| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Endocrine Care |
London Center for Pediatric Endocrinology, University College London (E.C., C.G.D.B., P.C.H.), London W1T 3AA, United Kingdom; Diabetes Research Laboratories, Radcliffe Infirmary (D.R.M.), Oxford OX2 6HE, United Kingdom; and Department of Clinical Pharmacology, St. Bartholomew’s and The Royal London School of Medicine and Dentistry (A.J.), London EC1M 6BQ, United Kingdom
Address all correspondence and requests for reprints to: Dr. Evangelia Charmandari, Pediatric and Reproductive Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, 10 Center Drive, Building 10, Suite 9D42, Bethesda, MD 20892-1583. E-mail: charmane{at}mail.nih.gov
Abstract
One of the main aims in the management of patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency is to achieve adequate suppression of the adrenal cortex with the smallest possible dose of glucocorticoid substitution. To evaluate the administration schedule of current replacement therapy regimens, we investigated the cortisol-17-hydroxyprogesterone interrelation in 36 patients (13 males and 23 females; median age, 12.3 yr; range, 6.1–18.8 yr) with salt-wasting congenital adrenal hyperplasia. As sufficient variation in 17-hydroxyprogesterone concentrations was required to allow analysis of the cortisol-17-hydroxyprogesterone interrelation, patients were divided into 2 groups depending on the adequacy of hypothalamic-pituitary-adrenal axis suppression. The first group consisted of 17 patients with suppressed 17-hydroxyprogesterone concentrations (group 1), and the second group consisted of 19 patients with nonsuppressed 17-hydroxyprogesterone concentrations (group 2).
We determined serum cortisol and 17-hydroxyprogesterone concentrations
at 20-min intervals for a total of 24 h while patients were
receiving their usual replacement treatment with hydrocortisone and
9
-fludrocortisone. We also determined the lowest dose of
dexamethasone required to suppress the 0800 h serum ACTH
concentrations when administered as a single dose (0.3 or 0.5
mg/m2) the night before.
Mean 24-h cortisol and 17-hydroxyprogesterone concentrations were 3.9 µg/dl (SD = 2.1) and 66.2 ng/dl (SD = 92.7), respectively, in group 1 and 4.1 µg/dl (SD = 2.5) and 4865.7 ng/dl (SD = 6951) in group 2. The 24-h 17-hydroxyprogesterone concentrations demonstrated circadian variation, with peak values observed between 0400–0900 h. In group 2, 17-hydroxyprogesterone concentrations decreased gradually in response to the rise in cortisol concentrations during the day, but remained low during the night despite the almost undetectable cortisol concentrations between 1600–2000 h. Mean 0800 h androstenedione concentrations correlated strongly with integrated 17-hydroxyprogesterone concentrations (r = 0.81; P < 0.0001), but not with integrated cortisol concentrations. There was a significant negative correlation between cortisol and 17-hydroxyprogesterone at lag time 0 min (r = -0.187; P < 0.0001), peaking at lag time 60 min (r = -0.302; P < 0.0001), with cortisol leading 17-hydroxyprogesterone by these time intervals. Finally, 0800 h serum ACTH concentrations were sufficiently suppressed after a dexamethasone dose of 0.3 mg/m2 in all but three patients.
These findings indicate that in classic 21-hydroxylase deficiency, hydrocortisone should be administered during the period of increased hypothalamic-pituitary-adrenal axis activity, between 0400–1600 h, with the biggest dose given in the morning. Blood investigations performed as part of monitoring of congenital adrenal hyperplasia patients should include androstenedione and 17-hydroxyprogesterone concentrations determined in the morning before the administration of hydrocortisone. It should also be emphasized that blood investigations are only complementary to the overall assessment of these patients, which is primarily based on the evaluation of growth and pubertal progress.
