Endocrine Abstracts

Introduction: Insulin-like growth factor 1 is a single-chain polypeptide of 70 amino acids. Quantitative determination of IGF1 is a one-step sandwich chemiluminescence immunoassay (CLIA). IGF1 is being used by physicians as a screening test for GH deficiency and excess. It became crucial to find an alternative automated platform for the current available methods.

Design: Evaluation took place in an HMO central lab, currently using the SIEMENS IMMULITE 2000. Seventy-nine randomly outpatients serum samples collected from Clalit Central Laboratory. Fifty-three routine samples were tested on pre-modified IMMULITE kit, delivered from Screening Department Institute of Mother and Child, Warsaw Poland. Patients, controls and NEQAS samples were tested by: DiaSorin LIAISON IGF1, IMMULITE IGF1. Results were analysed according to patients’ age and gender.

Results: Correlation between LIAISON IGF1 and IMMULITE IGF1 was analysed for: A. samples from Clalit central laboratory. B. samples delivered from abroad, pre-modified IMMULITE vs LIAISON. C. Samples delivered from abroad, new modified IMMULITE vs LIAISON. D. Samples delivered from abroad, new modified IMMULITE vs pre-modified IMMULITE. The r values were 0.9750, 0.9849, 0.9750, 09758, 09770, 0.9453 and 0.9729 respectively. Total clinical agreement between new modified IMMULITE vs pre-modified IMMULITE and between pre-modified IMMULITE vs LIAISON were 85 and 100%, respectively. Correlation between LIAISON and IMMULITE IGF1 of NEQAS samples showed r=0.995. Controls within run precision showed 2.36–3.35% CV. Between run precision showed 4.79–7.75% CV. Functional sensitivity showed values of 4.11 and 6.43 pg/ml. Dilution test showed linearity of r=0.9953.

Conclusions: High correlation was observed between LIAISON and IMMULITE IGF1 together with high clinical agreement. It is concluded that the LIAISON IGF1 can be used as reliable and accurate kit for high throughput laboratories.