DOES THE TOTAL KIDNEY VOLUME REFLECT ALPORT SYNDROME PROGRESSION?

Abstract Background and Aims The kidney volume can reflect kidney function and predict renal disease progression. The aim of the study was to define the clinical significance of kidney volume in children with Alport syndrome (AS). Method The medical records were obtained from 86 children (age Me 8(5;11) years; 50M/36F) with genetically (n=78) and morphologically (n=8) confirmed AS; follow-up Me 4(2;6) years. Albuminuria (Alb), proteinuria (Pr), nephrotic proteinuria (nPr) and decreased eGFR were defined as urine Alb>30 mg/gr Cr, Pr≥100 mg/m2/day, Pr≥960 mg/m2/day and eGFR<90 ml/min/1,73m2, respectively. The Body Superficial Area Related Total Kidney Volume (BSARTKV) was calculated as relation of US kidney volume to BSA: BSARTKV[ml/m2]=(L*W*D*π/6)/BSA and compared with normal volume range (Th.Scholbach, D.Weitzel, 2012). Results The renal volume ≥95‰ was revealed in ½ and ¾ of children at initial and last evaluation, respectively (0.51 vs 0.76, p>0.05); two boys (q=0.02) with CKD stage 4 had a BSARTKV ≤10‰ at the last presentation. BSARTKV correlated with age (r=0.3, p<0.05), mean blood pressure percentile (r=-0,22, p<0,05), Alb (r=0.25, p<0.05), Pr (r=0.4, p<0,001) and eGFR (r=0.23, p<0.05). No correlation was found between BSARTKV and birth weight and gender. Each 1SD (23.5 ml/m2) increase in BSARTKV was related with higher eGFR: OR=6.7 (95%CI 3.51;8.69, p<0,001). The children with nPr and eGFR>35 ml/min/1,73m2 had enlarged kidneys: OR=30.75(95%CI 2.56;369, p<0,001); the patients with eGFR≤35 ml/min/1,73m2 had small BSARTKV: OR=167 (95%CI 10.4;2681.3, p<0,0001). Conclusion The kidney volume reflects the progression of nephropathy in AS. Probably, an increased renal mass compensates decreased glomerular function, whereas small kidney volume represents the loss of function of most nephrons.