Hypokalemia , also spelled hypokalaemia , is a low potassium (K ) level in blood serum. Normal potassium levels are between 3.5 and 5.0 mmol/L (3.5 and 5.0 mEq/L) with levels below 3.5 mmol/L defined as hypokalemia. A rather low level usually does not cause symptoms. Symptoms may include fatigue, leg cramps, weakness, and constipation. This increases the risk of abnormal heart rhythms, which are often too slow, and can lead to heart attacks.
The causes of hypokalemia include diarrhea, drugs such as furosemide and steroids, dialysis, diabetes insipidus, hyperaldosteronism, hypomagnesemia, and insufficient intake in food. This is quite severe when levels are less than 2.5 mmol/L. Low levels can also be detected on the electrocardiogram (EKG). Hyperkalemia refers to a high level of potassium in blood serum.
The rate at which potassium should be replaced depends on whether there are symptoms or ECG changes. A slightly low level can be managed with changes in the diet. Potassium supplements can be either drunk or intravenously. If given intravenously, generally less than 20 mmol is administered over an hour. High concentration solutions (& gt; 40 mmol/L) should be given in the center line if possible. Magnesium replacement may also be required.
Hypokalemia is one of the most common water-electrolyte imbalances. It affects about 20% of people who are hospitalized. The word "hypokalemia" comes from hypo - means "below"; potassium which means potassium, and -emia means "blood condition".
Video Hypokalemia
Signs and symptoms
Mild hypokalemia is often asymptomatic, although it can lead to an increase in blood pressure, and can lead to the development of abnormal heart rhythms. Severe hypokalemia, with a potassium serum concentration of 2.5-3 meq/l (Nl: 3.5-5.0 meq/l), can cause muscle weakness, myalgia, tremor, and muscle cramps (due to impaired skeletal muscle function) and constipation (from impaired smooth muscle function). With more severe hypokalemia, flaccid paralysis and hyporeflexia may occur. Reports of rhabdomyolysis occur with deep hypokalemia with potassium serum levels of less than 2 meq/l. Respiratory depression due to severe disorders of skeletal muscle function is found in many patients.
Maps Hypokalemia
Cause
Hypokalemia can be produced from one or more of these medical conditions:
Insufficient potassium intake
Perhaps the most obvious cause is insufficient consumption of potassium (ie a low potassium diet) or starvation. However, without the loss of excessive potassium from the body, this is a rare cause of hypokalemia. Usually seen only in patients with anorexia nervosa and people with ketogenic diets.
Gastrointestinal or skin loss
About 98% of the body's potassium is found inside the cell, with the remainder in extracellular fluids including blood. This concentration gradient is maintained mainly by the Na /K pump.
Potassium is very important for many body functions, including muscle and nerve activity. The electrochemical gradient of potassium between the intracellular and extracellular spaces is essential for nerve function; in particular, potassium is required to convert the cell membrane into a resting state after the potential action has passed. Lower potassium levels in the extracellular space lead to hyperpolarization of resting membrane potential. This hyperpolarization is caused by the effect of potassium gradient that changes on the resting membrane potential as defined by the Goldman equation. As a result, a larger than normal stimulus is required for membrane depolarization to initiate the action potential.
At heart, hypokalemia causes arrhythmias because of a more complete recovery of sodium channel inactivation, thus triggering lesser action possibilities. In addition, reduced extracellular potassium (paradoxically) inhibits the current potassium subliminal activity and delay ventricular repolarization. This delayed repolarization may promote reentrant arrhythmias.
Diagnosis
Blood
Normal potassium levels are between 3.5 and 5.0 mmol/L with levels below 3.5 mmol/L (less than 3.5 mEq/L) defined as hypokalemia.
