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Slide 2 Management of Hypokalemia in the Hospital J Rush Pierce Jr, MD, MPH Section of Hospital Medicine, Univ of New Mexico Hospitalist Best Practices December 16, 2010 Slide 3 Agenda Review (briefly) physiology of potassium homeostasis and clinical disturbances thereof Review (briefly) common causes of hypokalemia, emphasizing those of importance to inpatient care Discuss management of hypokalemia in the hospital Derive some specific clinical care issues 12/17/20102Hospital treatment of hypokalemia Slide 4 Management issues When should hypokalemia be corrected? What is the preferred agent for correction of hypokalemia? What is the preferred route of administration to correct hypokalemia? 12/17/20103Hospital treatment of hypokalemia Slide 5 Cases select a response 1.20 y/o vomiting, K = 2.9 2.30 y/o asthmatic K = 2.9 3.40 y/o with DTs, K = 2.9 4.50 y/o with CHF, K = 2.9 5.60 y/o old with Childs C cirrhosis, K = 2.9 A.No treatment w/KCl B.Oral KCl to get K 3.5 C.Oral KCl to get K 4.0 D.IV KCl to get K 3.5 E.IV KCl to get K 4.0 12/17/20104Hospital treatment of hypokalemia Slide 6 Potassium homeostasis general principles and teaching points Potassium is mainly an intracellular cation Serum potassium is surrogate marker for total body potassium With marked production of cells, may see hypokalemia Treatment of vitamin B12 def With neupogen Potassium is major determinant of membrane potential 12/17/20105Hospital treatment of hypokalemia Slide 7 Potassium homeostasis general principles and teaching points Cellular shifts of K influenced by hydrogen Alkalosis cause intracellular shift and may cause hypokalemia on this basis alone Magnitude of effect is ~0.4 mEq decrease K for each 0.1 increase in pH (pH 7.4 ->7.6 = K 3.5 -> 2.7) Very often clinical conditions causing alkalosis promote renal excretion of potassium Cellular shifts of K influenced also by beta- agonists, insulin, and thyroxin 12/17/20106Hospital treatment of hypokalemia Slide 8 Potassium homeostasis general principles and teaching points Dietary intake of potassium almost always exceeds obligate potassium losses in urine, stool, and sweat Usual dietary intake of K = 40 120 mEq/d Very difficult to become hypokalemia due to decreased dietary intake (exc = 800 cal protein diets) Obligate renal and GI loss = 5 25 mEq/d 12/17/20107Hospital treatment of hypokalemia Slide 9 Potassium homeostasis general principles and teaching points 12/17/20108Hospital treatment of hypokalemia Slide 10 Non-renal causes of hypokalemia Poor intake Shift (hypokalemic periodic paralysis, alkalosis, insulin, beta-adrenergics, hyperthyroidism) Excess extrarenal loss Sweat Dialysis, plasmpheresis Vomiting (5 10 mEq/l) Diarrhea (20 50 mEq/l) 12/17/20109Hospital treatment of hypokalemia Slide 11 Renal causes of hypokalemia Diseases of kidney RTA, salt-wasting nephropathies (incl Bartters) Delivery of non-reabsorbable anions (ketoacids, bicarb, toluene, PCN) Excess mineralocorticoid Hypomagnesemia Drugs diuretics, Amphotericin B, platinum 12/17/201010Hospital treatment of hypokalemia Slide 12 Management of hypokalemia in the hospital When to treat What agent to use What route of administration 12/17/201011Hospital treatment of hypokalemia Slide 13 Adverse effects of hypokalemia Effects: Hepatic encephalopathy