Potassium Disorders Preface normal metabolism of potassium 1

Potassium Disorders

Preface: normal metabolism of potassium 1. normal serum potassium: 3. 5 -5. 5 mmol/L 2. distribution of potassium ICF: 98% (muscle: 75%) ECF: 2% 3. balance between intra- and extracellular K+ normal: 15 h 4. intake and loss of potassium intake: food; loss: urine; feces; sweat

5. influencing facter of potassium homeostasis acidosis hypoxia catabolism alkalosis insulin ADS anabolism distal flow rate damage of cells serum [K+]

I. Hypokalemia concept: serum potassium＜ 3. 5 mmol/L 1. cause and pathogenesis ① intake fast alkalosis injection of insulin ② move into Barium poisoning cells hypokalemic periodic paralysis

③ losses GI: vomiting; diarrhea; Gastrointestinal suction Skin: excessive sweats furosemide diuretic diamox diuretic phase of ARF ren: pyelonephritis primary hyperaldosteronism lack of magnesium renal tubular acidosis

3. effect on body 1) nerves and muscles excitability 0 mv serum[K+] -30 mv -60 mv -90 mv hyperpolarization AP TP(Et) RP(Em)

2) heart arrhythmia 0 mv serum[K+] -30 mv -60 mv -90 mv depolarization

Excitability: [K+]ECF K+ permeability depolarization repolarization excitability ECG T wave Conductivity: RP 0 phase of AP conductivity unidirectional block conductive block ECG P-R

Autorhythmicity: Contractility: acute ; chronic ③ Ren polyuria (sensitivity of ADH ) ④ GI smooth muscles (hyperpolarization) ⑤ acid-base balance (metabolic alkalosis) 4. principles of treatment supply potassium 口服最好。原则：见尿补钾。 血浓缩 anuria 不排钾 补钾速度： 10 -20 mmol/h 可能有酸中毒 补钾浓度： 20 -40 mmol/L

II. Hyperkalemia Concept: serum [K+]＞ 5. 5 mmol/L 1. cause and pathogenesis acute renal failure chronic renal failure GFR ① loss of shock potassium Addison’s disease 抗醛固酮利尿药(antisterone)

② K+ move out of cells Acidosis; hypoxia; hemolysis; crush syndrome; 高钾血症型周期性麻痹 ③ intake of 10% KCl potassium penicillin potassium transfusion of bank blood 2. effects on body ① skeletal muscle ＜ 8 mmol/L RP (depolarization) excitability stabbing; tremor ＞ 8 mmol/L RP inactivation of Na+ channel depolarization paralysis

② heart (hyperkalemia K+ permeability ) 5. 5 -7 mmol/L→ RP → E excitability 7 -9 mmol/L→ RP → E PR QT T wave ; QT short cardiac arrest

Autorhythmicity: K+ out ward of phase 4 Spontaneous depolarization heart rate Conductivity: RP Na+ inward of phase 0 conductivity conductive block unidirectional block Contractility : inhibition of Ca 2+ inward flow contractility ③ acid-base balance

3. principles of treatment ① transfusion of insulin and glucose ② transfusion of sodium bicarbonate ③ transfusion of calcium