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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}} |
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| 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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| {{Hypokalemia}} | | {{Hypokalemia}} |
| {{CMG}}'''; Associate Editor-In-Chief:''' {{CZ}}; '''Assistant Editor(s)-In-Chief:''' [[User:Jack Khouri|Jack Khouri]]
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| ==[[Hypokalemia overview|Overview]]==
| | '''For patient information on this page, click [[Hypokalemia (patient information)|here]]''' |
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| ==[[Hypokalemia pathophysiology|Pathophysiology]]==
| | {{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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| ==[[Hypokalemia causes|Causes]]==
| | {{SK}} Hypokalaemia; potassium levels low (plasma or serum); potassium - low; low blood potassium; potassium depletion |
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| ==[[Hypokalemia differential diagnosis|Differential diagnosis]]== | | ==[[Hypokalemia overview|Overview]]== |
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| ==Diagnosis== | | ==[[Hypokalemia historical perspective|Historical Perspective]]== |
| === Symptoms ===
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| The severity of symptoms depends on the degree of hypokalemia, but keep in mind that there is marked individual variability.
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| ==== Constitutional ====
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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 and paralysis (the lower extremity muscles are most commonly involved) which may involve the intestine and cause ileus
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| * Respiratory muscle weakness leading to respiratory failure
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| ==== Cardiac ==== | |
| * Hypertension
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| * Arrhythmias including premature atrial and ventricular complexes, paroxysmal atrial or junctional tachycardia and even ventricular tachycardia or fibrillation
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| * Heart block
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| * Digoxin therapy, CAD and left ventricular hypertrophy potentiate hypokalemia effects on the heart
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| ==== Renal ====
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| *Nephrogenic diabetes insipidus due to decreased concentrating ability. As a consequence, the patient presents with polyuria and polydipsia
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| *Increased bicarbonate reabsorption
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| *Increased ammonia formation which may precipitate hepatic encephalopathy in cirrhotic patients
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| *Decreased sodium reabsorption resulting in hyponatremia
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| ==== Other ====
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| * Rhabdomyolysis
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| * [[Ddx:Hyperglycemia|Hyperglycemia]]
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| === History === | | ==[[Hypokalemia pathophysiology|Pathophysiology]]== |
| A detailed history can help depict the cause of hypokalemia.
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| ==== Dietary history ==== | | ==[[Hypokalemia causes|Causes]]== |
| Malnutrition: lack of meat and fruit intake
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| ==== Medication history ==== | | ==[[Hypokalemia differential diagnosis|Differentiating Hypokalemia from other Diseases]]== |
| *Diuretics (loop and thiazides)
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| *Beta agonists
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| *Chloroquine
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| *Theophylline
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| *Insulin
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| *Corticosteroids
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| *Licorice
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| *Nephrotoxic drugs (platinum-based chemotherapy, aminoglycosides)
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| *Laxatives
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| ==== Past medical history ==== | | ==[[Hypokalemia epidemiology and demographics|Epidemiology and Demographics]]== |
| *Uncontrolled diabetes
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| *Hyperthyroidism
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| *Pernicious anemia
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| *COPD (treated with Beta agonists and theophylline)
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| *Cushing’s disease
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| *Periodic paralysis
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| *Ileostomy/short bowel
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| *Primary hyperaldosteronism
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| *Liddle syndrome
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| *Bartter and Gitelman syndrome
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| *Prolonged starvation
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| *Cancer
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| *Renal tubular acidosis type I and type II
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| == Laboratory Findings == | | ==[[Hypokalemia risk factors|Risk Factors]]== |
| * 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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| * Aldosterone level
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| * Renin levels
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| * Urinary sodium
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| * Urine potassium
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| ** Levels <25 meq/'''day''' (or <15 meq/L on urine '''spot''') rule out a renal cause of hypokalemia and suggest extrarenal potassium loss or transcellular shift
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| ** Higher potassium excretion suggest renal losses.
