Sestamibi scintigraphy, topography, and histopathology of parathyroid glands in secondary hyperparathyroidism.

BACKGROUND: Several imaging techniques presently are available to assess the location of hyperplastic parathyroid glands. The purpose of the present study is to assess the place of dual-phase technetium Tc 99m-sestamibi (MIBI) scintigraphy in the preoperative localization of hyperplastic parathyroid glands in patients with severe secondary hyperparathyroidism (SHPT). METHODS: We studied 35 consecutive adult white hemodialysis patients undergoing a first parathyroidectomy after performing MIBI scintigraphy. Hyperplasia of the parathyroid glands was classified as diffuse (DH) or nodular (NH). Statistical analysis was conducted by comparing patients with MIBI-negative (no focal area of increased uptake) with MIBI-positive (> or = 1 focal area of increased uptake) results and stratifying parathyroid glands according to location (superior and inferior). RESULTS: MIBI scintigraphy showed focal areas of increased uptake in at least 1 gland in 25 patients (71.4%). Total number of focal areas of increased uptake was 42 of 121 glands removed (sensitivity, 34.7%; specificity, 100%). One hundred one glands showed NH and 20 glands showed DH. The 25 patients with MIBI-positive results had 85 pathological glands removed, and the 10 patients with MIBI-negative results had 36 pathological glands removed: in the former, most glands showed NH (77 of 85 glands; 90.6%), and in the latter, 24 of 36 glands showed NH (66.7%; P = 0.004 at chi-square test). The sensitivity of MIBI scintigraphy for distinguishing specific subtypes of hyperplasia was 37.6% (38 of 101 glands) for NH and 20.0% (4 of 20 glands) for DH (P = 0.0005). The following values were significantly greater in inferior compared with superior glands: (1) estimated weight (2.1 +/- 0.8 versus 1.6 +/- 1.2 g; P = 0.04), (2) percentage of MIBI positivity (34 of 42 inferior glands [80.9%] versus 8 of 42 superior glands [19.1%]; P = 0.0001), and (3) percentage of localization permitted by MIBI scintigraphy (34 of 63 inferior glands [54.0%] versus 8 of 58 superior glands [13.8%]; P = 0.0001). Thus, NH, although equally distributed between inferior (53 of 63 glands) and superior (48 of 58 glands) glands, showed a percentage of MIBI positivity significantly greater in inferior (34 of 53 glands [64.1%]) compared with superior glands (8 of 48 glands [16.7%]; P = 0.0001). CONCLUSION: MIBI scintigraphy did not show high sensitivity in identifying hyperplastic glands, although it was able to identify those with NH better than those with DH. Thus, MIBI scintigraphy has limited value preoperatively for patients with SHPT. Estimated weight, percentage of MIBI positivity, and percentage of localization permitted by MIBI scintigraphy were significantly greater in inferior glands.

Calcitriol pulse therapy and histology of parathyroid glands in hemodialysis patients.

BACKGROUND: Calcitriol pulse therapy (CPT) is considered the most appropriate treatment of secondary hyperparathyroidism (sHPTH). This treatment inhibits parathyroid hormone (PTH) synthesis and secretion, suppresses parathyroid cell proliferation and controls parathyroid gland growth. However, not much is known about the effect of such therapy on parathyroid morphology. METHODS: To investigate this, we studied all first parathyroidectomies (PTx, either total or subtotal) effected in 30 hemodialysis (HD) patients referred to our surgery department by five regional dialysis units in 2000-2001. Six patients were excluded from the study because of either the persistence or the precocious relapse (in the 1st 6 months post-operation) of sHPTH. Twenty-four HD patients were considered eligible as four parathyroid glands were ablated in each patient; 96 glands were then examined histologically. The cohort consisted of 16 males and 8 females with a mean age of 54 +/- 13 SD yrs (range 20-73) and a dialysis duration of 142 +/- 71 months (range 14-289). Data concerning calcitriol treatment (doses, administration route and treatment duration) were collected for each patient. The patients were subdivided into two groups according to the treatment effected in the months preceding PTx: group A (n=13), treated by either intravenous (i.v.) (n=12) or per os (n=1) CPT, and group B (n=11), not treated at all with calcitriol or vitamin D sterols. Parathyroid gland morphology and the parenchymal cell distribution of the parathyroid glands were evaluated by a semiquantitative assessment. Serum intact PTH (iPTH), alkaline phosphatase (AP), calcium (Ca) and phosphate (P) levels were studied pre- and post-PTx. RESULTS: Chief cells (CC) were found in all glands, either alone or associated with oxyphil cells (OC). OC were present in 13 of 24 patients (54%); however, it must be underlined that they were present 12 times in group A parathyroid glands (92%), and only once in group B (9%) (p<0.01). Nodular hyperplasia was found in 71% (17/24) of patients: 92% (12/13) in group A, and 45% (5/11) in group B (p<0.05). There were no significant differences in age, gender, dialysis duration, serum levels of iPTH, AP, Ca and P levels between the two groups. CONCLUSIONS: There was a strong association between OC presence in parathyroid glands and CPT. Furthermore, nodular hyperplasia appeared to be associated significantly with CPT. There is still speculation regarding the meaning of these CPT effects on parathyroid gland histology and consequently on sHPTH pathophysiology.