MIBI scintigraphy, indicators of cell proliferation and histology of parathyroid glands in uraemic patients.

BACKGROUND Although scintigraphy with (99m)Tc-sestamibi (MIBI) has been used to localize parathyroid glands prior to surgery for hyperparathyroidism, using it to evaluate parathyroid function remains controversial. The purpose of this study was to evaluate the possible association of MIBI uptake with gland weight, histological pattern and proliferative activity of parathyroid cells. METHODS We studied 18 patients with secondary hyperparathyroidism (SHP); mean age 38+/-3 years, 55% female, mean time on haemodialysis 7.7+/-0.9 years. All patients had parathyroidectomy (PTx). The weights of the removed glands were estimated, and parathyroid hyperplasia was classified as diffuse (n = 28) or nodular (n = 29). The expression of proliferative cell nuclear antigen (PCNA) was evaluated by immunohistochemistry. Before PTx, all patients underwent MIBI evaluation and were categorized using a 0-3 uptake scoring system. Low uptake (scores of 0 and 1) was seen in 39 glands and high uptake (scores of 2 and 3) in 18. RESULTS Estimated gland weights, percentage of nodular hyperplasia and PCNA expression were greater in glands with high MIBI scores than in those with low scores (P<0.01). In glands with nodular hyperplasia, PCNA expression was higher (318+/-66 cells/mm2) than in those with diffuse hyperplasia (104+/-16 cells/mm2; P<0.001). CONCLUSIONS High MIBI scores were associated with high estimated gland weight, degree of cell proliferation and presence of nodular hyperplasia. MIBI scintigraphy is useful in clinical practice for localizing parathyroid glands, and it could guide the management of SHP by indicating the degree of its severity.