SFEBES2021 Poster Presentations Neuroendocrinology and Pituitary (47 abstracts)
1PGIMER, Chandigarh, India; 2SEHEAC, New Delhi, India; 3GMSH-16, Chandigarh, India; 4Christie NHS Foundation Trust, Manchester, United Kingdom; 5Queen Mary University of London, London, United Kingdom
Context: Serum IGF-binding protein-3 (IGFBP-3) and molar IGF-I to IGFBP-3 ratio can aid the diagnosis of GH-related diseases. However, their clinical utility is limited by lack of validated reference intervals.
Objectives: To establish age-, gender- and Tanner stage-specific reference intervals for IGFBP-3 and IGF-I to IGFBP-3 ratio for Indian ethnicity.
Setting and Participants: We conducted a cross-sectional epidemiological study (age 5-18 years) from the north Indian city of Chandigarh including 2191 apparently normal subjects (1141 males; 1050 females). With robust exclusion criteria, 1746 subjects (males=889; females=857) were available.
Main Outcome Measures: Serum IGFBP-3 (ng/mL) and IGF-I (nmol/l) to IGFBP-3 (nmol/l) ratio by the Immunodiagnostic Systems (IDS) iSYS assays were measured and reference intervals (2.5th to 97.5th centiles) were generated.
Results: Both IGFBP-3 and the IGF-I to IGFBP-3 ratio are mainly determined by age and gender. In females, median IGFBP-3 peak was at 13 years (4095.9), and in males it was at 16 years (4225.3). Determined by the high pubertal peak in IGF-I, the peak in the IGF-I to IGFBP-3 ratio, occurred with an earlier and higher peak in females [36.8 (14 years)] compared with males [32.7 (16 years)]. IGFBP-3 concentrations were higher in females until age 13, with males developing a higher peak and having higher values after 13 years. In Tanner-specific data (n = 1735), females (n = 855) had IGF-I to IGFBP-3 ratio median peak in Tanner stage IV (39.5), while for males (n = 880) it was in stage III (32.3). IGFBP-3 had median peak in stage V (4049.1) for females and stage IV (4203.3) for males.
Conclusions: We presented the largest cohort with Indian ethnicity data on age-, gender- and Tanner stage-specific reference intervals for IGFBP-3 and molar IGF-I to IGFBP-3 ratio and demonstrated distinct gender and Tanner stage-specific differences. These data will support the diagnostics of growth disorders.