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Dehydroepiandrosterone (DHA or DHEA) and its sulfate (SDHA or SDHEA) are androgenic steroids which are secreted by the adrenal cortex.
DHEA is a precursor for a number of other physiological steroids (testosterone in men and estradiol in women). It is produced at low levels (2 to 4 mg/day) and has a very short half-life (between 15 and 30 min) before being sulfated in the liver. Blood levels flutuate enormously in a diurnal cycle and are very sensitive to stress.
Excessively high levels are seen if it is being secreted by a tumor and in patients with certain adrenal enzyme deficiencies (notably 3 beta-hydroxysteroid dehydrogenase deficiency).
SDHEA is generated at higher levels (20 to 30 mg/day in young adults) and it has a longer half-life (7 to 10 hours). In consequence, its levels remain more stable over a twenty-four hour period .
In metabolic terms, DHEA and SDHEA are interconvertible (respectively, sulfatase and sulfotransferase activities).
Blood SDHEA levels are at their highest sometime between the ages of 25 and 35 (depending on the subject), after which they fall by about 2 % per annum, i.e. a reduction of 20 % every ten years after the age of forty. It is this fall-off that led investigators to study the role of this compound in the aging process.
Chez la femme enfin, les concentrations sont habituellement inférieures à celle de l'homme de 10 à 20 %.
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The ideal situations in which to order these two tests are the following :
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When the test is ordered on its own, as part of a check-up on a woman showing evidence of virilism,
for puberty problems in children or in the investigation of aging, the order should read "SDHA" for
DHEA sulfate. This test is carried out every day on serum samples (the ideal volume to send is 1 ml).
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When the assay is part of
a Corticotropin Challenge Test, the order should read "DHEA"; this assay is carried out twice a week
and lasts two days (the ideal volume of serum to send in this case is 2 ml).
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There is about 500 times as much
SDHA as DHEA in circulating blood because the former is so much more stable over the diurnal cycle.
Free DHEA levels can be raised as a result of the stress of the blood drawing procedure or due to
conversion of SDHA into DHEA in the sample.
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The high, stable levels of SDHEA in the blood make this parameter more reliable and easier to interpret than DHEA levels (SDHEA levels are 400 to 500 times higher than those of DHEA).
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Il existe
, dans la littérature, des valeurs usuelles de SDHEA par tranche
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There are published reference values for SDHEA levels at different ages.
In 1984, Orentreich assayed SDHEA in 981 men and 481 women of between 11 and 89 years of age and confirmed that levels tended to drop by a factor of about 20 % every ten years from the age of forty on.
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The currently prescribed doses are close to the average daily production and are designed to give similar circulating concentrations as those found in young adults, i.e. about 2000 ng/ml in women and 3000 ng/ml in men.
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As with all forms of hormone
replacement therapy, no dose should be taken on the morning of the drawing of the test blood sample.
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Care is warranted when interpreting the results of a DHEA test if the patient is taking any kind of corticosteroid, be it to treat a rheumatoid or a dermatological problem, as replacement therapy, or for allergy. Ask the patient about this because corticosteroids inhibit adrenal secretory function and may induce low SDHEA levels.
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The DHEAge Study was conducted on 280 healthy, motivated volunteer subjects of between 60 and 70 years of age. The effects of one year of a daily dose of 50 mg were compared with those of a placebo: in parallel to a rise in SDHEA levels to those seen in young adults, improvements were recorded in skin quality (hydration, sebum secretion, pigmentation and thickness), libido and bone density (especially in the women). At the daily dose of 50 mg, no accumulation was observed.
( E.-E. Baulieu, PNAS 2000, vol. 97, n°8, p4279-4284).
The DHEAge Study only covered healthy subjects of over 60 years of age (and the most convincing
results-notably the effects on bone tissue-were observed in the over-70 year-olds).
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What effect would taking DHEA have in subjects with some chronic disease ?
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What effect would taking DHEA have in younger subjects ?
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What would be the effect of doses higher than the 50 mg administered in this study ?
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What would be the effect of taking DHEA for a long time ?
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What about substituting conventional Hormone Replacement Therapy (HRT)
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What about substituting conventional Hormone Replacement Therapy (HRT)
for menopausal women with DHEA, or adding DHEA to this therapeutic modality ?
At this time, these tests do not add anything to the blood SDHEA result.
Conclusion : in the light of all the unknown factors, it would be better to tend towards a cautious approach (especially when it comes to patients with breast and prostate problems) and encourage patients to seek medical advice before embarking on a course of DHEA..
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