The use of deuterium-labeled cortisol for in vivo evaluation of renal 11beta-HSD activity in man: urinary excretion of cortisol, cortisone and their A-ring reduced metabolites

This study describes a new approach using stable isotope methodology in evaluating 11beta-HSD activities in vivo based on urinary excretion of cortisol, cortisone, and their A-ring reduced metabolites. The method involved the measurement of deuterium-labeled cortisol and its deuterium-labeled metabolites by GC/MS simultaneously with endogenous cortisol, cortisone, and their A-ring reduced metabolites after oral administration of deuterium-labeled cortisol to normal human subjects. This stable isotope approach offered unique advantages in assessing the appropriateness of measuring unconjugated and total (unconjugated + conjugated) cortisol, cortisone, and their A-ring reduced metabolites in urine as indices of renal 11beta-HSD2 activity in man. Our results strongly support that the measurement of urinary unconjugated cortisol and cortisone is a significant advance in assessing 11beta-HSD2 activity.     

Renal 11 beta-hydroxysteroid dehydrogenase activity: effects of age, sex and altered hormonal status

The enzyme 11 beta-hydroxysteroid dehydrogenase, by converting cortisol and corticosterone to their receptor-inactive 11-keto metabolites cortisone and 11-dehydrocorticosterone, appears crucial to the aldosterone-selectivity of renal mineralocorticoid receptors. Levels of enzyme activity in the rat kidney, measured by conversion of cortisol to cortisone, are unaltered by changes in adrenal or thyroid status, or by castration in either sex; in contrast, oestrogen administration increases enzyme activity in male rats.     

In vitro metabolism studies of (1, 2, 6, 7-3-H)-cortisol in human gingiva in health and disease.

The major conversion products of incubation of 3-H-cortisol with slices of human clinically normal and inflamed gingiva were identified as 11beta-hydroxyandrostenedione and cortisone. Reduction of C-20 of cortisol to 20alpha- and 20beta-dihydro metabolites was found only after incubation of cortisol with normal gingiva and not with inflamed tissue. Thus the two major pathways of metabolism of cortisol in the gingiva appear to be the oxidative cleavage of the side chain and the oxidation of 11beta-ol while the reduction of the 20-one appear limited to the normal tissue. The mean rates of conversion of cortisol to its various metabolites in 12 normal and 12 chronically inflamed gingival tissue samples were 147 and 55.2 pmoles hr-1-mg-1 respectively. The less conversion of cortisol in inflamed tissue might explain its effectiveness as a naturally occuring antiinflammatory hormonal steroid.     

Urine volume dependency of specific dehydroepiandrosterone (DHEA) and cortisol metabolites in healthy children

Urine volume should be considered as a confounder when using urinary free cortisol (UFF) and cortisone (UFE) to assess glucocorticoid (GC) status. We aimed to examine whether adrenal androgen (AA) metabolites may be also affected by urine volume in healthy children. To compare the flow dependence of GC and AA metabolites, specific GC metabolites were examined. In 24-h urine samples of 120 (60 boys) healthy children (4-10 yr), steroid profiles were determined by GC-MS analysis, UFF and UFE by radioimmunoassay. To assess daily AA and GC secretion rates, 7 quantitatively most important AA (∑C19) and GC (∑C21) metabolites were summed. Sum of DHEA and its 16α-hydroxylated metabolites were denoted as DHEA&M. Association of urine volume with AA (∑C19, DHEA&M, DHEA, 16α-hydroxy-DHEA, 3β,16α,17β-androstenetriol) and GC (∑C21, UFF, UFE, 6β-hydroxycortisol, 20α-dihydrocortisol) were examined in linear regression models. Among the examined AA metabolites, 16α-hydroxy-DHEA (β=0.56, p<0.0001) and DHEA (β=0.43, p=0.05) showed relatively strong association with urine volume. A trend was seen for ∑C19 (β=0.23, p=0.08), but not for DHEA&M (p>0.1). Regarding GC metabolites, urine volume showed a stronger association with cortisol's direct metabolites, i.e., cortisone, 6β-hydroxycortisol and 20α-dihydrocortisol (β=0.4-0.6, p<0.01) than with cortisol itself (β=0.28, p<0.05). ∑C21 was not associated with urine volume. In conclusion, like UFF and UFE, renal excretion of DHEA, 16α-hydroxy-DHEA, 6β-hydroxycortisol, and 20α-dihydrocortisol may also depend on urine volume. The intrarenal production of the latter three and cortisone might explain their relative strong water-flow-dependency. Total AA or GC secretion marker appears not to be relevantly confounded by urine volume.     

