RESUMEN
BACKGROUND: Sensitivity and specificity of the most widely employed techniques of parathyroid glands localization, namely echography and scintigraphy, are mostly obtained with short-term follow-up data and do not underline the existence of a methodological problem. As a matter of fact, both methods identify only pathological glands, with no "normal" results; therefore "true negatives" cannot be obtained. Aim of our study was to compare, by means of a statistically appropriate approach, the results of echography, scintigraphy and surgery with the data obtained after a mid term follow-up period, enabling us to discover all parathyroid glands. METHODS: Twenty six consecutive dialysis patients (14M/12F; age 50+/-12 years) underwent echography and scintigraphy immediately before a total parathyroidectomy with autotransplantation and were followed-up for 6 months to recognize all the existing glands (PTH levels and scintigraphy). RESULTS: Total identified glands were: 73 by scintigraphy, 86 by echography, 99 by surgery and 103 by follow-up data. The concordance indexes (K0) between the number of glands effectively present in the individual patient (follow-up data) and those identified with each method were rather low with scintigraphy (0.071) and echography (0.218), and acceptable (0.578) with surgery. The number of patients correctly classified was: 9/26 (34,6%) with scintigraphy, 13/26 (50%) with echography and 22/26 (85%) with surgery. Finally, the number of wrongly identified glands (from zero to three) in each patient was similar with scintigraphy (65,4%) and echography (50%) and significantly better with surgery (15,6%; p<0.01). CONCLUSIONS: The most reliable technique to identify parathyroid glands in uremic subjects is surgery, nonetheless a meticulous clinical follow-up is necessary to recognize all of them.