Transcript Hypokalemia
Hypokalemia • • • • 55 y/o male CC: chronic diarrhea Farmer in La Trinidad, Benguet Noted progressive weakness for the past weeks Na Cl K Blood Test 140 meq/L 110 meq/L 2.0 meq/L Hypokalemia • Urine potassium: 15 meq/L pH pCO2 HCO3 Arterial Blood Gas 7.28 39 mmHg 16 Diagnostic approach to hypokalemia Urinary K+ excretion <15 mmol/d >15 mmol/d Assess acidbase status Assess K+ secretion Diagnostic approach to hypokalemia Assess acidbase status Metabolic acidosis Metabolic alkalosis Lower gastrointestin al K+ loss Remove diuretic use, vomitting and K+ loss via sweat Diagnostic approach to hypokalemia Assess K+ secretion Transtubular K+ concentration gradient > 4 Transtubular K+ concentration gradient < 2 Acid-base status Na+ wasting nephropathy, osmotic diuresis, diuretic Diagnostic approach to hypokalemia Acid-base status Metabolic acidosis Metabolic alkalosis Diabetic ketoacidosis, proximal RTA, distal RTA, amphotericin B Hypertension? Diagnostic approach to hypokalemia Hypertension? YES NO Mineralocorticoid excess, Liddle’s syndrome Vomiting,Bartter’s syndrome, exclude diuretic use, hypomagnesemia Significance of Urinary K levels • This can be established after eliminating decreased intake and intracellular shift as potential causes of hypokalemia • Appropriate response to K+ depletion is to excrete less than 15 mmol/d of K+ in the urine, due to increased reabsorption and decreased distal excretion • This is exemplified by the diagnostic approach shown previously Adverse medical implications • More severe hypokalemia may lead to progressive weakness, hypoventilation (due to respiratory involvement involvement, and even complete paralysis • Impaired muscle metabolism and blunted hyperemic response to exercise leads to rhabomyolysis • Leads to prolonged PR interval, decreased voltage and widening of the QRS complex, with increased risk of ventricular arrhythmia Symptoms of Hypokalemia • • • • • • • • • Palpitations Skeletal muscle weakness or cramping Paralysis, paresthesias Constipation4 Nausea or vomiting Abdominal cramping Polyuria, nocturia, or polydipsia Psychosis, delirium, or hallucinations Depression Signs of Hypokalemia • • • • • Signs of ileus Hypotension Ventricular arrhythmias Cardiac arrest Bradycardia or tachycardia • Premature atrial or ventricular beats • Hypoventilation, respiratory distress • Respiratory failure • Lethargy or other mental status changes • Decreased muscle strength, fasciculations, or tetany • Decreased tendon reflexes • Cushingoid appearance (eg, edema) Treatment • • • • ECG monitoring Establish IV access Assess respiratory status Infuse potassium chloride, since his serum potassium is < 2.5 meq/L, in other cases oral is the preferred route for potassium repletion because it is easy to administer, safe, inexpensive, and readily absorbed from the GI tract • Check serum Mg levels since it is difficult to restore K if the former is low