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| * Transtubular potassium gradient (TTKG)
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| ** TTKG= (Urine K x Plasma osmolarity)/(Plasma K x Urine osmolarity)
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| ** A TTKG less than 2-3 indicates renal potassium conservation in a hypokalemic patient
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| ** A urine osmolality less than plasma osmolality or urine sodium <20 mEq/L, the formula is not applicable
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| * Urine chloride
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| ** <25 meq/L: vomiting or remote diuretic use
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| ** >40 meq/L: diuretics, Bartter's, Gitelman's and mineralocorticoid excess
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| == Electrocardiography == | | ==[[Hypokalemia natural history|Natural History, Complications and Prognosis]]== |
| ==== Overview ====
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| *Caused mainly by delayed ventricular repolarization
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| *Seen at potassium levels <3 meq/L (90% of patients with potassium levels <2.7 meq/L have abnormal ECG findings)
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| *Rapidly reversible with potassium repletion
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| ==== ECG changes ==== | | ==[[Hypokalemia Diagnosis|Diagnosis]]== |
| # ST segment depression, decreased T wave amplitude, prominent U waves
| | [[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]] |
| #* 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 | |
| # 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">
| | ==[[Hypokalemia treatment|Treatment]]== |
| <gallery heights="175" widths="175">
| | [[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]] |
| 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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| | ==Case Studies== |
| | [[Hypokalemia case study one|Case #1]] |
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| <div align="center">
| | ==Related Chapters== |
| <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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| * Patients treated with loop or thiazide diuretics can be offered medications that counteract their kaliuretic effect such as aldosterone antagonists (spironolactone and eplerenone) or distal sodium channel blockers (eg, amiloride).
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| * The combination of thiazide and loop diuretics should be avoided.
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| * Oral potassium administration is safer than the IV route.
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| * An oral dose should '''not''' exceed 20-40 mEq.
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| * IV potassium infusion should be reserved for symptomatic patients with severe hyperkalemia and patients who can't take oral supplements.
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| === Mild hypokalemia ===
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| * Potassium levels in the range 3.0-3.5 mEq/L.
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| * Represent potassium deficit of 200-400 mEq.
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| * May be treated with oral potassium salt supplements: potassium chloride KCl (Sando-K®, Slow-K®) or potassium bicarbonate KHCO3 (which can be generated from the metabolism of many organic salts eg, potassium citrate, potassium gluconate, etc).
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| * Potassium-containing foods may be recommended, such as tomatoes, oranges or bananas, but they are less effective than oral supplements.
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| * Both dietary and pharmaceutical supplements are used for people taking diuretic medications (see '''Causes''', above).
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| * KCl is the most effective replacement for metabolic alkalosis-associated hypokalemia.
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| * KHCO3 and the organic "alkalinizing" salts K-citrate and K-gluconate are recommended for hypokalemia associated with metabolic acidosis (chronic diarrhea, renal tubular acidosis,etc).
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| === Severe hypokalemia ===
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| * Potassium levels below 3.0 mEq/L
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| * Potassium levels between 2.0 and 3.0 correspond to 400-800 mEq deficit.
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| * It may require [[intravenous]] supplementation. Typically, [[saline (medicine)|saline]] is used, with 20-40 mEq KCl per liter over 3-4 hours (ie, at an infusion rate of 10 mEq/L/h)
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| * '''Giving IV potassium at faster rates may predispose to [[ventricular tachycardia]]s and requires intensive ECG monitoring.'''
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| * '''Giving IV KCl at doses >60 mEq/L are painful and can cause venous necrosis.'''
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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 and the aforementioned venous necrosis. 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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| * Potassium infusions via a central line can reach 200 mEq/L (20 mEq in 100 mL of '''isotonic saline''' (see below)) but '''the administration rate should not be greater than 10–20 mEq per hour.'''
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| * Saline solutions are preferred to prevent potassium transcellular shifting that is triggered by dextrose-induced insulin release!
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| ==See also==
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| * [[Hypomagnesemia]] | | * [[Hypomagnesemia]] |
| * [[Hyperkalemia]] | | * [[Hyperkalemia]] |
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| ==References==
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| {{Reflist|2}}
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| [[Category:Electrophysiology]] | | [[Category:Electrophysiology]] |
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| [[Category:Intensive care medicine]] | | [[Category:Intensive care medicine]] |
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| [[fr:Hypokaliémie]]
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| [[pl:Hipokaliemia]]
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| [[pt:Hipocaliémia]]
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| [[ru:Гипокалиемия]]
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| [[vi:Hạ kali máu]]
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| [[Category:Inborn errors of metabolism]]
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| {{WikiDoc Help Menu}} | | {{WikiDoc Help Menu}} |
| {{WikiDoc Sources}} | | {{WikiDoc Sources}} |
</figure-inline></figure-inline>