Pharmacological Sciences Management of thyrotoxic crisis

1 European Review for Medical and Pharmacological Sciencesgoiter. There is no clear cut off value of cir-culating thyroid hormones (TH) defining thethyroid storm, since the results of laboratorytests show, in most cases, similar serum levelsof TH to those observed in uncomplicatedthyrotoxicosis2. Nevertheless, the rapidrecognition of the thyrotoxic crisis and theinstitution of immediate drug therapy is im-portant in limiting the morbidity and mortal-ity associated with this condition3,4. It is diffi-cult to estimate the exact prevalence of thy-roid storm, but it may account for <1-2% ofhospital admissions for thyrotoxicosis5.

2 Themortality of this condition is still high, rang-ing from 20 to 30% thyrotoxic crisis typically occurs inpatients in whom preexisting hyperthy-roidism has not been diagnosed or has beentreated insufficiently. The crisis has anabrupt onset, and is almost always evokedby a precipitating factor. How such precipi-tating events result in an accentuation ofthyrotoxicosis is unclear. A further increaseof circulating TH s levels or an increased re-ceptor occupancy have been advocated2. Asthere are no TH s serum levels above whichthyroid storm inevitably occurs, it is possi-ble that the magnitude and the steepness ofthe hormone increase may be more impor-tant than the absolute values of circulatingTH s levels1,6.

3 Other possible mechanismsexplaining the progression from uncompli-cated thyrotoxicosis to thyroid storm in-clude an increase of tissue iodothyroninelevels or an enhancement of the cellular re-sponse to TH. Many symptoms and signs of the thyrotox-ic crisis result from a concomitant sympa-thoadrenal hyperactivity, although the con-69 Abstract. The thyrotoxic crisis is amedical emergency caused by an exacerbationof the hyperthyroid state characterized by de-compensation of one or more organ recognition and aggressive treatment arefundamental in limiting the morbidity and mor-tality associated with this condition.

4 The crisishas an abrupt onset, and is evoked by a precip-itating factor such as infectious diseases, ke-toacidosis, acute trauma, thyroidal surgery,131-I radio-metabolic treatment, administrationof iodine-containing materials (amiodarone),parturition. The clinical picture is characterizedby four main features: fever, tachycardia orsupraventricular arrhythmias, central nervoussystem symptoms and finally gastrointestinalsymptoms. The diagnosis of thyrotoxic crisesis often made on the basis of clinical findingsalone, since it is difficult in most emergencydepartments to obtain rapid confirmatory labo-ratory or nuclear medicine tests.

5 The ultra-sound thyroid scan, if available in the emer-gency room, may suggest an hyperthyroidstate showing typical images of Basedow s dis-ease or nodular goiter with their characteristiccolor-Doppler pattern of hyperactivity, easilydistinguishable from a normal gland. The prin-ciples of thyroid storm treatments are: reduc-tion of circulating TH s levels; inhibition of theperipheral effects of circulating thyroid hor-mones (TH); supportive care, in order to re-verse systemic decompensation and treatmentof the underlying precipitating Words: Thyrotoxicosis, Thyroid storm, Emergency, Manage-ment, thyrotoxic crisis , or thyroid storm, is alife threatening exacerbation of the hyper-thyroid state characterized by decompensa-tion of one or more organ systems1.

6 Usuallyit complicates Graves disease, but sometimesit occurs in association with toxic nodular2005; 9: 69-74 Management of thyrotoxic crisisA. MIGNECO, V. OJETTI, A. TESTA, A. DE LORENZO*, N. GENTILONI SILVERID epartment of Emergency Medicine, Catholic University - Rome (Italy)*Department of Human Nutrition, University of Tor Vergata - Rome (Italy)70centrations of catecholamines in both plasmaand urine are normal or even low in hyper-thyroidism7. However, it is known that TH in-crease cellular adrenoceptor expression ormodify postreceptor pathways leading to atissue hypersensitivity to catecholamines8, precipitating events are infectiousdiseases, ketoacidosis, acute trauma, vigorouspalpation of the thyroid gland, thyroidalsurgery, 131-I radio-metabolic treatment, ad-ministration of iodine-containing materials(iodinated contrast dyes, amiodarone)

