Albumin/globulin ratio and platelet/albumin ratio as a predictive non-invasive biomarker for lupus nephritis (LN) presence and severity

Lupus nephritis (LN) is one of the most frequent and severe manifestations of systemic lupus erythematosus (SLE) and serves as a major predictor of poor prognosis . Delayed diagnosis significantly increases the risk of renal insufficiency and progression to end-stage renal disease (ESRD) . Conventional laboratory markers-such as proteinuria, urine protein-to-creatinine ratio, creatinine clearance, anti-double-stranded DNA (anti-dsDNA) antibodies, and complement levels-are commonly used to assess LN . However, these markers often lack sufficient sensitivity and specificity for early diagnosis and disease monitoring .This limitation has prompted interest in identifying reliable, non-invasive, and cost-effective biomarkers for LN. The albumin/globulin (A/G) ratio is one such biomarker, reflecting systemic inflammation and immune dysregulation. In SLE, inflammation or proteinuria often leads to hypoalbuminemia, while increased immunoglobulin production elevates globulin levels, reducing the A/G ratio. Lower ratios have been associated with increased disease activity and organ damage .

Another emerging marker is the platelet/albumin (P/A) ratio, which integrates inflammatory status with nutritional and renal function indicators. It has demonstrated prognostic value in diabetes mellitus ,cardiovascular, hepatic, and autoimmune conditions .Despite their promise, these biomarkers have not been adequately studied in Egyptian LN patients. Given that regional and demographic variations may influence disease expression, evaluating these ratios in Upper Egypt may provide clinically relevant insights and inform local disease management strategies.

Inclusion Criteria:

• Patients aged 18 years or older diagnosed as SLE according to 2019 ACR/EULAR classification criteria and with lupus nephritis (LN) according to the ACR criteria.
• Patients with available baseline laboratory investigations and renal biopsy.

Exclusion Criteria:

• Patients with chronic liver disease, hematological disorders, or malignancies affecting albumin/globulin ratio or platelet counts.
• Patients on nephrotoxic medications not related to SLE management.
• Recent infections or acute inflammatory conditions.

Aged ≥18 years.

• SLE patients fulfilling the SLE International Collaborating Clinics (SLICC) - ----classification criteria and matched controls.
• Patients cooperative and can answer questions.
• Patients who are able and willing to give written informed consent.