Hypokalemia
Encyclopedia
Hypokalemia or hypokalaemia (British English
), also hypopotassemia or hypopotassaemia (ICD-9), refers to the condition in which the concentration of potassium
(K+) in the blood is low. The prefix hypo- means "under" (contrast with hyper-, meaning "over"); kal- refers to kalium, the Neo-Latin for potassium, and -emia means "condition of the blood."
Normal serum potassium levels are between 3.5 to 5.0 mEq/L; at least 95% of the body's potassium is found inside cells
, with the remainder in the blood. This concentration gradient is maintained principally by the Na+/K+ pump.
, and can occasionally provoke cardiac arrhythmias. Moderate hypokalemia, with serum potassium concentrations of 2.5-3 mEq/L (Nl: 3.5-5.0 mEq/L), may cause muscular weakness, myalgia
, and muscle cramps (owing to disturbed function of the skeletal muscles), and constipation (from disturbed function of smooth muscles). With more severe hypokalemia, flaccid paralysis
and hyporeflexia
may result. There are reports of rhabdomyolysis
occurring with profound hypokalemia with serum potassium levels less than 2 mEq/L. Respiratory depression from severe impairment of skeletal muscle function is found in many patients.
Some electrocardiographic (ECG) findings associated with hypokalemia include flattened or inverted T waves, a U wave
, ST depression and a wide PR interval. Due to prolonged repolarization of ventricular Purkinje fibers
, a prominent U wave occurs, that is frequently superimposed upon the T wave and therefore produces the appearance of a prolonged QT interval.
and nerve
activity. The electrochemical gradient of potassium between the intracellular and extracellular space is essential for nerve function; in particular, potassium is needed to repolarize the cell membrane
to a resting state after an action potential
has passed. Decreased potassium levels in the extracellular space will cause hyperpolarization of the resting membrane potential. This hyperpolarization
is caused by the effect of the altered potassium gradient on resting membrane potential as defined by the Goldman equation
. As a result, a greater than normal stimulus is required for depolarization of the membrane in order to initiate an action potential.
In certain conditions, this will make cells less excitable. However, in the heart, it causes myocytes to become hyperexcitable. Lower membrane potentials in the atrium may cause arrhythmias because of more complete recovery from sodium-channel inactivation, making the triggering of an action potential more likely. In addition, the reduced extracellular potassium (paradoxically) inhibits the activity of the IKr potassium current and delays ventricular repolarization. This delayed repolarization may promote reentrant arrythmias.
or stopping an offending medication. Patients without a significant source of potassium loss and who show no symptoms of hypokalemia may not require treatment.
Mild hypokalemia (>3.0 mEq/L) may be treated with oral potassium chloride supplements (Klor-Con, Sando-K, Slow-K). As this is often part of a poor nutritional intake, potassium-containing foods may be recommended, such as leafy green vegetables, tomato
es, citrus fruits, orange
s or banana
s. Both dietary and pharmaceutical supplements are used for people taking diuretic medications (see Causes, above).
Severe hypokalemia (<3.0 mEq/L) may require intravenous (IV) supplementation. Typically, a saline
solution is used, with 20-40 mEq KCl per liter over 3–4 hours. Giving IV potassium at faster rates (20-25 mEq/hr) may predispose to ventricular tachycardia
s and requires intensive monitoring. A generally safe rate is 10 mEq/hr. Even in severe hypokalemia, oral supplementation is preferred given its safety profile. Sustained release formulations should be avoided in acute settings.
Difficult or resistant cases of hypokalemia may be amenable to a potassium-sparing diuretic
, such as amiloride
, triamterene, or spironolactone
or eplerenone
. Concomittant hypomagnesiumemia will inhibit potassium replacement as magnesium is a cofactor for potassium uptake.
