LAUSR

Nephrotic syndrome (NS) is a common indication for renal biopsy, and a frequent presenting clinical syndrome for certain glomerulonephritis (GN), particularly minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS) or membranous nephropathy (MN). However, less is known on the spectrum of clinicopathological diagnosis and characteristics in patients with nephrotic-range proteinuria without nephrotic syndrome (NRP). We aim to evaluate the differences in clinicopathological diagnosis and characteristics of patients with NS versus NRP. All patients who underwent a renal biopsy from the 1st January 2014 to 31st December 2016 were included in the study. Patients with no urine protein quantification, serum albumin or lipid panel done at the time of renal biopsy or no glomeruli seen on renal histology were excluded. Data for renal histopathology, clinical diagnosis and patient characteristics were obtained from review of medical records. A total of 362 patients underwent a renal biopsy from the 1st January 2014 to 31st December 2016. Of these, 76 patients had NS and 106 patients had NRP. Mean age was 51.1±17.0, 51.5% were male and 70.9% were Chinese. In the NS group, there were 25 (32.9%) MCD, 10 (13.2%) FSGS of which 8 were primary, 14 (18.4%) lupus nephritis (LN), 11 (14.5%) MN, 8 (10.5%) diabetic glomerulosclerosis, 2 (2.6%) Immunoglobulin A nephropathy (IgAN), 2 (2.6%) amyloidosis and 4 (5.3%) with other diagnoses (2 membranoproliferative GN, 1 acute interstitial nephritis, 1 chronic glomerulosclerosis). In the NRP group, there were 26 (24.5%) diabetic nephropathy, 21 (19.8%) IgAN, 15 (14.2%) LN, 13 (12.3%) FSGS of which 12 were secondary FSGS, 12 (11.3%) chronic glomerulosclerosis, 8 (7.5%) MN, 4 (3.8%) pauci-immune GN and 7 (6.6%) with other diagnosis (2 infection-related glomerulonephritis, 3 had mild chronic changes with proteinuria attributable to overflow proteinuria from myeloma, 1 Alport syndrome, 1 thrombotic microangiopathy). There were significantly more cases of primary GN in the NS group (63.2% versus 28.3%, p<0.001), while the NRP group had more secondary GN and non-GN cases. The most common cause of primary GN is MCD in the NS group and IgAN in the NRP group. LN is the most common secondary GN in both NS and NRP groups. There was no significant difference in age, gender and race between the NS and NRP group. The NS group had a significantly higher proteinuria (10.8±5.5 versus 6.3±3.5, p<0.001) and lower serum albumin (17.0±5.7 versus 28.0±7.6, p<0.001). The NRP group had significantly more patients with abnormal renal function at the time of biopsy (83 (78.30%) versus 39 (51.32%) patients, p<0.001), a higher mean systolic BP (144.1±26.3mmHg versus 134.2±26.2mmHg, p=0.014) and a higher percentage of diabetes mellitus (38 (35.85%) versus 15 (19.74%) patients, p=0.018) compared to the NS group. The clinicopathological diagnosis between patients with NS and NRP differ significantly. Patients with NRP are more likely to have secondary glomerular disease or non-glomerular disease, with abnormal renal function and higher prevalence of hypertension and diabetes mellitus.