Objective: There is a clinical need for population based reference values for serum insulin-like growth factor I (IGF-I). We have therefore determined serum IGF-I concentrations in a random population sample from Sweden and have related the levels to age, sex, life style factors, blood pressure, body composition, blood lipids, plasma fibrinogen, parathyroid hormone (PTH) and osteocalcin.
Patients: Within the framework of the WHO MONICA Project in the city of Göteborg, Sweden, 197 men and 195 women aged 25-64 years were studied.
Results: Women aged 25-34 years had higher IGF-I concentration than men (mean 278 vs 227 micrograms/l) but in the interval 55-64 years values were lower in women than in men (158 vs 171 micrograms/l). IGF-I correlated positively with height and inversely with age, body mass index, systolic blood pressure and total cholesterol in both sexes. Negative relations between IGF-I and high density lipoprotein-cholesterol, as well as with amount of tobacco smoked, were found in men, and between IGF-I and diastolic blood pressure, triglycerides and PTH in women. When age was allowed for in multivariate analyses, most of these relations disappeared. However, among men IGF-I was positively associated with fibrinogen and negatively with age and smoking. IGF-I was negatively associated with age and coffee consumption in women.
Conclusion: The present data can be used as reference values for IGF-I (at least in Caucasians) for the diagnosis of growth hormone disturbances and as guidelines for growth hormone substitution.