Urinary steroid profile in adrenocortical tumors
E. Kikuchi1, H. Yanaihara1, J. Nakashima1, K. Homma2, T. Ohigashi1, H. Asakura1, M. Tachibana1, H. Shibata3, T. Saruta3, M. Murai1
’ Department of Urology, Keio University School of Medicine, Tokyo; 2 Department of Laboratory Medicine, Keio University School of Medicine, Tokyo; 3 Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
Summary - Determination of the urinary steroid profile has been proposed as a sensitive tool for diagnosing adrenocortical tumors. The urinary steroid profiles were determined for patients with adrenocortical tumors. Urinary steroids were extracted, derivatized to form methyloxime-trimethylsilyl ether and analyzed by gas chromatography/mass spectrometry.
Patients with adrenal adenomas from primary hyperaldosteronism had increased metabolites of 18-hydroxycorticosterone and aldosterone, and those with Cushing’s syndrome had elevated excretion of 11-deoxycortisol, cortisol, 18-hydroxycortisol, and cortisone metabolites. In patients with adrenocortical carcinomas, increased levels of metabolites of 11-deoxycortisol or 30-hydroxy-5-ene steroids were observed. The urinary steroid profiles of adrenal adenomas and adrenocortical carcinomas were quite different, suggesting the diagnostic validity for discriminating malignant from benign diseases. @ 2000 Éditions scientifiques et médicales Elsevier SAS
adrenocortical tumor / steroidogenesis / urine
Steroids secreted from adrenals are metabolized in the liver and the kidney, and excreted in the urine as free steroids or conjugated to glucuronic or sulphuric acid. Most of these urinary steroids may be identified by gas chromatography/mass spectrometry. Urinary steroid metabolite measurement is superior to serum steroid measurement, not only because it is not invasive to the patients, but also because it makes it possible to know the states of all the adrenal steroids simultaneously.
Determination of the urinary steroid profile has been proposed as a sensitive tool for diagnosing adreno- cortical neoplasms. We analyzed 24-hour urinary samples from patients with primary aldosteronism and Cushing’s syndrome who had surgically verified adrenal adenomas, and with adernocortical carcino- mas by gas chromatography/mass spectrometry as described by Shackleton [1]. It is important to inves- tigate whether increased urinary levels of some spe- cific steroids can be observed in patients with adreno- cortical neoplasms.
URINARY STEROID PROFILE OF PATIENTS WITH ADRENAL ADENOMAS
Primary aldosteronism
In our study, the urinary steroid profiles of patients with primary aldosteronism revealed excessive excretion of 18-hydroxytetrahydro-11-dehydrocorticosterone (a metabolite of 18-hydroxycorticosterone) and tetrahydro- aldosterone (a metabolite of aldosterone) and slightly elevated tetrahydro-corticosterone (a metabolite of cor- ticosterone), confirming increased activity in the min- eralocorticoid pathway (figure 1). Our findings on the urinary steroid profile of patients with primary aldos- teronism were compatible with those reported by Shackleton [1].
It is considered that a hyperfunctioning adrenal tumor may be the result of abnormal expression of steroidogenic enzymes [2, 3]. There are six major steroidogenic enzymes: 3ß-hydroxysteroid dehydro- genase, cytochrome P-450 for cholesterol side chain cleavage (P-450scc), aldosterone synthase (P- 450aldo), 17a-hydroxylase (P-450c17), 21-hydroxy- lase (P-450c21), and 11ß-hydroxylase (P-450c11). Ogo et al. [2] found steroidogenic P-450 mRNAs in adrenocortical adenomas in patients with primary
Steroid profile in urine
Cholesterol
P-450scc
P-450c17
E1
Pregnenolone
17-OH pregnenolone
☒
3 B -hydroxysteroid dehydrogenase ☒ ☒
DHEA ☒
E2
E3
Progesterone
17-OH progesterone
Androstenedione
☒
☒
P-450c21
☒
11-deoxycorticosterone
11-deoxycortisol
Testosterone
P-450aldo
☒ P-450c11
Corticosterone
Cortisol
☒
18-OH corticosterone
Cortisone
18-OH cortisol
11-dehydrocorticosterone
Aldosterone
in serum
tetrahydro-
18-hydroxytetra
in urine
corticosterone
-hydro-11-dehydro
İ
tetrahydro- aldosterone
tt
-corticosterone
aldosteronism and suggested that the overproduction of aldosterone in aldosterone-producing adenomas resulted from increased expression of P-450c11 mRNA and decreased expression of P-450c17 mRNA. Shibata et al. [3] demonstrated overexpression of P-450aldo in aldosterone-producing adenomas, measuring both activities and amounts of steroidogenic cytochrome P-450s at the post-translational protein level. The finding of increased expression of P-450c11 mRNA described by Ogo et al. [2] may point to mRNA of P- 450aldo [3].
P-450aldo catalyzes three hydroxylation reactions of 11-deoxycorticosterone to yield corticosterone, 18-hydroxycorticosterone, and aldosterone. In aldos- terone-producing adenomas, increased P-450aldo activity may be one candidate for the pathogenesis of primary aldosteronism, and may cause overproduc- tion of metabolites of 18-hydroxycorticosterone and aldosterone as revealed by the urinary steroid profile.
