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| {{Infobox_Disease | | | __NOTOC__ |
| Name = Hypokalemia |
| | {| class="infobox" style="float:right;" |
| Image = K-TableImage.png |
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| Caption = [[Potassium]] |
| | | <figure-inline><figure-inline>[[File:Siren.gif|link=Hypokalemia resident survival guide|41x41px]]</figure-inline></figure-inline>|| <br> || <br> |
| DiseasesDB = 6445 |
| | | [[Hypokalemia resident survival guide|'''Resident'''<br>'''Survival'''<br>'''Guide''']] |
| ICD10 = {{ICD10|E|87|6|e|70}} |
| | |} |
| ICD9 = {{ICD9|276.8}} |
| | {{Hypokalemia}} |
| ICDO = |
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| OMIM = |
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| MedlinePlus = 000479 |
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| MeshID = D007008 |
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| }} | |
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| {{SI}}
| | '''For patient information on this page, click [[Hypokalemia (patient information)|here]]''' |
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| {{CMG}} | | {{CMG}}'''; Associate Editor-In-Chief:''' {{CZ}}; {{AIDA}} [[User:Aditya Govindavarjhulla|Aditya Govindavarjhulla, M.B.B.S.]] [mailto:agovi@wikidoc.org] ; '''Assistant Editor(s)-In-Chief:''' [[User:Jack Khouri|Jack Khouri]] |
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| '''Associate Editor-In-Chief:''' {{CZ}}
| | {{SK}} Hypokalaemia; potassium levels low (plasma or serum); potassium - low; low blood potassium; potassium depletion |
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| {{Editor help}}
| | ==[[Hypokalemia overview|Overview]]== |
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| ==Overview== | | ==[[Hypokalemia historical perspective|Historical Perspective]]== |
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| '''Hypokalemia''' is a potentially fatal condition in which the body fails to retain sufficient [[potassium]] to maintain health. The condition is also known as '''potassium deficiency'''. The prefix ''hypo-'' means low (contrast with ''hyper-'', meaning high). The middle ''kal'' refers to ''kalium'', which is Neo-Latin for potassium. The end portion of the word, ''-emia'', means "in the blood" (note, however, that hypokalemia is usually indicative of a ''systemic'' potassium deficit).
| | ==[[Hypokalemia pathophysiology|Pathophysiology]]== |
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| ==Causes== | | ==[[Hypokalemia causes|Causes]]== |
| Hypokalemia can result from one or more of the following [[medical]] conditions:
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| * Perhaps the most obvious cause is insufficient [[eating|consumption]] of potassium (that is, a low-potassium diet). However, without excessive potassium loss from the body, this is a rare cause of hypokalemia.
| | ==[[Hypokalemia differential diagnosis|Differentiating Hypokalemia from other Diseases]]== |
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| * A more common cause is excessive loss of potassium, often associated with excess [[water]] loss, which "flushes" potassium out of the body. Typically, this is a consequence of [[vomiting]], [[diarrhea]], or excessive [[perspiration]].
| | ==[[Hypokalemia epidemiology and demographics|Epidemiology and Demographics]]== |
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| * Certain [[medication]]s can accelerate the removal of potassium from the body; including [[thiazide diuretic]]s, such as [[hydrochlorothiazide]]; [[loop diuretic]]s, such as [[furosemide]]; as well as various [[laxative]]s. The antifungal [[amphotericin B]] has also been associated with hypokalemia.
| | ==[[Hypokalemia risk factors|Risk Factors]]== |
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| * A special case of potassium loss occurs with [[DKA|diabetic ketoacidosis]]. In addition to urinary losses from [[polyuria]] and volume contraction, there is also obligate loss of potassium from kidney tubules as a [[cationic]] partner to the negatively charged [[ketone]], β-hydroxybutyrate.
| | ==[[Hypokalemia natural history|Natural History, Complications and Prognosis]]== |
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| * [[Hypomagnesemia]] can cause hypokalemia. [[Magnesium]] is required for adequate processing of potassium. This may become evident when hypokalemia persists despite potassium supplementation. Other electrolyte abnormalities may also be present.
