Use of Mahalonobis generalized distance in interpreting low-resolution gas-chromatographic profiles of urinary steroids.

We used low-resolution gas-chromatography of urinary steroid metabolites, as their trimethylsilyl ethers, in conjunction with the Mahalonobis generalized distance to assess the analyses in terms of a multivariate normal distribution in two populations of women: 18-50 years old and older. We compare the use of this method of interpretation, presenting several cases to illustrate the use of this approach in a routine clinical chemistry laboratory. The improved accuracy of classification as abnormals and to the ability to identify an analysis result as abnormal, even when values for all the analyses fall within the univariate 95% regions of each constituent.