Comparison of hypoalbuminemia-corrected serum calcium using BCP albumin assay to ionized calcium and impact on prescribing in hemodialysis patients
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BACKGROUND: Albumin-corrected calcium (cCa) is recommended over ionized calcium (iCa) in hemodialysis (HD) patients per the Kidney Disease: Improving Global Outcomes position statements due to cost and feasibility. Two common albumin assays, bromocresol green (BCG) and bromocresol purple (BCP), produce differing results in uremic patients. All previous studies compared iCa to cCa from a BCG assay. This study, using the BCP assay, aimed to compare cCa and total calcium, respectively, to iCa. We also sought to assess phosphate binders and dialysis prescribing patterns following abnormal calcium measurements. MATERIALS AND METHODS: Retrospective review of 122 stable chronic HD patients with iCa, serum calcium, and albumin measured together throughout 6 blood work periods for a total of 338 sets of comparison values. Payne and Jain calcium correction equations were used. Prescription changes within 2 weeks of abnormal iCa values were recorded. RESULTS: Mean iCa, cCa, and total calcium were 1.17 ± 0.08, 2.37 ± 0.16, and 2.28 ± 0.15 mmol/L, respectively. Total calcium and cCa compared to iCa had κ-coefficients of 0.19 and 0.08, respectively, for hypocalcemia, 0.19 and -0.02 for normocalcemia and 0.59 and 0.46 for hypercalcemia. 21 interventions were made in hypocalcemic patients using iCa as reference; however, if total or corrected calcium values were used, only 8 and 5 interventions, respectively, would result. CONCLUSION: When BCP assay is used, conventional correction equations should not be utilized in hemodialysis patients; uncorrected serum calcium has a better predictive value.
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Reference intervals for the P-Albumin bromocresol purple method.

Correct reference intervals are an important part of test results. As establishing own reference intervals is a very expensive task, the NORIP reference intervals are often transferred for use in Nordic laboratories. The NORIP reference interval on P-Albumin was here compared to current results for laboratories using the bromocresol purple (BCP) method for P-Albumin. External quality control reports were used to investigate the change in levels between the BCP and BCG methods on P-Albumin. An algorithm was built for extracting and isolating the laboratory's healthy subject population. The algorithm was used to extract test results from the laboratory information system. Parametric and non-parametric statistical methods were used to evaluate the P-Albumin test result populations. The indirect method used here clearly shows that the NORIP reference intervals for P-Albumin are not fit for the current bromocresol purple methods. The method was also used to suggest new reference interval limits.

Albumin concentration determined by the modified bromocresol purple method is superior to that by the bromocresol green method for assessing nutritional status in malnourished patients with inflammation.

BACKGROUND: The controlling nutritional status (CONUT) score (CS), a simple score for assessing nutritional status, is calculated using laboratory data, including serum albumin concentration. Although dye-binding assays such as the bromocresol green (BCG) and modified bromocresol purple (mBCP) methods are widely used for albumin measurement, acute-phase proteins interfere with the BCG method. OBJECTIVE: We aimed to determine whether the choice of albumin assay affects assessment of nutritional status using CONUT scores (CSs). DESIGN: We measured serum albumin concentrations by the BCG (ALBBCG) and mBCP (ALBmBCP) methods in 44 malnourished inpatients, 27 of whom underwent nutritional intervention, and compared them to 30 age-matched healthy volunteers. In treated patients, CSs were calculated by ALBBCG (CS-BCG) and ALBmBCP (CS-mBCP). RESULTS: C-reactive protein (CRP) concentrations were positively correlated with the difference between ALBBCG and ALBmBCP in malnourished inpatients (r = 0.59, p < 0.001). CS-BCG was always lower than CS-mBCP (lower CS indicates superior nutritional status) in treated patients with persistently high CRP levels. However, in patients whose CRP decreased gradually, this difference diminished over the clinical course. CS-BCG and CS-mBCP were similar throughout their courses in patients with normal CRP concentrations. Adding haptoglobin to the human albumin solutions increased ALBBCG in a dose-dependent manner. CONCLUSIONS: The choice of albumin assay affected the assessment of nutritional status using CSs in patients with inflammation. We recommend that the modified BCP assay be used to assess nutritional status, particularly in patients with inflammation.