In healthy individuals, small amounts of urinary albumin are filtered by the glomerulus, and, while most albumin is reabsorbed by the tubules, if protein leak exceeds the capacity of tubular cells to absorb it, it is found in the urine [20]. In glomerular lesions (e.g. HIVAN and HIVICK), the structure and charge barrier to filtration are damaged, and albumin and other protein are filtered, resulting in a higher level of albuminuria [20]. In tubular disease (e.g. cART-related tubular toxicity), urinary proteins are derived from a failure to reabsorb filtered protein and other proteins that originate from damage to tubular cells [21],
and are not picked up by the assay for albumin, but will be picked up by a total protein assay (e.g. uPCR). Some tubular proteins learn more [e.g. neutrophil gelatinase-associated lipocalin (NGAL), N-acetyl-β-D-glucosaminidase (NAG), cystatin C and β2-microglobulin] may be quantified using specific assays, but these assays are expensive and not routinely available. We recently showed that a urine albumin/total protein ratio (uAPR), which is the ratio check details of urine albumin to total protein (uACR/uPCR), was highly sensitive and specific for tubulointerstitial disease in
the general population [22]. This was tested by examining the urine immunoelectrophoretic pattern and in some cases correlating this with histology. We hypothesized that, as in HIV infection one of the key decisions in patient management is to decide if the treatment is causing renal dysfunction (primarily through tubular dysfunction), the measurement of uAPR might be helpful in such assessments. Thus, we tested the hypothesis that uAPR may help to distinguish those patients with cART-associated toxicity from patients requiring further nephrological input, and possibly mafosfamide biopsy in patients in whom there is significant proteinuria. The study sample consisted of HIV-infected patients attending an urban HIV out-patient
clinic in Brighton, UK between 1 September 2007 and 31 August 2009. All uPCR results were retrospectively identified from clinic and laboratory databases. A subsample of patients with concurrent uACR and uPCR results was identified and the uAPR calculated. Patient demographics (sex, ethnicity, sexuality and age at time of uAPR sampling), HIV factors (nadir CD4 count, duration of HIV diagnosis and cART details) and relevant biochemical markers of renal function [estimated glomerular filtration (eGFR), random plasma phosphate and fractional excretion of phosphate] were assessed. The association between cART use and proteinuria was evaluated by ascertaining whether any TDF, boosted PI or simultaneous TDF and boosted PI were used before or at the time of uPCR and uACR sampling. Urine total protein was measured by turbidimetry and urine albumin by immunoturbimetric assay.