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INTRODUCTION: Chronic kidney disease of undetermined aetiology (CKDu) is an important public health problem. Indian data are mostly based on studies from rural regions in south and east India. We examined the burden and profile of CKDu in patients attending a tertiary care hospital in north India. METHODS: We assessed records of consecutive new CKD patients registered in a nephrology clinic from January 2015 to June 2022. Patients were classified as having CKDu based on predefined inclusion and exclusion criteria. Clinical and laboratory parameters at presentation and kidney biopsy when done were noted. RESULTS: Records of 32,369 patients with CKD were screened, and 29,663 were included (2,706 excluded due to inadequate data). A total of 370 (1.2%) patients were categorized as CKDu. Mean age was 41 ± 14.7 years, 58.1% being male. Of them, 158 (42.7%) patients were in CKD stage 3, 89 (24.1%) in stage 4, 84 (22.7%) in stage 5, and 39 (10.5%) were dialysis dependent at presentation; 232 (62.7%) patients had proteinuria <0.5 gm/day and 138 (37.3%) between 0.5 and 1 gm/day. Renal histology was available for 65 CKDu patients: 62 had chronic tubulointerstitial nephritis (CTIN) and 3 had non-specific changes. CONCLUSION: When defined using strict criteria with intensive diagnostic workup, burden of CKDu is low in our hospital-based cohort of CKD patients. CTIN is the predominant histopathological finding in kidney biopsy.
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Genetic focal segmental glomerulosclerosis (FSGS) is an important but underestimated cause of inherited proteinuric chronic kidney disease (CKD) in adults. We discuss a case of familial CKD due to inverted formin 2 (INF2) gene mutation, where three siblings had disparate phenotypic presentations ranging from CKD with subnephrotic proteinuria to nephrotic-range proteinuria with collapsing FSGS on kidney biopsy over a period of 8 years. The youngest sibling was the index case. The family agreed to undergo genetic testing only after two more siblings were diagnosed with kidney disease. This case highlights how clinical heterogeneity, absence of family history in the index case, initial lack of specific biopsy-proven diagnosis and reluctance to undergo genetic testing can delay the diagnosis of genetic kidney disease in adults.