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Int J Clin Pharmacol Ther Toxicol. 1991 Nov;29(11):441-5.

A simple non-invasive procedure for the investigation of cytochrome P-450 IIIA dependent enzymes in humans.

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Département de Pharmacologie Périnatale et Pédiatrique, Hôpital Saint-Vincent de Paul, Paris, France.


Urinary 6 beta-hydroxycortisol (6 beta OHF) is a specific marker of the induction of the cytochrome P-450 IIIA. Often, the production of 6 beta OHF is expressed from 24-h urine collection as the ratio 6 beta OHF/17-hydroxycorticosteroids or even better 6 beta OHF/free cortisol in order to adjust for minor day to day variation in adrenal cortisol production. A 24-h urine collection is a non-invasive method applicable to clinical studies in adult man, but more difficult to realize in newborn and infants. Therefore, we have tested the validity of a single urine sampling for the determination of the 6 beta OHF/free cortisol ratio as a clinical test to estimate cytochrome P-450 IIIA enzyme activity. Urinary 6 beta OHF and free cortisol have been measured in 19 healthy volunteers by high performance liquid chromatography methods using the same extraction procedure. A good correlation was found between 6 beta OHF/free cortisol ratio in morning urine samples and in 24h-collections (r = 0.899). Thus, a morning spot urine sampling is a simple procedure that may be helpful for investigations on cytochrome P-450 IIIA enzyme activity in humans, particularly in newborn and in children.

[Indexed for MEDLINE]

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