Establishment of a reference interval for calculated globulin on the Roche platform

Area of Science:

• Clinical Chemistry
• Laboratory Medicine

Background:

• Calculated globulin, derived from total protein and albumin measurements, can enhance liver profile assessments.
• A specific reference interval for calculated globulin using the common Roche methods (albumin bromocresol green and total protein biuret) was previously unavailable.

Purpose of the Study:

• To establish a direct reference interval for calculated globulin using Roche methods.
• To provide a validated reference range for laboratories utilizing the Roche albumin BCG and total protein biuret assays.

Main Methods:

• A direct reference interval study was conducted on 310 adults using Roche methods for total protein (biuret) and albumin (BCG), adhering to CLSI EP28-A3c guidelines.
• An indirect reference interval was also established using data from 8466 unselected primary care patients for comparative analysis.

Main Results:

• The direct method yielded a reference interval for calculated globulin of 23 g/L (90% CI 22-24 g/L) to 35 g/L (90% CI 34-36 g/L).
• The indirect method, with a larger cohort, produced a reference interval of 22 g/L (90% CI 22-22 g/L) to 37 g/L (90% CI 37-37 g/L).
• Both methods showed similar medians, with the indirect range being slightly broader.

Conclusions:

• A specific reference interval for calculated globulin has been established for the Roche total protein and albumin BCG methods.
• This validated reference interval facilitates adoption by other laboratories using the same Roche methods, requiring only a simple transference study.
• The established range is robust, showing minimal alteration even with relaxed exclusion criteria or a significantly larger data mining approach.