Low circulating insulin-like growth factor-1 levels are associated with high serum uric acid in nondiabetic adult subjects

- Circulating IGF-1 and uric acid levels show an inverse relationship.
- This correlation remains significant after adjustment for several confounders.
- Exposure of HepG2 cells to uric acid induced a down-regulation of GH-stimulated IGF-1 expression.
- High uric acid levels may directly affect hepatic IGF-1 synthesis.

Background and aimsLow insulin-like growth factor-1 (IGF-1) levels and high uric acid concentrations are associated with cardio-metabolic disorders. Acute IGF-1 infusion decreases uric acid concentration in healthy individuals. In this study, we aimed to examine the relationship between IGF-1 and uric acid levels.Methods and results1430 adult non diabetic subjects were stratified into quartiles according to their circulating IGF-1 values. Significant differences in uric acid concentration, measured by the URICASE/POD method were observed between low (quartile 1), intermediate (quartile 2 and 3), and high (quartile 4) IGF-1 levels groups after adjusting for age, gender, and body mass index (P = 0.02). These differences remained significant after adjustment for blood pressure, total cholesterol, high density lipoprotein, triglycerides, fasting and 2 h post-load glucose levels, HOMA-IR index (P = 0.005), liver enzymes (P = 0.03), glucose tolerance status (P = 0.02), growth hormone levels (GH) (P = 0.05), anti-hypertensive treatments (P = 0.04) or diuretics use (P = 0.04)). To clarify the molecular links between IGF-1 and uric acid, we performed an in vitro study, incubating human hepatoma cells with uric acid for 24 or 48 h in the presence of GH and observed a 21% and 26% decrease, respectively, in GH-stimulated IGF-1 mRNA expression (P = 0.02 and P = 0.012, respectively). This effect appears to be mediated by uric acid ability to down regulate GH intracellular signaling; in fact we observed a significant decrease of GH activated JAK2 and Stat5 phosphorylation.ConclusionsThese data demonstrate an inverse relationship between IGF-1 and uric acid levels in adults and suggest that uric acid might affect hepatic IGF-1 synthesis.