A patient with severe primary hypokalemic periodic paralysis improved significantly on a regimen low in carbohydrate, restricted in sodium and high in potassium. Moderate weakness persisted in the proximal muscles and was associated with persistent vacuolation of muscle fibers. Enlargement of the motor end-plate zone is described in this case of primary hypokalemic periodic paralysis. Considerable weakness occurred even when serum potassium values were within the normal range. On an isocaloric nonreducing diet, the patient lost weight when the carbohydrate intake was reduced. Most of the weight loss could be accounted for by a loss of body water that was not associated with a negative sodium balance. Data obtained in the course of an acute attack are compatible with an increase in the total body water content and a shift of fluid from the extracellular into the intracellular compartment. Renal retention of potassium, sodium and chloride preceded changes in the patient's strength and the decrease in serum potassium. Not more than 10 mEq. of potassium could have been lost from the patient's erythrocytes during the attack despite the decreasing serum potassium levels. A fully paralyzed muscle and a muscle only somewhat weak were similar in their electrolyte and water content, except for the higher calcium and magnesium contents of the weaker muscle. Both muscles had chloride space and water levels which were higher than most normal values; sodium, chloride and magnesium levels higher than normal; and a potassium level which was lower than most normal values. The chloride space values were too high to be a measure of the extracellular space and could not be used for calculating intracellular electrolyte concentrations. Small doses of epinephrine, administered intra-arterially, had a direct adverse effect on the muscles of the perfused forearm. These effects were not mediated by systemic hypokalemia or hyperglycemia but may have been related to an acceleration of glycogenolysis and glycolysis in muscles. An increased uptake of sodium by the forearm tissues followed rather than preceded the decrease in action potential and twitch tension. Maximal voluntary exercise followed by rest caused a transient potentiation and then a depression of the action potential and of the twitch tension in the patient and in healthy subjects, but the patient's response was at times quantitatively greater. The deviation from normal tended to be greatest when the patient was weakest. Excessive accumulation of lactic and pyruvic acids in the blood occurred after a standard work load. This may indicate a greater than normal release of these metabolites from muscle or an impaired metabolism by muscle, or both. There appears to be no impairment in glycogenolysis or glycolysis in muscle during exercise. A close relationship was again observed between carbohydrate metabolism and primary hypokalemic periodic paralysis. The present study points to a possible metabolic lesion, or a contributing mechanism, that can be activated by rapidly induced glycolysis.
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