The metabolism of 3-H-cortisone and 3-H-cortisol by the isolated perfused rat and guinea pig lungs.

Isolated perfused rat lungs removed more than 35% of 3-H-cortisone (1 times 10-9M) from the perfusate during one passage through the pulmonary circulation. The cortisone in the lungs was then rapidly converted to cortisol, which was returned to the perfusate. The tritiated steroid taken up was so rapidly washed from the lung, that only 10% remained after a 12 minute perfusion with steroid-free medium. In recirculating experiments, nearly 60% conversion to cortisol occurred over 32 cycles; in addition, there was a slow increase in the percentage of polar compounds in the medium. Similarly, the perfused hindlimbs preparation from the rat converted cortisone to cortisol and returned the cortisol to the perfusate. In contrast, guinea pig isolated perfused lungs had neglible effect on cortisone. Rat lungs demonstrated only a limited ability to convert 3-H-cortisol to cortisone. The results suggest that the lungs may play an important role in maintaining cortisone/cortisol levels in the plasma.     

Urinary steroid excretion rates in acromegaly

Using gas chromatography/mass spectrometry, urinary excretion rates of cortisol, cortisone and of various steroid metabolites were determined in 35 acromegalic patients (18 men, 17 women) and in 45 age- and weight-matched controls. The ratio of excreted cortisol/cortisone was similar in acromegalics (0.75 +/- 0.20) and in controls (0.75 +/- 0.24). Hence, the preponderance of the main cortisone-derived metabolite, tetrahydrocortisone, over the main metabolites of cortisol (tetrahydrocortisol and allotetrahydrocortisol; p < 0.01), which was seen both in female and in male acromegalics and which was directly correlated with the postglucose concentrations of growth hormone (r = 0.508, p < 0.01), suggests a decreased activity of 11beta-hydroxysteroid dehydrogenase type 1 in acromegaly. Furthermore, the preponderance of etiocholanolone over androsterone (p < 0.01) in men (though not in women) with acromegaly--the ratio androsterone/etiocholanolone being negatively correlated with the serum concentrations of insulin-like growth factor type 1 (r = -0.406, p < 0.05)--suggests a relatively reduced activity of hepatic 5alpha-reductase in male acromegalics.     

Exaggerated adrenarche and altered cortisol metabolism in Type 1 diabetic children

Reported literature data strongly suggest that steroid metabolism is dysregulated in Type 1 diabetes mellitus. The aim of this study was to non-invasively examine the cortisol metabolism in children with Type 1 diabetes mellitus (T1DM) in detail and to test the hypothesis that adrenarche is affected under conventional intensive insulin therapy. In 24-h urine samples of 109 patients aged 4-18 years with T1DM of more than 1 year, steroids were profiled using gas chromatography-mass spectrometry. Additionally, urinary free cortisol (UFF) and cortisone (UFE) were quantified by RIA after extraction and chromatographic purification. Data on urinary steroids from 400 healthy controls served as reference values. Enzyme activities were assessed by established steroid metabolite ratios, e.g. 5alpha-reductase and 11beta-hydroxysteroid dehydrogenase Type 2 (11beta-HSD2) by 5alpha-tetrahydrocortisol/tetrahydrocortisol and UFE/UFF, respectively. Urinary markers of adrenarche, especially dehydroepiandrosterone and its direct metabolites were elevated in patients, as were urinary 6beta-hydroxycortisol, UFE, and 11beta-HSD2 activity. However, overall cortisol secretion, as reflected by the sum of major urinary cortisol metabolites, was mostly normal and activity of 5alpha-reductase clearly reduced. Our study provides evidence for an exaggerated adrenarche in T1DM children, which may help to understand reported sequelae in female patients like hyperandrogenic symptoms. The findings also suggest a reduced cortisol inactivation via 5alpha-reductase that is not compensated by a fall in cortisol secretion. Whether the elevated urinary 6beta-hydroxycortisol and cortisone excretion, observed in the patients, are also present in other forms of hypercortisolism and may thus serve as non-invasive clinical stress markers deserves further study.     

