A case of thyrotoxic periodic paralysis in a 24-year-old male with hyperthyroidism is presented. Clinical manifestations included progressive symmetrical weakness that led to flaccid paralysis due to hypokalemia with concurrent thyrotoxicosis. Intravenous administration of potassium chloride resulted in complete regression of the symptoms of muscle weakness and paralysis. Hypokalemic periodic paralysis is an uncommon complication of thyrotoxicosis, which primarily occurs in Orientals, with a high male predominance, and has rarely been described in Caucasians.U radu je prikazan 24-godišnji muškarac s napadajem periodične paralize u hipertireozi. Prikazan je bolesnik s progresivnom simetričnom slabošću koja je dovela do mlohave paralize uslijed hipokalijemije tijekom tireotoksikoze. Nakon parenteralnog dodatka kalija (intravenskom primjenom kalijevog klorida) došlo je do potpunog povlačenja simptoma mišićne slabosti i paralize. Hipokalijemična periodična paraliza rijetka je komplikacija tireotoksikoze opisana u stanovnika Dalekog Istoka, i to prvenstveno u mlađih muškaraca, a iznimno se rijetko javlja u bijelaca

Branko Ostrički

Dijana Zelenika

Jadranka Morović-Vergles

Krešimir Galešić

Mirko Škoro

English

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Acta clin Croat 2002; 41:99-102 Case Report99THYROTOXIC PERIODIC PARALYSIS: A CASE REPORTJadranka MoroviÊ-Vergles1, Branko OstriËki1, Kreπimir GaleπiÊ1,Mirko ©koro1 and Dijana Zelenika21Department of Medicine, Dubrava University Hospital, Zagreb, Croatia, and 2Department of Medicine,Mostar Clinical Hospital, Mostar, Bosnia and HerzegovinaSUMMARY ∑ A case of thyrotoxic periodic paralysis in a 24-year-old male with hyperthyroidism ispresented. Clinical manifestations included progressive symmetrical weakness that led to flaccidparalysis due to hypokalemia with concurrent thyrotoxicosis. Intravenous administration of potas-sium chloride resulted in complete regression of the symptoms of muscle weakness and paralysis.Hypokalemic periodic paralysis is an uncommon complication of thyrotoxicosis, which primarily occursin Orientals, with a high male predominance, and has rarely been described in Caucasians.Key words: Thyrotoxicosis, complications; Hypokalemia, complications; Paralysis, etiology; Case reportCorrespondence to: Professor Jadranka MoroviÊ-Vergles, M.D., Ph.D.,Department of Medicine, Dubrava University Hospital, Avenija Gojka©uπka 6, HR-10000 Zagreb, CroatiaE-mail: jmorovic@kbd.hrReceived January 18, 2002, accepted April 26, 2002IntroductionPeriodic paralysis is a rare complication of hyperthy-roidism1. It has been described in diverse racial and eth-nic groups2-4, predominantly in Oriental and Latin-American young males5-7. Thyrotoxic periodic paralysis(TPP) is a disorder characterized by concurrent thyrotoxi-cosis, hypokalemia and progressive symmetrical weaknessleading to paralysis of extremities and other musclegroups. In TPP, hypokalemia is usually associated with hy-pophosphatemia and mild hypomagnesemia4. The patho-physiology of TPP remains largely unexplained and con-troversial.In this report, clinical and biochemical findings in ayoung man with hyperthyroidism who experienced threeattacks of periodic paralysis are described. All three attacksoccurred during or shortly after sleep. The first two attacksof muscle weakness required no medical intervention andresolved spontaneously. On the third attack, however, thepatient was admitted to the hospital for complete muscleparalysis, which regressed upon intravenous administra-tion of potassium chloride. The attacks of TPP ceasedcompletely with resolution of the hyperthyroidism.Case ReportA 24-year-old male was admitted to the EmergencyUnit for myalgia and abrupt onset of tetraparesis afterseveral hours of sleep. History data revealed similar attacksto have occurred on two occasions in the past four months,during the night or at dawn, which spontaneously re-gressed within a few hours. The patient had not beenhospitalized before. Six months before, the patient hadexperienced tremor of his hands, hyperhidrosis, palpita-tions, nervousness, and hyperorexia with weight loss.Three months after the onset of these symptoms, the di-agnosis of hyperthyroidism was made and therapy withmetamizole was initiated. After seven days, this therapyhad to be discontinued due to pronounced side effects(polyarthralgia, myalgia, generalized