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A 21-year-old white man comes to the emergency department because of muscular weakness. He has had episodes of weakness for the past year. After coming home from the gym, he feels the inability to reach the cabinets in the kitchen. Sometimes he is unable to rise from a seated position. The attacks occur approximately 3 times per week, last 3 hours, and subside spontaneously. The attacks also occur after heavy meals. On physical examination, you note 2/5 motor strength in the bicep muscles bilaterally, with 3/5 strength of the handgrip, and 2/5 motor strength of the quadriceps bilaterally, with 4/5 strength on dorsiflexion of the feet. He has no prior medical history. Laboratory studies reveal:
Sodium 140 mEq/L; potassium 2.0 mEq/L; chloride 112 mEq/L; bicarbonate 15 mEq/L; BUN 10 mg/dL, creatinine 0.8 mg/dL.
What is the next best step in the management of this patient?
(A) Repeat potassium level
(B) Potassium chloride orally
© Acetazolamide
(D) Potassium chloride intravenously
(E) Spironolactone
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I would have said IV K but not sure if IV KCl since the Cl levels are also high?
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another try ben..........
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doctor_goraya I am afraid to try now can you give complete explanation
of course after other have their chance to answer
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Is this hypokalemic periodic paralysis,?
(B) Potassium chloride orally
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yes pth u are right but answer is potassium chloride IV
This patient has an acute attack of hypokalemic periodic paralysis (HPP). This is a disorder in a group of periodic paralyses that are due mainly to defects in the sodium and calcium channels in the muscles. Mutations in the calcium channels are present in this disorder. They are also thought to be related to an abnormal effect of insulin on the uptake of potassium at the muscle membrane. The onset is rare before age 25. The symptoms of HPP most often occur after resting after exercise, stress, or a high-carbohydrate meal. Thyrotoxicosis may also cause the syndrome. The symptoms typically last for 2 to 12 hours. The weakness is usually in proximal limb muscles, although the extraocular and respiratory muscles can occasionally be involved. Attacks of paralysis can occur after high-carbohydrate meals. Hypoactive reflexes and cardiac arrhythmias can also be seen.
The diagnosis of HPP is confirmed by the history of repeated episodes of weakness with hypokalemia. In this case, the patient came into the emergency department with mostly proximal muscle paralysis and hypokalemia confirming the diagnosis. A muscle biopsy may be done that will show single or multiple centrally placed vacuoles. When the patient does not present with dramatic paralysis, a provocative test using glucose and insulin may be used, but this needs to be done only in a carefully monitored setting.
The usual treatment is to give potassium orally for the acute episode every 15 to 30 minutes with careful monitoring of the EKG, the potassium level, and muscle strength. Intravenous potassium is reserved for patients such as this who have profoundly severe muscular weakness. When giving intravenous potassium, it should be mixed with mannitol rather than dextrose because the insulin that is generated by the dextrose will cause more intracellular shift of potassium and can worsen the paralysis. Acetazolamide, a carbonic anhydrase inhibitor, has been used to prevent attacks presumably by causing a metabolic acidosis. It may paradoxically cause a drop in the potassium level, and potassium supplements may need to be given as well. Beta-blockers may also decrease the frequency of attacks. Avoidance of high-carbohydrate meals and eating a low-salt diet should also be helpful. In this patient, overcoming the acute attack is the most important step, and the best treatment for this patient is to give potassium intravenously because he is so profoundly weak.
