Magnesium Flashcards
Magnesium
1% in extra cellular fluid the rest in cells. 66% ionised and the rest bound to proteins, excreted in kidneys, vital to enzyme reactions, synthesis of protein/nucleic acids, exerts sedative effect on neuromuscular junction, decreasing acetylcholine release, affected by calcium/potassium levels
Hypomagnesaemia
Deficient intake, excessive loss, shift from intracellular to extra cellular
Risk factors- loss of GI fluids, disruption of GI absorption, alcoholism, malnutrition, diabetes keto acidosis, diuretics/antibiotics, rapid administration of citrates blood (used to prevent clotting and preservative-if given fast liver can’t metabolise citrate and it binds to calcium=hypocalcaemia), kidney disease
S&S- muscle weakness, tremors, tetany, digitalis toxicity, positive chvostek/trousseau sign, hyper reflexive
GI- dysphagia, anorexia, nausea/vomiting, reduced motility
Cardio- tachycardia, arrhythmias, HT (due to increased vasoconstriction)
CNS- personality changes, parasthesia, hallucinations, psychosis
ECG- prolonged PR interval, widened QRS, depression of ST, T wave inversion
Hypermagnesaemia
Renal failure, antacids/laxatives containing magnesium
Less common
S&S- hypotension, flushing, sweating, Brady-arrhythmias, nausea/vomiting, weakness, lethargy, absent reflexes, resp depression, ECG changes- bradycardia/heart block
