Electrolytes: Potassium Flashcards
___________
-AKA _____
-Major_______________
-Important analyte in terms of an abnormality being immediately life threatening
-only ___% of the body’s total potassium circulates in the plasma
-involved in the proper transmission of the nerve impulses
-important for contraction of the heart, abnormal levels can lead to altered ______________________ patterns
-Functions:
*_____
*_____
*_____
*_____
-Reference value: ________
-Threshold critical value:
*__________ (hyperkalemia)
*__________ (hypokalemia)
Potassium
Kalium
Intracellular cation
2%
ECG
-Functions:
*heart contraction
*neuromuscular excitability
*ICF volume regulation
*hydrogen concentration
3.5-5.2 mmol/L
6.5 mmol/L (hyperkalemia)
2.5 mmol/L (hypokalemia)
Hyperkalemia
-almost always to due to ______________________
-3 major mechanisms of diminished renal potassium excretion:
*___________
*___________
*___________
-elevations in serum potassium directly stimulate the__________ to release __________
1.Decreased renal excretion
a.___
b.___
c.___
2.Extracellular shift
a.___
b.___
c.___
d.___
e.___
3.Increased intake
-__________
4.Use of immunosuppressive drugs
-_______ and _______
*Effects of Hyperkalemia to Cardiac Muscles
-Decreases the _____ (____) of the cells
-Severe hyperkalemia –> lack of muscle excitability (______)
*Hyperkalemic drugs – ___, ___, _____, _____, and ____________.
impaired renal excretion
*Reduced aldosterone (aldosterone responsiveness)
*Renal failure
*Reduced distal delivery of sodium
adrenal cortex to release aldosterone
1.Decreased renal excretion
a. Acute or chronic renal failure
b. Severe dehydration
c. Addison’s disease
- Extracellular shift
a. Acidosis
b. Muscle/cellular injury
c. Chemotherapy
d. Vigorous exercise
e. Digitalis intoxication - Increased intake
-oral or IV infusion - Use of immunosuppressive drugs
-tacrolimus and cyclosporine
Effects of Hyperkalemia to Cardiac Muscles
-RMP - resting membrane potential
-8mmol/L
*captopril, spironolactone, digoxin, cyclosporine, and heparin therapy.
Pseudohyperkalemia
-_____________ and _____________ can cause potassium release from platelets and WBCs during blood clotting
-High blast counts in _____________
-Serum and plasma potassium must be obtained ___________
-_______________________ - after centrifugation, serum layer, will not only develop above the gel layer but also at the bottom. During recentrifugation, serum layer at the bottom of gel will move upwards causing pseudohyperkalemia
-causes: (8)
Thrombocytosis and severe leukocytosis
acute/accelerated leukemias
simultaneously
Recentrifugation of SST
- Sample hemolysis
- Thrombocytosis
- Prolonged tourniquet application
- Fist clenching
- Blood stored in ice
- IV fluid
- High blast counts in acute/accelerated leukemias
- Recentrifugation of SST
Hypokalemia
-_____________ - mild hypokalemia
-_____________ - leads to hypokalemia, promotes urinary loss of potassium
-____________________ - most common cause
-_____________________ - increased activity of aldosterone or other mineral or corticoids
-_____________ - leads to lower urine anion gap, most common cause of extrarenal loss of potassium, direct potassium loss in the stool
-_____________ - hypokalemia is result of potassium loss in the urine, causes metabolic alkalosis and the subsequent renal excretion of bicarbonate results to renal potassium wasting.
- Gastrointestinal loss
a._____
b._____
c._____
d._____ - Renal loss
a._____
b._____
c._____
d._____
e._____
f._____
g._____
h._____ - _________________- alkalosis and insulin overdose
*Causes of Hypokalemia to Cardiac Muscles
-Decreases __________ by increasing ____ -> arrythmia and paralysis
-Heart may experience ____________________in either hyperkalemia or hypokalemia
-3-3.4 mmol/L
-Hypomagnesia
-Impaired renal function or renal loss
-Increased renal wasting of potassium
-Diarrhea
-Vomiting
- Gastrointestinal loss
a. Gastric suction and laxative abuse
b. Intestinal tumor and malabsorption
c. Cancer and radio therapy
d. Vomiting and diarrhea - Renal loss
a. Diuretics use (thiazides)
b. Hyperaldosteronism
c. Cushing syndrome
d. Leukemia
e. Bartter’s syndrome
f. Gitelman’s syndrome
g. Liddle’s syndrome
h. Malignant hypertension - Intracellular shift
*Causes of Hypokalemia to Cardiac Muscles
oDecreases cell excitability by increasing RMP
ocessation of contraction
Methodologies
1.__________________________
-_________ or ______ as internal standard
-potassium produces a _____ color when exposed to flame
-emits light at _______ nm
-dilute sample with _________________________ (1:100 or 1:200/ 1:100-200) first to prevent interferences, atomizer plugging, and to acquire increased sensitivity
2. ____________________________
3. _______________________
-use __________ membrane
4. Colorimetry (________ and ___________)
Flame Emission Photometry
lithium or cesium
violet
768
high purity water
Atomic absorption spectrophotometry
Ion-selective electrode
valinomycin
Lockhead and Purcell
Pseudohypokalemia
-__________- cause false decrease of potassium levels as potassium is taken up by WBCs if sample is stored at _____
leukocytosis
RT
Differential Diagnosis of Hyperkalemia
1. Rule out ______________________
2. Differentiate among the three major causes of hyperkalemia
-three major causes of hyperkalemia:
___________________________ - to distinguish, measure 24-hour urine
___________________________
___________________________
pseudohyperkalemia
increased potassium intake
shift of potassium from cells
impaired renal excretion
Differential Diagnosis of Chronic Hyperkalemia
1. Measure plasma ____________, plasma _____________, and urinary excretion of _________ and __________
renin activity
aldosterone
urinary excretion of sodium and potassium
Differential diagnosis of Hypokalemia
1. Measure urinary excretion of potassium.
-if urinary potassium excretion is low (__________ or ___________ of creatinine), cause is low intake, extrarenal loss, or intracellular shift
-if urinary potassium is normal or increased (_________ or ____________ of creatinine), cause is renal loss
2. Once renal cause is suspected - measure __________ and _______________
<20 mEq/day or <0.01 mEq/mg of creatinine - cause is low intake, extrarenal loss, or intracellular shift
>30 mEq/day or 0.02 mEq/mg of creatinine - cause is renal loss
plasma renin activity and plasma aldosterone.
Values to Remember
Reference Values
* Serum: _______________
* 24-hour urine: ____________
Conversion factor
* mEq/L to mmol/L = ____
Serum: 3.4 to 5.0 mmol/L
24-hour urine: 25 to 125 mmol/day
mEq/L to mmol/L = 1.0
