Electrochemistry & Electrolytes

Question 1

Na+ reference range

Answer 1

133 - 146 mmol/L
Crit = <125 or >155 mmol/L

Question 2

Common methodology for measuring Na+

Answer 2

Glass ISE

Question 3

Sources of error for Na+

Answer 3

Electrolyte exclusion effect

Question 4

Causes for increased Na+

Answer 4

Primary aldosteronism (Conn’s Syndrome)

Cushing’s Syndrome (hyperadrenalism)

Secondary aldosteronism

Diabetes Insipidus

Question 5

Causes for decreased Na+

Answer 5

Increased osmolality:
hyperglycemic state, uremia, mannitol and is due to shift in water or sodium between ECF and ICF

Decreased osmolality:
liver, kidney, or heart disease, SIADH, Addison’s disease, diuretics, external fluid loss

Question 6

K+ reference range

Answer 6

3.5 - 5 mmol/L
Crit = < 2.6 or >6.2

Question 7

Common methodology for measuring K+

Answer 7

Liquid polymer
(valinomycin is an ionophore)

Question 8

Sources of error for K+

Answer 8

Hemolysis

Prolonged venous occlusion

fist clenching/forearm exercise prior to venipuncture

leukocytosis

thrombocytosis

Question 9

Causes for increased K+

Answer 9

acidosis, IVH, rhabdomyolysis, burns, tissue hypoxia

Addison’s disease, hypoaldosteronism, treatment with ACE inhibitors

Question 10

Causes for decreased K+

Answer 10

insulin therapy

renal tubular acidosis or necrosis

decreased intake/excessive loss

Question 11

Cl- reference range

Answer 11

96 - 109 mmol/L

Question 12

Common methodology for measuring Cl-

Answer 12

Liquid polymer ISE
(ion exchange is lipophilic quaternary ammonium salts)

Solid state ISE

Question 13

Sources of error for Cl-

Answer 13

competing halides
organic salts such as thiocyanate or lactate

Question 14

Causes of increased Cl-

Answer 14

Similar to those of hypernatremia

may be seen in respiratory alkalosis where HCO3- is excreted in the kidney with Na+ instead of Cl-

Question 15

Causes of decreased Cl-

Answer 15

similar to those of hyponatremia

Furosemide antidiuretic inhibits Cl- reabsorption in the kidney

Question 16

HCO3- (total CO2) reference range

Answer 16

23 -31 mmol/L

Question 17

Common methodology for HCO3-

Answer 17

Spectrophotometric

Question 18

Sources of error for HCO3-

Answer 18

exposure to atmospheric air decreases [CO2] in specimen

Question 19

Causes for increased HCO3-

Answer 19

metabolic alkalosis

hypochloremic alkalosis (prolonged diarrhea, vomiting)

Excess mineralocorticoids or corticoids

Excess administration or ingestion of HCO3- (IV therapy, massive transfusion)

Question 20

Causes for decreased HCO3-

Answer 20

metabolic acidosis

Increased endogenous acids

Increased exogenous acids

inability to excrete HCO3- (renal failure)

loss of HCO3- (diarrhea, pancreatitis)

Question 21

CO2 reference range

Answer 21

35 - 45 mmHg

Question 22

Common methodology to measure CO2

Answer 22

Gas permeable ISE

Question 23

Sources of error for CO2

Answer 23

Exposure to atmospheric air decreases [CO2]

Question 24

Causes for increased CO2

Answer 24

Respiratory acidosis (hypoventilation)

Mechanical obstruction of airways

factors that depress the respiratory system

Question 25

Causes for decreased CO2

Answer 25

Respiratory alkalosis (hyperventilation) Factors that have stimulatory effect on respiratory system Factors that affect the pulmonary mechanism and lead to tissue hypoxia

Question 26

Calcium reference range

Answer 26

2.10 - 2.60 mmol/L Crit = <1.65 or >3.25 mmol/L

Question 27

Common methodology for Calcium (total)

Answer 27

spectrophotometric

Question 28

Sources of error for calcium (total)

Answer 28

Anticoagulants that bind divalent ions Hemolysis, icterus, lipemia, magnesium ions, gadolinium compounds, paraproteins

Question 29

Causes for increased calcium

Answer 29

Primary hyperparathyroidism (parathyroid adenoma) Malignancy/tumors renal failure endocrine disorders (hyper/hypothyroidism, acromegaly)

Question 30

Causes for decreased calcium

Answer 30

hypocalcemia hypoalbuminemia (pseudohypocalcemia) Liver, heart, renal disease proteinuria causing hypoalbuminemia hyperphosphatemia hypoparathyroidism removal/destruction of parathyroid gland

Question 31

Common methodology for calcium (ionized)

Answer 31

Liquid Polymer ISE (neutral carrier ETH 1001)

Question 32

Sources of error for calcium (ionized)

Answer 32

anticoagulants other than dry heparin collection and transportation temp fist pumping ethanol, proteins, phosphate, lactate

Question 33

Phosphorus reference range

Answer 33

0.80 - 1.45 mmol/L Crit = < 0.40 mmol/L

Question 34

Common methodology for phosphorus

Answer 34

spectrophotometric

Question 35

Sources of error for phosphorus

Answer 35

delay in separation of serum/plasma from cells Hemolysis, icterus, lipemia EDTA, citrate, and oxalate monoclonal free light chains

Question 36

Causes for increased phosphorus

Answer 36

hypoparathyroidism pseudohypoparathyroidism acromegaly

Question 37

Causes for decreased phosphorus

Answer 37

respiratory alkalosis, glucose administration, insulin renal wasting hyperparathyroidism, Fanconi's Syndrome, inherited rickets, osteomalacia

Question 38

Magnesium reference range

Answer 38

0.70 - 1.00 mmol/L Crit = < 0.40 or > 1.90 mmol/L

Question 39

Common methodology for magnesium

Answer 39

spectrophotometric

Question 40

sources of error for magnesium

Answer 40

Hemolysis, icterus, lipemia EDTA, potassium oxalate, sodium citrate

Question 41

Causes for increased magnesium

Answer 41

hospital patients with renal failure, and is the result of excessive administration of antacids, enemas, and fluids containing magnesium

Question 42

Causes for decreased magnesium

Answer 42

observed in hospital patients, caused by diarrhea, bowel surgery, vomiting diabetes mellitus, diuretics, antibiotics, alcoholism

Question 43

Cushing's Syndrome

Answer 43

Increased cortisol (may suppress ADH) Increased plasma Na+ Decreased K+

Question 44

Conn's Syndrome

Answer 44

hypersecretion of aldosterone Increased plasma Na+ Decreased K+

Question 45

Secondary hyperaldosteronism

Answer 45

decreased blood flow to kidney Increased plasma Na+ Decreased K+

Question 46

Addison's Disease

Answer 46

decreasing cortisol and aldosterone, increasing ATCH Decreased plasma Na+ Increase K+

Question 47

Syndrome of Inappropriate Antidiuretic Hormone (SIADH)

Answer 47

overproduction of ADH Decreased plasma Na+, osmolality Increased urine osmolality

Question 48

Rhabdomyolysis

Answer 48

breakdown of skeletal muscle after trauma myoglobinuria hyperkalemia (increased K+)

Question 49

Fanconi's Syndrome

Answer 49

renal tubular defects hypophosphatemia (decreased phosphate)

Question 50

Rickets and Osteomalacia

Answer 50

metabolic bone disorders hypophosphatemia (decreased phosphate)