When replacing potassium intravenously, infusion via a central line
is encouraged to avoid the frequent occurrence of a burning sensation at the site of a peripheral IV, or the rare occurrence of damage to the vein. When peripheral infusions are necessary, the burning can be reduced by diluting the potassium in larger amounts of IV fluid, or mixing 3 ml of 1% lidocaine to each 10 meq of KCl per 50 ml of IV fluid. The practice of adding lidocaine, however, raises the likelihood of serious medical errors.
has been described in Burmese kittens, which appears to be related to an autosomal recessive mutation. Although these kittens are not hypokalemic between episodes, regular supplementation of [KCl] seems effective.
British English
British English, or English , is the broad term used to distinguish the forms of the English language used in the United Kingdom from forms used elsewhere...
), also hypopotassemia or hypopotassaemia (ICD-9), refers to the condition in which the concentration of potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
(K+) in the blood is low. The prefix hypo- means "under" (contrast with hyper-, meaning "over"); kal- refers to kalium, the Neo-Latin for potassium, and -emia means "condition of the blood."
Normal serum potassium levels are between 3.5 to 5.0 mEq/L; at least 95% of the body's potassium is found inside cells
Intracellular
Not to be confused with intercellular, meaning "between cells".In cell biology, molecular biology and related fields, the word intracellular means "inside the cell".It is used in contrast to extracellular...
, with the remainder in the blood. This concentration gradient is maintained principally by the Na+/K+ pump.
Signs and symptoms
Mild hypokalemia is often without symptoms, although it may cause a small elevation of blood pressureBlood pressure
Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...
, and can occasionally provoke cardiac arrhythmias. Moderate hypokalemia, with serum potassium concentrations of 2.5-3 mEq/L (Nl: 3.5-5.0 mEq/L), may cause muscular weakness, myalgia
Myalgia
Myalgia means "muscle pain" and is a symptom of many diseases and disorders. The most common causes are the overuse or over-stretching of a muscle or group of muscles. Myalgia without a traumatic history is often due to viral infections...
, and muscle cramps (owing to disturbed function of the skeletal muscles), and constipation (from disturbed function of smooth muscles). With more severe hypokalemia, flaccid paralysis
Flaccid paralysis
Flaccid paralysis is a clinical manifestation characterized by weakness or paralysis and reduced muscle tone without other obvious cause .-Polio:...
and hyporeflexia
Hyporeflexia
Hyporeflexia is the condition of below normal or absent reflexes. It can be tested for by using a reflex hammer. It is the opposite of hyperreflexia....
may result. There are reports of rhabdomyolysis
Rhabdomyolysis
Rhabdomyolysis is a condition in which damaged skeletal muscle tissue breaks down rapidly. Breakdown products of damaged muscle cells are released into the bloodstream; some of these, such as the protein myoglobin, are harmful to the kidneys and may lead to kidney failure...
occurring with profound hypokalemia with serum potassium levels less than 2 mEq/L. Respiratory depression from severe impairment of skeletal muscle function is found in many patients.
Some electrocardiographic (ECG) findings associated with hypokalemia include flattened or inverted T waves, a U wave
U wave
The U wave is a wave on an electrocardiogram that is not always seen. It is typically small, and, by definition, follows the T wave. U waves are thought to represent repolarization of the papillary muscles or Purkinje fibers.-Interpretation:...
, ST depression and a wide PR interval. Due to prolonged repolarization of ventricular Purkinje fibers
Purkinje fibers
For the nervous cells, see Purkinje cellPurkinje fibers are located in the inner ventricular walls of the heart, just beneath the endocardium...
, a prominent U wave occurs, that is frequently superimposed upon the T wave and therefore produces the appearance of a prolonged QT interval.
Inadequate potassium intake
- Perhaps the most obvious cause is insufficient consumptionEatingEating is the ingestion of food to provide for all organisms their nutritional needs, particularly for energy and growth. Animals and other heterotrophs must eat in order to survive: carnivores eat other animals, herbivores eat plants, omnivores consume a mixture of both plant and animal matter,...
of potassium (that is, a low-potassium diet) or starvation. However, without excessive potassium loss from the body, this is a rare cause of hypokalemia.