Apparent cortisone reductase deficiency: a rare cause of hyperandrogenemia and hypercortisolism

A 55-year-old woman presented with androgenetic alopecia which had started at age 40. Her clinical history revealed that, unlike her younger sister, she was unable to conceive and was diagnosed as being sterile at age 30. At age 45, 21-hydroxylase deficiency (late-onset CAH) was assumed and glucocorticoid treatment suggested, but not initiated. There was slight hirsutism, but no other sign of virilization. Retesting of plasma steroids revealed elevated 17-OH-progesterone and free testosterone. Treatment with prednisone, cyproterone acetate, and spironolactone was started with significant clinical success. Surprisingly, the analyses of urinary steroid metabolites revealed a pattern that did not support the diagnosis of 21-hydroxylase deficiency (pregnanetriolone absent, pregnanediol, 17-OH-pregnanolone and pregnanetriol not increased). Abdominal CT showed bilateral adrenal hyperplasia and masses in both ovaries. Bilateral adnexectomy was performed, and cystic teratomas were diagnosed. Postoperative urinary steroid analyses showed a decreased tetrahydrocortisol/tetrahydrocortisone ratio (values around 0.08 as compared to age- and sex-matched controls with a ratio of about 0.5-0.8). Plasma cortisol appeared to be repeatedly elevated with exogenous sources excluded. Mass spectrometry showed that, while the tetrahydro metabolites were mainly cortisone-derived, the metabolites not reduced in A ring were mostly cortisol derivatives. This constellation clearly indicates cortisone reductase deficiency, a defect of hepatic 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD1). This enzyme catalyzes the oxidation of cortisol to cortisone and the reduction of cortisone to cortisol. In contrast to the corresponding kidney enzyme (11 beta-HSD2), its primary activity is, however, reductive. Although this is only the fifth reported case of that defect, more attention should be paid to this condition in hyperandrogenic women, even if elevated 17-OH-progesterone and testosterone suggest a more frequent cause.     

Increased ratio of serum cortisol to cortisone in acute-phase response

BACKGROUND/OBJECTIVES: 11beta-Hydroxysteroid dehydrogenase (11beta-HSD) enzymes convert cortisol into inactive cortisone and vice versa. While 11beta-HSD type 2 (mainly localized in the kidney) unidirectionally inactivates cortisol to cortisone, type I isoform (mainly localized in the liver) acts bidirectionally and can thus potentially restore cortisone to active cortisol. The aim of this pilot study was to investigate whether the serum cortisol:cortisone ratio is altered during the acute-phase response, possibly due to altered modulation of 11beta-hydroxysteroid dehydrogenase isoforms. METHODS: Using liquid chromatography electrospray tandem mass spectrometry, cortisol and cortisone were measured in the serum of hospitalized patients with normal and abnormal CRP concentrations, the latter indicating acute-phase response. Fifteen unselected samples were analyzed, all with a CRP concentration within one of the following ranges to cover a wide range of CRP concentrations evenly: <5, 5-20, 21-50, 51-100, 101-200, and >200 mg/l. RESULTS: In the heterogeneous study population, increased CRP concentrations significantly correlated with an increased cortisol:cortisone ratio (p < 0.001; r = 0.65, Spearman correlation coefficient). This correlation was independent of increased serum cortisol concentrations found by multivariate regression analysis. The median ratio was 6.4 (interquartile range 5.5-7.4; n = 30) in patients with a CRP concentration < or =20 mg/l, and 11.2 (interquartile range 8.8-13.9; n = 60) in patients with CRP >20 mg/l (p < 0.01). CONCLUSION: The balance between serum cortisol and cortisone is altered during acute-phase response with a shift towards active cortisol, suggesting that 11beta-HSD isoenzymes play a role in the modulation of systemically available cortisol during acute illness.     

Validation and application of a highly specific and sensitive ELISA for the estimation of cortisone in saliva, urine and in vitro cell-culture media by using a novel antibody