urticaria), and pro-pylthiouracil was introduced, which was well tolerated bythe patient. The patient had normal appetite, normal uri-nation, and frequent evacuation (up to 4 loose stoolsdaily). He smoked about 20 cigarettes a day, and used noalcohol drinks.MoroviÊ-Vergles J. et al Thyrotoxic periodic paralysis100 Acta clin Croat, Vol. 41, No. 2, 2002On examination at the Emergency Unit, the patientwas immobile due to tetraparesis, conscious, moist skin,afebrile, eupneic. There were no cranial nerve symptoms.The thyroid was enlarged and insensitive on inspectionand palpation. Rhythmical heart action, c/p 96/min, bloodpressure 130/80 mm Hg. Normal respiratory sound overthe lungs. The abdomen soft, insensitive on palpation, noorganomegaly. Mild edema of the metacarpophalangealarticulation I. Flaccid tetraparesis.Laboratory findings on admission: one-hour erythro-cyte sedimentation rate (ESR) 3; complete blood count(CBC), blood glucose (BG), creatinine, transaminases,bilirubin, creatine phosphokinase (CPK), and lactic de-hydrogenase (LDH) were normal; potassium (K) 1.5(normal range 4.1 ∑ 5.5) mmol/L.Laboratory findings during hospitalization: phospho-rus (P) 2.11 (0.65 ∑ 1.62) mmol/L; magnesium (Mg) 0.62(0.45 ∑ 1.15) mmol/L; calcium (Ca) 2.52 (2.25 ∑ 2.75)mmol/L; chloride (Cl) 101 (95 ∑ 105) mmol/L. Electro-lytes in 24-hour urine: potassium (K) 140 (60 ∑ 80) mmol/DU.Arterial blood gases and acid ∑ base balance were withinthe normal range. Urine: pH 5.0; specific weight 1.025;sediment normal; 24-hour urine protein negative. Thyroidhormones: thyroxine (T4) 185 (71 ∑ 141) nmol/L; triiodot-hyronine (T3) 8.1 (1.5 ∑ 2.6) nmol/L; thyroid-stimulatinghormone (TSH) <0.02 (0.27 ∑ 4.68) mU/L, indicatinghyperthyroidism. Cortisol, aldosterone and plasma reninactivity were within the reference values. Waaler-Rose, la-tex and dsDNA tests were negative. Thyroid ultrasonog-raphy (US) indicated diffuse goiter; computed tomography(CT) of adrenal glands showed no pathologic alterations;upper abdomen US was normal; electromyoneurography(EMNG) of upper and lower extremities revealed no myo-pathic cause; gastroscopy and rectoscopy yielded normalfindings, and so did stool parasitology and bacteriology.Upon admission, the patient received 40 mmol potas-sium chloride i.v., which resulted in complete regressionof tetraparesis. The treatment of hyperthyroidism wascontinued by propylthiouracil. On control outpatient ex-aminations after restitution of euthyroidism, the patientwas subjectively well, free from TPP attacks, and withnormal serum potassium values.DiscussionMost common clinical manifestations of hypokalemia(serum potassium <3.5 mmol/L) include neuromuscular(muscle weakness, rhabdomyolysis, ileus), cardiovascular(ventricular arrhythmias, hypotension, arrest), renal (poly-uria, nocturia), and metabolic (hyperglycemia) distur-bances. Hypokalemia can be induced by various causes: 1)reduced potassium intake (anorexia nervosa, deficientnutrition in alcoholics); 2) gastrointestinal losses (vomit-ing, diarrhea, laxative abuse, fistulas, villous adenoma,ureterosigmoidostomy); 3) intracellular potassium shift(metabolic alkalosis, insulin and adrenergic agonist over-dosage, hypokalemic periodic paralysis, theophylline,barium and toluene intoxication); 4) renal losses (diuret-ics, aminoglycosides, penicillin antibiotics, primary andsecondary hyperaldosteronism, Bartter’s syndrome, exces-sive intake of exogenous mineralocorticoids, Cushing’ssyndrome, ectopic ACTH secretion, renal tubular acido-sis, leukemias, magnesium depletion); and 5) some heredi-tary disorders (familial hypokalemic periodic paralysis,congenital androgenital syndrome, Little’s disease, familialinterstitial nephritis).We have presented a 24-year-old man admitted to theDepartment of Medicine Emergency Unit and transferredto the ward for tetraplegia associated with pronouncedhypokalemia (potassium level, 1.5 mmol/L). Hyperthy-roidism had been diagnosed on an outpatient basis threemonths before the present admission, and the patientsustained episodes of muscle weakness progressing tocomplete paralysis of the extremities on three occasions.The attacks occurred immediately after sleep and re-gressed spontaneously in several hours on two occasions.The third attack, which occurred following discontinua-tion of metamizole therapy, required medical attentionand the patient was admitted to our emergency room. Onhis