Gastrointestinal/integument loss
- A more common cause is excessive loss of potassium, often associated with heavy fluid losses that "flush" potassium out of the body. Typically, this is a consequence of diarrheaDiarrheaDiarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
, excessive perspiration, or losses associated with surgical procedures. Vomiting can also cause hypokalemia, although not much potassium is lost from the vomitus. Rather, there are heavy urinary losses of K+ in the setting of post-emetic bicarbonaturia that force urinary potassium excretion (see Alkalosis below). Other GI causes include pancreatic fistulae and the presence of adenoma.
Urinary loss
- Certain medications can cause excess potassium loss in the urine. Diuretics, including thiazide diuretics (e.g. hydrochlorothiazideHydrochlorothiazideHydrochlorothiazide, abbreviated HCTZ, HCT, or HZT, is a first-line diuretic drug of the thiazide class that acts by inhibiting the kidneys' ability to retain water. This reduces the volume of the blood, decreasing blood return to the heart and thus cardiac output and, by other mechanisms, is...
) and loop diureticLoop diureticLoop diuretics are diuretics that act on the ascending loop of Henle in the kidney. They are primarily used in medicine to treat hypertension and edema often due to congestive heart failure or renal insufficiency...
s (e.g. furosemideFurosemideFurosemide or frusemide is a loop diuretic used in the treatment of congestive heart failure and edema. It is most commonly marketed by Sanofi-Aventis under the brand name Lasix...
) are a common cause of hypokalemia. Other medications such as the antifungal, amphotericin BAmphotericin BAmphotericin B is a polyene antifungal drug, often used intravenously for systemic fungal infections...
, or the cancer drug, cisplatinCisplatinCisplatin, cisplatinum, or cis-diamminedichloroplatinum is a chemotherapy drug. It is used to treat various types of cancers, including sarcomas, some carcinomas , lymphomas, and germ cell tumors...
, can also cause long-term hypokalemia. - A special case of potassium loss occurs with diabetic ketoacidosis. In addition to urinary losses from polyuriaPolyuriaPolyuria is a condition usually defined as excessive or abnormally large production or passage of urine . Frequent urination is sometimes included by definition, but is nonetheless usually an accompanying symptom...
and volume contraction, there is also obligate loss of potassium from kidney tubules as a cationic partner to the negatively charged ketoneKetoneIn organic chemistry, a ketone is an organic compound with the structure RCR', where R and R' can be a variety of atoms and groups of atoms. It features a carbonyl group bonded to two other carbon atoms. Many ketones are known and many are of great importance in industry and in biology...
, β-hydroxybutyrate. - HypomagnesemiaHypomagnesemiaHypomagnesemia is an electrolyte disturbance in which there is an abnormally low level of magnesium in the blood. Usually a serum level less than 0.7 mmol/L is used as reference. The prefix hypo- means low . The middle 'magnes' refers to magnesium...
can cause hypokalemia. MagnesiumMagnesiumMagnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
is required for adequate processing of potassium. This may become evident when hypokalemia persists despite potassium supplementation. Other electrolyte abnormalities may also be present. - AlkalosisAlkalosisAlkalosis refers to a condition reducing hydrogen ion concentration of arterial blood plasma . Generally, alkalosis is said to occur when pH of the blood exceeds 7.45. The opposite condition is acidosis .-Causes:...
can cause transient hypokalemia by two mechanisms. First, the alkalosis causes a shift of potassium from the plasmaBlood plasmaBlood plasma is the straw-colored liquid component of blood in which the blood cells in whole blood are normally suspended. It makes up about 55% of the total blood volume. It is the intravascular fluid part of extracellular fluid...
and interstitial fluidInterstitial fluidInterstitial fluid is a solution that bathes and surrounds the cells of multicellular animals. It is the main component of the extracellular fluid, which also includes plasma and transcellular fluid...
s into cells; perhaps mediated by stimulation of Na+-H+ exchangeSodium-hydrogen antiporterThe sodium–hydrogen antiporter or sodium–hydrogen exchanger is a membrane protein found in many cells, and especially in those of the nephron of the kidney...
