Tubular dysfunction in renal transplant patients using sirolimus or tacrolimus.
BACKGROUND
Tubular dysfunction is prevalent among kidney transplant patients using calcineurin inhibitors, but our knowledge of the tubular effects of mTOR inhibitors is more limited.


METHODS
60 kidney transplant outpatients using either the calcineurin inhibitor tacrolimus or the mTOR inhibitor sirolimus were investigated for renal tubular dysfunction. Proximal tubule function was assessed by quantification of albumin and β2-microglobulin, tubular reabsorption of phosphate and fractional excretion of bicarbonate. Distal tubular function was evaluated by water deprivation test and by urinary acidification test using furosemide and fludrocortisone for pH, ammonium and titratable acidity measurements.


RESULTS
The prevalence of distal renal tubular acidosis (dRTA) was 17% for both treatment groups. 70% of patients treated with sirolimus and 94% using tacrolimus presented with urine concentrating defect (p=0.04).


CONCLUSIONS
Distal RTA and urine concentrating defect were highly prevalent after kidney transplantation both in the sirolimus and tacrolimus treated patients. Acidification test was essential for the appropriate diagnosis of dRTA while dipstick urine specific gravity test was able to detect urine concentrating defect in this population.
Pedro B
PB
Banhara
Renato T
RT
Gonçalves
Pedro T
PT
Rocha
Alvimar G
AG
Delgado
Maurilo
M
Leite
Carlos P
CP
Gomes
D000141:Acidosis, Renal Tubular / Q000139:chemically induced; D000328:Adult; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007166:Immunosuppressive Agents / Q000009:adverse effects*; D016030:Kidney Transplantation; D007684:Kidney Tubules / Q000187:drug effects* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D020123:Sirolimus / Q000009:adverse effects*; D016559:Tacrolimus / Q000009:adverse effects*
D007166:Immunosuppressive Agents; D020123:Sirolimus; D016559:Tacrolimus