presentation to the emergency room, the diagnosis ofthyrotoxic periodic paralysis was initially failed, however,the accurate diagnosis of thyrotoxic hypokalemic periodicparalysis (THPP) was subsequently made. THPP is a rarecomplication that sporadically occurs, mostly in youngmales of Asian and Latin-American origin2,4-7, and con-siderably less commonly in Caucasians and blacks3,8-10.According to the literature data available, the incidenceof THPP in hyeperthyroidism patients ranges from 0.1%- 0.2% in American Caucasians10 to 4.3% in Japanese5 .The male to female ratio is 20:15.Clinically, THPP cannot be differentiated from famil-ial periodic paralysis, although the former predominantlyaffects males, rarely is associated with positive family his-tory, and develops later in life. There was no case of peri-odic paralysis among close relatives of our patient. Theinitial clinical manifestations of THPP include myalgiaMoroviÊ-Vergles J. et al Thyrotoxic periodic paralysisActa clin Croat, Vol. 41, No. 2, 2002 101and progressive muscle weakness with exacerbation to pa-ralysis of the extremities. Laboratory findings show hy-pokalemia (100%), hypophosphatemia (80%), and mildhypomagnesemia4. Rebound hyperkalemia occurs in some40% of patients4. In our patient, marked hypokalemia wascorrected by 40 mmol potassium chloride i.v. (the levelsof magnesium and phosphorus were not determined inEmergency Room). On day 2 of admission, however, thelevels of potassium and magnesium were within the nor-mal limits. The finding of mild hyperphosphatemia, re-corded on day 2 of admission, is consistent with literaturedata on mild to moderate hypophosphatemia being re-corded when phosphorus was determined within 1.5 hourfrom admission to hospital, or while the level of potas-sium was still low; upon paralysis resolution, the level ofphosphorus returned to normal or was slightly elevated4.THPP usually occurs in patients with Graves’ disease,however, any cause of hyperthyroidism including exces-sive use of a substitute may lead to this disorder. The clini-cal and laboratory parameters of hyperthyroidism may belatent or very discrete. In our patient, hyperthyroidism wasdiagnosed three months before his admission to the De-partment and showed overt clinical manifestations. Theattacks of periodic paralysis, such as those that occurredin our patient, may be precipitated by the rest (sleep). TPPattacks after several hours of sleep are usually preceded byextreme physical activity or excessive carbohydrate in-take10. Attacks of periodic paralysis may (although notalways) be experimentally induced by a provocation testwith glucose (3 g/kg) and insulin (0.1 IU/kg i.v.)11.Pathophysiologically, various attempts have beenmade to explain THPP, e.g., by the intracellular shift ofpotassium due to thyroxine-stimulated enhancement ofK-Na ATP-ase activity on cellular membrane, or by dy-namic disturbances, or by some morphological features ofthe neuromuscular unit itself2,12.Light microscopy of the muscle biopsy specimens re-vealed changes in terms of sarcolemmic nuclear prolifera-tion, muscle fiber atrophy, fatty infiltration and vacuola-tion, while no changes could be detected in one fourth ofpatients. Electron microscopy generally showed vacuola-tion (90%), mitochondrial abnormalities (100%), accumu-lation of glycogen granules (100%), myofibril interruption(50%), and T-system changes (40%). These alterations didnot correlate with the severity of muscle weakness13. Inour patient, EMNG of both upper and lower extremitiesshowed no deviations from normal, thus muscle biopsywas not considered necessary. Quadriplegia was promptlyreversed by correction of hypokalemia (40 mmol potas-sium chloride administered as 2-hour i.v. infusion). Dur-ing the first few days of his hospital stay, renal loss ofpotassium (hyperkaluria) was recorded, along with clini-cally and laboratory overt hyperthyroidism. Serum andurine values of other electrolytes, as well as blood pressure,diuresis, arterial blood pH, urine pH, specific weight andsediment, cortisol, aldosterone and plasma renin activitywere within the normal limits. The finding of transitoryhyperkaluria could not be explained (the increased intra-cellular concentration of potassium in the main cells of therenal collecting ducts may stimulate its secretion by elec-trochemical gradient through specific potassium channelsin the luminal membrane), however, the