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Tubular functions in familial Mediterranean fever
Semra Akkuş1, Salim Calişkan, Ozgür Kasapçopur
1Department of Pediatrics, Istanbul University Cerrahpaşa Faculty of Medicine, Istanbul, Turkey.
Abstract:
In this study, we aimed to evaluate renal tubular function in familial Mediterranean fever (FMF). Urinary N-acetyl-beta-D glucosaminidase (U-NAG, beta2-microglobulin (U-beta2M) and microalbumin (Ua) levels were measured in children with different clinical stages of FMF (58 patients with FMF, 9 patients with amyloidosis secondary to (FMF). Control groups were healthy children (n=21), children with upper respiratory tract infection (URTI) (n=21) and with steroid sensitive nephrotic syndrome (SSNS) (n=18). U-NAG was significantly increased in patients with a recent diagnosis of FMF compared to patients with FMF on colchicine and to healthy controls. In patients with recently diagnosed FMF, a marked decrease in U-NAG, U-beta2M and Ua were determined after three months on colchicine therapy. On the other hand, U-NAG and Ubeta2M levels were increased in patients with FMF during attacks and then decreased in the post-attack period. U-beta2M in patients with FMF during attacks was significantly different from patients with URTI. Finally, U-NAG and U-beta2M were increased significantly in patients with FMF-amyloidosis and SSNS when compared with other FMF groups and healthy controls, respectively. In conclusion, the high U-NAG value in newly diagnosed patients compared to that of patients taking colchicine and the decline of U-NAG and U-beta2M levels after attack to the levels observed in colchicine users (without a significant change in Ua value) suggest that the renal injury early in the course of FMF might be dominantly at the level of the tubuli.
Insights
Familial Mediterranean Fever (FMF) patients show early kidney tubule damage, indicated by increased urinary N-acetyl-beta-D glucosaminidase (U-NAG) and beta2-microglobulin (U-beta2M) levels, which improve with colchicine treatment.
Area of Science:
- Nephrology
- Pediatrics
- Rheumatology
Background:
- Familial Mediterranean Fever (FMF) is a genetic autoinflammatory disorder.
- Renal involvement, particularly tubular dysfunction, is a potential complication of FMF.
- Early detection of renal tubular damage is crucial for managing FMF complications.
Purpose of the Study:
- To evaluate renal tubular function in children with FMF at various clinical stages.
- To assess the impact of colchicine therapy on renal tubular markers in FMF patients.
- To differentiate FMF-related renal changes from other pediatric kidney conditions.
Main Methods:
- Measured urinary N-acetyl-beta-D glucosaminidase (U-NAG), beta2-microglobulin (U-beta2M), and microalbumin (Ua) levels.
- Included 58 children with FMF, 9 with FMF-amyloidosis, and control groups (healthy, URTI, SSNS).
- Compared marker levels in newly diagnosed FMF, FMF on colchicine, during FMF attacks, and post-attack.
Main Results:
- U-NAG was elevated in newly diagnosed FMF patients compared to colchicine-treated patients and healthy controls.
- Colchicine therapy significantly decreased U-NAG, U-beta2M, and Ua levels in recently diagnosed FMF patients.
- U-NAG and U-beta2M levels increased during FMF attacks and decreased post-attack.
- Elevated U-NAG and U-beta2M were observed in FMF-amyloidosis and SSNS patients.
Conclusions:
- Newly diagnosed FMF patients exhibit elevated U-NAG, suggesting early renal tubular dysfunction.
- Colchicine treatment effectively reduces these markers, indicating its protective role.
- Renal injury in early FMF appears predominantly at the tubular level, evidenced by U-NAG and U-beta2M changes.