Editing Potassium (section)

== '''Hypokalaemia''' ==

* '''Aetiology'''
** '''Trans-cellular shift''' - potassium movement into cells
*** Alkalosis (variable and unpredictable)
*** Hypothermia (transient)
*** Insulin
*** Inhaled beta-2 agonist bronchodilators in combination with diuretics
** '''Decrease in total body potassium'''
*** Urine loss - diuretics, NGT (loss of volume and H+), alkalosis, magnesium depletion (impairs potassium reabsorption in renal tubules). Urine chloride levels are low with NGT and alkalosis, and high with diuretics and magnesium depletion.
*** GIT loss - diarrhoea
**
* '''Clinical manifestations'''
** Mostly asymptomatic
** Symptoms <2.5
*** ECG abnormalities - prominent U waves, flattening and inversion of T waves, prolongation of QT interval. Hypokalaemia alone is not a risk factor for severe arrhythmias, but can add to others
*** Diffuse muscle weakness
* '''Management'''
** Eliminate or treat any condition leading to trans-cellular shifts
** '''Identify and correct hypomagnesaemia'''
** Estimate potassium deficits (mEq and mmol are 1:1 for potassium)
***
** '''Replace'''
*** IV if potassium <3.3 or questionable GIT absorption. Reasonable to give both in many cases.
*** Check again in 12 hours if K < 3, otherwise check again 24 hours
*** Potassium chloride (best option in most)
**** 600mg PO tablets contain 8mmol potassium
***** Slow-K is modified release
***** Span-K is immediate release
**** Chlorvescent contains 14mmol potassium (not good for patients with ileus or struggling with fluid intake)
**** Can put 10mmol potassium chloride in 100mL normal saline
*** Potassium phosphate - can be used in concomitant hypophosphataemia, best choice in DKA because of phosphate depletion
*** Potassium bicarbonate - good in hypokalaemia and combined metabolic acidosis
** Serum K can be slow to rise, as explained by the total body K/serum K curve above, and the large total estimated deficits for near-normal serum levels
** Don't need to give calcium gluconate

[[Category:Nutrition]]
[[Category:Intern education]]