available litera-ture provides no data on transient hyperkaluria followingTHPP attack. Our patient did not develop rebound hy-perkalemia after parenteral potassium substitution (per-haps just these patients experiencing transient hyperkalu-ria after THPP attack and substitution therapy with po-tassium are not prone to the development of reboundhyperkalemia!?). The episodes of paralysis are reduced bypotassium substitution, and attacks can be prevented bythe administration of beta-blockers, potassium substitu-tion and spironolactone until restitution of euthyroidism8.Definitive treatment of thyrotoxic periodic paralysisshould be directed at the establishment of euthyroid state,and it is usually sufficient to prevent the occurrence ofspontaneous attacks. Indeed, in our patient, serum levelsof potassium normalized with the introduction of propy-lthiouracil and restitution of euthyroidism, even withoutpotassium substitution and with no record of hyperkaluria.ConclusionOn differential diagnosis, thyrotoxic hypokalemic pe-riodic paralysis should be considered in any acute episodeof motor paralysis in young patients, especially males.Although the pathogenesis of this dramatic disorder hasnot yet been fully elucidated, and the reason for sexual andracial predisposition remains unknown, there is strongevidence that successful therapy for hyperthyroidism leadsto regression of all clinical and laboratory parameters ofthe disorder, as also observed in our patient. This is a typi-cal case of thyrotoxic periodic paralysis in an epidemio-logical group which, to our knowledge, has not yet beendescribed.MoroviÊ-Vergles J. et al Thyrotoxic periodic paralysis102 Acta clin Croat, Vol. 41, No. 2, 2002References1. MILLIKAN CH, HAINES SF. The thyroid gland in relation toneuromuscular disease. Arch Intern Med 1953;92:5-39.2. FERREIRO J, ARGUELLES DJ, RAMS H Jr. Thyrotoxic peri-odic paralysis. Am J Med 1986;80:146-50.3. KELLY TM, FISHMAN LM. Thyrotoxic periodic paralysis in ablack male. J Endocrinol Invest 1984;7:517-9.4. MANOUKIAN MA, FOOTE JA, CRAPO LM. Clinical andmetabolic features of thyrotoxic periodic paralysis in 24 episodes.Arch Intern Med 1999;159:601-6.5. SHIZUME K, SHISHIBA Y, KUMA K, NOGUCHI S, TAJIRIJ, ITO K, NOH JY. Comparison of the incidence of associationof periodic paralysis and hyperthyroidism in Japan in 1957 and1991. Endocrinol Jpn 1992;39:315-8.6. SAEIAN K, HECKERLING PS. Thyrotoxic periodic paralysis ina Hispanic man. Arch Intern Med 1998;148:708.7. McFADZEAN AJS, YEUNG R. Periodic paralysis complicatingthyrotoxicosis in Chinese. Br Med J Clin Res 1967;1:451-5.SaæetakTIREOTOKSI»NA PERIODI»NA PARALIZA: PRIKAZ SLU»AJAJ. MoroviÊ-Vergles, B. OstriËki, K. GaleπiÊ, M. ©koro i D. ZelenikaU radu je prikazan 24-godiπnji muπkarac s napadajem periodiËne paralize u hipertireozi. Prikazan je bolesnik s progresivnomsimetriËnom slaboπÊu koja je dovela do mlohave paralize uslijed hipokalijemije tijekom tireotoksikoze. Nakon parenteralnogdodatka kalija (intravenskom primjenom kalijevog klorida) doπlo je do potpunog povlaËenja simptoma miπiÊne slabosti iparalize. HipokalijemiËna periodiËna paraliza rijetka je komplikacija tireotoksikoze opisana u stanovnika Dalekog Istoka, i toprvenstveno u mlaih muπkaraca, a iznimno se rijetko javlja u bijelaca.KljuËne rijeËi: Tireotoksikoza, komplikacije; Hipokalijemija, komplikacije; Paraliza, etiologija; Prikaz sluËaja8. OBER KP. Thyrotoxic periodic paralysis in the United States.Report of 7 cases and review of the literature. Medicine (Baltimore)1992;71:109-20.9. CELANI MF, BONATI ME, CAVALLI M. Hypokalemic thy-rotoxic paralysis in Caucasian male with Graves disease. JEndocrinol Invest 1995;18:228-31.10. KELLY DE, GHARIB H, KENNEDY FP, DUDA RJ, McMA-NIS PG. Thyrotoxic periodic paralysis. Report of 10 cases andreview of electromyographic findings. Arch Intern Med 1998;149:2597-600.11. SCHULZE-BONHAGE A, FIEDLER M, FERBERT A. Pe-riodic paralysis as the first manifestation of hyperthyroidism. DtschMed Wochenschr 1996;121:1498-500.12. ACKERMAN MJ, CLAPHAM DE. Ion channels: basic scienceand clinical disease. N Engl J Med 1997;336:1575-86.13. CHEAH JS, TOCK EP, KAN SP. The light and electron micro-scopic changes in the skeletal muscles during paralysis in thyro-toxic periodic paralysis. Am J Med Sci 1975;296:365-74.

Tireotoksična periodična paraliza: prikaz slučaja

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