CONGENITAL ADRENAL HYPERPLASIA (CAH) due to 21-hydroxylase deficiency is an autosomal recessive condition in which deletions or mutations of the cytochrome P450 21-hydroxylase gene cause glucocorticoid and often mineralocorticoid deficiency. Substitution therapy with glucocorticoids is offered in an attempt to suppress the excessive secretion of CRH and ACTH by the hypothalamus and anterior pituitary, respectively, and to reduce the circulating concentrations of adrenal androgens and androgen precursors (1, 2, 3). The preferred glucocorticoid option is hydrocortisone, because its short half-life minimizes growth suppression as well as other adverse side-effects of more potent, longer-acting glucocorticoids (4, 5, 6, 7, 8, 9, 10).
Achieving and maintaining adrenal suppression in patients with classic 21-hydroxylase deficiency are far more challenging than preventing adrenal crises and often require increased doses of glucocorticoid substitution, which may produce an unacceptable and undesirable degree of hypercortisolism (11). Treatment efficacy reflects the adequacy of adrenocortical suppression and is assessed by monitoring annualized growth velocity, the rate of skeletal maturation, and serum concentrations of 17-hydroxyprogesterone (17OHP) and androstenedione (1, 12, 13, 14, 15).
Although the circadian variation in 17OHP concentrations in patients with CAH has been well documented (16, 17, 18, 19), to our knowledge no information exists on the relationship between cortisol and 17OHP concentrations in these patients. The aim of the present study was to determine the cortisol-17OHP interrelation in patients with classic CAH and to evaluate current replacement therapy in the light of these findings.
Subjects and Methods
Subjects
Thirty-six patients (13 males and 23 females; median age, 12.3
yr; range, 6.1–18.8 yr) with salt-wasting CAH attending the London
Center for Pediatric Endocrinology were studied prospectively. They
consisted of 14 prepubertal (5 males and 9 females; median age, 9.6 yr;
range, 6.1–11.0 yr; Tanner stage I), 19 pubertal (7 males and 12
females; median age, 13.3 yr; range, 10.6–16.8 yr; Tanner stage
III–V), and 3 postpubertal (1 male and 2 females; median age, 18.4 yr;
range, 18.1–18.8 yr) patients. The clinical characteristics of all
patients are shown in Table 1
.
|
-fludrocortisone given once daily.
Patients were excluded from the study if there was evidence of central
precocious puberty or other associated endocrine disorder. No patient
had clinical or biochemical evidence of hepatic or renal disease, and
none was taking drugs known to alter corticosteroid-binding globulin
concentrations or to induce mixed function oxidase enzymes.
Because sufficient variation in 17OHP concentrations was required to
allow analysis as well as interpretation of the cortisol-17OHP
interrelation findings, patients were divided into two groups depending
on the adequacy of hypothalamic-pituitary-adrenal (HPA) axis
suppression, as defined by the 0800 h ACTH concentrations (<75
pg/ml) and serial measurements of 17OHP concentrations (<662 ng/dl)
determined on the first day of the study. The first group consisted of
17 patients (3 males and 14 females; median age, 10.8 yr; range,
6.1–18.4 yr) with suppressed 17OHP concentrations (group 1), and the
second group consisted of 19 patients (10 males and 9 females; median
age, 12.8 yr; range, 6.2–18.8 yr) with nonsuppressed 17OHP
concentrations (group 2). Daily hydrocortisone and 9-fludrocortisone
doses were similar in the 2 groups of patients (Table 1
). In group 1,
hydrocortisone was given twice daily in 8 patients and 3 times daily in
9 patients. In group 2, 14 patients were receiving hydrocortisone twice
daily, and 5 patients were on a 3 times daily regimen.
The study was approved by the University College London Hospitals committees on the ethics of human research. Written informed consent was obtained in all cases from a parent, and assent was given by children older than 7 yr.
