Multicentric reference values for some quantities measured with the Elecsys 2010 analyser.

Several clinical laboratories in different regions of Spain have shared the search for reference individuals and the production of reference values for quantities concerning thyrotropin, non-protein bound thyroxine, triiodothyronine, cobalamines and folates, using an Elecsys 2010 analyser. All the logistic work has been done in co-operation with the supplier of the analyser (Roche Diagnostics España, S.L., Barcelona). The reference limits produced in the virtual laboratory are in fact derived from the blend of reference values obtained by each laboratory. The multicentric reference limits were estimated according to the recommendations of the International Federation of Clinical Chemistry. The work done represents a model of co-operation between the in vitro diagnostic industry and clinical laboratories for the production of reference values.

[Sensitivity of the clonidine and guanfacine tests (alpha-2-adrenergic agonists) as pharmacologic stimulants of growth hormone. Effects on plasma cortisol]. / Sensibilidad del test de clonidina y test de guanfacina (agonistas alpha-2-adrenérgicos) como estímulos farmacológicos de la hormona de crecimiento. Efectos sobre el cortisol plasmático.

OBJECTIVE: The effects of two pharmacological alpha-2-adrenergic stimuli (clonidine and guanfacine) on GH and cortisol concentrations in the blood in a group of non-growth-hormone-deficient children with short stature was compared. PATIENTS AND METHODS: Seventeen children (10 males and 7 females) with short stature (height standard deviation score: -2.3 +/- 0.5) were studied. The mean age was 9.4 +/- 2.5 years. The GH response to the clonidine or guanfacine test was positive (> 10 ng/ml) in all subjects. RESULTS: Oral clonidine test: In 14 cases (82.4%) the GH response was positive (peak value: 17.2 +/- 6.3 ng/ml) and in 3 cases (17.6%) the GH response was negative (false negatives). A significant decrease in plasma cortisol concentration was noted, from a basal level of 17.0 +/- 8.0 to 5.9 +/- 3.8 micrograms/ml at 120 minutes (p < 0.05). Blood pressure decreased significantly (p < 0.05), but without symptoms of hypotension. Somnolence was noted in 16 cases (94.1%). Oral guanfacine test: In 8 cases (47%) the GH response was positive (peak value: 14.2 +/- 3.7 ng/ml) and in 9 cases (52.9%) the GH response was negative (false negatives). A significant decrease in plasma cortisol concentration was noted, from a basal level of 14.2 +/- 6.4 to 7.2 +/- 3.7 at 90 minutes (p < 0.05). Blood pressure did not change and none of the patients had somnolence during the test. CONCLUSIONS: The alpha-2-adrenergic agonists, clonidine and guanfacine, appear to be reliable agents for testing of the growth hormone reserve of the pituitary gland. Plasma cortisol levels decreased significantly with either stimuli. The clonidine test is more sensitive than the guanfacine test and can be recommended as a definitive test for the diagnosis of classical growth hormone deficiency.