| | ==[[Hypokalemia Diagnosis|Diagnosis]]== |
| | [[Hypokalemia laboratory findings#Diagnostic Algorithm|Diagnostic Algorithm]] | [[Hypokalemia history and symptoms | History and Symptoms]] | [[Hypokalemia physical examination|Physical Examination]] | [[Hypokalemia laboratory findings | Laboratory Findings]] | [[Hypokalemia electrocardiogram | Electrocardiogram]] | [[Hypokalemia other diagnostic studies|Other Diagnostic Studies]] |
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| * Disease states that lead to abnormally high [[aldosterone]] levels can cause hypertension and excessive urinary losses of potassium. These include [[renal artery stenosis]] and tumors (generally non-malignant) of the [[adrenal]] glands. Hypertension and hypokalemia can also be seen with a deficiency of the 11β-hydroxylase enzyme which allows cortisols to stimulate aldosterone receptors. This deficiency can either be congenital or caused by consumption of [[glycyrrhizin]], which is contained in extract of licorice, sometimes found in [[Herbal supplements]], candies and chewing tobacco.
| | ==[[Hypokalemia treatment|Treatment]]== |
| | [[Hypokalemia medical therapy| Medical Therapy]] | [[Hypokalemia primary prevention|Primary Prevention]] | [[Hypokalemia secondary prevention|Secondary Prevention]] | [[Hypokalemia cost-effectiveness of therapy|Cost-Effectiveness of Therapy]] | [[Hypokalemia future or investigational therapies|Future or Investigational Therapies]] |
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| * Rare [[hereditary]] defects of renal salt transporters, such as [[Bartter syndrome]] or [[Gitelman syndrome]] can cause hypokalemia, in a manner similar to that of diuretics.
| | ==Case Studies== |
| | [[Hypokalemia case study one|Case #1]] |
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| * Rare [[hereditary]] defects of muscular ion channels and transporters that cause [[hypokalemic periodic paralysis]] can precipitate occasional attacks of severe hypokalemia and muscle weakness. These defects cause a heightened sensitivity to [[catechols]] and/or [[insulin]] and/or [[thyroid hormone]] that lead to sudden influx of potassium from the extracellular fluid into the muscle cells.
| | ==Related Chapters== |
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| ==Pathophysiology== | |
| Potassium is essential for many body functions, including [[muscle]] and [[nerve]] activity. Potassium is the principal [[intracellular]] [[cation]], with a concentration of about 145 mEq/L, as compared with a normal value of 3.5 - 5.0 mEq/L in [[extracellular]] fluid, including blood. More than 98% of the body's potassium is intracellular; measuring it from a blood sample is relatively insensitive, with small fluctuations in the blood corresponding to very large changes in the total bodily reservoir of potassium.
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| The electrochemical gradient of potassium between 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 (biology)|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.
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| ==Pathophysiology of Hypokalemic Heart Arrythmias==
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| Potassium is essential to the normal muscular function, in both voluntary (i.e skeletal muscle, e.g. the arms and hands) and involuntary muscle (i.e. smooth muscle in the intestines or cardiac muscle in the heart). Severe abnormalities in potassium levels can seriously disrupt [[heart|cardiac function]], even to the point of causing [[cardiac arrest]] and [[death]]. As explained above, hypokalemia makes the resting potential of potassium [E(K)] more negative. In certain conditions, this will make cells less excitable. However, in the heart, it causes myocytes to become hyperexcitable. This is due to two independent effects that may lead to aberrant cardiac conduction and subsequent arrhythmia:
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| #There are more inactivated sodium (Na) channels available to fire, and
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| #The overall potassium permeability of the ventricle is reduced (perhaps by the loss of a direct effect of extracellular potassium on some of the potassium channels), which can delay ventricular repolarization.
