Cystatin C, a protease inhibitor produced by most nucleated cells, is freely filtered by the kidneys, and its plasma assay reflects the GFR.

Compare, in HIV patients, the predictive performance of 11 formula to estimate GFR based on assay plasma cystatin C with that of the MDRD formulas.

Inclusion Criteria:

• Patients infected with HIV, and included in the cohort NADIS

Exclusion Criteria:

• Patient with a known allergy
• Patients treated with metformin
• Patients with severe hepatic impairment defined as a TP spontaneously below 50%
• Patients with a history of dysthyroidism
• Patient with active neoplasia other than skin cancer
• Degradation recent (not older than 3 months) in renal function defined as the deterioration of GFR over 25%.
• Estimated GFR less than 15 mL/min/1, 73m2
• Pregnant or lactating
• Subjects under the protection of justice