It is generally acknowledged that local tissue concentrations of cortisol and cortisone are modulated by site-specific actions of 11β-hydroxysteroid dehydrogenase (11β-HSD) isoenzymes 1 and 2. Cortisone, the inactive metabolite of cortisol is produced by 11βHSD type 2. To assess 11β-HSD types 1 and 2 activities, the cortisol/cortisone ratio has to be accurately determined. Immunoassays to measure cortisone levels are not widely available and tend to lack specificity. The aim of this project was to develop a highly specific and sensitive ELISA method for the estimation of free cortisone levels in urine, saliva and in vitro media samples without chromatographic separation. Antibodies against cortisone were raised in rabbits using cortisone-3-CMO-KLH as immunogen. HRP-goat anti-rabbit IgG conjugate was used as enzyme tracer. Cross-reactivities of the untreated cortisone antiserum with major interfering steroids were minimal except for cortisol (3.15%). However, following an immune-affinity purification of the antibodies using CNBr-activated sepharose-cortisol-3-CMO-BSA, cross-reactivity of the purified cortisone antibody with cortisol was reduced to 0.27%. The minimum detection limit of cortisone ELISA was 28 pg/mL (77.7 pM). The validity of the cortisone ELISA was confirmed by the excellent correlation obtained before and after an HPLC fractionation step (Y=1.09X-0.21, R2=0.98). Intra-assay and inter-assay imprecision were 5.5-11.7% and 8.7-12.8% CV, respectively. Using this assay, salivary cortisone levels showed a circadian rhythm in men and women (11.2±7.3 nM at 08.00 h and 5.1±3.6 nM at 18.00 h), and the levels were reduced following liquorice ingestion. In media of adrenocortical H295 cell line incubations, basal cortisone levels were 4.24±0.22 nM that increased to 8.6±1.2 nM post forskolin treatment. Urinary free cortisone excretion levels in healthy subjects were 56.66±36.9 nmol/day. In human volunteers following ingestion of green coffee bean extract for 2 weeks, urinary free cortisol excretion reduced significantly from 66.67±22.3 to 42.66±17.5 nmol/day (p=0.02) and the cortisol/cortisone ratio from 2.04±1.33 to 1.49±1.13, p=0.05. In conclusion, a simple and highly specific and sensitive ELISA has been developed and applied to estimate cortisone levels in biological fluids and culture media.     

Incorporation and metabolism of cortisol in oocytes of tilapia (Oreochromis mossambicus)

The entry and metabolism of 3H-cortisol in oocytes were investigated using isolated follicles of the tilapia (Oreochromis mossambicus) in order to examine the mechanisms of incorporation of maternal hormones into oocytes. The composition of 3H-labeled steroids in the oocyte was analyzed by high-performance liquid chromatography. A significant amount of cortisol was converted to cortisone and an unidentified molecule by the follicular layer. The contents of 3H-cortisol and 3H-cortisone in the oocyte reached an equilibrium level within 12 hr, whereas the content of the unidentified metabolite continued to increase for 36 hr. The total content of the incorporated cortisol and its metabolites was proportional to cortisol in the medium over the concentration range of 5 ng/ml to 5 microg/ml. The amounts of cortisone and the unidentified molecule increased proportionally when the concentration of cortisol in the medium was lower than 500 ng/ml, whereas they reached a plateau when the concentration of cortisol exceeded 500 ng/ml. Cortisol entry was reversible, because 90% of cortisol and cortisone in the oocyte was lost within 18 hr when the medium was changed to that without 3H-cortisol. On the other hand, 50% of the unidentified molecule was preserved at the end of the incubation. In conclusion, the entry of cortisol into the oocyte was considered to be nonspecific and due probably to simple diffusion. However, a considerable amount of cortisol (50-70%) was specifically converted to cortisone and another unidentified molecule during passage through the follicular layer.     

Effect of glucocorticoid excess on the cortisol/cortisone ratio

OBJECTIVE: The conversion of cortisol, which binds avidly to the mineralocorticoid receptor, to cortisone, which no longer has mineralocorticoid function, is predominantly catalyzed by the 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD 2). It was the objective of the present study to examine the impact of different forms of glucocorticoid excess on the cortisol/cortisone ratio and to differentiate their role in the genesis of hypertension. DESIGN AND METHODS: Plasma cortisol and cortisone levels were determined in 12 adults with Cushing's disease, 12 adults with hypercortisolism due to an adrenal tumor, and 20 healthy volunteers before and after an intravenous ACTH test, using specific radioimmunoassays after automated Sephadex LH 20 chromatography. RESULTS: The cortisol/cortisone ratios were significantly higher in patients with Cushing's disease (13.9 +/- 1.1), adrenal tumors (11.5 +/- 2.3), and in healthy volunteers after ACTH stimulation (14.1 +/- 2.0) than in untreated controls (6.0 +/- 0.5) (P < 0.001, P < 0.05, and P < 0.001, respectively). Similar differences were seen for cortisol plasma concentrations, whereas cortisone concentrations did not differ among the groups. CONCLUSIONS: Our data suggest that the excessive mineralocorticoid effects in patients with hypercortisolism are inflicted by elevated cortisol/cortisone ratios possibly due to an insufficient conversion of cortisol to cortisone by 11beta-HSD 2. This may provide a possible explanation for the occurrence of hypertension. This effect seems to be independent of the role of ACTH in the mechanism of hypercortisolism.     

