SERUM IGF-I REFERENCE VALUES USING A CHEMILUMINESCENT ASSAY IN ADULTS FROM A PUBLIC HOSPITAL IN BUENOS AIRES CITY

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SAT 109-133-GHRH, GH & IGF Biology & Signaling
Bench to Bedside
Saturday, June 15, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SAT-132
Patricia Glikman*, Marcelo Junco, Mirna Lopez, Alejandra Furioso and Amelia Rogozinski
Hospital J. M. Ramos Mejia, Buenos Aires, Argentina
 

INTRODUCTION: Serum insulin-like growth factor I(IGF-I) levels are used for diagnosis/ monitoring of Growth Hormone  related disorders in children and adults. IGF-I measurements have been related to the assay, population, age and gender. 

OBJECTIVE: a)To establish reference values for serum IGF-I in healthy adult population, adjusted by age and gender, using an automated chemiluminescent assay(QLIA). b)To compare our data with those referred by the manufacturer(MF) (1).

MATERIALS AND METHODS: Serum samples from 599 healthy adults (351 women/248 men), 18-85 years old, were aliquotted and stored at -20 °C. IGF-I was measured using a QLIA (IMMULITE 2000,Siemens). Interassay CV was< 7% for IGF-I levels of 78.7 and 529.3 ng/mL. For comparison purposes, the population was subdivided according to gender in the same age groups referred by the MF. Median and 95% confidence limits(CL) were calculated for each group. Statistics: Unpaired t test, Multiple regression analysis and Wilcoxon test were performed (GraphPad InStat software, 3.06); p<0.05 was considered significant.

RESULTS: IGF-I values were significantly dependent on age (p< 0.0001) but not on gender. Therefore we unified women and men in the analysis of the data by age group in order to make the comparison. The data of the age group(years old),  IGF-I median/95% CL(ng/mL) obtained in our laboratory vs MF´s were: 18: 285/249-319 vs 308/163-584, 19: 219/199-261 vs 261/141-483, 20: 215/212-264 vs 232/127-424, 21-25: 192/184-218 vs 203/116-358, 26-30: 161/153-179 vs 196/117-329, 31-35: 149/148-171 vs 188/115-307, 36-40: 130/122-142 vs 176/109-284, 41-45: 135/130-152 vs 164/101-267, 46-50: 109/114-139 vs 154/94-252, 51-55: 109/107-128 vs 144/87-238, 56-60: 101/92-111 vs 135/81-225, 61-65:97/92-115 vs 126/75-212, 66-70: 104/96-142 vs 118/69-200, 71-75. 103/96-140 vs 110/64-188, 76-80: 99/88-146 vs 102/59-177, 81-85: 109/98-129 vs 95/55-166. Our total number of individuals in each group were(women/men): 13/11, 15/10, 12/16, 32/26, 27/25, 30/21, 31/22, 30/24, 28/20, 40/19, 23/14, 17/14, 8/8, 13/7, 12/5, 20/6, respectively. IGF-I data in our population were significantly lower than those referred by the MF (p< 0.0002).

CONCLUSIONS:

a) We established the adult reference range for IGF-I in our population.

b) IGF-I levels were significantly lower than the manufacturer´s reported data (1)

c) The differences found could be due either to ethnic reasons or alterations in the performance of this assay, very recently reported by the manufacturer.

(1) Elmlinger MW et al. Clin. Chem. Lab. Med 2004; 42: 654

Nothing to Disclose: PG, MJ, ML, AF, AR

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm