Endocrine Abstracts

The characterization and measurement of steroids in health and disease has been a cornerstone of endocrinology since the 1930s. The first example of a diagnostic steroid for an endocrine disorder was the discovery of pregnanetriol in the urine of patients with the adrenogenital syndrome (CAH) by Guy Marrian in 1937. He went on to head the Clinical Endocrinology Research unit in Edinburgh for many years. For decades, paper and TLC dominated metabolomic (urinary steroid) approaches to steroid analysis, while from the 1960s RIA of circulating hormones and precursors was pre-eminent and remains useful.

Mass spectrometry now dominates the steroid analytical field but it has taken a long time to reach this position. The breakthrough came in the mid-1960s, when a Swedish company introduced the LKB 9000 GC/MS instrument. Researchers at the Karolinska institute had invented a way of combining two very modes, GC with its high-pressure gas flow and mass spectrometry which is conducted in a vacuum. In 1967 this presenter had the privilege to use the first UK LKB 9000 in Professor Charles Brooks’ lab in Glasgow to document the structures of steroids excreted by the human newborn.

In the 50 years of steroid mass spectrometry there have been continuous advances, notably for GC/MS the introduction of capillary columns, chemical derivatisation methods and advanced data systems.

The most important advances have been combining HPLC and MS and the introduction of Tandem MS which provides high specificity and sensitivity. Automated HPLC MS/MS systems now allow quick separations and accurate measurement of vanishingly small amounts of hormonal steroids. The high throughput has rendered HPLC/tandem MS the desired method for routine clinical steroid measurements. In spite of being labour intensive GC/MS still holds its own for metabolomic studies, particularly with the introduction of machine learning techniques for disorder diagnosis. Interestingly, pregnanetriol, the mother of steroid metabolites, remains an essential analyte for our metabolic profile studies almost 80 years after Marrian’s painstaking identification.