Limitations in Clinical Use of a Screening Test for Protein.

1’TIIE FORMULA of an indicator strip test* for proteinuria, which utilizes the protein error of indicators, was modified in 1959. There have been few reports of experiences with the modified test. Because this strip test is designed to indicate only protein concentrations in excess of about 30 mg./100 ml., it might be thought that the test would readily differentiate a normal cerebrospinal fluid from one having a protein concentration of more than 30 mg./100 ml. Indeed, Jacobs (3) has advocated this method as a reliable one, describing the testing of CSF by this method as most helpful when laboratory facilities are not immediately available, and useful as a “rapid check on determinations by other methods.” Experiences in this laboratory with simple quantitative tests for urine and CSF protein would appear to be of interest. Preliminary screening of urine specimens was done by adding 2 drops of 25% w/v salicylsulfonic acid (SSA) to 1-2 ml. of urine. If this produced turbidity or increased turbidity, 1 ml. of filtered urine was mixed with 3 ml. of Meulemans’ reagent (3% w/v SSA contain-