Abstract
Background and Aims
Renal Fanconi syndrome (RFS) is characterized by generalized dysfunctions of renal proximal tubular (PT) transport. The causes of FS can be inherited or acquired, the latter of which mostly includes drugs, heavy metals, monoclonal light chains (LC), and primary Sj gren’s syndrome (pSS). We intended to observe the clinico-pathological features of RFS with different etiologies.
Method
From January 2012 to September 2018, all the patients diagnosed as RFS in our hospital were enrolled. Their clinicopathological records were retrospectively reviewed. The diagnosis of RFS was defined as existence of ≥ 3 of the following five items alone or ≥ 2 items combined with an evidence of PT damages in kidney pathology: (I) normoglycemic glycosuria; (II) generalized aminoaciduria; (III) hypophosphatemia and hyperphosphaturia; (IV) hypouricemia and hyperuricosuria; (V) proximal RTA.
Results: 1.
Clinical characteristics
We identified 150 RFS patients, with an average age of (45.9±14.2) years old and male: female ratio 1.3:1. They presented with different degrees of PT dysfunctions and the most common were hypophosphatemia (83.2%) and aminoaciduria (80.6%). Their mean eGFR levels were 76.3 (4.5-188.6) ml/min/1.73m2 with 73.5% had proteinuria.
2. Renal pathological features
47 RFS patients received kidney biopsy and the most common pathological diagnosis was interstitial nephritis. They all presented with different degrees of proximal tubule atrophy, defective brush border, interstitial edema and fibrosis.
3. Etiology-related clinicopathologic features
The most common causes of our RFS were LC (14.0%), drugs (13.3%), and pSS (9.3%). Compared to pSS associated RFS, LC associated RFS patients showed a higher prevalence of bone involvement, more severe proteinuria and less severe hypokalemia (P < 0.05) despite similar eGFR levels. Specific renal pathological features were seen in different etiology groups, including crystalline formation and increased lysosomes in PT cells under electron microscope in LC associated RFS, and CD21 positive ectopic germinal center formation in renal interstitum in parts of the pSS associated RFS.
Conclusion
We identified 150 RFS with different etiologies and they showed etiology-specific patterns of PT dysfunctions and renal pathologic changes.
MO142A SINGLE-CENTER CASE SERIES OF 150 PATIENTS WITH RENAL FANCONI SYNDROME
