IGF Binding Protein 3

General Information:

IGF-binding protein 3 (IGFBP-3) is a peptide produced in the liver that plays an important role in controlling the transport and bioavailability of IGF (especially IGF-1, which is the main mediator of the anabolic and growth-stimulating effects of growth hormone-GH).

About 1% of IGF-2 and IGF-95 are bound to IGFBP-3, which is the main IGF transport protein and whose

One of the main functions is to increase the half-life of IGF from 8 minutes to several hours. In this way, IGFBP-3 acts as a stabilizer, ensuring a constant level of IGF. IGFBP-3 serum concentration is constant over 24 hours, which is also dependent on growth hormone (GH), so determination of IGFBP-3 is informative for evaluation of GH (growth hormone) secretion. Unlike GH secretion, which is characterized by diurnal pulsatile variations, IGFBP-3 and IGF-1 levels show only small fluctuations.

Low serum levels of IGFBP-3 and IGF-1 are observed in growth hormone deficiency or resistance.

These changes acquired in childhood cause growth retardation. GH deficiency in children can be an isolated abnormality or associated with changes in other pituitary hormones. Multiple hormonal failure can be caused by the presence of pituitary or hypothalamic tumors, or the result of X-ray therapy and chemotherapy for various malignant tumors.

In childhood (growth hormone) resistance to GH is mostly mild or moderate; Causes range from malnutrition to severe systemic diseases such as chronic kidney failure. These individuals may have IGF-1 and IGFBP-3 levels within the reference range. Severe forms of resistance are rare and usually result from receptor defects.

Both mild and moderate forms of GH deficiency and GH resistance can be treated with injections of recombinant human GH (rhGH).

The goal of GH replacement therapy in both children and adults is to achieve a reference range of serum IGF-1 and IGFBP-3 values, ideally the middle third. Higher levels are rarely associated with additional therapeutic benefit and may cause long-term side effects.

The prevalence and causes of GH resistance in adults are not well understood, although GH deficiency is most common in patients with pituitary tumors. GH deficiency in adults is associated with decreased muscle mass and increased cardiovascular morbidity and mortality, while replacement therapy remains controversial.

Elevated serum concentrations of IGFBP-3 and IGF-1 indicate excessive secretion of GH (growth hormone) or excessive therapy. Endogenously excess GH is mainly caused by GH-secreting pituitary adenomas and causes gigantism if acquired before the closure of cartilage growth, followed by acromegaly. Both conditions are associated with generalized organomegaly, high blood pressure, diabetes, cardiomyopathy, osteoarthritis, compressive neuropathy, a small increase in cancer risk, and reduced life expectancy.

The advantage of determining IGFBP-3 compared to IGF-1 is that it has high concentration rates at a young age and is used diagnostically in children with growth retardation who have normal levels of growth hormone.

IGFBP-3 is a reliable parameter for monitoring treatment efficacy, which is an important test in combination with IGF-1 measurement;

When should we take the test?

Indirect marker of somatotropic hormone (somatotropin; growth hormone) secretion and reception:

• Diagnosis of growth disorders;
• Diagnosis of GH (growth hormone) deficiency in adults;
• Treatment monitoring of human recombinant GH (rhGH) - using growth hormone;
• Diagnosis and monitoring of acromegaly and gigantism (with IGF-1 and GH).

How to prepare for the test?

Venous blood is required for analysis. The test is required on an empty stomach.

Possible interpretation of the results:

• Serum IGFBP-3 values ​​can be influenced by several factors: age, sexual development, nutrition, liver and kidney function. IGFBP-3 increases in early childhood and puberty and then decreases slightly in adults.
• IGFBP-3 concentration decreases during starvation and chronic malnutrition (malnutrition). Serum IGFBP-3 levels are low in liver failure and diabetes but elevated in chronic renal failure.
• In cases of growth hormone (GH) deficiency or severe resistance, serum IGF-1 and IGFBP-3 levels are lower compared to age data. Patients with incomplete deficiency or mild to moderate resistance may have plasma values ​​in the reference range.
• Recording elevated IGF-1 and IGFBP-3 values ​​confirms the diagnostics of acromegaly or gigantism in people who have corresponding suspicious signs and symptoms.

Increase in IGFBP-3 levels:

• Acromegaly, gigantism;
• Chronic renal failure

Decreased IGFBP-3 levels:

• Growth hormone deficiency;
• Laron's dwarf;
• Malnutrition and prolonged fasting;
• Liver failure;
• diabetes