Methods
Patients were admitted to the Endocrine Unit, Middlesex
Hospital, 1 d before the study, and standard anthropometric
measurements, including pubertal Tanner staging (20, 21),
were obtained by a single trained observer. An indwelling venous
catheter for frequent blood sampling was inserted at least 12 h
before sampling to allow a period of adaptation. Patients were allowed
normal ambulatory activity and received their oral hydrocortisone
tablets at 0900 and 2100 h or at 0800, 1500, and 2200 h
depending on whether they were on twice or three times daily
hydrocortisone replacement. 9-Fludrocortisone was given with the
morning hydrocortisone tablets.
On the first day of the study baseline investigations, including ACTH, recumbent PRA, and androgen concentrations, were performed at 0800 h before administration of the hydrocortisone dose. Blood samples for serum cortisol and 17OHP were collected at 20-min intervals for a total of 24 h from 0800 h. Blood samples were centrifuged, separated, and stored at -20 C until assayed.
On the second and third days of the study, an overnight, single dose,
dexamethasone suppression test was performed after randomization to two
different doses of dexamethasone (0.3 and 0.5 mg/m2). The
dexamethasone dose (0.3 mg/m2 1 night and 0.5
mg/m2 the following night, or vice versa)
was administered instead of the evening hydrocortisone dose at
2200 h on d 2 and 3. There was no alteration in the administration
schedule of 9-fludrocortisone. A blood sample for measurement of
ACTH concentrations was taken the following morning before the
administration of hydrocortisone. Blood samples were centrifuged and
separated immediately after collection and were stored at -20 C until
assayed.
We arbitrarily divided the 24-h period into two 12-h intervals, from 0400–1600 h (daytime) and from 1600–0400 h (nighttime), because we expected maximal increases in 17OHP concentrations in the early morning hours. Cortisol concentrations were expected to be maximal during the same period (0400–1600 h), because all patients had the largest hydrocortisone dose given in the morning. In this way we could examine the main peaks of both cortisol and 17OHP in parallel.
Assays
Cortisol assay. Serum total cortisol was measured using the Coat-A-Count RIA (Diagnostic Products, Los Angeles, CA). This is a solid phase RIA with a sensitivity of 0.2 µg/dl. The within-assay coefficients of variation (CVs) were 5.7% and 2.6% at serum concentrations of 1.0 and 20.0 µg/dl, respectively, and the between-assay CVs were 6.3% and 4.5% at serum concentrations of 5.0 and 10.0 µg/dl, respectively.
17OHP assay. 17OHP was measured using the 17-OHP
Coat-A-Count assay (Diagnostic Products). This is a solid
phase RIA with a sensitivity of 7.0 ng/dl. The intraassay CVs were
6.7% and 3.5% at serum concentrations of 29.8 and 652.1 ng/dl,
respectively. The interassay CVs were 11% and 8.5% at serum
concentrations of 35.1 and 612.4 ng/dl, respectively.
Androstenedione assay. Androstenedione was measured by RIA (Ortho Clinical Diagnostics, Amersham Pharmacia Biotech, Little Chalfont, UK) with a sensitivity of 10.0 ng/dl. The intraassay CVs were 8.3% and 4.9% at serum concentrations of 63.0 and 623.5 ng/dl, respectively.
ACTH assay. The RIA used to determine ACTH concentrations (ACTH 125I RIA kit, DiaSorin, Inc., Stillwater, MN) had a sensitivity of 15 pg/ml. The within-assay variations were 12.5% and 8.1% at concentrations of 69 and 600 pg/ml, respectively, whereas the between-assay variations were 6.0% and 6.7% at 23 and 218 pg/ml, respectively.
PRA assay. PRA was measured using a RIA that estimates the amount of angiotensin I generated by the action of renin on angiotensinogen (22). The sensitivity of the assay was 1.29 ng/dl/h. Intraassay CVs were 5.4%, 4.4%, 5.6%, 6.8%, and 7.5% at plasma concentrations of 16.0, 62.0, 106.9, 151.7, and 179.0 ng/dl/h respectively. Interassay CVs were 6.0%, 4.8%, 6.2%, 7.4%, and 8.0% at plasma concentrations of 16.0, 62.0, 106.9, 151.7, and 179.0 ng/dl/h, respectively.
