Hypokalemia

Study guide:

Potassium is one of the main Intracellular cation and it’s very important for cardiac and neuromuscular functions. It’s tightly regulated by Kidney (90% of excretion), GIT (10% of excretion), and Transcellular shifts (between intracellular and extracellular, e.g. Insulin and catecholamine stimulate Na-K/ATPase).

Definition:

  • Decrease in Potassium levels below 3.5 mEq/ml.

  • It’s normal blood levels 3.5-5.0 mEq/ml.

Epidemiology:

  • 20% of Hospitalized patients have hypokalemia.

  • 1% of general population (healthy adults).

Risk factors:

  • Patient having medical conditions like: AIDS, Anorexia nervosa, and Alcoholism are at higher risk.

  • Also patient taking drugs like: Digoxin, Diuretics.

Causes:

Pathophysiology

 

 

Signs and Symptoms:

  • Depends on the severity of the hypokalemia:

    • In mild to moderate: patient might be asymptomatic of complains of fatigue, myalgia, numbness, muscle weakness (presented by dyspnea, abdominal distention, constipation and exercise intolerance), polyuria, polydipsia, depression, and confusion.

    • In sever hypokalemia (<2.5 mEq/ml): rhabdomyolysis, palpitation, cardiac arrhythmia, respiratory depression, and hyporeflexia.

  • ECG Finding:

    • Prolonged Q-T interval.

    • Flattening of T wave

    • U wave.

    • ST segment depression.

Diagnostic evaluation:

Treatment:

  • Treat the underlying cause or stop medication that causing or aggravating the problem.

  • If the cause is one of the redistribution problems, treating cause would be enough sometimes to restore normal K levels (e.g. metabolic alkalosis correction).

  • Oral KCl is better to use if the patient can tolerate PO (10 mEq/ml of KCL elevate K levels by 0.1 mEq/ml). retest K levels after starting treatment.

  • IV KCL in saline (dextrose may aggravate hypokalemia) in severe cases:

  • Infusion must be slow and not more than 10 mEq/hour in peripheral IV line or more than 20 mEq/hour in central line.

  • Check K levels and cardiac rhythm regularly.

  • If Hypomagnesaemia is the cause, Mg must be corrected.

Complications:

  • Cardiac arrhythmia or arrest.

  • Nephrogenic diabetes insipidus.

  • Muscular paralysis.

  • Respiratory depression.

  • Rhabdomyolysis.

  • Dehydration.

Reference:

  1. Agabegi, Steven, and Elizabeth Agabegi. Step-Up To Medicine. 3rd ed. Philadelphia: Lippincott Williams & Wilkins, 2013. Print.

  2. Hall, Justin, and Azra Premji. Toronto Notes 2015. Print.

  3. Huang, C.-L., and E. Kuo. "Mechanism Of Hypokalemia In Magnesium Deficiency". Journal of the American Society of Nephrology 18.10 (2007): 2649-2652. Web. 12 Mar. 2016.

  4. nurko, sual. "Hypokalemia And Hyperkalemia". Clevelandclinicmeded.com. N.p., 2016. Web. 12 Mar. 2016.

  5. Best Practice - English". Us.bp.api.bmj.com. N.p., 2016. Web. 12 Mar. 2016.

  6. "Osmotic Diuresis | Rcemlearning". Rcemlearning.co.uk. N.p., 2016. Web. 12 Mar. 2016.

  7. Walker, Brian R et al. Davidson's Principles And Practice Of Medicine. Print.

 

Written by:            Eman Bablghaith

 

Reviewed by:        Basma Abdulkader

                              Abdullah Al-Beshri

Web Publisher:    Seba AlMutairi