REEVALUATION OF GROWTH-HORMONE (GH) SECRETION IN 69 ADULTS DIAGNOSED AS GH-DEFICIENT PATIENTS DURING CHILDHOOD

At present, the most appropriate method for diagnosing GH deficiency ( GHD) in adults remains unclear. Recently, it has been demonstrated tha t GHD in adults can be identified by insulin tolerance test (ITT). Mor eover, it has been described that the GHRH plus pyri dostigmine (GHRHPD) test is more accurate than an arginine, glucagon, levodopa, or GHR H test to diagnose GHD in adults. In the current study, firstly we ree valuated GH secretion by the GHRH+PD test in adults previously diagnos ed as GH deficient in childhood. The study included 69 patients and 38 healthy subjects. After the GHRH+PD test, the patients and the health y subjects had peak GH levels of 10.6 - 11.2 and 56.7 +/- 28.1 mu g/L, respectively (P < 0.001). The patients were divided into two groups, responder patients and nonresponder patients, considering an arbitrary cut-off of 10 mu g/L as the GH peak after the GHRH+PD test. Thirty-ni ne patients had GH peak below 10 mu g/L, 11.9 +/- 1.7 mu g/L), whereas the remaining 30 patients above 10 mu g/L (21.6 +/- 8.1 mu g/L; P < 0 .001). Secondly, we compared the GHRH+PD test and the ITT in diagnosin g GHD. Twenty-one of the 39 patients with a GH peak below 10 mu g/L an d 29 of the 30 patients with a GH peak above 10 mu g/L after the GHRHPD test underwent an ITT. The GH peak after insulin administration was 2.1 +/- 1.7 mu g/L in nonresponder patients and 21.1 +/- 9.3 mu g/L i n responder patients after the GHRH+PD test (P < 0.001). Three of the responder patients to the GHRH+PD test were identified as GH deficient by the ITT. The relative diagnostic accuracies of the two tests to di scriminate GH-deficient patients from healthy subjects were similar (I TT vs. GHRH test: sensitivity, 100%, specificity, 90%; GHRH+PD vs. ITT : sensitivity, 88%; specificity, 100%). In conclusion, in adults previ ously diagnosed as GH deficient, it is mandatory to reevaluate GH secr etion. GHRH+PD and/or ITT are able to diagnose GHD in adults with simi lar accuracies. Taking into account the potential side-effects of the ITT, however, the GHRH+PD test is the most reliable and safe test to a ccurately diagnose GHD status in adults.