The 11beta hydroxysteroid dehydrogenase 2 exists as an inactive dimer

The 11beta-hydroxysteroid dehydrogenase types 1 and 2 enzymes (11beta-HSD1 and 11beta-HSD2), modulate glucocorticoid occupation of the mineralocorticoid and glucocorticoid receptors by interconverting corticosterone and cortisol to the inactive metabolites 11-dehydrocorticosterone and cortisone within the target cells. The NAD(+)-dependent 11-HSD 2 in the kidney inactivates corticosterone and cortisol, allowing aldosterone, which is not metabolized, access to the receptor. Studies of the kinetics of 11-HSD 2 activity in the rat kidney have produced inconsistent results. Western blots done in the absence of the reducing agent beta-mercaptoethanol showed two bands with approximate MW of 40 and 80 kDa. When beta-mercaptoethanol was used, only the 40 kDa was detected, indicating that under non-denaturing conditions a significant proportion of the 11beta-HSD 2 exists as a dimer. NAD(+)-dependent conversion of 3H-corticosterone by 20 microg of microsomal protein increased approximately 10 fold with the addition of 5 mM DTT concentration. NADP(+)-dependent activity with 20 microg of microsomal protein was very low and did not change significantly when using DTT. In the presence of DTT, the predominant 11-HSD activity in the rat kidney is NAD(+)-dependent with a K(m) of 15.1 nM, similar to that of the cloned and expressed enzyme. These data suggest that dimerization and subsequent enzyme inactivation occur when protocols promoting oxidation of this protein are used.     

Differences in plasma cortisol and cortisone dynamics during stress in two strains of rainbow trout (Oncorhynchus mykiss)

Plasma levels of cortisone, a steroid hormone of potential physiological significance in fish, have rarely been measured. This study examines the interrelationship between circulating levels of cortisone and the major teleost corticosteroid, cortisol, in the blood of two strains of rainbow trout subject to confinement stress, a condition know to stimulate corticosteroidogenic activity. In unstressed fish from both strains, mean plasma cortisol levels were within the range 0.4–7.5 ng ml⁻¹. Mean plasma cortisone levels were within the range 7.1–15.9 ng ml⁻¹. Plasma cortisol levels were elevated within 5 min of the onset of strees and reached peak values within 45 min, although there was a marked difference betweed the maxima observed in the two strains (strain 1:70 ng ml⁻¹; strain 2:150 ng ml⁻¹). The rate of increase of plasma cortisone levels during strees was more rapid than that of cortisol, maximum values (strain 1:100ng ml⁻¹; strain 2:160 ng ml⁻¹) being reached within 10 to 20 min of the onset of stress. This rapid stress-induced elevation of plasme cortisone has not previously been reported in fish. We suggest that rapid conversion of cortisol to cortisone during the initial response to stress accounts for the appearance of large amounts of cortisone in the blood, indicating that circulating for the appearance of large amounts of cortisone in the blood, indicating that circulating levels of cortisol alone do not fully reflect the secretory activity of the interregnal during the initial of cortisol alone do not fully the secretory activity of the interregnal during the initial phase of the stress response. The results also indicate that the rate of clearance of cortisone from the circulation may be a major factor in determining stress-stimulated levels of plasma cortisol.     

Separation of some natural and synthetic corticosteroids in biological fluids and tissues by high-performance liquid chromatography

A high-performance liquid chromatography (HPLC) technique was developed for the determination of radiolabeled triamcinolone acetonide (TAC), cortisol and their metabolites in rhesus monkey plasma, urine and tissue samples. After protein precipitation, the parent compounds and metabolites were simultaneously resolved using a single-column reversed-phase HPLC system. TAC was subsequently verified by mass spectrometry and TAC glucuronide was tentatively identified by enzymatic hydrolysis and mass spectrometry of the hydrolysis product. The endogenous hormones, cortisol and cortisone were presumptively identified by cochromatography with authentic standards on two different HPLC systems and positively identified by reverse-isotope recrystallization. Other metabolites of both compounds were detected by selective enzymatic hydrolysis and HPLC. This method is rapid and reproducible with a total recovery > 80%.     

