TY - JOUR
T1 - The introduction of the IDSiSYS total IGF1 assay may have farreaching consequences for diagnosis and treatment of GH deficiency
AU - Varewijck, A. J.
AU - Lamberts, S. W.J.
AU - Van Der Lely, A. J.
AU - Neggers, S. J.C.M.M.
AU - Hofland, L. J.
AU - Janssen, J. A.M.J.L.
N1 - Publisher Copyright:
© 2015 by the Endocrine Society.
PY - 2015/1/1
Y1 - 2015/1/1
N2 - Context: IGF-1 measurements are used for screening and monitoring GH deficiency (GHD) and acromegaly. Objective: Our objective was to study whether the introduction of the IDS-iSYS IGF-1 assay would lead to different clinical interpretations in GHD and acromegaly. Design: In 106 GHD subjects and in 15 acromegalic subjects visiting our university hospital, total IGF-1 levels were measured before and during therapy by using the Immulite (IM) assay and IDS-iSYS (ID) assay. Z-scores were calculated by using assay-specific age-specific normative range values. All treatment decisions were based upon results obtained by the IM assay. Results: In GHD subjects, absolute IGF-1 concentrations differed significantly between both IGF-1 assays before treatment (P < .001) but not during GH treatment (P = .32), and mean Z-scores for IGF-1 differed significantly before starting (IM, -2.23, vs ID, -1.43; P < .001) and during GH treatment (IM,-0.60, vs ID,+0.21; P<.001). In acromegalic subjects, absolute IGF-1 concentrations did not differ between both IGF-1 assays before treatment (P=.18) but were significantly different during treatment (P = 0.009), and mean Z-scores for IGF-1 were not different before starting (IM, 10.93, vs ID, 10.78; P = .41) or during treatment (IM, 3.60, vs ID, 3.18; P = .23). Conclusions: In GHD subjects, mean IGF-1 Z-scores significantly differed when measured by the IM assay compared with the ID assay irrespective of treatment. In contrast, in acromegaly, mean IGF-1 Z-scores did not differ significantly between both assays. Our study suggests that replacement of the IM assay by the ID assay may have far-reaching consequences for the clinical diagnosis and treatment of GHD.
AB - Context: IGF-1 measurements are used for screening and monitoring GH deficiency (GHD) and acromegaly. Objective: Our objective was to study whether the introduction of the IDS-iSYS IGF-1 assay would lead to different clinical interpretations in GHD and acromegaly. Design: In 106 GHD subjects and in 15 acromegalic subjects visiting our university hospital, total IGF-1 levels were measured before and during therapy by using the Immulite (IM) assay and IDS-iSYS (ID) assay. Z-scores were calculated by using assay-specific age-specific normative range values. All treatment decisions were based upon results obtained by the IM assay. Results: In GHD subjects, absolute IGF-1 concentrations differed significantly between both IGF-1 assays before treatment (P < .001) but not during GH treatment (P = .32), and mean Z-scores for IGF-1 differed significantly before starting (IM, -2.23, vs ID, -1.43; P < .001) and during GH treatment (IM,-0.60, vs ID,+0.21; P<.001). In acromegalic subjects, absolute IGF-1 concentrations did not differ between both IGF-1 assays before treatment (P=.18) but were significantly different during treatment (P = 0.009), and mean Z-scores for IGF-1 were not different before starting (IM, 10.93, vs ID, 10.78; P = .41) or during treatment (IM, 3.60, vs ID, 3.18; P = .23). Conclusions: In GHD subjects, mean IGF-1 Z-scores significantly differed when measured by the IM assay compared with the ID assay irrespective of treatment. In contrast, in acromegaly, mean IGF-1 Z-scores did not differ significantly between both assays. Our study suggests that replacement of the IM assay by the ID assay may have far-reaching consequences for the clinical diagnosis and treatment of GHD.
UR - http://www.scopus.com/inward/record.url?scp=84920619178&partnerID=8YFLogxK
U2 - 10.1210/jc.2014-2558
DO - 10.1210/jc.2014-2558
M3 - Article
C2 - 25337924
AN - SCOPUS:84920619178
SN - 0021-972X
VL - 100
SP - 309
EP - 316
JO - Journal of Clinical Endocrinology and Metabolism
JF - Journal of Clinical Endocrinology and Metabolism
IS - 1
ER -