Steroid profiling is ideal for detection of altered steroid metabolism, whether due to defects in steroidogenic enzymes, associated with certain clinical states (eg: anorexia, porphyrias) or as a result of drug treatment.
Profiling has special relevance to the perinatal period, when gender ambiguity or salt wasting may indicate a possible inborn error of steroid metabolism. These need to be identified rapidly post partum to anticipate life threatening steroid deficiency and in the case of sexual ambiguity, to establish the sex of rearing as soon as possible. There are marked differences in steroid metabolism at this stage of life and standard steroid immunoassays frequently give discrepant results owing to the presence of cross-reactants.
Urinary steroid profiling by GC and GC-MS provides qualitative and quantitative data on excretion of steroid metabolites. Most of these originate in the adrenal cortex, while the gonads after puberty contribute to the metabolites of androgens and 17a-Hydroxyprogesterone. A profile provides a composite picture of the quantitatively major biosynthetic and catabolic pathways. This is not synonymous with biological importance: metabolites of cortisol, progesterone, corticosterone and testosterone are readily detected whereas those of oestradiol and aldosterone are not, unless analysed by GC-MS in selected ion monitoring mode.
Plain 24 hour urine is preferred specimen. Random 20 mL urine in a plain universal container can be used in cases where 24 hour collection would be difficult e.g paediatrics, neonates, patients with learnng difficulties, etc.
Preservatives, with the exception of merthiolate, should be avoided. When investigating suspected inborn errors of steroid metabolism, it is important to make a collection before instituting steroid replacement.
King’s College School of Medicine