and a subsequent activation of Na+/K+-ATPase activity. Second, an acute rise of plasma HCO3-BicarbonateIn inorganic chemistry, bicarbonate is an intermediate form in the deprotonation of carbonic acid...
concentration (caused by vomiting, for example) will exceed the capacity of the renal proximal tubuleProximal tubuleThe proximal tubule is the portion of the duct system of the nephron of the kidney which leads from Bowman's capsule to the loop of Henle.-Structure and appearance:...
to reabsorb this anion, and potassium will be excreted as an obligate cation partner to the bicarbonate. Metabolic alkalosis is often present in states of volume depletion, so potassium is also lost via aldosteroneAldosteroneAldosterone is a hormone that increases the reabsorption of sodium ions and water and the release of potassium in the collecting ducts and distal convoluted tubule of the kidneys' functional unit, the nephron. This increases blood volume and, therefore, increases blood pressure. Drugs that...
-mediated mechanisms. - Disease states that lead to abnormally high aldosteroneAldosteroneAldosterone is a hormone that increases the reabsorption of sodium ions and water and the release of potassium in the collecting ducts and distal convoluted tubule of the kidneys' functional unit, the nephron. This increases blood volume and, therefore, increases blood pressure. Drugs that...
levels can cause hypertension and excessive urinary losses of potassium. These include renal artery stenosisRenal artery stenosisRenal artery stenosis is the narrowing of the renal artery, most often caused by atherosclerosis or fibromuscular dysplasia. This narrowing of the renal artery can impede blood flow to the target kidney...
and tumors (generally non-malignant) of the adrenal glands, e.g., Conn's syndromeConn's syndromePrimary aldosteronism, also known as primary hyperaldosteronism, is characterized by the overproduction of the mineralocorticoid hormone aldosterone by the adrenal glands., when not a result of excessive renin secretion. Aldosterone causes increase in sodium and water retention and potassium...
(primary hyperaldosteronism). Cushing's syndrome can also lead to hypokalaemia due to excess cortisol binding the Na+/K+ pump and acting like aldosterone. Hypertension and hypokalemia can also be seen with a deficiency of the 11-beta-hydroxysteroid dehydrogenase type 2 enzyme which allows cortisols to stimulate aldosterone receptors. This deficiency—known as apparent mineralocorticoid excess syndrome—can either be congenital or caused by consumption of glycyrrhizinGlycyrrhizinGlycyrrhizin is the main sweet-tasting compound from liquorice root. It is 30–50 times as sweet as sucrose . Pure glycyrrhizin is odorless....
, which is contained in extract of licorice, sometimes found in herbal supplements, candiesCandyCandy, specifically sugar candy, is a confection made from a concentrated solution of sugar in water, to which flavorings and colorants are added...
and chewing tobacco. - Rare hereditary defects of renal salt transporters, such as Bartter syndromeBartter syndromeBartter syndrome is a rare inherited defect in the thick ascending limb of the loop of Henle. It is characterized by low potassium levels , increased blood pH , and normal to low blood pressure. There are two types of Bartter syndrome: neonatal and classic...
or Gitelman syndromeGitelman syndromeGitelman syndrome is a rare inherited defect in the distal convoluted tubule of the kidneys. It causes the kidneys to pass sodium, magnesium, chloride, and potassium into the urine, rather than allowing it to be resorbed into the bloodstream....
, can cause hypokalemia, in a manner similar to that of diuretics. As opposed to disease states of primary excesses of aldosterone, blood pressure is either normal or low in Bartter's or Gitelman's.
Distribution away from ECF
- In addition to alkalosis, other factors can cause transient shifting of potassium into cells, presumably by stimulation of the Na-K-ATPase. These hormones and medications include insulinInsulinInsulin is a hormone central to regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle....
, epinephrineEpinephrineEpinephrine is a hormone and a neurotransmitter. It increases heart rate, constricts blood vessels, dilates air passages and participates in the fight-or-flight response of the sympathetic nervous system. In chemical terms, adrenaline is one of a group of monoamines called the catecholamines...
