Figure 6 Hypothetical effect of starting therapy for autosomal dominant polycystic kidney disease (ADPKD) at 18 years or 35 years of age Figure 6 | Hypothetical effect of starting therapy for autosomal dominant polycystic kidney disease (ADPKD) at 18 years or 35 years of age. These graphs, which are based on the assumption that decline in glomerular filtration rate (GFR) in ADPKD is linked to the progressive increase in total kidney volume (TKV), show the potential effect of treatment on the annual rate of TKV growth. GFR values above the dashed horizontal line fall within chronic kidney disease stage 1. The baseline rate of 5% increase in TKV per year can be reduced to 2.5% or 1.25% per year regardless of whether treatment is started at 18 years or 35 years of age. a | If treatment is started at 18 years of age, a patient with a TKV growth rate of 5% per year will experience a decline in GFR to 0.0 ml/min/1.73 m2 at 57 years of age; a patient with a TKV growth rate of 2.5% per year will reach a GFR of 0.0 ml/min/1.73 m2 at around 70 years of age; a patient with a TKV growth rate of 1.25% per year will reach a GFR of 0.0 ml/min/1.73 m2 at >70 years of age. b | If treatment is initiated at 35 years of age, reductions in TKV from baseline and in the rate of GFR decline are more modest than if treatment is started at 18 years of age. A TKV growth rate reduction to 2.5% per year at the age of 35 years will lead to a GFR decline to 0.0 ml/min/1.73 m2 at 65 years of age, whereas a TKV growth rate reduction to 1.25% per year will lead to a GFR decline to 0.0 ml/min/1.73 m2 at 70 years of age. The model illustrates that reductions in the rate of TKV growth might be associated with substantial preservation of renal function if treatment is initiated relatively early in life, and that beginning treatment by 35 years of age could provide a modest, but worthwhile preservation of renal function. Grantham, J. J. & Torres, V. E. (2016) The importance of total kidney volume in evaluating progression of polycystic kidney disease Nat. Rev. Nephrol. doi:10.1038/nrneph.2016.135