The Ratio of 6β‐Hydroxycortisol to Cortisol in Urine as a Measure of Cytochrome P 450 3 A Activity in Postmortem Cases

Poisoning can occur with chronic accumulation of a drug due to reduced metabolic capacity; conversely, under‐treatment may occur due to an increased metabolic rate. Over half of all drugs are metabolized by the cytochrome P 450 3 A complex ( CYP 3 A ). The activity of CYP 3 A can be assessed by the urinary ratio of 6β‐hydroxycortisol to cortisol. The aim of this study was to determine the usefulness of this ratio as a postmortem marker for determining whether altered CYP 3 A enzyme activity occurred prior to death. In a series of 244 postmortem cases, this ratio ranged from 0.014 to 78.6 (median 3.50). The median was significantly higher (5.14) in a subgroup of 28 cases that exhibited the presence of CYP 3 A ‐inducing drugs. In cirrhosis, the median ratio was 1.69. This pointed to a reduced metabolic capacity of CYP 3 A . Thus, the ratio may constitute a rough indicator of the CYP 3 A metabolic capacity, which could be of value in special cases.