RESUMEN
OBJECTIVE: To evaluate 2 highly sensitive assays for serum insulin-like growth factor-1 (IGF-1) and growth hormone (GH) determination following an oral glucose tolerance test (OGTT) in healthy controls. METHODS: Nineteen healthy adults underwent a standard 75g OGTT and GH and IGF-1 were measured. Serum GH and IGF-1 levels were assayed by a sensitive immunoradiometric assay (IRMA) and a highly sensitive chemiluminescent immunometric assay (CLIA). RESULTS: The mean IGF-1 concentration was 153±65ng/ml measured by IRMA and 144±56ng/ml measured by CLIA. The median (interquartile range) basal GH concentrations by IRMAvs CLIA were 0.8 (0.5-3) µg/l vs 0.5 (0.1-2.4) µg/l. The median nadir GH measured by IRMA in these subjects was 0.4 (0.3-0.5) µg/l, and the mean nadir GH by CLIA was 0.08 (0.01-0.22) µg/I. When a ratio of basal IRMA/CLIA GH was calculated in each subject, the median ratio of basal IRMA/CLIA GH concentrations in subjects overall was 1.68. Similarly, the median ratio of nadir IRMA/CLIA GH values was 4.44. One of the subjects did not achieve GH suppression into the established normal range, with a GH nadir of 1.2 µg/l by IRMA and 1 µg/l by CLIA, overlapping with the traditional cut-off defining acromegaly when GH suppression was measured by IRMA. CONCLUSIONS: Highly sensitive chemiluminescent immunometric assays should be used to assess the GH/IGF-1 axis. In our opinion, there is no need for a lower GH suppression cut-off for diagnosing acromegaly. We found no significant gender-, BMI- or age-related differences in nadir GH levels and thus our results do not support different OGTT criteria for screening of acromegaly in men and women, or in younger and older subjects.
RESUMEN
BACKGROUND: Although consensus guidelines have been proposed in 2010 for the diagnostic screening of paroxysmal nocturnal hemoglobinuria (PNH) by flow cytometry (FCM), so far no study has investigated the efficiency of such medical indications in multicentric vs. reference laboratory settings. METHODS: Here we evaluate the efficiency of consensus medical indications for PNH testing in 3,938 peripheral blood samples submitted to FCM testing in 24 laboratories in Spain and one reference center in Brazil. RESULTS: Overall, diagnostic screening based on consensus medical indications was highly efficient (14% of PNH+ samples) both in the multicenter setting in Spain (10%) and the reference laboratory in Brazil (16%). The highest frequency of PNH+ cases was observed among patients screened because of bone marrow (BM) failure syndrome (33%), particularly among those with aplastic anemia (AA; 45%) and to a less extent also a myelodysplastic syndrome (MDS; 10%). Among the other individuals studied, the most efficient medical indications for PNH screening included: hemolytic anemia (19%), hemoglobinuria (48%) and unexplained cytopenias (9%). In contrast, only a minor fraction of the patients who had been submitted for PNH testing because of unexplained thrombosis in the absence of cytopenia, were positive (0.4%). CONCLUSIONS: In summary, our results demonstrate that the current medical indications for PNH screening by FCM are highly efficient, although improved screening algorithms are needed for patients presenting with thrombosis and normal blood cell counts. © 2016 International Clinical Cytometry Society.