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| == Differential Diagnosis<ref>Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:89</ref><ref>Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:202-203</ref> ==
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| * Acute hyperventilation
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| * [[Pancreatitis|Acute pancreatitis]]
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| * [[Adrenogenital Syndrome]]
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| * Alcoholism with reduced intestinal absorption of potassium
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| * Alkalosis
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| * Anabolic states or conditions of rapid cell multiplication
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| * [[Anorexia Nervosa]]
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| * Barium or toluene ingestion
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| * [[Bartter's Syndrome]]
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| * [[Bilateral Adrenal Hyperplasia]]
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| * [[Bulimia]]
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| * Carbenoxolon
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| * Chewing tobacco
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| * Chloroquine overdose
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| * Chronic glomerulonephritis
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| * [[Inflammatory Bowel Disease|Chronic inflammatory bowel disease]]
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| * Chronic laxative abuse
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| * Clay ingestion
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| * [[Cushing's Syndrome]]
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| * [[Diabetes Insipidus]]
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| * Diabetes with glucosuria
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| * [[Diabetic Ketoacidosis]]
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| * [[Ddx:Diarrhea|Diarrhea]]
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| * Digibind therapy
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| * Drugs
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| * Excessive sweating
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| * "Fad" diets
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| * [[Gastroenteritis]]
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| * Gastrointestinal (GI) fistula
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| * Geophagia
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| * Heart failure
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| * Heriditary pseudohyperaldosteronism
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| * Hyperaldosteronism
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| * Hypokalemic periodic paralysis
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| * Hypomagnesemia
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| * [[Ddx:Hypothermia|Hypothermia]]
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| * Hypovolemia
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| * [[Ileus]]
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| * [[Leukemia]]
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| * Licorice excess
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| * [[Liddle's Syndrome]]
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| * Malabsorption syndrome
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| * [[Hypertension|Malignant hypertension]]
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| * Metabolic acidosis
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| * Mineralacorticoid excess
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| * Nasogastric suction
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| * Polyuric phase after acute renal failure
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| * Postoperative
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| * Pseudohypokalemia
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| * [[Pyloric Stenosis]]
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| * [[Renal Artery Stenosis]]
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| * [[Renal Tubular Acidosis]]
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| * Renin-secreting tumor
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| * Starvation
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| * Steroid therapy
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| * Stress
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| * Total parenteral nutrition
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| * Ureterosigmoidostomy
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| * Villous adenoma of the rectum
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| * [[Ddx:Nausea and Vomiting|Vomiting]]
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| ==Diagnosis==
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| === History and Symptoms ===
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| * [[Ddx:Fatigue|Fatigue]]
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| * Weakness
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| * [[Ddx:Nausea and Vomiting|Vomiting]]
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| * [[Ddx:Constipation|Constipation]]
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| * Muscle cramps
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| * Respiratory muscle weakness
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| ==== Heart ====
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| * Hypertension
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| * Life-threatening arhythmias
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| * Heart block
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| * Potentiation of digoxin
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| ==== Other ====
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| * Rhabdomyolysis
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| * Dehydration
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| * Ileus
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| * Hepatic encephalopathy
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| * [[Ddx:Hyperglycemia|Hyperglycemia]]
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| * Nephrogenic diabetes insipidus
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| ===Signs and symptoms===
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| There may be no symptoms at all, but severe hypokalemia may cause:
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| *[[Muscle weakness]] and [[myalgia]]
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| *Increased risk of [[hyponatremia]] with resultant [[mental confusion|confusion]] and [[seizure]]s
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| *Disturbed heart rhythm (ranging from [[Cardiac ectopy|ectopy]] to [[arrhythmias]])
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| *Serious [[arrhythmia]]s
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| == Laboratory Findings ==
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| * Complete blood count (CBC)
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| * Blood urea nitrogen (BUN)/creatinine
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| * Calcium
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| * Magnesium
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| * Glucose
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| * Arterial blood gases
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| * Renin levels
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| * Urinary sodium
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| * Urine potassium
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| * Transtubular potassium gradient
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| ===Electrocardiographic Findings===
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| # ST segment depression, decreased T wave amplitude, prominent U waves
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| #* seen in 78% of patients with a K < 2.7 meq
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| #* seen in 35% of patients with a K > 2.7 and < 3.0
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| #* seen in 10% of patients with a K > 3.0 and < 3.5
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| #* U waves are also prominent in bradycardia and LVH
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| # Prolongation of the QRS duration
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| #* uncommon except in severe hyperkalemia
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| # Increase in the amplitude and duration of the P-wave
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| # Cardiac arrhythmias and AV block
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| # Contrary to popular belief there is not prolongation of the QTc, this is artifactually prolonged due to the U wave. In some cases there is fusion of the T and the U wave making interpretation impossible.
