5 5 meqliter normal hyperkalemia increased plasma k

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Unformatted text preview: ce from tumors • Treatment – often just water restriction – may prescribe intake of salt Sodium Sodium • Regulated along with water – it is the major ion regulating plasma volume and, therefore, total fluid volume • 135-145 mEq/liter = normal Other Electrolytes Other • K+, Ca++, Mg++ – All three ions affect neuromuscular function • explains major side effects when imbalance occurs Normal Ion Distribution Normal Potassium Potassium 3.5-5 mEq/liter = normal • Hyperkalemia (increased plasma K+) – causes: • • • • decreased aldosterone renal failure cellular damage (burns, crushing, etc.) metabolic acidosis (causes K+ shift from cells) – symptoms: • decreased neuromuscular function – weakness, abdominal distention, diarrhea • A-V block, cardiac arrest – Note: mental function usually remains normal although mental confusion is possible – treatment: • calcium, sodium bicarbonate, dextrose plus insulin – all move K+ into cells; • resins work more slowly. Hypokalemia Hypokalemia + Decreased plasma K+ • causes: – decreased K+ intake • starvation or intestinal blockage – increased G.I. loss • vomiting, diarrhea – metabolic alkalosis • causes K+ shift into cell and • K+ secretion due to H+ unavailability – increased aldosterone secretion Hypokalemia Decreased plasma K+ • symptoms: – decreased neuromuscular function • muscle cramps,jitteriness • decreased ventilation and small muscle function – increased HR, impaired conduction (fibrillation) • Note: mental function usually remains normal • treatment: – Oral intake preferred unless an emergency – Parenteral -- usually use chloride salt (bicarbonate, acetate, gluconate also available). • Often 40 mEq/L I.V. fluid with 40-150 mEq/day being given (i.e. normal dietary intake). Calcium Calcium • Uses – keeps cell membranes less permeable • especially muscle and nerve – initiates muscle contraction • will see direct effect on heart – works with enzyme systems such as those in blood clotting Hypercalcemia Hypercalcemia • causes: – Hyperparathyroidism • or tumor mimicking PTH – vitamin D intoxication – excessive "mineral" intake – acidosis – bone cancer Hypercalcemia • symptoms: – nerve membranes less excitable • stupor, muscle flaccidity, weakness, peripheral vasodilation – direct action on heart • increases heart contractions – stones and calcium deposits – Polyuria • impaired concentrating ability Hypocalcemia Hypocalcemia • causes: – hypoparathyroidism – too little vitamin D – chronic renal insufficiency • kidneys retain phosphate which combines with Ca++ • also, kidneys activate vitamin D – bed rest and inactivity (long term only) – alkalosis – stored blood (calcium binds to citrate) Hypocalcemia Hypocalcemia • symptoms: – nerve membranes more excitable • (irritability, tetany, convulsions) – heart weak • treatment: – if parenteral treatment required, calcium gluconate is least irritating Magnesium • Uses – activator for many enzyme systems – mimics Ca++ effects on nervous system (seems to affect acetylcholine release) Hypermagnesemia Hypermagnesemia Too much magnesium • causes: – renal insufficiency • especially if increased intake – acidosis may make worse • shift out of cells • symptoms: – sedation and depression – muscle weakness Hypomagnesemia Hypomagnesemia Too little magnesium • causes: – starvation – diarrhea – over intake of Ca++ • symptoms: – increased irritability – convulsions – cardiac arrhythmia Pharmacology Unit 9: Pharmacology End of Slides...
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