Comparison of interferon gamma release assay & tuberculin skin tests for diagnosis of latent tuberculosis in patients on maintenance haemodialysis.

Background & objectives: Tuberculosis (TB) is a common infection in patients on haemodialysis. There is a definite role of treatment of latent TB (LTB) in these patients. However, diagnosis of LTB in these patients by tuberculin skin test (TST) is unreliable. There is suggestion that interferon gamma release assay (IGRA) will be more reliable test for diagnosis of LTB in this setting. Thus, we evaluated value of IGRA and TST for the diagnosis of LTB in patients on dialysis in an Indian setting. Methods: Patients with end stage kidney disease on dialysis were included. Patients with active TB were excluded. Each patient was subjected to TST (induration of ≥10 mm was taken as positive) and QuantiFERON TB Gold In-Tube test (QFT-GIT) for diagnosis of LTB. Results: A total of 185 patients were included; 129 (69.7%) were males and mean age was 36.7 ± 12.3 yr. Past history of TB was present in 18 (9.7%) patients. One hundred and thirty four (72.4%) patients had scar of BCG vaccination. QFT-GIT test was positive in 66 (36%), TST in 32 (17%) and both in 13 (7%) patients. Of the 66 patients positive with QFT-GIT, only 13 (19.6%) were positive for TST. Of the 32 patients positive with TST, only 13 (40.6%) were positive with QFT-GIT; 100 (54%) patients were negative for both the tests. Overall, 85 (45.9%) patients were positive for either of the two tests. Poor agreement was shown between the two methods. On logistic regression analysis, odds of QFT-GIT to be positive in patients with BCG vaccination was 1.23 and with history of TB 0.99, both being insignificant. odds of tuberculin skin test to be positive in patients with BCG vaccination was 1.04 and with history of TB 0.99, both again being insignificant. Interpretation & conclusions: Our findings showed that more number of patients (36%) on haemodialysis were positive for QuantiFERON Gold In-Tube test as compared to TST (17%). There was poor agreement between the two tests. no significant effect of BCG vaccination and history of TB in past was observed on both tests.

Crescentic glomerulonephritis: A clinical and histomorphological analysis of 46 cases.

Background: Crescentic glomerulonephritis (CrGN), defined as crescents involving more than 50% of the glomeruli, includes pauci-immune, immune complex-mediated and anti-glomerular basement membrane disease. Objectives: The present study was aimed at evaluating the various clinical, biochemical and histological parameters in CrGN with respect to these categories and clinical outcome. Materials and Methods: Renal biopsies diagnosed as CrGN between Jan 2008 and Feb 2010 were included. Clinical and laboratory parameters were retrieved along with the therapeutic approach and clinical outcome, wherever available. Renal biopsy slides were evaluated for various glomerular, tubulo-interstitial and arteriolar features. Appropriate statistical tests were applied for significance. Results: A total of 46 cases of CrGN were included; majority (71.7%) of cases were pauci-immune (PI) while 28.3% were immune complex-mediated (IC). Among clinical features, gender ratio was significantly different between PI and IC groups (P = 0.006). The various histological parameters, including proportion of cellular crescents, tuft necrosis and Bowman's capsule rupture, were similar in both the groups. Four unusual associations, including idiopathic membranoproliferative glomerulonephritis (MPGN), multibacillary leprosy, acute lymphoblastic leukemia and C1q nephropathy were detected. Adequate follow-up information was available in 21 (46%) of the patients. Of these, 11 (52.4%) were dialysis-dependent at the last follow-up. Adult patients required renal replacement therapy more frequently than pediatric cases (P = 0.05). Presence of arteriolar fibrinoid necrosis also showed association with poor clinical outcome (P = 0.05). Conclusions: Crescentic glomerulonephritis remains one of the main causes of acute renal failure with histological diagnosis. Immunohistologic examination is essential for accurate classification into one of the three categories. This condition should be considered in rare causal associations like leprosy or MPGN with renal failure, to allow for timely performed renal biopsy and appropriate aggressive therapy.

Multiple myeloma presenting as collapsing glomerulopathy.

A 54 year old male patient was admitted with advanced renal failure of recent onset. Serology was noncontributory. Renal biopsy showed collapsing glomerulopathy with interstitial fibrosis. Bone marrow examination confirmed the diagnosis of multiple myeloma. With chemotherapy multiple myeloma went into remission. However he continued to remain dialysis dependent and a repeat kidney biopsy showed progression to endstage renal disease.