An obsolete, non-specific test for altered proteins in spinal fluid. As originally used by Lange in 1912, the test was thought to be specific for neurosyphilis; however, this proved to be incorrect. Dilutions of spinal fluid are made in saline and to these a colloidal gold solution is added; if altered proteins are present, there is a colour change or precipitate formed. at present, its chief use is to demonstrate cerebrospinal fluid protein abnormalities in multiple sclerosis.
Synonym: gold sol test, zsigmondys test.