Background: Silent lupus nephritis (SLN) is a life menacing consequence of systemic lupus erythematous (SLE). This condition is characterized by pathological impairment of the kidney in the obscurity of clinical or laboratory manifestations.
Objective: To reveal the existence of SLN along with the potential differences between overt lupus nephritis (OLN) and SLN among a sample of Egyptian patients based on histopathological assessment.
Patients and Methods: It is a prospective case-control study which was performed at nephrology units, internal medicine department, Elhussein and Sayed Galal university hospitals, faculty of medicine, Al-Azhar University, Cairo, Egypt, throughout the entire period April 2016 to November 2019. Patients aged more than 18 years (216 months) and fulfilled at least 4 of the American College of Rheumatology criteria for the classification of systemic lupus erythematosus (SLE) were enrolled in the current study. Patients were further assorted into two groups; patients with SLN and those with OLN.
     Patients were subjected to the following investigations: 1.Complete blood count, using Coulter counter Max-M (Coulter Cooperation, Florida, USA) 2.Erythrocyte sedimentation rate, (Wester green method) (Ref: < 20mm/hr) 3.S. Albumin, S. Creatinine. Albumin/Creatinine ratio. Creatinine clearanc & eGFR using the Modification of Diet in Renal Disease (MDRD) formula. 4. Liver function tests. 5. Coagulation profile. 6. Urine analysis (Fresh morning midstream urine) to exclude infection. 7. Quantitative assessment of proteinuria by Pr/creat. Ratio (Ref. <0.2).
     Assessment of auto-antibodies and complement system: Autoantibodies to ds-DNA, RNP. SSA, SSB, Sm and Scl-70, C4 and C3 serum levels were assessed in all of the included patients. In particular, the titer of anti-dsDNA antibodies was evaluated by enzyme-
     Radiological evaluation: Patients were subjected to pelvi-abdominal ultrasound in order to obtain valuable data about the morphological appearance of the kidney and to detect any urological abnormality.
Renal biopsy: Percutaneous renal biopsy was carried out under local anesthesia.
Results: An overall 40 patients with SLE who developed lupus nephritis were enrolled in the current study. Among them, 20 patients had OLN, whereas 20 patients were SLN. Based on ISN/RPS Classification, stage II was the predominant stage, 13 patients, among patients with SLN, whilst stage V was the predominant stage among the OLN patients. Additionally, five and three patients were stage III among the SLN and OLN groups, respectively. Furthermore, the presence of RBCs Cast (r=0.479, P=0.032) in urine and decreased levels of complement (r=0.676, P=0.001) showed a statistically significant positive correlation with the high grades of lupus nephritis among SLN group.
Conclusion: Patients with SLE should be subjected to close follow up evaluation and renal biopsy for early detection of SLN to determine the activity, severity, and chronicity of LN.