Determining nephrotoxicity in childhood solid tumor cases

ABSTRACTIn this study, late phase nephrotoxicity findings of 65 patients (37 boys, 28 girls) stillbeing monitored in remission and whose childhood solid tumor treatments had beencompleted between 1993-2005, were examinedMild and moderate nephrotoxicity was found in 36 patients (%55,4) and in threepatients (%4,6), respectively, according to nephrotoxicity grading system being used.Proximal tubular nephrotoxicity found in thirty patients (%46,1) was determined to be themost common nephrotoxicity finding. Decreased Tmp/GFR and hypophosphatemiadeveloped secondary to this were determined to be the most common proximal tubulartoxicity finding. Moreover, it has been found in determining proximal subclinic tubulartoxicity that urine B2-MG and α1-MG levels are highly sensitive determinants. In 18 patients(%27,7) distal tubular toxicity was found. Hypomagnesemia which was seen in fourteenpatients (%21,5) was found to be the most common distal tubular toxicity finding. It has alsobeen found out significantly that all patients who developed hypomagnesemia turned out tohave received KT protocols including platinum. Meaningful linkage was assessed betweenincreased FeMg level and hypomagnesemia and between hypophosphatemia and decreasedTmp/GFR. Moreover, patients who developed nefrotoxicity had hypophosphatemia,hypomagnesemia and significantly low Tmp/GFR, compared to non-nephrotoxic patients.Also, it has been found that in determining subclinic tubular toxicty, urine NAG enzymeactivity has low sensitivity. Glomerular toxicity was found in 18 (%27,7) patients with <80ml/min./1.73 m2 GFR according to CrCI. Four patients (%6,2) had increased serum cystatin-C, two (%3,1) had increased serum Cr levels according to other parameters used in assessingglomerular function and two (%3,1) patients had decreased GFR according to Schwartzformula. To determine glomerular dysfunctioning in patient group, when other parameters?diagnostic efficiency were assessed compared to CrCI; serum cystatin-C level and GFRmeasurement based on Schwartz formula are obtained to be significantly better for diagnosticefficiency. Glomerular and proximal tubular toxicity were significantly common in patients,%66,7 of patients with glomerular toxicity also developed proximal tubular toxicity.There was no meaningful link between development of nephrotoxicity andnephroctomy, age or other medical management (amicasin, vancomycin, amphotericin-B,aciclovir). But, there was a relation between RT and nephrotoxicity at limit. When the effectsof cumulative nephrotoxic drug dosages on nephrotoxicity development were assessed, onlyifosfamide?s cumulative mean dosage and development of nephrotoxicity had a meaningfulrelation. Besides, there was a negative correlation between nephrotoxicity and the periodafter treatment. Mean time passed before the start of study was 10,25 months in 39 patientswho developed nephrotoxicity, while the period was 26,5 months in 26 non-nephrotoxicpatients.When GFR measurement was predicated according to CrCI in patients and controlgroups, diagnostic efficiency of CrCI is seen to be significantly high compared to all threeparameters if we assess diagnostic efficiencies of serum cystatin-C, serum Cr levels and GFRmeasurement based on Schwartz formula to determine glomerular dysfunctioning. Alsodiagnostic efficiency of serum cystsatin-C level, compared to serum Cr level is statisticallyhigher in determining glomerular dysfunction.