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Management of Hypokalemia in the Hospital J Rush Pierce Jr, MD, MPH Section of Hospital Medicine, Univ of New Mexico Hospitalist Best Practices December.

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Presentation on theme: "Management of Hypokalemia in the Hospital J Rush Pierce Jr, MD, MPH Section of Hospital Medicine, Univ of New Mexico Hospitalist Best Practices December."— Presentation transcript:

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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

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

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

5 Cases – select a response 1.20 y/o vomiting, K = y/o asthmatic K = y/o with DTs, K = y/o with CHF, K = 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 /17/20104Hospital treatment of hypokalemia

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

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

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

9 Potassium homeostasis –general principles and teaching points 12/17/20108Hospital treatment of hypokalemia

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

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

12 Management of hypokalemia in the hospital When to treat What agent to use What route of administration 12/17/201011Hospital treatment of hypokalemia

13 Adverse effects of hypokalemia Effects: – Hepatic encephalopathy <3.5 [case reports] – Cardiac arrhythmias (acute MI < 4.0, cardiac surgery < 3.7; CHF; in normal, rarely unless <3.0; Class I anesthesia <2.6) [epidemiologic data] – Rhabdomyolisis < 2.5 [case reports] – Diaphragmatic muscle paralysis <2.0 [case reports] More likely with rapid decline of K Arrhythmias more likely with CHF, IHD, digoxin 12/17/201012Hospital treatment of hypokalemia

14 Risk of hypokalemia in acute MI Am J Kidney Dis 45: /17/201013Hospital treatment of hypokalemia

15 Risk of hypokalemia in acute MI J Am Coll Cardiol 2004; 43:155–61 12/17/201014Hospital treatment of hypokalemia

16 Risk of hypokalemia in cardiac surgery 12/17/201015Hospital treatment of hypokalemia

17 Risk of hypokalemia in cardiac surgery 12/17/201016Hospital treatment of hypokalemia

18 Risk of hypokalemia in LV Failure J Am Coll Cardiol 2004; 43:155–61 12/17/201017Hospital treatment of hypokalemia

19 Risk of hypokalemia in HTN J Am Coll Cardiol 2004; 43:155–61 12/17/201018Hospital treatment of hypokalemia

20 Risks of treatment of hypokalemia 12/17/201019Hospital treatment of hypokalemia

21 Risks of treatment of hypokalemia 12/17/201020Hospital treatment of hypokalemia

22 When to treat – Brenner and Rector recommendations < 4.0 – Acute MI, CHF, digoxin, severe hepatic dz < 3.5 – HTN or sxs < others 12/17/201021Hospital treatment of hypokalemia

23 Treatment – K-containing foods Least expensive Less effective because potassium in foods predominantly potassium phosphate of citrate Only 40% as effective as KCL 12/17/201022Hospital treatment of hypokalemia

24 Treatment –oral therapy K-bicarb – if acidosis KPO4 - if hypophosphatemic KCl – all others Quantity – Studies in normal subjects – 0.3 mEq K 100 mEq total body K depletion – 75 mEq KCl 1 – 1.5 mEq in 90 mins – 125 mEq 2.5 – 3.5 mEq in 60 – 120 mins 12/17/201023Hospital treatment of hypokalemia

25 Treatment – intravenous therapy (Brenner and Rector) Reserve for those unable to take orally, K 2.5 and true emergencies (significant arrythmias, muscle weakness) Use non-dextrose containing solutions If > 10 mEq/hr, cardiac monitoring KPO4 50 mEq over 8 hours 12/17/201024Hospital treatment of hypokalemia

26 Treatment – intravenous therapy Crit Care Med 1991;19:694 12/17/201025Hospital treatment of hypokalemia

27 Treatment – potassium sparing diuretics Amiloride, triamterene – block Na/K channels Spironolactone, eplerone – inhibit aldosterone Caution in diabetics, renal insuff Freq monitoring of K 12/17/201026Hospital treatment of hypokalemia

28 Cases – select a response 1.20 y/o vomiting, K = y/o asthmatic K = y/o with DTs, K = y/o with CHF, K = 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 /17/ Hospital treatment of hypokalemia

29 Discussion re: consensus practice Treat urgently – all pts with K < 2.5 – sxtic pts with K <3.5 (serious vent ectopy, new atrail fib, or new muscle weakness) – Pts with acute MI and K < 3.5 Treat promptly pts with CHF, IHD, serious liver dz and K < 3.5 Oral therapy is preferred Use smaller doses and more freq monitoring in pts with hematologic malignancy or if receiving Mg 12/17/201028Hospital treatment of hypokalemia

30 Possible items to include in a hypokalemia order set Evaluate pt for underlying conditions (CHF, IHD, cirrhosis) Option to check magnesium Option to order K/creat if etiology unclear Reminder that certain conditions may be due to shifts (periodic paralysis, B-agonists, hyperthyroidism) Options for routes of administration and types 12/17/201029Hospital treatment of hypokalemia


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