Insulin-like growth factor binding protein-3 (IGFBP-3)
Biochemistry Overview / Directory
Purpose of the test
IGFBP-3 is produced largely by the liver but to a lesser extent in fibroblasts, the ovaries, and the placenta. The Insulin like growth factor binding proteins bind IGF-I and IGF-II with high affinity and control the ability of IGF-1 and IGF-II to bind to their receptors. The major functions of the IGF-binding proteins in circulation are:
a) to transport IGFs in the vascular system,
b) to regulate their half-lives, and
c) to control transcapillary transport into the extravascular fluid compartments.
IGFBP-3 is the predominant IGF carrier of six distinct IGF binding proteins structurally characterised. It is responsible for complexing and transporting approximately 95% of circulating IGF-I and IGF-II.
Similarly to age-related changes for IGF-I, serum IGFBP-3 concentrations vary with age. In growth hormone deficient children, IGFBP-3 concentrations increase following GH administration whilst in contrast IGFBP-2 decreases following administration. Measurement of the binding proteins is useful in discriminating between growth hormone deficiency and short stature due to other aetiologies in children. IGFBP-3 may also be low in patients with short stature due to poorly controlled diabetes. In addition, IGFBP-3 decreases in calorific and protein restriction therefore IGFBP-3 measurement offers a useful tool in assessing nutritional status.
Reference Range
Paediatric references ranges (mg/L) by age
1yr: 0.7 - 3.6;
2yr: 0.8 - 3.9;
3yr: 0.9 - 4.3;
4yr: 1.0 - 4.7;
5yr: 1.1 - 5.2;
6yr: 1.3 - 5.6;
7yr: 1.4 - 6.1;
8yr: 1.6 - 6.5;
9yr: 1.8 - 7.1;
10yr: 2.1 - 7.7;
11yr: 2.4 - 8.4;
12yr: 2.7 - 8.9;
13yr: 3.1 - 9.5;
14yr: 3.3 - 10;
15yr: 3.5 - 10;
16yr: 3.4 - 9.5;
17yr: 3.2 - 8.7;
18yr: 3.1 - 7.9;
19yr: 2.9 - 7.3;
20yr: 2.9 - 7.2
Adult reference ranges (µg/mL) by age
21-25yr: 3.4 - 7.8;
26-30yr: 3.5 - 7.6;
31-35yr: 3.5 - 7.0;
36-40yr: 3.4 - 6.7;
41-45yr: 3.3 - 6.6;
46-50yr: 3.3 - 6.7;
51-55yr: 3.4 - 6.8;
56-60yr: 3.4 - 6.9;
61-65yr: 3.2 - 6.6;
66-70yr: 3.0 - 6.2;
71-75yr: 2.8 - 5.7;
76-80yr: 2.5 - 5.1;
81-85yr: 2.2 - 4.5
Sample Requirements
Serum or heparinized plasma (250 µL). EDTA plasma unsuitable
Storage and Transport
Stable at 4°C for up to 24 hours.
Turnaround Time
1 week
Price
Price available on application - please contact adrian.turner@kch.nhs.uk. Discounts could be available for significant workloads.
Contacts
Dr Roy Sherwood
T 020 3299 3726
Miss Rachel Langworthy
T 020 3299 4130
