Journal of Aging Science

Abstract

Proximal Tubule Function and Free Water Clearance: Comparison between Healthy Elderly and Young HIV+ Patients

Carlos Musso, Matilde Navarro, Mariana de Paz Sierra, Ariel Perelsztein, Marisa Sanchez, Manuel Vilas, Bernardo Martinez, Ricardo Jauregui and Waldo Belloso

In previous studies it was documented that proximal tubule sodium reabsorption capability was preserved in healthy elderly, while Thick Ascending Loop of Henle (TALH) one was reduced.

Aim: Since, it has also been documented that senile changes are accelerated in HIV patients, we performed a prospective study in order to evaluate if there was a significant difference in proximal and TALH function between healthy elderly and HIV patients.

Methods: Proximal and TALH was analyzed by performing hyposaline infusion test in 10 young (≥ 18-≤ 40 years old) HIV volunteers under treatment with tenofovir, free of viral charge, and normal renal function: serum creatinine, urinary sediment, and renal ultrasound), with the control group made up of 10 healthy old volunteers (≥ 65 years old).

Results: During the test, it was observed that the HIV group had a significant reduction of natremia (HIV: 133 ± 1 mmol/l vs. healthy elderly: 139 ± 1 mmol/l, p=0.03), serum osmolarity (HIV: 276 ± 4 mOsm/l vs. elderly: 288 ± 3 mOsm/l, p=0.03) and free water clearance (HIV: 3.5 ± 3 ml/min/1.73 m² vs. elderly: 5 ± 8 ml/min/1.73 m², p ≤ 0.01). Besides, HIV patients showed an inadequate and significant increase in their urinary tonicity in comparison with the healthy elderly group: HIV: 170 ± 18 mOsm/l vs. elderly: 90 ± 10, p ≤ 0.01. Regarding proximal tubular function, it was found that it was preserved in both groups.

Conclusion: Proximal tubule sodium reabsorption was normal, while free water clearance was significantly reduced in young HIV patients in comparison with healthy elderly volunteers.