HYPOKALEMIC PERIODIC PARALYSIS: A RARE AND TREATABLE FORM OF ACUTE PROFOUND WEAKNESS

Charles J VanHook, M.D.*;Britt Warner, PA;Jacquelynn Gould, M.D. and Angela Taylor, M.D., Longmont United Hospital, Longmont, CO

Meeting: Hospital Medicine 2017, May 1-4, 2017; Las Vegas, Nev.

Abstract number: 770

Categories: Adult, Clinical Vignette Abstracts

Case Presentation: A 43-year old man presented with the acute onset of paralysis.  The patient had helped a sibling move heavy furniture throughout the day prior to admission.  He awoke from sleep that evening unable to move his extremities.  Ambulance personnel were required to transport the patient to the emergency department. The patient had experienced sporadic episodes of transient weakness since the age of 13.  He reported that in those instances, his weakness had either resolved spontaneously, or after the administration of intravenous fluids.  The patient stated that his mother had experienced similar health issues.  On arrival to the hospital, physical exam was remarkable for 1/5 strength (British Medical Research Council rating), in all extremities. Laboratory exam revealed a serum potassium of 1.9 mm/L. Thyroid-stimulating hormone was normal. EKG was remarkable for non-specific ST-T changes.  The patient was treated with intravenous potassium replacement, and his strength recovered to baseline within twenty-four hours. 

Discussion: Hypokalemic periodic paralysis (HPP) is a rare neuromuscular disorder, with a prevalence estimated at 1/100,000.  The male to female ratio is approximately four to one.  HPP may be inherited in an autosomal dominant pattern. Genetic mutations have been identified that affect skeletal muscle sarcolemma calcium and sodium channels, resulting in inadequate depolarization. In a minority of cases of HPP, identical pathophysiologic abnormalities are acquired rather than hereditary, most often in the setting of hyperthyroidism.  Attacks may be precipitated by stress or vigorous physical exertion, where excessive adrenergic stimuli trigger decompensation by promoting intracellular potassium shift.  High carbohydrate intake, with endogenous increases in insulin, and a similar effect on intracellular potassium movement, has also been identified as an etiologic factor.  The acute paralysis is always reversible, but a chronic progressive secondary myopathy occurs with aging.  Treatment is the cautious replenishment of serum potassium.  A rebound effect may occur as intracellular potassium moves back to the extracellular environment.  Because of the risk of cardiac arrhythmias, treatment should take place in the setting of continuous cardiac monitoring.  Long-term pharmacologic treatment includes carbonic anhydrase inhibitors and potassium sparing diuretics.  Vigorous physical exertion and high carbohydrate meals should be avoided. 

Conclusions: Hypokalemic periodic paralysis should be included in the differential diagnosis of any patient presenting with acute paralysis and unchanged mental status. Because of the potential for life-threatening cardiac complications, prompt recognition and treatment is imperative.  Patient education regarding precipitating factors, in conjunction with pharmacotherapy, may mitigate morbidity and mortality.

To cite this abstract:

VanHook, CJ; Warner, B; Gould, J; Taylor, A . HYPOKALEMIC PERIODIC PARALYSIS: A RARE AND TREATABLE FORM OF ACUTE PROFOUND WEAKNESS. Abstract published at Hospital Medicine 2017, May 1-4, 2017; Las Vegas, Nev. Abstract 770. Journal of Hospital Medicine. 2017; 12 (suppl 2). https://www.shmabstracts.com/abstract/hypokalemic-periodic-paralysis-a-rare-and-treatable-form-of-acute-profound-weakness/. Accessed September 17, 2019.

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