IGF BINDING PROTEIN-3

Code
000.0000
Name
IGF BINDING PROTEIN-3
Category
None
Department
Send-Out
Start Date
Expiration Date
Synonyms
IGFBP-3
CPT Codes
82397
Site
SBMF
Reference Test
44142
ATLAS Test Code

Specimen Information

Type

Gold, SST

Volume

0.5 ml

Transport Info

Centrifuge and immediately transfer serum to separate plastic tube
Frozen

Fasting Required?
False
Patient Instructions

Reference Range

See Report

Methodology

Quantitative Chemiluminescent Immunoassay (CLIA)

Clinical Significance

Insulin-like growth factors (IGF-1 and IGF-2) are peptides with structural homology to insulin. They exhibit growth-promoting effects as well as insulin-like activity through autocrine, paracrine, and endocrine actions. The serum concentrations of IGFs are regulated by two influences: Growth hormone (GH) in a feedback relationship. Nutritional status. Circulating IGF-1 is almost totally protein bound to high-affinity binding proteins called IGF binding proteins (IGFBPs). Six IGFBPs have been identified. IGFBP-3 is the major carrier of IGFs in serum and is present in the highest concentrations. More than 90% of IGF-1 and IGF-2 is bound to IGFBP-3 and the complex in humans has a half life of 12-15 hours. IGFBP-3 may provide a storage pool for IGF-1 and may be involved in the transport of IGF-1 to tissues. Serum concentrations of IGFBP-3 are fairly constant throughout the day and are controlled by GH and IGF-1 levels. The measurement of IGFBP-3 is useful in the evaluation of several clinical situations: Short stature in children, Acromegaly, Nutritional status. In the assessment of short stature in children, the secretion of GH fluctuates throughout the day and the half life is only 15-20 minutes, making a single random measurement of GH difficult to interpret. IGFBP-3 exhibits much less diurnal variation and can provide more reliable and useful information. IGFBP-3 levels are less age-dependent and are higher in young children than IGF-1 levels. This allows for better differentiation between normal and subnormal levels. IGFBP-3 levels show a better correlation with GH sufficiency than single measurements of IGF-1 or IGF-2. IGFBP-3 measurements can also be useful for monitoring the efficacy of treatment for GH deficiency. A combination of both IGFBP-3 and IGF-1 measurements can provide improved information concerning the evaluation of short stature in children. For patients with acromegaly, serum IGFBP-3 levels have been shown to be useful in diagnosis and may serve as a marker of GH excess. In addition, IGFBP-3 measurement may be useful in assessing surgical cure of somatotroph tumors. IGFBP-3 measurements can also be useful in the evaluation of nutritional status. The levels of IGFBP-3 decline during fasting and chronic malnutrition as do IGF-1 levels. Measurement of both proteins can aid in assessing nutritional status and in monitoring the response to therapy.

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