**4. Diagnosis and classification**

Current non-invasive SLE biomarkers such as proteinuria or active urine sediment, serum creatinine, anti dsDNA and hypocomplementemia could not reliably confirm the presence, severity and/or chronicity, or predict the outcome of LN. Many novel biomarkers are currently being explored in the management and

as therapeutic target in LN; unfortunately, none so far had been utilised in daily clinical practice [45].

In patients suspected of LN, certain clinical and laboratory features may however predict the class of LN a patient may have. In a retrospective study analysing 297 renal biopsies of SLE patients with some degree of proteinuria, absence of malar rash, negative anti-dsDNA and urine leukocytes of <5/high power field under microscopy are independent predictors for class II LN. Class III or IV can independently be predicted by younger age at diagnosis (<32 years), musculoskeletal involvement, hypertension, presence of anti-dsDNA, elevated creatinine level, absence of nephrotic range proteinuria and presence of leucocytes and cellular cast in urine. Older age, malar rash and low C3 level may be predictive for class V LN [46].