Electrocardiogram
The earliest electrocardiographical (EKG) findings associated with hypokalemia are a decrease in T wave height. Then, ST depression and T inversion occur as further reducing serum potassium. Due to the repolarization of the fiber length of Purkinje ventricles, prominent U waves occur (usually seen in leads V2 and V3), often rising above the T wave and therefore result in a prolonged QT interval when the potassium serum is reduced to below 3 mEq/L.
Amount
The amount of deficit of potassium can be calculated using the following formula: K deficit (in mmol) = ( K lower limit normal - K measured ) ÃÆ'â € "weight (kg) ÃÆ'â €" 0.4
Meanwhile, the daily requirement of the potassium body is calculated by multiplying 1 mmol to weight in kilograms. Adding a potassium deficit and daily potassium requirement will give the total amount of potassium that needs to be corrected in mmol. Dividing mmol by 13.4 will give potassium in grams.
Treatment
Treatments include treating the cause, such as improving diet, treating diarrhea, or stopping offending drugs. People without significant sources of potassium loss and who show no symptoms of hypokalemia may not require treatment.
Mild hypokalemia (& gt; 3.0 meq/l) may be treated with oral potassium chloride supplements (Chlor-Con, Sando-K, Slow-K). Since this is often part of a poor nutritional intake, foods containing potassium can be recommended, such as green vegetables, avocados, tomatoes, coconut water, citrus fruits, oranges, or bananas. Dietary and pharmaceutical supplements are used for people taking diuretic medications.
Severe hypokalemia (& lt; 3.0 meq/l) may require intravenous supplementation. Typically, a saline solution is used, with 20-40 meq/l KCl per liter for 3-4 hours. Giving potasium IV at a faster rate (20-25 meq/h) may cause ventricular tachycardia and requires intensive monitoring. The generally safe level is 10 meq/hour. Even in severe hypokalemia, oral supplementation is preferably given its safety profile. Continuous release formulations should be avoided in acute settings.
A difficult or resistant case of hypokalemia may be able to receive potassium-sparing diuretics, such as amiloride, triamterene, spironolactone, or eplerenone. Concomitant hypergagnesemia will inhibit the replacement of potassium, because magnesium is a cofactor for potassium intake.
When replacing intravenous potassium, infusion by the midline is encouraged to avoid frequent occurrence of burning sensation in the peripheral infusion site, or rarely damage to the blood vessels. When peripheral infusions are required, combustion can be reduced by diluting potassium in greater amounts of liquid, or mixing 3 ml of 1% lidocaine to every 10 meq KCl per 50 ml of liquid. The practice of adding lidocaine, however, raises the possibility of serious medical errors.
See also
- Bartter's Syndrome
- Gitelman's Syndrome
- Hypokalemic acidosis
- Potassium deficiency (plant disturbance)
- Superior mesenteric artery syndrome
References
Further reading
- J, Firth (2010). "Chapter: Disturbance of potassium homeostasis". In David A. Warrell, Timothy M. Cox, John D. FirthÃ,; sub-editor, Graham S. Ogg. Oxford medical textbook (5th ed.). Oxford: Oxford University Press. doi: 10.1093/med/9780199204854.003.210202_update_001. ISBNÃ, 0199204853. < span> CS1 maint: Using parameter editor (link)
- Greenlee, M; Wingo, CS; McDonough, AA; Youn, JH; Kone, BC (May 5, 2009). "Narrative review: a concept developed in potassium and hypokalemia homeostasis" (PDF) . Annals of Internal Medicine . 150 (9): 619-25. doi: 10.7326/0003-4819-150-9-200905050-00008. PMCÃ, 4944758 . PMID 19414841.
External links
- MayoClinic.com: Low potassium (hypokalemia)
- MedicineNet.com: Low Potassium (Hypokalemia)
- eMedicineHealth.com: Low Potassium (Hypokalemia)
- Selected Food Content per Action General, sorted by nutritional content (Potassium)
- List of foods rich in potassium (U. Mass. Med.)
- National Organization for Rare Disorders: Hypokalemia
Source of the article : Wikipedia
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