, and other beta agonistsBeta-adrenergic agonistBeta-adrenergic agonists are adrenergic agonists which act upon the beta receptors.-β1 agonists:β1 agonists: stimulates adenylyl cyclase activity; opening of calcium channel....
(e.g. salbutamolSalbutamolSalbutamol or albuterol is a short-acting β2-adrenergic receptor agonist used for the relief of bronchospasm in conditions such as asthma and chronic obstructive pulmonary disease. It is marketed as Ventolin among other brand names....
or salmeterolSalmeterolSalmeterol is a long-acting beta2-adrenergic receptor agonist drug that is currently prescribed for the treatment of asthma and chronic obstructive pulmonary disease. It is currently available as a dry powder inhaler that releases a powdered form of the drug...
), and xanthines (e.g. TheophyllineTheophyllineTheophylline, also known as dimethylxanthine, is a methylxanthine drug used in therapy for respiratory diseases such as COPD and asthma under a variety of brand names. Because of its numerous side-effects, the drug is now rarely administered for clinical use. As a member of the xanthine family, it...
).
- Rare hereditary defects of muscular ion channels and transporters that cause hypokalemic periodic paralysisHypokalemic periodic paralysisHypokalemic periodic paralysis is a rare channelopathy characterized by muscle weakness or paralysis with a matching fall in potassium levels in the blood...
can precipitate occasional attacks of severe hypokalemia and muscle weakness. These defects cause a heightened sensitivity to the normal changes in potassium produced by catechols and/or insulinInsulinInsulin is a hormone central to regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle....
and/or thyroid hormoneThyroid hormoneThe thyroid hormones, thyroxine and triiodothyronine , are tyrosine-based hormones produced by the thyroid gland primarily responsible for regulation of metabolism. An important component in the synthesis of thyroid hormones is iodine. The major form of thyroid hormone in the blood is thyroxine ,...
, which lead to movement of potassium from the extracellular fluid into the muscle cells.
Other/ungrouped
- There have been a handful of published reports describing individuals with severe hypokalemia related to chronic extreme consumption (4-10 L/day) of colaColaCola is a carbonated beverage that was typically flavored by the kola nut as well as vanilla and other flavorings, however, some colas are now flavored artificially. It became popular worldwide after druggist John Pemberton invented Coca-Cola in 1886...
s. The hypokalemia is thought to be from the combination of the diureticDiureticA diuretic provides a means of forced diuresis which elevates the rate of urination. There are several categories of diuretics. All diuretics increase the excretion of water from bodies, although each class does so in a distinct way.- Medical uses :...
effect of caffeineCaffeineCaffeine is a bitter, white crystalline xanthine alkaloid that acts as a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants...
and copious fluid intake, although it may also be related to diarrheaDiarrheaDiarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
caused by heavy fructoseFructoseFructose, or fruit sugar, is a simple monosaccharide found in many plants. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbed directly into the bloodstream during digestion. Fructose was discovered by French chemist Augustin-Pierre Dubrunfaut in 1847...
ingestion. A physiological response to HypercapniaHypercapniaHypercapnia or hypercapnea , also known as hypercarbia, is a condition where there is too much carbon dioxide in the blood...
, blood potassium (as well as calcium) helps offset AcidosisAcidosisAcidosis is an increased acidity in the blood and other body tissue . If not further qualified, it usually refers to acidity of the blood plasma....
, which is consistent with chronic, extreme consumption of carbonated beverages.
Pseudohypokalemia
- Pseudohypokalemia is a decrease in the amount of potassium that occurs due to excessive uptake of potassium by metabolically active cells after blood has been drawn. It is a laboratory artifact that may occur when blood samples remain in warm conditions for several hours before processing.
