Total protein concentration before Elisa

[kazi]

Is total protein determination always necessary before an Elisa assay?
I want to measure a protein in Bronchoalveolara Lavage Fluid (BALf) which is the lining fluid from the bronchial and alveolar epithelium. It is aspirated with saline through Bronchoscope

What is the point of measuring the total protein concentration??
The most papers i have reviewed, using Elisa in BALf, have results in pg/ml or ng/ml or ug/ml and they have not performed an assay for the total protein concentration.

Thanks in advance for the replies

[Elisadeveloper]

Collection of BALF is variable by nature. If you are confident that the collection procedure being applied is consistent from individual sample to individual sample, then results in ng/mL are good...if you think that the procedure is highly variable, or there are vastly variable protein contents from sample to sample for other reasons, then it my be more applicable to express results in ng/g total protein (for example).

[Biologymad]

It cannot be fully controlled as to how much is got, due to nature, as is said above. It is a good idea to go on your instincts on this one, as to whether procedures are being carried out consistantly or changed to suit.