7 , partu-rition, toxemia of pregnancy, withdrawal ofantithyroid medication, cerebrovascular acci-dents, pulmonary embolism, acute heart fail-ure and hypoglicemia2. Rarely, no precipitat-ing event is presentation and diagnosisThe clinical picture of the thyroid stormis characterized by four main features: (1)fever10,11, (2) sinus tachycardia or a varietyof supraventricular arrhythmias (paroxys-mal atrial tachycardia, atrial flutter and atri-al fibrillation), often accompanied by vari-ous degrees of congestive heart failure7,12,(3) central nervous system symptoms (agita-tion, restlessness, confusion, delirium andcoma)13-15, and finally (4) gastrointestinalsymptoms, in particular vomiting, diarrhea,intestinal obstruction16,17.

8 Unexplained jaun-dice is suggestive for thyroid storm, but is apoor prognostic sign3,18. Dehydration withelectrolytes imbalance is another frequentfeature. Other typical symptoms and signsof thyrotoxicosis may complete the clinicalpresentation (goiter, ophtalmopathy,tremor, hyperreflexia, Plummer s nail, sys-tolic hypertension). Younger patients oftenpresent sympathetic related symptoms,while older one frequently show cardiovas-cular dysfunctions19. Atypical presentations,such as normothermic crisis , hepatic failureor apathetic storm (extreme weakness) havebeen storm is not an entity distinct fromthyrotoxicosis, but rather one end of a spec-trum of severity of hyperthyoridism.

9 Burchand Wartofsky s scoring system (Table I) ishelpful in distinguishing thyroid storm, im-pending storm and uncomplicated thyrotoxi-cosis21. Nevertheless, the distinction betweensevere but compensated thyrotoxicosis com-plicated by other serious diseases (pulmonaryembolism, toxemia, acute heart failure) andthyroid storm precipitated by these diseasesis not possible. The differentiation betweenA. Migneco, V. Ojetti, A. Testa, A. De Lorenzo, N. Gentiloni SilveriTable and Wartofsky s scoring systemParametersScoring systemTThheerrmmoorreegguullaattoorryy ddyyssffuunnccttiioonnOral temperature( F) ddyyssffuunnccttiioonnTachycardia90-1095 110-11910120-12915130-13920>14025 Congestive heart failureAbsent0 Mild (pedal edema)5 Moderate (bibasal rales)10 Severe (pulmonary oedema)15 Atrial fibrillationAbsent0 Present10 CCeennttrraall nneerrvvoouuss ssyysstteemm ssyymmppttoommssAbsent0 Mild agitation10 Moderate (Delirium, psychosis, 20extreme lethargy)Severe (Seizure, coma)

10 30 GGaassttrrooiinntteessttiinnaall //hheeppaattiicc ddyyssffuunnccttiioonnAbsent0 Moderate (Diarrhea, nausea, 10vomiting, abdominal pain)Severe (Unexplained jaundice)20 PPrreecciippiittaattiinngg eevveennttAbsent0 Present10A cumulative score system of 45 or more is highly sug-gestive of thyroid storm; 25-44 is suggestive of impend-ing storm and a score below 25 is unlikely to representthyroid storm. Modified fromBurch HB, Wartofsky treating thyrotoxicosis. Endocrinol Metab ClinNorth Amer 1993; 22: Since the mortality of the thyrotoxic crisisis high, and the confirmation of the diagnosismay be difficult or delayed, treatment shouldbe initiated once thyroid storm is suspectedon clinical should be admitted in the Inten-sive Unit principles of thyroid storm treatmentsare: (1) lower circulating TH s levels; (2)block peripheral effects of circulating TH.