Biochemical evidence in favor of revising Cortina criteria.

There is evidence that the Cortina criteria for the cure of acromegaly are not strict enough if the aim is to predict patients where cure will be successful as opposed to patients who will suffer disease recurrence or will have mortality and morbidity return to disease-like levels. These criteria depend on biochemical measurements of GH and IGF-I that are not universally standardised or comparable, even when excluding the older, less sensitive polyclonal radio immuno assay (RIA). The biochemical evidence suggesting a revision of the criteria for curing acromegaly and derived proposals can be summarised as follows: A) Using immunoradiometric assay (IRMA) for GH measurement, no acromegalic patient with elevated IGF-I suppressed GH after 100 g oral glucose tolerance test (OGTT) to < or = 0.14 microg/l, but 50% suppressed to <1microg/l. B) With hourly GH measurements using IRMA, cured acromegalic patients exhibit basal GH values < or = 0.33 microg/l (x +/- 2 SD). C) In patients with normal IGF-I having GH after OGTT suppressed to < or = 0.14microg/l no recurrences were observed, while in 19% with GH >0.14 microg/ showed recurrences (4, 5); however, this was not the experience of others. D) Polyclonal assays for GH exhibit overlap of GH suppression after OGTT between normal subjects and active patients and should therefore be avoided. E) A recent agreement for implementing universal rhGH reference standards by September 2006 will hopefully facilitate the comparison of different assays in the future. F) Reliable IGF-I assays require age- and sex-matched reference ranges. G) For evaluation of long-term biochemical assessment after treatment, both GH and IGF-I should be undertaken. H) In order to monitor treatment with GH-receptor antagonists, a reliable IGF-I assay is of critical importance, since GH measurements cannot be used to evaluate treatment efficacy.