Following the introduction of phenolsulphonephthalein as a test of renal function, the analogous use of dyestuffs to test the function of other organs has been attempted. For instance, phenoltetrachlorphthalein, indigocarmin and methylene blue have proved of some value as liver function tests. On account of the ease with which gastric contents may be recovered, and the fact that certain dyestuffs are readily excreted into the stomach, chromoscopy has also recently been applied to the study of the secretory function of the stomach.
Fuld, in 1908,1 had observed that neutral red was excreted by the gastric mucosa. Finkelstein,2 using a Pawlow pouch in dogs, found that the neutral red was excreted in the gastric juice in large quantities and that fluorescin and methylene blue were excreted only in traces, while eosin, indigocarmin, phenolsulphonephthalein, congo red, acridin red and phenoltetrachlorphthalein did not appear in the stomach after subcutaneous administration. Saxl
WINKELSTEIN A, MARCUS JM. THE EXCRETION OF NEUTRAL RED INTO THE HUMAN STOMACH. JAMA. 1925;85(18):1397-1398. doi:10.1001/jama.1925.02670180053014