Table 1. Technical characteristics of some widely used, automated GH and IGF-I assays.
| Assay platform | Assay type | range | Sensitivtiy (LoQ) | Sensitivity (LoD) | Specificity/Interference | Standard | |
|---|---|---|---|---|---|---|---|
| GH (ng/mL) | IDS iSYS | CLIA | 0.04-100 | 0.04 | 0.015 | No cross-reactivity | WHO IS 98/574 |
| Diasorin Liaison | CLIA | 0.05-80 | 0.05 | 0.05 | Pegvisomant (false positive), 20kDa hGH, placental GH, human placental lactogen | ||
| Roche Cobas | ECLIA | 0.03-50 | 0.05 | 0.03 | Pegvisomant (effect not specified), 20 kDa hGH, placental GH | ||
| Siemens Immulite | CLIA | 0.1-40 | 0.05 | 0.01 | Pegvisomant (false negative), 20kDa hGH, placental GH, human placental lactogen | ||
| IGF-I (ng/mL*) | IDS iSYS | CLIA | 10-1200 | 8.8 | 4.4 | WHO IS 02/254 | |
| Diasorin Liaison | CLIA | 10-1000 | 10 | 3 | |||
| Roche Cobas | ECLIA | 7-1600 | 15 | 7 | |||
| Siemens Immulite | CLIA | 20-1600 | 19.7 | 14.4 |
GH: growth hormone; IGF-I: insulin-like growth factor I; CLIA: chemiluminescence immunoassay; ECLIA: electrochemiluminescence immunoassay; LoQ: limit of quantification; LoD: limit of detection; WHO IS: World Health Organization International Standard;
*Conversion factor IGF-I to nmol/Lng/mL: x 0.131.