P2.3- POTASSIUM

Question 1

• the major intracellular cation

– regulation of neuromuscular excitability, contraction of the heart, ICF volume, and H+ concentration

Answer 1

POTASSIUM (Kalium)

Question 2

• only___% of the body’s total potassium circulates in the plasma

Answer 2

2%

Question 3

Regulation mechanisms of potassium

Answer 3

proximal tubules reabsorb K

aldosterone increases K secretion

cells uptake extra K in plasma

Question 4

Area of almost total reabsorption of K+

Answer 4

Proximal tubules

Question 5

Enzyme that induces additional
K+ secretion into the urine in exchange for Na+ in both the distal tubules and the collecting ducts.

Answer 5

Aldosterone

Question 6

is important in normalizing an acute rise in plasma K+ concentration.

Answer 6

cellular uptake of excess K+

Question 7

• 3 factors that influence the distribution of K+ in cells

Answer 7

ATPase pump is inhibited

Insulin

Catecholamines

propranolol

Question 8

Conditions that affect Na+, K+- ATPase pump

Answer 8

hypoxia, hypomagnesemia, or digoxin overdose

Question 9

Na+, K+- ATPase pump inhibition effect

Answer 9

cellular K+ loss frequently occurs

Question 10

promotes acute entry of K+ into skeletal muscle and liver by increasing Na+, K+-ATPase
activity

Answer 10

Insulin

Question 11

promote cellular entry of K+

Answer 11

Catecholamines

Question 12

impairs cellular entry of K+

Answer 12

propranolol

Question 13

3 factors that influence the distribution of K+ in ECF

Answer 13

EXERCISE
HYPEROSMOLALITY
CELLULAR BREAKDOWN

Question 14

Mild to moderate exercise causes plasma K+ to?

Answer 14

increase by 0.3-1.2 mmol/L

Question 15

Exhaustive exercise causes plasma K+ to

Answer 15

increase by 2-3 mmol/L

Question 16

Uncontrolled DM leads to hyperosmolality, in return the body tries to compensate by doing what with K+?

Answer 16

gradual depletion of K+

Question 17

CELLULAR BREAKDOWN
effect on plasma K+

Answer 17

Increased due to Releases K+ into the ECF

Question 18

Hypokalemia possible causes

Answer 18

GI or urinary loss of K+
Renal loss
Reduced dietary intake of K+
Increased cellular uptake of K+

Question 19

▪ GI or urinary loss of K+ is caused by

Answer 19

▪ vomiting, diarrhea, gastric suction, or discharge
from an intestinal fistula
▪ tumors, malabsorption, cancer therapy and large
doses of laxatives

Question 20

▪ Renal loss of K+ is caused by

Answer 20

▪ Diuretics (thiazide - most common), K+-losing
nephritis and renal tubular acidosis
▪ Hyperaldosteronism, hypomagnesemia, acute
leukemia

Question 21

• Alkalosis effect on plasma K+

Answer 21

decreases by about 0.4 mmol/L
per 0.1 unit rise in pH

Question 22

Alkalosis can be a side effect of?

Answer 22

• Insulin overdose

Question 23

Rare cause or error that causes hypokalemia

Answer 23

blood sample from a leukemic patient (high WBC count)

Question 24

Symptoms of hypokalemia
* < 3 mmol/L plasma K+

Answer 24

muscle weakness or paralysis, fatigue, constipation

Question 25

Symptoms of * Mild hypokalemia (3-4 mmol/L)

Answer 25

– Asymptomatic

Question 26

* Treatment of hypokalemia

Answer 26

– oral KCl replacement/ IV replacement – Mild hypokalemia: high intake of K+-rich foods

Question 27

Hyperkalemia (>5.1 mmol/L) possible causes

Answer 27

* underlying disorder * therapeutic K+ administration * impairment of urinary K+ excretion * cellular shift of K+ from cells into plasma * drugs

Question 28

* underlying disorders causing hyperkalemia

Answer 28

renal insufficiency, diabetes mellitus, or metabolic acidosis

Question 29

most common cause of hyperkalemia (hospitalized patients)

Answer 29

therapeutic K+ administration

Question 30

drugs that cause hyperkalemia

Answer 30

captopril, NSAIDs, spironolactone, digoxin, cyclosporine, heparin therapy

Question 31

Symptoms of hyperkalemia

Answer 31

* muscle weakness, tingling, numbness, or mental confusion by altering neuromuscular conduction * disturbs cardiac conduction

Question 32

level of hyperkalemia that may alter ECG

Answer 32

6-7 mmol/L

Question 33

Level of hyperkalemia that may cause fatal cardiac arrest

Answer 33

> 10 mmol/L

Question 34

Treatment for hyperkalemia

Answer 34

Calcium; sodium bicarbonate, glucose or insulin; diuretics or sodium polysterene sulfonate

Question 35

Collection of Samples for potassium determination possible errors

Answer 35

Uncoagulated blood Prolonged tourniquet application or excessive fist clenching Prolonged tourniquet application or excessive fist clenching Hemolysis

Question 36

cause of coagulation to Potassium determination

Answer 36

Coagulation process releases K+ from platelets - serum K+may be 0.1–0.7 mmol/L higher than plasma K+ concentrations

Question 37

most common cause of artifactual hyperkalemia

Answer 37

Hemolysis

Question 38

Slight hemolysis (approx. 50 mg/dL Hb cause to Potassium levels

Answer 38

3% increase

Question 39

- Gross hemolysis (> 500 mg/dL Hb) cause to potassium levels

Answer 39

30% increase

Question 40

Specimen used for potassium determination

Answer 40

Serum, plasma, and urine

Question 41

the anticoagulant of choice for potassium determination

Answer 41

Heparin

Question 42

What blood component is preferred for potassium determination and why

Answer 42

Plasma over serum ▪ Elevated platelet counts may cause hyperkalemia

Question 43

Type of urine specimen used for potassium determination

Answer 43

24-hour urine collection

Question 44

Methods for potassium determination

Answer 44

ISE and Colorimetry

Question 45

Membrane used for ISE determination for potassium

Answer 45

valinomycin membrane is used to selectively bind K

Question 46

is the inner electrolyte solution for ISE determination of Potassium

Answer 46

KCl

Question 47

Colorimetric method for potassium determination

Answer 47

Lockhead and PurcellR

Question 48

Reference range for Potassium

Answer 48

Serum 3.5-5.1 mmol/L Urine (24 Hour) 33-86 mmol/d