Cushing’s syndrome
In our study, the urinary steroid profile revealed exces- sive excretion of tetrahydro-11-deoxycortisol (a metabolite of 11-deoxycortisol), tetrahydro-cortisol (a metabolite of cortisol), 18-hydroxycortisol (a metabo- lite of 18-hydroxycortisol), and tetrahydro-cortisone (a metabolite of cortisone), confirming increased activity in the glucocorticoid pathway. The profile also demon- strated decreased excretion of androstenetriol (a metabolite of dehydroepiandrosterone), androsterone, and etiocholanolone (metabolites of androstenedione) (figure 2). The level of tetrahydro-aldosterone in Cush- ing’s syndrome was elevated but significantly lower than that in primary aldosteronism.
Ogo et al. [4] demonstrated a significantly increased amount of P-450c17 mRNA and slightly increased level of P-450c21 mRNA in adrenocortical adenomas associated with Cushing’s syndrome. Shibata et al. [3] noted overexpressions of P-450c17 and P-450c21 in
Cholesterol
P-450scc
P-450c17
E1
Pregnenolone
17-OH pregnenolone
DHEA
E2
☒
3 B -hydroxysteroid dehydrogenase
☒
E3
Progesterone
17-OH progesterone
Androstenedione
☒ Testosterone
P-450c21
11-deoxycorticosterone
11-deoxycortisol
☒ P-450aldo
☒
P-450c11
Corticosterone
Cortisol
☒
18-OH corticosterone
Cortisone 18-OH cortisol
11-dehydrocorticosterone
in serum
Aldosterone
in urine
androstenetriol
tetrahydro- aldosterone
tetrahydro-11 -deoxycortisol
tetrahydro- cortisol
18-hydroxycortisol
androsterone
tetrahydro- cortisone
etiocholanolone
cortisol-producing adenomas, when measuring both activities and amounts of steroidogenic cytochrome P-450s at the post-translational protein level. They concluded that the overexpressions of P-450c17 and P-450c21 may play some role in the pathogenesis of Cushing’s syndrome.
The increased activity of P-450c17 may cause an overproduction of 17a-hydroxyprogesterone, the pre- cursor of 11-deoxycortisol, and an overproduction of P-450c21 may accelerate the production of 11-deoxy- cortisol, the precursor of cortisol. These mechanisms may result in increased urinary levels of tetrahydro-11- deoxycortisol, tetrahydro-cortisol, 18-hydroxycortisol, and tetrahydro-cortisone in patients with cortisol- producing adrenocortical adenomas.
Decreased metabolites of dehydroepiandrosterone and androstenedione in patients with cortisol-producing adenoma, as demonstrated by the urinary steroid profile, may be the result of suppression of ACTH levels by neg- ative feedback inhibition of cortisol overproduction [3].
URINARY STEROID PROFILE OF PATIENTS WITH ADRENOCORTICAL CARCINOMAS
Lipsett et al. [5] suggested that relative enzyme defi- ciencies in the steroid metabolic pathway were more common in patients with an adrenocortical carcinoma than in those with benign adrenocortical disease. Gron- dal et al. [6] used gas chromatography/mass spectrom- etry in their investigation of the urinary steroid profiles of 24 patients with adrenocortical carcinoma. Of these patients, 23 had elevated levels of metabolites of 11- deoxycortisol and/or metabolites of 3ß-hydroxy-5-ene steroids. By analyzing biochemical enzyme activities, Sasano et al. [7] demonstrated that P-450c21 activity was markedly low, but P-450c11 activity was only mod- erately decreased in adrenocortical carcinoma tissue as compared with that in normal adrenal tissue.
Of five patients with adrenocortical carcinomas, three had increased urinary levels of androstenetriol (a metabolite of dehydroepiandrosterone), pregnenediol
(a metabolite of pregnenolone), and pregnenetriol (a metabolite of 17-hydroxypregnenolone), and these were metabolites of the 3ß-hydroxy-5-ene steroids in our study. Two patients had elevated urinary tetrahydro- 11-deoxycortisol (a metabolite of 11-deoxycortisol). These findings suggested a relative deficit or low activ- ity of 3ß-hydroxysteroid dehydrogenase or P-450c11 in the tissue of the adrenocortical carcinoma.
URINARY STEROID PROFILE: A USEFUL TOOL FOR DISCRIMINATING ADRENAL ADENOMA FROM ADRENOCORTICAL CARCINOMA
It is occasionally difficult to differentiate between ade- noma and carcinoma at the time of initial surgery, even by histopathologic examination [8]. Various chemical methods have been used to analyze steroids in serum and urine, but these studies have not necessarily been successful [9]. Patients with adrenocortical carcinomas had quite different excretory patterns of urinary steroid metabolites as compared with those with adrenal ade- nomas. The urinary levels of metabolites of dehy- droepiandrosterone in patients with cortisol-producing adenomas were much lower than those in patients with adrenocortical carcinomas. To clarify the states of uri- nary steroids in patients with adrenal neoplasms, and to measure the urinary levels of such metabolites as dehy- droepiandrosterone are important for accurate diagno-
sis, and urinary steroid profile may be a useful tool for discriminating malignant from benign diseases.
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