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Insulin-like growth factor-1 (IGF-1)

Insulin-like growth factor-1 (IGF-1)

Code:
IGF

Sample Type:

Lithium Heparin or EDTA plasma (green or purple top) or serum (with or without gel) (yellow top)

Ref Ranges/Units:

Ranges vary significantly with age and sex. Appropriate ranges are reported alongside results but contact duty biochemist if more information required.

Units = nmol/L

Turnaround:

7 days

Special Precautions/Comments:

IGF-1 is normally requested together with human growth hormone (hGH).

Samples should be processed and frozen on the day of collection.

Additional Information:

IGF‑1, a 70 amino‑acid polypeptide with a molecular mass of 7.5 kDa,1 is ubiquitously expressed in every tissue, but it is mainly synthesized and secreted by the liver (~75 % of circulating IGF‑1) and regulated by growth hormone (GH). Around 80 % of IGF‑1 in the circulation is bound in a ternary complex with IGFBP‑3 (Insulin‑like growth factor binding‑protein 3) and ALS (Acid‑labile subunit).

IGF‑1 (also known as somatomedin) was the first established marker to screen for growth hormone deficiency (GHD). GH is secreted in pulses peaking every 60‑90 minutes and has a short half-life. Additionally, GH levels are affected by external factors (e.g. exercise, fasting). In contrast, IGF‑1 levels are more robust and as a consequence, the determination of IGF‑1 is widely used as a first step in diagnosis of both GH deficiency and excess.

The determination of IGF‑1 is also recommended for screening of growth disorders by GH excess like acromegaly.