Pathophysiology
Potassium is essential for many body functions, including muscleMuscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
and nerve
Nerve
A peripheral nerve, or simply nerve, is an enclosed, cable-like bundle of peripheral axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons. Nerves are found only in the peripheral nervous system...
activity. The electrochemical gradient of potassium between the intracellular and extracellular space is essential for nerve function; in particular, potassium is needed to repolarize the cell membrane
Cell membrane
The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...
to a resting state after an action potential
Action potential
In physiology, an action potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory. Action potentials occur in several types of animal cells, called excitable cells, which include neurons, muscle cells, and...
has passed. Decreased potassium levels in the extracellular space will cause hyperpolarization of the resting membrane potential. This hyperpolarization
Hyperpolarization (biology)
Hyperpolarization is a change in a cell's membrane potential that makes it more negative. It is the opposite of a depolarization.Hyperpolarization is often caused by efflux of K+ through K+ channels, or influx of Cl– through Cl– channels. On the other hand, influx of cations, e.g...
is caused by the effect of the altered potassium gradient on resting membrane potential as defined by the Goldman equation
Goldman equation
The Goldman–Hodgkin–Katz voltage equation, more commonly known as the Goldman equation is used in cell membrane physiology to determine the equilibrium potential across a cell's membrane taking into account all of the ions that are permeant through that membrane.The discoverers of this are David E...
. As a result, a greater than normal stimulus is required for depolarization of the membrane in order to initiate an action potential.
In certain conditions, this will make cells less excitable. However, in the heart, it causes myocytes to become hyperexcitable. Lower membrane potentials in the atrium may cause arrhythmias because of more complete recovery from sodium-channel inactivation, making the triggering of an action potential more likely. In addition, the reduced extracellular potassium (paradoxically) inhibits the activity of the IKr potassium current and delays ventricular repolarization. This delayed repolarization may promote reentrant arrythmias.
Treatment
The most important treatment in severe hypokalemia is addressing the cause, such as improving the diet, treating diarrheaDiarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
or stopping an offending medication. Patients without a significant source of potassium loss and who show no symptoms of hypokalemia may not require treatment.
Mild hypokalemia (>3.0 mEq/L) may be treated with oral potassium chloride supplements (Klor-Con, Sando-K, Slow-K). As this is often part of a poor nutritional intake, potassium-containing foods may be recommended, such as leafy green vegetables, tomato
Tomato
The word "tomato" may refer to the plant or the edible, typically red, fruit which it bears. Originating in South America, the tomato was spread around the world following the Spanish colonization of the Americas, and its many varieties are now widely grown, often in greenhouses in cooler...
es, citrus fruits, orange
Orange (fruit)
An orange—specifically, the sweet orange—is the citrus Citrus × sinensis and its fruit. It is the most commonly grown tree fruit in the world....
s or banana
Banana
Banana is the common name for herbaceous plants of the genus Musa and for the fruit they produce. Bananas come in a variety of sizes and colors when ripe, including yellow, purple, and red....
s. Both dietary and pharmaceutical supplements are used for people taking diuretic medications (see Causes, above).
Severe hypokalemia (<3.0 mEq/L) may require intravenous (IV) supplementation. Typically, a saline
Saline (medicine)
In medicine, saline is a general term referring to a sterile solution of sodium chloride in water but is only sterile when it is to be placed intravenously, otherwise, a saline solution is a salt water solution...
solution is used, with 20-40 mEq KCl per liter over 3–4 hours. Giving IV potassium at faster rates (20-25 mEq/hr) may predispose to ventricular tachycardia
Ventricular tachycardia
Ventricular tachycardia is a tachycardia, or fast heart rhythm, that originates in one of the ventricles of the heart...
s and requires intensive monitoring. A generally safe rate is 10 mEq/hr. Even in severe hypokalemia, oral supplementation is preferred given its safety profile. Sustained release formulations should be avoided in acute settings.
Difficult or resistant cases of hypokalemia may be amenable to a potassium-sparing diuretic
Diuretic
A diuretic provides a means of forced diuresis which elevates the rate of urination. There are several categories of diuretics. All diuretics increase the excretion of water from bodies, although each class does so in a distinct way.- Medical uses :...
