Hypokalemia

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Movement of K+ into cells may transiently decrease the plasma [K+] without altering total body K+ content. These shifts can result from alkalemia, insulin, and catecholamine release, periodic paralysis

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Nội dung Text: Hypokalemia

Hypokalemia Definition Hypokalemia is defined as a plasma [K+] < 3.5 mEq/L. Etiology decreased net intake is seldom the sole cause of K+ depletion because urinary excretion can be effectively decreased to
Nonrenal K+ loss. Hypokalemia may result from the loss of potassium-rich fluids from the lower GI tract, from the loss of upper GI contents is typically more attributable to renal K secretion from secondary hyperaldosteronism.excessive sweating Renal K+ loss accounts for most cases of chronic hypokalemia Augmented distal urine flow rate occurs commonly with diuretic use and osmotic diuresis, Bartter's and Gitelman's syndromes Promote K+ loss by increasing the lumen-negative gradient , Distal Na+ reabsorption Primary mineralocorticoid excess Secondary hyperaldosteronism Liddle's syndrome. DIAGNOSIS Clinical Presentation The clinical features of K+ depletion vary greatly, and their severity depends in part on the degree of hypokalemia. Symptoms seldom occur unless the plasma [K+] is
complaints of constipation or frank paralytic ileus. Severe hypokalemia may lead to complete paralysis, hypoventilation, or rhabdomyolysis. Diagnostic Testing renal K+ excretion and the acid-base status can help identify the cause Urine K+. The appropriate response to hypokalemia is to excrete 4 suggests inappropriate renal K+ secretion Acid-Base status. Intracellular shifting and renal excretion of K+ are often closely linked with the acid-base statusThe finding of metabolic acidosis in a patient with hypokalemia thus narrows the differential significantly, implying lower GI loss, distal RTA, or the excretion of a nonreabso rbable anion from an organic acid (DKA, hippurate from toluene intoxication). Electrocardiogram (ECG) changes associated with hypokalemia include flattening or inversion of the T wave, a prominent U wave, ST -segment depression, and a prolonged QT interval. Severe K+ depletion may result in a prolonged PR interval, decreased voltage, and widening of the QRS complex.