. This potential is referenced to a sodium reference electrode in which small temperature variations and electrical noise are compensated through the use of common mode rejection techniques.

Back 10

The potential follows the Nernst equation and allows the calculation of potassium concentration in a solution.Under ideal conditions, the electrode imparts a selectivity of 1000:1 over sodium ions and is insensitive to hydrogen ions in solutions buffered from pH 3 to 9.

Front 11

What is the clinical significance of CHLORIDE?

Back 11

Detect electrolyte and metabolic disorders such as cystic fibrosis and diabetic acidosis.

Front 12

What is the type of the chloride ion-electrode is called
What is the equilibrium dependent on ?

Back 12

The chloride ion-selective electrode is a two-phase Ag/AgCl type.
This equilibrium is dependent on the solubility product (Ksp) of the silver and chloride ions in the solution, according to the following reaction:
AgCL --> Ag+ + Cl-

Front 13

When chloride ions are introduced into the system, the developed equilibrium is disrupted as Ag+ ion concentration at the electrode surface changes.
This change results in a shift of the electrode potential according to the Nernst equation which is indirectly related to the chloride activity in the sample

Back 13

The potential developed at the chloride electrode is referenced to a sodium reference electrode in which small temperature variations and electrical noise are compensated through the use of common mode rejection techniques.

Front 14

What is the clinical significance of CARBON DIOXIDE ?

Back 14

Detect numerous potentially serious disorders associated with changes in body acid-base balance.

Front 15

What type of PH electrode membrane does Carbon Dioxide use ?

Back 15

The pH electrode with a silicone rubber membrane is used to measure carbon dioxide by differential pH rate of change. When the sample solution is mixed with acid, all forms of carbon dioxide are converted to their gaseous form.

Front 16

A proportional amount of liberated gas diffuses through the membrane lowering the pH of the bicarbonate solution located between the membrane and the face of the electrode.

Back 16

The rate of pH change is directly proportional to the carbon dioxide in the sample

Front 17

Fill in the blanks:

1. Potential changes involve measuring : _______________________
2. Conductivity and Coulometry involve measuring:

Back 17

1. Votage
2.Resistance and Charge

Front 18

Analyte H+ K Cl- pCO2 pO2
Potentiometry with valinomycin selective membrane

Back 18

K

Front 19

Analyte H+ K Cl- pCO2 pO2
Coulometry with end-point of Ag titration detected

Back 19

CL-

Front 20

Analyte H+ K Cl- pCO2 pO2
Clark Polarography with reduction at cathode detected

Back 20

PO2

Front 21

Analyte H+ K Cl- pCO2 pO2
ISE with indicator electrode of specific glass

Back 21

H+

Front 22

Analyte H+ K Cl- pCO2 pO2
Severinghaus modified pH potentiometry

Back 22

PC02

Front 23

Cite the Nernst equation and explain the purpose of using the Nernst equation

Back 23

E=delta PH x 0.059V
Relates voltage of an ISE to the activity of the ion being measured

Front 24

Patient 1 has a glucose level of 90 mg/dL, and BUN of 10 mg/dL . Calculate the plasma osmolality using the above reported data.

Back 24

265 mosmo/kg
Formula:
2[Na]+[Glucose]+[Bun]
20 3

Front 25

The measured osmolality for this patient is 350mOsmo/Kg. Calculate Osmolal gap. Is the gap increased, decreased or normal? What does the result indicate?

Back 25

osmolal gap= measured osmo - calculated osmo
normal value (included in the calculated osmo) = 9 mOsm/Kg

Front 26

List any two reasons for failed calibrations?

Back 26

Qc is out of date or Hoding probe too long in the sample

Front 27

List reference ranges for serum/plasma sodium, potassium, chloride, carbon dioxide and Anion gap

Back 27

Sodium136 – 145 mmol/L
Potassium 3 – 5 mmol/L
Chloride100 – 107 mmol/L
Carbon dioxide 23 – 29 mmol/L
Anion Gap 10 – 20 mmol/L

Front 28

What would be the affect of hemolysis on electrolyte results? Why?

Back 28

Falsely increase sample because a hemolyzed RNC would release Na and Cl

Front 29

What would be the affect of lipemia on electrolyte results? Why?

Back 29

Not so much

Front 30

Difference of wet chemistry and flurorescence or dry chemistry.

Back 30

Dry doesn’t measure CO2, less maintenance
Wet does measure CO2, more maintain ace