On the prognosis of IDDM patients with large kidneys

Background. Approximately 10-30% of IDDM patients develop diabetic nephropathy depending on the metabolic control. Previous examinations on the significance of the kidney size prior to the manifestation of nephropathy produced varying results. Methods. The present study, therefore, was designed to assess the correlation between sonographically determined kidney size and kidney function over 8 years in a follow-up examination, and to evaluate a potential risk pattern. Data could be collected from 73 (66%) of 110 IDDM patients with initially normal serum creatinine whose sonographically determined kidney volume (cm(3) = L cm x W cm x D cm x pi/6) and kidney function (creatinine, albuminuria, beta(2)-microglobulin in serum) had been examined in 1986, and who had a diabetes duration of 1 month to 25 years at that time. Results. 30% (11 of 37) patients with large kidneys (>170 cm(3)) reached at least one serious renal endpoint (increase of serum creatinine by more than 50%, requirement of dialysis or kidney transplantation, or death in end-stage renal disease) versus one of 36 patients with normal kidney size (P<0.002). As many as 42% of patients with large kidneys developed abnormal creatinine values (>106 mu mol/l) in contrast to only 20% of the patients with normal kidney volume (P<0.05). Six of seven patients with a more than 50% increase of serum creatinine from baseline showed large kidneys in 1986, but had a normal serum creatinine, and four also a normal urine albumin excretion. Furthermore all five patients with more severe endpoints (two deaths in end stage renal disease and three patients presently requiring dialysis) exhibited either an increased serum creatinine or large kidneys at baseline; four of these, however, were still in the normoalbuminuric state in 1986. Conclusions. These results indicate that large kidneys might be a morphological marker for subsequent diabetic nephropathy, and as a consequence, renal insufficiency.