Urinary free cortisol and cortisone excretion in healthy individuals: influence of water loading

The influence of water loading on urinary excretion of free cortisol and cortisone was investigated in healthy men. The results were as follows: water loading tests (intake of 0.25-1.5 L) in a single individual showed that a water load of 1.5 L reliably increased the excretion of urine, free cortisol and cortisone (p < 0.01). Regression analyses gave significant correlations of urine volume with free cortisol and free cortisone, and of free cortisol and free cortisone. Corresponding results were obtained when water loading tests were performed in males who ingested 1.5 L of water (n = 8): the excretion of urine, free cortisol and free cortisone were significantly augmented; correlated was urine volume with free cortisol and free cortisone, and free cortisol with free cortisone. In a third set of tests, volunteers collected one 5 h urine (10:00-15:00 h) after the intake of 3 x 0.1 or 0.5 L at 11:00, 12:00 and 14:00 h. Excretion of urine, free cortisol and free cortisone in males of the low water loading group (3 x 0.1 L) was 0.59 mL/min, and 8.2 or 15.0 microg/5 h; corresponding values in individuals ingesting 3 x 0.5 L of water were 1.5 mL/min (p < 0.01), 12.3 microg/5 h (p > 0.05) and 26.3 microg/5 h (p < 0.02). In summary, urinary free cortisol and cortisone excretion in healthy men depends on urine volume, especially during water diuresis. Thus, interpretation of free cortisol and especially of free cortisone excretion is only possible if subjects strictly control their fluid intake and if urine volume is considered an important pre-analytical parameter-otherwise, interpretation of urinary free cortisol results is difficult and of urinary free cortisone data remains tenuous at best.     

Cortisol and cortisone levels in umbilical cord plasma and maternal plasma of normal pregnancies

A method for assaying cortisol and cortisone using chromatography on either paper or Sephadex LH-20 columns for isolation, followed by competitive protein binding, has been applied to umbilical cord and maternal plasma samples. In mixed cord plasma the mean cortisol concentration was 6.0 ± 0.8 μg/100 ml (n = 9) and the mean cortisone concentration was 13.5 ± 2.9 μg/100 ml (n = 9). In cord arterial plasma the mean cortisol concentration was 6.3 ± 2.9 μg/100 ml (n = 6) and the mean cortisone level was 10.1 ± 2.5 μg/100 ml (n = 6). For cord venous plasma, the mean level of cortisol was 5.6 ± 1.5 μg/100 ml (n = 6) and of cortisone was 13.5 ± 2.4 μg/100 ml (n = 6). Maternal plasma gave a mean value of cortisol of 42.3 ± 4.5 μg/100 ml (n = 6) and of cortisone of 6.2 ± 0.9 μg/100 ml. The results of this study suggest that the fetus at term-gestation produces cortisol. The significance of this production compared with placental transfer of maternal cortisol into the fetal circulation however is uncertain.     

Studies on the in vitro metabolism of [3H]cortisol and [3H]oestradiol by sheep skin and wool roots.

The in vitro metabolism of [3H]cortisol, [3H]cortisone and [3H]estradiol-17 beta by adult sheep skin and wool follicle tissue (wool roots) was examined. The main metabolic product of the incubation of [3H]cortisol with sheep skin was [3H]cortisone, and the conversion was reversible. Wool roots were unable to carry out detectable interconversion, nor did this tissue give rise to other significant metabolites. Sheep skin and wool roots both rapidly converted [3H]oestradiol-17 beta to [3H]oestrone and the conversion could be carried out by follicle and non-follicle skin structures. It is suggested that sheep skin contains both 11 beta- and 17 beta-hydroxysteroid dehydrogenases, but that wool follicles contain only the latter enzyme.     

Measurement of cortisol secretion rate by stable isotope methodology following oral administration of 13C-labeled cortisol to a human subject

Plasma concentration measurements of 13C-labeled cortisol ([1,2,4,19-13C(4)]cortisol, cortisol-13C(4)) and its metabolite cortisone-13C(4) were made simultaneously with measurements of endogenous cortisol and cortisone by gas chromatography-mass spectrometry (GC-MS). After administering a small amount (3mg) of cortisol-13C(4) to a human subject, changes in cortisol secretion rates were estimated by deconvolution techniques from the measured plasma cortisol and cortisone levels and the rates of elimination and interconversion of cortisol and cortisone were obtained from the plasma concentration-time data of cortisol-13C(4) and cortisone-13C(4). The objective of this study was to look for a novel approach to quantitate rates of minute-to-minute cortisol secretion in man by taking into account the interconversion of cortisol and cortisone by 11beta-hydroxysteroid dehydrogenase (11beta-HSD).