Living donor kidney transplants: a biopsy study 1 year after transplantation, compared with baseline changes and correlation to kidney function at 1 and 3 years.
BACKGROUND
Chronic changes in biopsies from long-term stable kidney allografts have been reported to correlate with graft prognosis. Morphological changes in baseline ('zero-hour') biopsies have been described as well, but their importance for long-term prognosis have been less clear. The aim of the present study was to evaluate biopsy changes from baseline to 1 year after transplantation in patients receiving kidneys from living donors, and to assess the possible prognostic implications of these findings.


METHODS
Light microscopical changes in 18 gauge full-core biopsies were scored semi-quantitatively in 33 patients 1 year after transplantation, and compared to baseline changes previously reported [1]. All cases were also examined with transmission electron microscopy. The semi-quantitative data from baseline and at 1 year were correlated with kidney function 1 and 3 years after transplantation. The reproducibility of baseline findings regarding arteriosclerosis and arteriolar hyalinosis was tested by comparison with biopsies 1 week after transplantation (n = 43).


RESULTS
We found a significant increase in mesangial glomerular sclerosis (P<0.001), interstitial fibrosis/tubular atrophy (if/ta) (P = 0.002), and mononuclear cell interstitial infiltration (P = 0.003) after 1 year, compared to baseline changes. There was an increase of arteriosclerosis (P = 0.028) and arteriolar hyalinosis (P = 0.006) when compared to biopsies taken 1 week after transplantation, but not when compared to the 'zero-hour' findings. Electron microscopy revealed one case of recurrent immune-complex glomerulonephritis and another case of recurrent light chain deposition kidney disease. Comparing 1-week vascular findings with baseline gave a low level of reproducibility, probably due to sampling error. Baseline biopsy findings could not predict long-term kidney function. In the 1-year biopsy, if/ta was significantly correlated with serum creatinine (P = 0.007) and glomerular filtration rate (GFR) (P<0.001) at 1 year, with serum creatinine at 3 years (P = 0.011), and with the first-year cumulative dose of methylprednisolone (P = 0.004). Serum creatinine at 1 year, however, was found to be the most accurate predictor of 3-year kidney function (P<0.001). Donor age was correlated to kidney function at 3 years (P = 0.013) but not at 1 year after transplantation.


CONCLUSIONS
Morphological changes in baseline biopsies of living donor kidneys tend to become more pronounced in well-functioning allografts during the first year after transplantation. In the 1 year biopsy, if/ta seems to be the most reliable variate for grading of chronic changes. However, 1-year serum creatinine predicted long-term kidney function more precisely than did the biopsy scores. Based on the results of the present study, a protocol 1-year biopsy does not seem warranted in the management of the graft recipient with a stable kidney function.
Sund
S
S
Institute of Pathology, The National Hospital, Rikshospitalet, University of Oslo, Norway.
Reisaeter
A V
AV
Fauchald
P
P
Bentdal
O
O
Hall
K S
KS
Hovig
T
T
D000328:Adult; D000368:Aged; D001161:Arteriosclerosis / Q000473:pathology; D001706:Biopsy; D001808:Blood Vessels / Q000473:pathology; D005260:Female; D005355:Fibrosis; D005500:Follow-Up Studies; D005923:Glomerulosclerosis, Focal Segmental / Q000473:pathology; D005938:Glucocorticoids / Q000008:administration & dosage / Q000627:therapeutic use; D006084:Graft Rejection / Q000097:blood / Q000503:physiopathology; D006801:Humans; D007668:Kidney / Q000473:pathology / Q000503:physiopathology; D016030:Kidney Transplantation; D019520:Living Donors; D008297:Male; D008775:Methylprednisolone / Q000008:administration & dosage / Q000627:therapeutic use; D008875:Middle Aged; D011184:Postoperative Period; D012079:Renal Circulation; D013997:Time Factors
D005938:Glucocorticoids; D008775:Methylprednisolone