Role of Albumin Assay on Calcium Levels and Prescription of Phosphate Binders in Chronic Hemodialysis Patients

Evaluation of the two-point calibration bromocresol green method, showing reduced deviation from the bromocresol purple method in sera from patients with hypoalbuminemia

BACKGROUND

The bromocresol green (BCG) and bromocresol purple (BCP) methods are widely used for albumin measurements in routine testing, but the BCG method is known to react with globulin fractions and to have low specificity for albumin. We evaluated a calibration method using different concentrations of human serum albumin standards (two-point calibration BCG method) with the aim of reducing the effect of globulin fractions on the BCG method in patients with hypoalbuminemia.

METHOD

In the two-point calibration BCG method, two concentrations of standard solutions and their calibration values are set based on the difference in albumin concentrations measured by the BCG method (BCG-HSA method) and the modified BCP (modified BCP-HSA method) calibrated with human serum albumin standard solution (HSA). Albumin concentrations were measured in 136 patient serum samples (healthy group: 52, hypoalbuminemic group: 84) by the two-point calibrated BCG method and compared with those obtained using the modified BCP-HSA method.

RESULTS

The mean albumin concentrations obtained using the two-point calibrated BCG and modified BCP-HSA methods were 39.18 ± 3.42 g/L and 39.37 ± 3.14 g/L (healthy group) and 26.20 ± 6.23 g/L and 26.23 ± 5.67 g/L (hypoalbuminemia group), respectively. The results of the two-point calibration BCG method were in a close agreement over the entire concentration range tested compared to the modified BCP-HSA method.

CONCLUSIONS

Based on these results, this calibration method reduces the influence of the globulin fraction on the BCG method. In the hypoalbuminemic group, the calibration method was shown to provide results consistent with the BCP method, which is highly specific for albumin.

Recommendations of the Spanish Society of Nephrology for the management of mineral and bone metabolism disorders in patients with chronic kidney disease: 2021 (SEN-MM)

As in 2011, when the Spanish Society of Nephrology (SEN) published the Spanish adaptation to the Kidney Disease: Improving Global Outcomes (KDIGO) universal Guideline on Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD), this document contains an update and an adaptation of the 2017 KDIGO guidelines to our setting. In this field, as in many other areas of nephrology, it has been impossible to irrefutably answer many questions, which remain pending. However, there is no doubt that the close relationship between the CKD-MBD/cardiovascular disease/morbidity and mortality complex and new randomised clinical trials in some areas and the development of new drugs have yielded significant advances in this field and created the need for this update. We would therefore highlight the slight divergences that we propose in the ideal objectives for biochemical abnormalities in the CKD-MBD complex compared to the KDIGO suggestions (for example, in relation to parathyroid hormone or phosphate), the role of native vitamin D and analogues in the control of secondary hyperparathyroidism and the contribution of new phosphate binders and calcimimetics. Attention should also be drawn to the adoption of important new developments in the diagnosis of bone abnormalities in patients with kidney disease and to the need to be more proactive in treating them. In any event, the current speed at which innovations are taking place, while perhaps slower than we might like, globally drives the need for more frequent updates (for example, through Nefrología al día).

Association between serum elastin-derived peptides and abdominal aortic calcification in peritoneal dialysis patients: a cross-sectional study

Background

Peritoneal dialysis (PD) patients experience accelerated arterial aging, which is characterized by elastin degradation. Elastin-derived peptides (EDPs) are direct products of elastin fragmentation. This study tried to explore the association between serum EDPs and abdominal aortic calcification (AAC) in PD patients.

Methods

Serum levels of EDPs were analyzed in 126 eligible PD patients and 30 controls. PD patients were grouped according to the annularity of AAC evaluated by an abdominal computed tomography (CT) scan. Serum EDPs were analyzed in relation to the presence of AAC or severe AAC in PD patients by logistic regression analysis.

Results

Serum EDPs in PD patients were significantly higher than age-matched controls. In 126 PD patients, higher EDPs was associated with greater risk of present AAC (OR = 1.056, 95%CI 1.010–1.103) and severe AAC (OR = 1.062, 95%CI 1.004–1.123). A combination of EDPs substantially improved the accuracy of diagnostic performance for AAC and severe AAC.

Conclusions

EDPs can predict the presence and extent of AAC in PD patients, indicating its possible role to recognize PD patients at risk for AAC and severe AAC.

Measurement of serum albumin in nephrology: we need to improve

Serum albumin is a widely used biomarker in clinical nephrology. Serum albumin cut-off values are used to define disease, to predict outcome, and to guide patient care. The available commercial assays to measure serum albumin rely on different analytical principles, all with their own (analytical) specifications. This paper provides an overview of the different clinical applications of serum albumin measurements in nephrology, the (dis)advantages of the available assays and the estimates of the effects of the measurement uncertainty between different assays in clinical decision making. This paper concludes that harmonisation of serum albumin assay results are needed.