Comparison of two ferritin assay platforms to assess their level of agreement in measuring serum and plasma ferritin levels in patients with chronic kidney disease

BACKGROUND

Ferritin levels are used to make decisions on therapy of iron deficiency in patients with chronic kidney disease (CKD). Hyperferritinaemia, common among patients with CKD from the Northern Territory (NT) of Australia, makes use of ferritin levels as per clinical guidelines challenging. No gold standard assay exists for measuring ferritin levels. Significant variability between results from different assays creates challenges for clinical decision-making regarding iron therapy. In the NT, different laboratories use different methods. In 2018, Territory Pathology changed the assay from Abbott ARCHITECT i1000 (AA) to Ortho-Clinical Diagnostics Vitros 7600 (OCD). This was during the planning of the INtravenous iron polymaltose for First Nations Australian patients with high FERRitin levels on haemodialysis (INFERR) clinical trial. The trial design was based on AA assay ferritin levels. We compared the two assays' level of agreement in measuring ferritin levels in CKD patients.

METHODS

Samples from INFERR clinical trial participants were analysed. Other samples from patients whose testing were completed the same day on OCD analyzers and run within 24 h on AA analyzers were added to ensure wide range of ferritin levels, adding statistical strength to the comparison. Ferritin levels from both assays were compared using Pearson's correlation, Bland-Altman, Deming and Passing-Bablok regression analyses. Differences between sample types, plasma and serum were assessed.

RESULTS

Sixty-eight and 111 (179) samples from different patients from Central Australia and Top End of Australia, respectively, were analyzed separately and in combination. The ferritin levels ranged from 3.1 µg/L to 3354 µg/L and 3 µg/L to 2170 µg/L for AA and OCD assays respectively. Using Bland-Altman, Deming and Passing-Bablok regression methods for comparison, ferritin results were consistently 36% to 44% higher with AA than OCD assays. The bias was up to 49%. AA ferritin results were the same in serum and plasma. However, OCD ferritin results were 5% higher in serum than plasma.

CONCLUSIONS

When making clinical decisions, using ferritin results from the same assay in patients with CKD is critical. If the assay is changed, it is essential to assess agreement between results from the new and old assays. Further studies to harmonize ferritin assays are required.

INFERR-Iron infusion in haemodialysis study: INtravenous iron polymaltose for First Nations Australian patients with high FERRitin levels on haemodialysis-a protocol for a prospective open-label blinded endpoint randomised controlled trial

Background

The effectiveness of erythropoiesis-stimulating agents, which are the main stay of managing anaemia of chronic kidney disease (CKD), is largely dependent on adequate body iron stores. The iron stores are determined by the levels of serum ferritin concentration and transferrin saturation. These two surrogate markers of iron stores are used to guide iron replacement therapy. Most Aboriginal and/or Torres Islander Australians of the Northern Territory (herein respectfully referred to as First Nations Australians) with end-stage kidney disease have ferritin levels higher than current guideline recommendations for iron therapy. There is no clear evidence to guide safe and effective treatment with iron in these patients. We aim to assess the impact of intravenous iron treatment on all-cause death and hospitalisation with a principal diagnosis of all-cause infection in First Nations patients on haemodialysis with anaemia, high ferritin levels and low transferrin saturation

Methods

In a prospective open-label blinded endpoint randomised controlled trial, a total of 576 participants on maintenance haemodialysis with high ferritin (> 700 μg/L and ≤ 2000 μg/L) and low transferrin saturation (< 40%) from all the 7 renal units across the Northern Territory of Australia will be randomised 1:1 to receive intravenous iron polymaltose 400 mg once monthly (200 mg during 2 consecutive haemodialysis sessions) (Arm A) or no IV iron treatment (standard treatment) (Arm B). Rescue therapy will be administered when the ferritin levels fall below 700 μg/L or when clinically indicated. The primary outcome will be the differences between the two study arms in the risk of hospitalisation with all-cause infection or death. An economic analysis and several secondary and tertiary outcomes analyses will also be performed.

Discussion

The INFERR clinical trial will address significant uncertainty on the safety and efficacy of iron therapy in First Nations Australians with CKD with hyperferritinaemia and evidence of iron deficiency. This will hopefully lead to the development of evidence-based guidelines. It will also provide the opportunity to explore the causes of hyperferritinaemia in First Nations Australians from the Northern Territory.

Trial registration

This trial is registered with The Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12620000705987. Registered 29 June 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05854-w.

Analysis of clinical presentation, pathological spectra, treatment and outcomes of biopsy-proven acute postinfectious glomerulonephritis in adult indigenous people of the Northern Territory of Australia

AIM

Acute postinfectious glomerulonephritis is common in indigenous communities in the Northern Territory, Australia. It is a major risk factor for the high prevalence of chronic kidney disease. We aimed to analyse the clinical presentation, pathological spectra, treatment and outcomes of biopsy-proven acute postinfectious glomerulonephritis in the Northern Territory.

METHODS

We performed a retrospective cohort analysis of all adult patients (≥18 years) who were diagnosed with acute postinfectious glomerulonephritis on native renal biopsies from 01/01/2004 to 31/05/2014. The outcome measure was end-stage renal disease requiring long-term dialysis.

RESULTS

Forty-three of 340 patients who had renal biopsies had acute postinfectious glomerulonephritis. Most were Aboriginals (88.4%). They had co-morbidities; diabetes mellitus (60.5%), hypertension (60.5%) and smoking (56.4%). Forty-nine per cent had multiple pathologies on biopsy. Predominant histological pattern was diffuse proliferative glomerulonephritis (72%). Main sites of infections were skin (47.6%) and upper respiratory tract infection (26.2%) with streptococcus and staphylococcus as predominant organisms. Fifty per cent of patients developed end-stage renal disease. On multivariable logistic regression analysis, those on dialysis had higher baseline creatinine (P = 0.003), higher albumin/creatinine ratio at presentation (P = 0.023), higher serum creatinine at presentation (P = 0.02) and lower estimated glomerular filtration rate at presentation (P = 0.012).

CONCLUSION

Overall, most patients had pre-existing pathology with superimposed acute postinfectious glomerulonephritis that led to poor outcomes in our cohort.

Renal failure in a patient with primary antiphospholipid syndrome

Antiphospholipid antibody syndrome (APLA) is a syndrome complex characterized by recurrent arterial or venous thrombosis, recurrent fetal wastage, thrombocytopenia and presence in serum of antibodies against negatively charged phospholipids like lupus anticoagulant (LA), anticardiolipin antibody (ACLA) and subgroups. These are classified further as primary (wherein this occurs in isolation) and secondary (associated with infection, drugs and malignancies). It is uncommon to find both LA and ACLA in primary APLA syndrome (unlike as in the secondary form). Renal manifestations which include renal arterial and venous occlusion and infarction and thrombotic microangiopathy have also been infrequently described. We hereby present a case of primary APLA syndrome with unusual features of LA and ACLA occurring together and also the presence of renal failure due to left renal artery thrombosis and right renal artery occlusion.