, such as amiloride
Amiloride
Amiloride is a potassium-sparing diuretic, first approved for use in 1967 , used in the management of hypertension and congestive heart failure. Amiloride was also tested as treatment of cystic fibrosis, but it was revealed inefficient in vivo due to it's short time of action, therefore...
, triamterene, or spironolactone
Spironolactone
Spironolactone , commonly referred to as simply spiro, is a diuretic and is used as an antiandrogen.It is a synthetic 17-lactone drug that is a renal competitive aldosterone antagonist in a class of pharmaceuticals called...
or eplerenone
Eplerenone
Eplerenone is an aldosterone antagonist used as an adjunct in the management of chronic heart failure. It is similar to the diuretic spironolactone, though it may be more specific for the mineralocorticoid receptor and is specifically marketed for reducing cardiovascular risk in patients...
. Concomittant hypomagnesiumemia will inhibit potassium replacement as magnesium is a cofactor for potassium uptake.
When replacing potassium intravenously, infusion via a central line
Central venous catheter
In medicine, a central venous catheter is a catheter placed into a large vein in the neck , chest or groin...
is encouraged to avoid the frequent occurrence of a burning sensation at the site of a peripheral IV, or the rare occurrence of damage to the vein. When peripheral infusions are necessary, the burning can be reduced by diluting the potassium in larger amounts of IV fluid, or mixing 3 ml of 1% lidocaine to each 10 meq of KCl per 50 ml of IV fluid. The practice of adding lidocaine, however, raises the likelihood of serious medical errors.
In other animals
Cats can develop hypokalemia, which may be manifested by abnormal gait and an inability to keep the head elevated. Cats respond well to dietary supplementation of potassium chloride. A feline form of hypokalemic periodic paralysisHypokalemic periodic paralysis
Hypokalemic periodic paralysis is a rare channelopathy characterized by muscle weakness or paralysis with a matching fall in potassium levels in the blood...
has been described in Burmese kittens, which appears to be related to an autosomal recessive mutation. Although these kittens are not hypokalemic between episodes, regular supplementation of [KCl] seems effective.
See also
- HyperkalemiaHyperkalemiaHyperkalemia refers to the condition in which the concentration of the electrolyte potassium in the blood is elevated...
- HypermagnesemiaHypermagnesemiaHypermagnesemia is an electrolyte disturbance in which there is an abnormally elevated level of magnesium in the blood. Usually this results in excess of magnesium in the body....
- HypernatremiaHypernatremiaHypernatremia or hypernatraemia is an electrolyte disturbance that is defined by an elevated sodium level in the blood. Hypernatremia is generally not caused by an excess of sodium, but rather by a relative deficit of free water in the body...
- HypomagnesemiaHypomagnesemiaHypomagnesemia is an electrolyte disturbance in which there is an abnormally low level of magnesium in the blood. Usually a serum level less than 0.7 mmol/L is used as reference. The prefix hypo- means low . The middle 'magnes' refers to magnesium...
- HyponatremiaHyponatremiaHyponatremia is an electrolyte disturbance in which the sodium concentration in the serum is lower than normal. In the vast majority of cases, hyponatremia occurs as a result of excess body water diluting the serum sodium and is not due to sodium deficiency. Sodium is the dominant extracellular...
- Potassium deficiency (plant disorder)
- Superior mesenteric artery syndromeSuperior mesenteric artery syndromeSuperior mesenteric artery syndrome is a very rare, life-threatening gastro-vascular disorder characterized by a compression of the third portion of the duodenum by the abdominal aorta and the overlying superior mesenteric artery...
External links
- Hypokalemia: MedlinePlus Medical Encyclopedia
- MayoClinic.com: Low potassium (hypokalemia)
- MedicineNet.com: Low Potassium (Hypokalemia)
- Medscape Reference: Hypokalemia
- Hypokalemia in Emergency Medicine - Medscape Reference
- eMedicineHealth.com: Low Potassium (Hypokalemia)
- Content of Selected Foods per Common Measure, sorted by nutrient content (Potassium)
- USDA National Nutrient Database for Standard Reference, Release 20