Chem 2

Front 1

What does sweat chloride determine?

Back 1

Cl conc in sweat. Increased levels are diagnostic for cystic fibrosis. GF affects mucous secretions, exocrine glands& sweat glands. Usually causes abnl viscous mucous secretions rich in glycoproteins that precipitate out & obstruct ducts & passageways thruout body.

Front 2

Reference ranges for sweat chloride:

Back 2

Nml: 0-40 mmol/L
Indeterminate for CF: 40-60 mmol//L
Suggestive for CF: >60 mmol/L

Front 3

Sweat chloride electrodes:

Back 3

Positive: pilocarpine reagent
Negative: potassium sulfate sol

Front 4

What is anion gap?

Back 4

The difference between measured cations & anions; the gap represents the amt of unmeasured anions which is greater than the unmeasured cations.

Front 5

Anion gap formula:

Back 5

(Na + K) - (Cl + HCO3) or
Na - (Cl + HCO3)

Front 6

What is the bicarbonate/carbonic acid buffering system?

Back 6

It is the main blood buffering system, resisting changes in pH. Equation: CO2 + H2O <-> H2CO3 <-> HCO3 + H

Front 7

In maintaining the blood's pH, the ?? controls the bicarbonate and the ?? controls the carbonic acid.

Back 7

Kidney controls HCO3
Lung controls H2CO3

Front 8

Explain most common method of measurement for electrolytes (Na, K, Cl, CO2)

Back 8

ISE. Na-glass-ion exchange, lithium silicate; K-valinomycin neutral-carrier membrane; Cl-silver-silver chloride or silver sulfide reference electrode; CO2-pH electrode.

Front 9

Reference range/critical values for Na.

Back 9

135-145 mmol/L
Critical: <120, >160 mmol/L
Nb: <130, >150 mmol/L

Front 10

Ref range/critical values for K:

Back 10

3.6--5.0 mmol/L
Crit: <2.5, >6.5
Nb: >7

Front 11

Ref range/critical values for Cl:

Back 11

101--111 mmol/L
Crit: none

Front 12

Ref range/critical values for CO2:

Back 12

21--31 mmol/L
Crit: <20, >70 mmol/L

Front 13

Ref range for HCO3:

Back 13

22--28 mmol/L

Front 14

Reference range for anion gap:

Back 14

8--16

Front 15

Major cation in extracelllar fluid and function?

Back 15

Na; maintain osmotic pressure and water distribution

Front 16

Explain Na & K concentrations in Addison's disease.

Back 16

Decreased adrenal activity results in decreased aldosterone levels. Less Na is reabsorbed in the kidney resulting in hyponatremia. Kidneys also have reduced ability to excrete K, resulting in hyperkalemia.

Front 17

Explain Na & K concentrations in Cushing's syndrome.

Back 17

Increased ACTH results in overstimulation of adrenal cortex resulting in increased aldosterone. Na is reabsorbed-->hypernatremia & K is decreased.

Front 18

Define hyponatremia/hypernatremia:

Back 18

Hyponatremia: Na <135 mmol/L
Hypernatremia: Na >145 mmol/L

Front 19

Major cation in intracellular fluid?

Back 19

K

Front 20

Discuss effects of hemolysis on K results & why.

Back 20

Hemolysis releases intracellular K, falsely increasing K results because of high K content in cells (98% of K in cells).

Front 21

Discuss functions of K & what organ it has a major effect on & why.

Back 21

Fxn: regulates cellular processes & responses; neuromuscular excitation.
Affected organ: Heart. Increase or decrease in K may lead to arhythmias & muscle paralysis.

Front 22

Major extracellular anion & function?

Back 22

Cl; it will compensate for HCO3 (Chloride shift); its metabolism is closely linked to Na & thus maintains fluid balance & osmotic pressure.

Front 23

Reference range/critical values for Mg:

Back 23

18.23-29.3 mg/L
Crit: <10 mg/L

Front 24

Ref range/crit values for Ca:

Back 24

80-105 mg/L
Nb: 85-105 mg/L
Crit: <60 mg/L, >130 mg/L

Front 25

Ref range for Ionized Ca:

Back 25

46.5-53.9 mg/L

Front 26

Ref range P:

Back 26

2.5-4.8 mg/dL

Front 27

Discuss importance of Mg.

Back 27

Mg is a cofactor for many intracellular enzymes, including all those that use ATP. It is present in all tissue & bone & about equally distributed between soft tissue & bone.

Front 28

Measurement for Mg:

Back 28

AAS (atomic absorption spect). Mg has a strong spectral emission or absorption line at 285.2nm, which can be readily isolated & used to measure Mg contentration.

Front 29

Cause & effects of hypermagnesemia:

Back 29

Effects of increased Mg: toxic effects on CNS & cardiac function; Causes: high dose TD agents (MgSO4 for hypertension induced by pregnancy), antacid overdose, renal failure-reduced Mg excretion.

Front 30

Cause & effects of hypomagnesemia:

Back 30

Effects decreased Mg: increased neuromuscular & cardiac excitability->arrhythmias; Causes: decreased intake; loss due to malnutrition, alcoholism, Diabetes mellitus, Paget's disease.

Front 31

State 3 hormones known to regulate serum Ca & whether they increase or decrease Ca absorption/reabsorption.

Back 31

Calcitonin: decreases Ca; inhibits reabsorption
Parathyroid hormone (PTH): increases Ca; enhances reabsorption
Vitamin D (converted to calcitriol): increases Ca; enhances reabsorption

Front 32

Discuss ionized Ca & its importance.

Back 32

Physioogically active form of Ca;
Needed for coagulation, enzyme cofactr, membrane permeability; when complexed, it makes bones/teeth rigid.

Front 33

Discuss handling for specimen for ionized Ca.

Back 33

Although serum is the preferred sample for measuring ionized Ca, the used of heparinized whole blood is useful when a result is needed immediately & allowing time for clotting/spinning is not acceptable.
Samples should be analyzed asap-within 1 hr.
Handle anaerobically.
Keep cool so that pH is accurate.

Front 34

Define tetany & what effects Ca has on tetany.

Back 34

What really causes tetany is low ionic calcium in extracellular & intracellular fluid. Characterised by cramping, convulsions, confusion, stupor & coma.

Front 35

List the 3 forms of Ca distribution & % of each:

Back 35

Ionized=47%
Protein bound=46%
Complexed (w/citrate, phosphate, lactate &/or sulfate)=7%

Front 36

When albumin & TP are low, what would you expect Ca to be?

Back 36

Ionized Ca is unaffected;
Total Ca would be decreased.

Front 37

What happens to Ca in an alcoholic patient?

Back 37

Decreased Ca due to decreased protein (less in the diet & less made by the liver).

Front 38

Discuss the distribution of phosphorous throughout the body.

Back 38

P is in & outside of cells. 85% of extracelular P is in hydroxyapatite (complexed w.Ca in bones). P is in organic phosphates like lipids, proteins, & nucleic acids (DNA/RNA).

Front 39

Discuss the method used for most P determinations.

Back 39

Phosphate complexes w/ammonium molyblate to form phosphomolyblate which is then reduced to form molybdenum blue. Measured photometrically.

Front 40

Phosphorus levels are universally proportional to ??

Back 40

Phosphorus levels are universally proportional to Ca levels.