IGF-1

IGF-1 testing is straightforward and involves a simple blood draw, typically performed in the morning for consistency [1]. The test measures the total concentration of IGF-1 in your blood serum, with results reported in nanograms per milliliter (ng/mL) [3].

Unlike many other hormone tests, fasting is usually not required for IGF-1 testing, though some laboratories may recommend it depending on their specific protocols [1]. The blood sample is collected in a serum separator tube (SST) and must be processed properly to ensure accurate results [3].

For optimal sample integrity, the blood must be allowed to clot completely before centrifugation, and the serum should be separated as soon as possible into a screw-capped plastic tube [3]. The sample is then stored frozen until analysis, as IGF-1 is unstable at room temperature and refrigerated conditions [3].

The test uses chemiluminescence methodology to measure IGF-1 concentrations with high precision [3]. Laboratory technicians must be careful to avoid certain conditions that can compromise results, including EDTA plasma samples, grossly hemolyzed specimens, or grossly lipemic specimens [3].

Several factors can influence IGF-1 test results, making proper interpretation essential. Age is the most significant factor, as IGF-1 levels change dramatically throughout life. Nutritional status, liver function, certain medications, and underlying medical conditions can also affect results [1]. Healthcare providers may order IGF-1 testing alongside growth hormone stimulation tests for a more comprehensive assessment of growth hormone function [1].

The test is primarily used to detect and monitor growth hormone disorders, including GH deficiency, GH insensitivity (Laron syndrome), gigantism in children, and acromegaly in adults [1]. Results typically take 1-3 days to process [3].