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| <div align="center">
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| <gallery heights="175" widths="175">
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| Image:Hypokalemia.jpg|Long QT interval, ST segment depression, low T waves amplitude and TU wave fusion in a hypokalemic patient.
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| Image:KJcasu18-3.jpg|Consecutive ECGs of a patient with hypokalemia. ECG1
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| </gallery>
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| </div>
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| <div align="center">
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| <gallery heights="117" widths="117">
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| Image:KJcasu18-2.jpg|Consecutive ECGs of a patient with hypokalemia. ECG2
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| Image:KJcasu18-1.jpg|Consecutive ECGs of a patient with hypokalemia. After correction of potassium levels.
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| Image:V10.ht14.jpg|Hypokalemia with LVH. Image courtesy of Dr Jose Ganseman
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| </gallery>
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| </div>
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| ==Treatment==
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| The most important step in severe hypokalemia is removing the cause, such as treating [[diarrhea]] or stopping offending medication.
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| Mild hypokalemia (>3.0 mEq/L) may be treated with oral potassium chloride supplements (Sando-K®, Slow-K®). As this is often part of a poor nutritional intake, potassium-containing foods may be recommended, such as tomatoes, orange oranges or bananas. Both dietary and pharmaceutical supplements are used for people taking diuretic medications (see '''Causes''', above).
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| Severe hypokalemia (<3.0 mEq/L) may require [[intravenous]] supplementation. Typically, [[saline (medicine)|saline]] is used, with 20-40 mEq KCl per liter over 3-4 hours. Giving intravenous potassium at faster rates may predispose to [[ventricular tachycardia]]s and requires intensive monitoring.
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| Difficult or resistant cases of hypokalemia may be amenable to [[amiloride]], a potassium-sparing diuretic, or [[spironolactone]].
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| When replacing potassium intravenously, infusion via 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 [http://www.ismp.org/newsletters/acutecare/articles/20040212_2.asp].
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| ==See also==
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| * [[Hypomagnesemia]] | | * [[Hypomagnesemia]] |
| * [[Hyperkalemia]] | | * [[Hyperkalemia]] |
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| ==References==
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| {{Reflist}}
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| ==Additional Resources==
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| * Kasper DL ''et al'' (Eds). ''[[Harrison's Principles of Internal Medicine]]'', 16th ed, chapter 41, pages 258-61. ISBN 0-07-140235-7.
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| * Rose, B.D. and T.W. Post, ''Clinical Physiology of Acid-Base and Electrolyte Disorders'', 5th ed. 2001, pages 836-887. ISBN 0-07-134682-1
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| * Feline Hypokalemic Polymyopathy. ''in'' The Merck Veterinary Manual, 9th edition By Merck & Co. 2006. ISBN 0-911910-50-6
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| ==External link==
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| * [http://www.dietitian.com/potassiu.html Potassium in the human diet]
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| {{Endocrine, nutritional and metabolic pathology}}
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| {{Electrocardiography}}
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| {{SIB}}
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| [[Category:Electrophysiology]] | | [[Category:Electrophysiology]] |
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| [[Category:Intensive care medicine]] | | [[Category:Intensive care medicine]] |
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| [[de:Hypokaliämie]]
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| [[fr:Hypokaliémie]]
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| [[it:Ipokaliemia]]
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| [[pl:Hipokaliemia]]
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| [[pt:Hipocaliémia]]
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| [[ru:Гипокалиемия]]
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| [[sv:Hypokalemi]]
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| [[vi:Hạ kali máu]]
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| [[Category:Inborn errors of metabolism]]
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