renal hyperparathyroidism ( rhpt ) is a serious complication of long - term dialysis treatment . the european dialysis and transplant association ( edta ) report published in 1991 showed that up to 40% of patients undergo surgical treatment for rhpt after 15 years of dialysis . rhpt is a form of renal osteodystrophy that causes increased bone fragility , and in addition , it has also been reported that hypercalcaemia and hyperphosphataemia associated with rhpt induce ectopic calcification in the vascular walls and heart valves , thereby significantly affecting the patient 's survival prognosis [ 49 ] . in patients with severe rhpt refractory to medical treatment there are two types of such methods , percutaneous ethanol injection therapy ( peit ) and a parathyroidectomy ( ptx ) . determining which of these methods is the most appropriate intervention for individual cases is therefore a major issue for clinicians . peit is easy to perform on an outpatient basis ; however , it has been associated with a significant adverse event , namely adhesion formation . an indistinct margin of the parathyroid gland is often found during surgery following peit due to the firm fibrous membrane . ptx is considered to be the last treatment option in patients with severe rhpt resistant to medical treatment and peit . this study was conducted to determine whether similar results can be expected when ptx is performed in patients who underwent peit by investigating the effect of peit on subsequent ptx . the patients had a diagnosis of rhpt , for which surgery was indicated , from january 2004 to december 2005 . the subjects were divided according to whether they underwent peit ( peit group ) or not ( non - peit group ) . an analysis was performed to compare the pre- and postoperative biochemistry results as well as intact pth levels ( preoperative , postoperative and year 1 postoperatively ) , number of the parathyroid glands detected by ultrasonography , operation time , the amount of bleeding , the number of parathyroid glands removed , the total weight of the removed glands and the frequency of the postoperative complication of hoarseness . informed consent was obtained from all subjects . for comparisons of the peit and non - peit groups , the homogeneity of variance for each group was confirmed using the f - test , and testing was performed using student 's t - test . if neither group had a normal distribution , then the mann in addition , for the analysis using a 2  2 contingency table , such as testing for the frequency of postoperative complications and patients with high postoperative pth levels , fisher 's exact probability test was performed . the results were shown as mean  sd . a p - value < 0.05 was considered to be statistically significant . for comparisons of the peit and non - peit groups , the homogeneity of variance for each group was confirmed using the f - test , and testing was performed using student 's t - test . if neither group had a normal distribution , then the mann in addition , for the analysis using a 2  2 contingency table , such as testing for the frequency of postoperative complications and patients with high postoperative pth levels , fisher 's exact probability test was performed . there were 19 patients in the peit group and 61 in the non - peit group , with no significant difference in the background of patients in these groups . the operation time was significantly longer in the peit group , but no significant differences were noted in the amount of bleeding or the frequency of recurrent nerve paralysis ( table 1 ) . pre- and postoperative blood test results showed no significant difference to exist in the preoperative biochemistry results and intact pth levels ; however , the intact pth levels immediately following surgery were slightly higher in the peit group . no difference was noted in the intact pth levels between the peit and non - peit groups at 1 year after the operation . pg / ml on postoperative day 1 was significantly higher in the peit group ( table 1 ) . a comparison of patients who underwent one course of peit and those who underwent two or more courses of therapy revealed no difference in the number of the parathyroid glands removed , the total weight of the removed glands and the operation time , although the postoperative intact pth levels were found to be significantly higher in those who underwent two or more courses of peit ( table 2 ) . there were 19 patients in the peit group and 61 in the non - peit group , with no significant difference in the background of patients in these groups . the operation time was significantly longer in the peit group , but no significant differences were noted in the amount of bleeding or the frequency of recurrent nerve paralysis ( table 1 ) . pre- and postoperative blood test results showed no significant difference to exist in the preoperative biochemistry results and intact pth levels ; however , the intact pth levels immediately following surgery were slightly higher in the peit group . no difference was noted in the intact pth levels between the peit and non - peit groups at 1 year after the operation . pg / ml on postoperative day 1 was significantly higher in the peit group ( table 1 ) . a comparison of patients who underwent one course of peit and those who underwent two or more courses of therapy revealed no difference in the number of the parathyroid glands removed , the total weight of the removed glands and the operation time , although the postoperative intact pth levels were found to be significantly higher in those who underwent two or more courses of peit ( table 2 ) . peit and ptx are both options for the treatment of severe rhpt refractory to medical treatment . peit can be performed with minimal invasiveness and it is easily performed on an outpatient basis . however , its efficacy is somewhat uncertain in some patients . a previous study showed that patients in whom these intact pth levels sufficiently decreased to the target levels were those with a lower density of blood flow distribution in the parathyroid glands . although the therapeutic outcome of ptx has been reported to be reliable and stable , it is difficult to perform ptx following peit due to adhesion , which is a significant adverse event associated with peit . postoperative data were studied to assess the degree of difficulty of surgery due to adhesions associated with peit . there was no significant difference in the amount of bleeding , which is an index for the difficulty of surgery ; however , a significant difference was observed regarding the operation time . in addition , the postoperative intact pth levels were somewhat but not significantly higher in the peit group than in the non - peit group . these findings suggest that repeated peit damages the capsule of the parathyroid gland , thus causing the dissemination of hyperplastic parathyroid cells . some residual parathyroid tissue caused by adhesions and dissemination might exist during a parathyroidectomy , thus leading to higher postoperative intact pth levels . peit can be a useful strategy for controlling rhpt if it is performed for patients who are likely to respond to the therapy . however , based on the surgical outcomes for patients who underwent peit , repeated peit should be avoided and surgical treatment is preferable in patients who demonstrate a poor response to the initial peit . in conclusion , peit prior to a ptx can affect subsequent surgical outcomes due to associated adhesion and dissemination ; therefore , peit should be performed only for those who are likely to respond to the therapy , and repeated peit should be avoided . peit should be administered with a full understanding of its advantages and disadvantages . for patients with a possibility of either a decreased efficacy or lack of efficacy for peit ,