The objective of the present study is to analyze the overall tubular function, and in particular that from the proximal tubule and the thick ascending loop of Henle (TALH) in patients with HIV infection receiving or not tenofovir-containing antiretroviral treatment in comparison with seronegative controls, by applying a validated tubular physiological test known as "Low sodium infusion test".

Hypothesis is that patients with HIV infection and normal renal function will show subclinical tubular abnormalities compared with seronegative controls

Renal disease is a well recognized complication among patients with HIV infection. Either viral infection itself and the use of some antiretroviral drugs contribute to this serious non AIDS-defining condition that may affect both the glomeruli and the renal tubules.

The thick ascending loop of Henle constitutes the main location for free-water clearance determining kidney´s ability to concentrate and dilute urine in a direct and indirect fashion, respectively.

Inclusion Criteria:

• Inclusion criteria are as follows: adult patients (≥18 years old) with confirmed chronic HIV-1 infection who agreed to provide written informed consent. Patients under antiretroviral treatment must had a stable regimen for over six months and undetectable (<50 copies/ml) viral load for at least three months. At study entry all selected patients were confirmed as having normal physical examination, routine clinical laboratory including urinalysis, as well as renal and cardiac ultrasound.

Exclusion Criteria:

• Exclusion criteria include patients with acute HIV infection (< 6 months of disease), personal history of nephropathy, plasma creatinine ≥1.3 mg/dl, Glomerular filtration rate ≤60ml/min/1.73 m² (as determined by Modification of Diet in renal Disease formula), presence of glucosuria/proteinuria (measured in spot urine sample), prior heart failure, concurrent opportunistic infection, chronic active hepatitis B or C, and use of potentially nephrotoxic agents in the prior week before the test (e.g diuretics, angiotensin converting enzyme antagonists, Angiotensin II receptor antagonists or non-steroidal anti-inflammatory agents).

Patients with and without HIV infection followed at Hospital Italiano de Buenos Aires, university-affiliated tertiary-care community hospital