P0141KIDNEY BIOPSY INDICATIONS AND OUTCOMES: SEVEN YEARS EXPERIENCE OF A SINGLE CENTRE IN SRI LANKA
Authors: Pilapitiya Dilukshi , Wadduwage Nayomi , Aberathna Chanaka , Galahitiyawa Chinthana , Herath Chula , Rodrigo Sonali 
Published: June 2020

Abstract

Background and Aims
Histopathological analysis of renal biopsy is the cornerstone of diagnosis in renal disease and guides treatment and prognosis. The prevalence of various renal diseases varies according to the geographical area, socioeconomic condition, race, age, demography and indication of renal biopsy.

Method
A retrospective study of all native and transplant kidney biopsies performed at the renal unit of Sri Jayewardenepura General Hospital, Sri Lanka, between 1st October 2012 and 30th September 2019. Samples were processed for light microscopy in all cases, with immunofluorescence in most cases.

Results
771 biopsies were analyzed. Majority of biopsies 514 (67%) were male patients. Most biopsies (n= 345, 45%) were in 40 – 59yr age group, followed by 267 (35%) 20–39yr, 117 (15%) 60–69yr, 12 (1%) &gt;70yrs, 30 (4%) 12–19yr age groups. Maximum age was 84 years. In 35 cases, tissue were inadequate.
547 (71%) were native biopsies and 224 (29%) were graft biopsies. Among transplants, majority was for an indication (n=146, 66%) followed by time-zeroes (n=59, 26%) and protocols (n=19, 9%). Rising creatinine (81%) was the strongest reason for transplant biopsies, next proteinuria (10%) and delayed graft function (7%). Time zeroes: majority were normal, few ATN, 1 chronic tubulointerstitial nephritis, and 1 hypertensive glomerulosclerosis. Grafts revealed, acute antibody-mediated rejection 41 (18%) with acute cell-mediated rejection 27 (12%), (total rejections n=68, 30%) followed by normal histology 48 (21%), acute tubular necrosis 43 (19%), chronic allograft nephropathy 23 (10%), BKV nephropathy 5 (2%), and 18% other etiologies: CNI-toxicity (n=4), hypertensive glomerulosclerosis (n=3), diabetic nephropathy (n=2), thrombotic microangiopathy (n=2), FSGS (n=2), MPGN (n=1), vasculitis (n=2), PTLD (n=1), cast nephropathy (n=1), and granulomatous interstitial nephritis (n=1).
The most common indication for native biopsy was nephrotic syndrome 209 (38%), followed by non-proteinuric CKD 105 (19%), unexplained renal failure 77 (14%), sub-nephrotic proteinuria 102 (18%), nephritic syndrome 54 (9%). Primary glomerulonephritis (GN) was the commonest 291 (53%). Commonest lesion amidst primary GN was IgA nephropathy 90 (16%), followed by FSGS 63 (12%), CGN 27 (4%), minimal change 36 (6%), MPGN 32 (5%), membranous 6 (1%), DPGN 22 (4%), mesangiocapillary GN 3 (0.5%) and post-streptococcal GN 11 (2%). In the secondary forms of GN, SLE was the commonest 39 (7%), next diabetic nephropathy 29 (5%), amyloidosis 2 (0.3%). Chronic tubulointerstitial nephritis 92 (16%) was the second common, with 42 (7%) CINAC – chronic interstitial nephritis in agricultural communities. Other etiologies: acute tubulointerstitial nephritis 14 (2.5%), hypertensive glomerulosclerosis 12 (2%), thrombotic microangiopathy 6 (1%), ischemic nephropathy 9 (1%), end stage disease 6 (1%), inconclusive 13 (2%). 5 cast nephropathy due to multiple myeloma, 1 monoclonal deposition disease due to lambda chain deposition, 1 sarcoidosis, 1 cholesterol embolism.

Conclusion
Female: male ratio 1:2 with commonest age group being 40 – 59yrs. Strongest indication for transplant biopsy was rising creatinine. Acute rejection was the most frequent finding in grafts, with normal histology being the next, probably due to high number of time zeroes and protocols performed in our centre. Biopsy proven BKV nephropathy was 2% (n=5).
Nephrotic range proteinuria was the commonest native biopsy indication, with non-proteinuric CKD being the second. Primary GN was the commonest finding with IgA nephropathy scoring the highest. This does not coincide with global data, which shows FSGS to be the leading cause. The second common histology was FSGS, and primary CTIN was third. The prevalence of biopsy-proven GN varies due to a wide array of factors and different studies have shown different leading patterns.