Establishment of Reference Values for Insulin-like Growth Factor 1 (IGF1) in the General Population

Healthy subjects will be recruited in 30 centers all around France. A total of 1000 healthy subjects are necessary. Each subject will have a clinical examination with measurement of height and weight. Personal medical history will be recorded and gonadal status evaluated. Biological standard workup will be performed and 80 ml of blood will be sampled and serum will be aliquoted, frozen and stored at -80°C. IGF-I level will be measured with all the assay methods available (sera kept in bank will be used in the future when new methods will be available) For each assay method and each age group (Four 3-years groups between 18 and 30 years and six decade age groups between 30 and 89 years) IGF-I will be measured.

Results will be expressed as mean, median, standard deviation, 2.5th and 97.5th percentiles, in mass units. Modelisation according to age and other factors will be performed in order to allow the reporting of IGF-I results for a given individual expression of IGF-I as Z-score.

Inclusion criteria

• Male or female 18 to 89 years old (18 years ≤ age ≤ 89 years)
• Consent given by the patient
• No history of : thyroid disease, liver disease or kidney disease or metabolic endocrine disease cardiovascular or pulmonary disease, neoplastic disease, gastroenterological disease (malabsorption, parasites, chronic diarrhea, peptic disease), psychiatric illness, epilepsy.
• No medication that can interfere with the concentration of IGF1: steroids, anti-androgens, distal diuretics, anti-estrogens, enzyme inducers (rifampin, rifabutin, phenobarbital, phenytoin, carbamazepine, herbal St. John's wort, efavirenz, nevirapine, griseofulvin , OP'DDD, mitotane).
• No intercurrent illness in the week preceding the inclusion
• No known chronic infectious disease (BVH, CVH, HIV)
• No active smoking
• Weight/height2 (BMI) less than 28 kg/m2 and greater than 19 kg/m2
• Normal clinical examination
• Normal blood pressure: children under 65 years (100 mm Hg <SBP <140 mmHg, 50 mmHg <PAD <90 mmHg) for over 65 years (100 mm Hg <SBP <150 mmHg, 50 mmHg <SBP <90mmHg )

Exclusion criteria

• Uncontrolled intercurrent illness
• Pregnant or lactating woman
• Excess alcohol consumption: more than 50 g/24h of chronic or acute or unable to restraint from consuming alcohol
• Susceptible to use drugs
• Donated blood in the 3 months preceding the study
• Blood transfusion in the 3 months preceding the test
• Exclusion period of a previous experimental trial.
• Fasting extended by several days.
• Patient not affiliated to a social security system (is or should be beneficiary)