Potassium Regulation and Disorders
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Questions and Answers

What is the major intracellular cation in the body?

Potassium (K+)

What are the functions of potassium in the body?

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

What is the normal range of potassium concentration in plasma?

  • 2.0 - 3.0 mmol/L
  • 5.5 - 6.0 mmol/L
  • 3.5 - 5.1 mmol/L (correct)
  • 6.0 - 7.0 mmol/L

    • What is hypokalemia?

    <p>A plasma K+ concentration below the lower limit of the reference range.</p> Signup and view all the answers

    What are common symptoms of hypokalemia?

    <p>Weakness, fatigue, and constipation.</p> Signup and view all the answers

    What is hyperkalemia?

    <p>A plasma K+ concentration higher than 5.1 mmol/L.</p> Signup and view all the answers

    Which method is the current method of choice for potassium determination?

    <p>Ion-selective electrode (ISE)</p> Signup and view all the answers

    Hemolysis can falsely elevate potassium levels.

    <p>True</p> Signup and view all the answers

    What is pseudohyperkalemia?

    <p>A false increase in potassium levels.</p> Signup and view all the answers

    The ______ is the anticoagulant of choice for potassium analysis.

    <p>heparin</p> Signup and view all the answers

    What is the reference range of potassium concentration in the reference range of sodium?

    <p>The reference range for potassium is the same as that of sodium.</p> Signup and view all the answers

    Study Notes

    Potassium in the Body

    • Plays a crucial role in regulating neuromuscular excitability, heart contraction, intracellular fluid volume, and hydrogen ion concentration.
    • Primarily found inside cells, with a concentration 20 times higher than outside.

    Potassium Balance Regulation

    • Renal function is key in maintaining potassium balance.
    • Proximal tubules reabsorb almost all potassium initially.

    Hypokalemia

    • Plasma potassium concentration below the lower limit of the reference range (3.5 mmol/L).
    • Can occur due to potassium loss through the gastrointestinal tract or urine, or increased cellular uptake.
    • Symptoms like weakness, fatigue, and constipation are common when potassium levels fall below 3 mmol/L.
    • Severe hypokalemia can lead to muscle weakness or paralysis, potentially affecting breathing.

    Hyperkalemia

    • Plasma potassium concentration above the upper limit of the reference range (5.1 mmol/L).
    • Often associated with underlying conditions such as renal insufficiency, diabetes mellitus, or metabolic acidosis.
    • Therapeutic potassium administration is a common cause in hospitalized patients.

    Potassium Determination

    • Samples for analysis include serum, plasma, and urine.
    • Hemolysis must be avoided due to the high potassium content of erythrocytes.
    • Heparin is the preferred anticoagulant.
    • Urine specimens should be collected over 24 hours to minimize diurnal variation influence.

    Potassium Testing Methodology

    • Ion-selective electrodes (ISE) are the current method of choice.
    • Valinomycin membranes are used in ISE to selectively bind potassium, leading to an impedance change that correlates with potassium concentration.
    • KCl serves as the inner electrolyte solution.

    Potassium Reference Range

    • Similar to sodium's reference range.
    • Flame emission color is violet/purple.

    Sources of Error

    • Pseudohyperkalemia (false increase in potassium) is the primary source of error.
    • Hemolysis, prolonged tourniquet application, excessive clenching, storing blood on ice, and release of potassium from cells after blood draw are other sources.

    Key Considerations For Accuracy

    • Room temperature is necessary for accurate potassium analysis
    • Heparin is preferred but avoid using if the platelet count is above 600,000 as it can interfere with potassium measurements.

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    Related Documents

    Potassium PDF - Biology

    Description

    Explore the vital roles of potassium in the body, including its effects on neuromuscular excitability and heart function. Understand the processes maintaining potassium balance and the implications of hypokalemia and hyperkalemia on health. This quiz will test your knowledge of potassium's physiological functions and disorders associated with its imbalance.

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