The Mechanism Of Dexamethasone Applied To Preoperative Preparation For Primary Hyperthyroidism

The incidence of primary hyperthyriodism is relatively higher, mostly occuring in the age group of 20-40. The rate of occurence is on rise, which may be attributed to modern lifestyles.Surgical technique have evolved to be one of the mainstays of treatment of patients with primary hyperthyriodism and practised widely in our country and aboard. The postoperative complication rate has decreased steeply in recent years, but still Thyroid storm is considered the nightmare of a surgeon. With the use of iodine and ATD, the incidence of thyroid crisis is lowered and is accepted as safe procedure but the time taken for preparation is the major drawback. Control of hyperthyroidism using ATDsometime will take more than two months. In addition, it is intoleratable to some patients due to allergic reaction to the medicine or due to leukopenia etc. There are a lot of research reports in both in China and abroad citing propanolol as the fast operative preparation. However, propanolol can only control the cardio-vascular (eg.palpitation) and neuromuscular (eg. nervousness, irritability, tremor etc.) symptoms, affecting thyroxine level very little, and the occurrence higher rate of the thyroid crisis. In addition, it still has some drawbacks and currently not accepted widely.Although the traditional preoperative preparation of primary hyperthyroidism is applicable but it not only cause the patient's burden of mental state but also cause heavy economic burden to the patient party. To study the method of short and valid for preoperative preparation also cause confusion. Dexamethasone applied before operation as preoperative preparation for primary hyperthyroidism is testified a safe and effective method. However, the mechanism that Dexamethasone applied before operation, as preoperative preparation for primary hyperthyroidism hasn't been get to clarify effectively. As to clarify it's mechanism which is carried out on the first step of research, the level of hormone is determined, and mechanism of the hormone conversion is investigated by observing the change of TT3, TT4, FT3, FT4, rT₃, TSH on the hospitalized patients, after the first and the third dose of dexamethasone. This research may provide the theories for curing this disease and expand the application of thismethod in the future .Materials and methods53 cases of primary hyperthyroidism from September 2003 to November 2004 were collected. All the patients were from the Department of General Surgery of the first Affiliated hospital, Zheng Zhou University and each patient has the all detailed clinical data. We observed the change of TT3, TT4, FT3, FT4, rT3, TSH on the hospitalized patients, after the first and the third dose of dexamethasone. Before operation, Lugol solution used (lOgetts/time, 3times/d) for 10 days. On the 8th day, dexamethasone (20mg) was added to 500ml (lOOg/L) and consecutively used for 3 days before operation. On the morning of the day before operation, if the patients' heart rate was still over 90 beats/min, we gave propanolol 10-20mg 6 hourly to control the heart rate below 90 beats/ min, the last time taking medicine on 1-2 hours before operation. The data were analyzed by softwere spsslO. 0,T-Test was used."p<0.05"was considered as level of tests.Results1. After the application of dexamethasone for the first time, the clinical symptom, the heart rate and the basal metabolism rate of patients were all to start alleviate application; after applying three times, the clinical symptom, the heart rate and the basal metabolism rate of patients were ability to be subjected to surgical operation. 2.There were no any complications, such as thyroid crisis occurredduring in this series.3.FT3 and TT3 fell to normal value after dexamethasone 20mg was used first dose. (p<0.05).4. FT3 and TT3 fell to normal value after dexamethasone 20mg was used third dose. (/?<0.05).5. FT4 and TT4 fell to normal value after dexamethasone had been used for first dose. (p<0.05).6. FT4 and TT4 fell to normal value after dexamethasone 20mg was used third dose. (p<0.05).7.rT3 increases obviously high(p<0.05) after dexamethasone had been used for 3 days.Conclusion1. Application of Dexamethasone before operation as preoperative preparation for primary hyperthyroidism, not only improves the clinical symptom of patients, but also the level of thyroxine decreases. It proves that application of dexamethasone before operation as preoperative preparation for primary hyperthyroidism is safe.2. After Dexamethasone had been used for 3 days, TT3, TT4 gradually fell to normal value.It hintes that Dexamethasone can ease the symptoms of high TT3, TT4;3. After application of Dexamethasone before operation as preoperative preparation for primary hyperthyroidism, FT3, FT4 quickly fell tonormal value. It plays a important role in the perioperative period ofprimary hyperthyroidism. 4. After Dexamethasone had been used for 3 days, not only TT3^ TT4fell to normal value, but also FT3^ FT4 fell to normal value. BothTT3 ^ TT4 and FT3 ^ FT4 had a same direction of change. It hintesFT3 n FT4 to take place the decomposition metabolism; 5.After Dexamethasone had been used for 3 days, rT3 increasedobviously. It suggests that FT3 and FT4 with biology activity partresolved into rT3, which has no biology activity.