We reviewed 140 patients with 3-HPT who underwent PTX (n=148) during the study period. The limited PTX group consisted of 29 patients who underwent resection of one (n=12) or two (n=17) parathyroid glands. The 111 patients in the subtotal or total PTX group underwent 119 surgeries: subtotal PTX (n=104), total PTX with autograft (n=3), or reoperative PTX (n=12). Eight patients in the subtotal or total PTX group underwent 2 operations at our hospital: 7 after an initial 3.5 gland resection and 1 after a 2.5 gland resection. Two of these 8 reoperations were performed for recurrence due to a supernumerary gland. The 4 other patients who underwent reoperative PTX had their initial surgery at outside institutions, and all underwent a previous subtotal PTX per their operative note. The mean and median duration of follow-up for the entire cohort were 78.7 and 60.4 months, respectively (range 0.1 to 22.9 years), and greater than 6 month follow-up was available after all but 12 operations (92%) (). Overall, 94 patients (69%) had symptomatic 3-HPT—17 limited PTX patients (59%) and 77 subtotal or total PTX patients (70%) (P = 0.26).
summarizes patient demographics and characteristics. The limited PTX and subtotal/total PTX patients were comparable in terms of age, gender distribution, duration of dialysis, and time since renal transplant (). The two groups also had similar preoperative and follow-up serum calcium, iPTH, phosphate, and estimated creatinine clearance (eCrCl) levels (). At follow-up, the serum calcium, iPTH, and eCrCl measurements were significantly lower than the respective preoperative values, while the serum phosphate levels were significantly higher (by paired t test; ). Additional analysis showed a strong direct correlation between preoperative and follow-up eCrCl (Pearson r = 0.66, P < 0.001), but no significant relationship between follow-up calcium and iPTH levels, and CKD stage.
Preoperative and follow-up laboratory values
Analysis of surgical data demonstrated that operative times were similar for the limited PTX and subtotal/total PTX patients (144 ± 7 vs 135 ± 4 mins, respectively, P = 0.32). Thirty-four percent of limited resection cases utilized ioPTH monitoring while 51% of subtotal/total PTX cases were performed with ioPTH (P = 0.15). The limited group also had a mean parathyroid gland weight of 951 ± 143 mg which was comparable to the mean gland weight for subtotal or total PTX patients (1114 ± 113 mg, P = 0.48). For all patients, preoperative iPTH levels positively correlated with gland weight suggesting that heavier gland secrete more PTH (Pearson r = 0.50, P < 0.0001). When adjusting for outliers, the groups also had average lengths of stay that were similar (2.2 ± 0.3 vs 2.2 ± 0.1 days, respectively, P = 0.98). In 7% of limited resection patients and 19% of subtotal/total PTX patients, ectopic parathyroid glands were discovered during surgery (P = 0.16). These ectopic glands were intrathymic (n=8), intrathyroidal (n=3), retroesophageal (n=3), mediastinal (n=2), and undescended (n=1). As a result of intrathymic or missing inferior glands, 11% and 17% of limited resection and subtotal or total resection patients, respectively, underwent concurrent thymectomy during surgery (P = 0.73). The incidence of permanent hypocalcemia was 0% after limited PTX compared to 7% following subtotal or total PTX (P = 0.36). Furthermore, after subtotal PTX, two patients had transient hoarseness and one had pneumonia. One patient suffered a permanent recurrent laryngeal nerve injury during a reoperative PTX for recurrent 3-HPT.
When examining our primary and secondary outcome variables, cases of reoperative PTX were excluded from the analyses. Those patients with available information regarding their first operation (n= 8) were included in the outcomes analysis. In the first 6 months after PTX, 98% of all patients (126 of 128) were eucalcemic, and 86% of all patients (95 of 111) had normal iPTH levels for their CKD stage. The 2 patients who had persistent hypercalcemia underwent reoperative PTX with subsequent eucalcemia. After 6 months, recurrent hypercalcemia developed in 5% of all patients (7 of 128), and recurrent iPTH elevation occurred in 38% of all patients (35 of 91). Thus, 94% of all patients were eucalcemic at their most recent follow-up. The rates of all outcome variables were similar between patients who underwent limited PTX and those who had subtotal or total PTX (). Recurrent hypercalcemia in conjunction with an elevated iPTH level was observed in only 2 patients both of whom underwent initial subtotal PTX (and subsequent reoperative PTX). summarizes these results by CKD stage.
Outcomes following parathyroidectomy
Outcomes following parathyroidectomy
Logistic regression was then used to examine predictors of recurrent hypercalcemia or recurrent iPTH elevation. Based on the significance of the correlation coefficients (P
< 0.15), the variables that were included in the modeling of recurrent hypercalcemia included the duration of dialysis, pre-operative iPTH levels, post-operative CKD stage and creatinine level, complication occurrence, and ioPTH testing use. The type of parathyroidectomy performed (limited PTX vs. subtotal/total PTX) also was included because previous data have suggested that limited resection increases the risk of developing persistent or recurrent 3-HPT (9
). None of the variables examined were significant predictors of recurrent hypercalcemia, including the extent of resection (P
= 0.58). The most predictive variable was the occurrence of a complication which only trended toward significance as a negative predictor of recurrent hypercalcemia (P
=0.06). We then analyzed factors predictive of the recurrent iPTH elevation, both the pre-operative iPTH level and the one-week post-operative serum calcium level were found to be predictive of iPTH recurrence (P
<0.05 for both). The relationship of these associations was such that a higher pre-operative iPTH or one-week post-operative serum calcium increased the odds of developing recurrent iPTH elevation. The extent of operation again was not associated with the development of recurrent iPTH elevation (P