Statistical analysis
24-h cortisol and 17OHP profiles. Nonnormally distributed data were logarithmically transformed before statistical analysis. Comparisons between two groups were performed using the t test. The relationship between baseline 0800 h androstenedione concentrations and integrated 17OHP and cortisol concentrations was investigated by linear regression and calculation of Pearson’s correlation coefficient. Integrated 17OHP and cortisol concentrations were calculated as the area under the serum concentration vs. time curve using the trapezoid method.
Cross-correlation studies. To search for a time-ordered relationship between cortisol and 17OHP, analysis of correlations between the absolute values of the time series of each hormone was computed at 20-min intervals at various time lags covering the 24-h period of the study. Only data from the group of CAH patients with nonsuppressed 17OHP concentrations were used for cross-correlation studies because they demonstrated significant variation in 17OHP concentrations to allow such analysis. All data were stationarized and processed as a three-point moving average to reduce assay noise, as previously described (23, 24). Cross-correlation was computed after lagging (shifting) the concentration-time series of 17OHP relative to the concentration-time series of cortisol. If rt is the coefficient of correlation between cortisol and 17OHP at a lag time t for one patient, then the mean rt for all patients was considered significant when it exceeded zero by more than 2 SE. The SE was calculated from the individual values of rt for all patients at the lag time t.
Single dose dexamethasone test. The proportion of patients who achieved suppression of 0800 h ACTH concentrations after administration of the two different dexamethasone doses was determined and compared between the two groups of patients.
Results
24-h cortisol and 17OHP profiles
The 24-h, daytime, and nighttime mean concentrations of cortisol
and 17OHP in both groups of patients are listed in Table 2 and are depicted in Figs. 1 and 2.
There was no significant difference in
mean 24-h cortisol concentrations between
the two groups of CAH patients (group 1 vs. group 2,
3.9 ± 2.1 vs. 4.1 ± 2. 5 µg/dl). Also, no
difference in daytime (7.5 ± 5.9 vs. 6.7 ± 5.0
µg/dl) or nighttime (6.0 ± 4.4 vs. 5.0 ± 3.0
µg/dl) mean cortisol concentrations was noted between groups (Table 2).
|
|
|
Peak 17OHP concentrations were observed between 0400 -0900 h in both
groups of patients (Figs. 1B and 2B). In group 2, 17OHP
concentrations decreased gradually in response to the rise in cortisol
concentrations during the daytime, but remained low during the
nighttime despite the almost undetectable cortisol concentrations
observed between 1600–2000 h (Fig. 2B).
Androstenedione and integrated 17OHP and cortisol concentrations
Mean 0800 h androstenedione concentrations were significantly higher in patients with nonsuppressed 17OHP concentrations than in patients with suppressed 17OHP (583.4 ± 880.9 vs. 20.0 ± 25.7 ng/dl; P < 0.0001). There was a strong positive correlation between 0800 h androstenedione concentrations and integrated 17OHP concentrations (r = 0.81; P < 0.0001), but not between 0800 h androstenedione and integrated cortisol concentrations.
Cross-correlation studies
The graphs depicting the first, second (median), and third
quartile coefficients of correlation from the cross-correlation
analyses over the 24-h period between cortisol and 17OHP values in the
group 2 patients are shown in Fig. 3. The analysis showed a significant
negative correlation between cortisol and 17OHP at lag time 0 min
(r = -0.187; P < 0.0001), peaking at lag time 60
min (r = -0.302; P < 0.0001). In addition, a
significant positive correlation was observed over time between
cortisol and 17OHP, peaking at lag time 6 h, 40 min (r =
0.359; P < 0.0001), with cortisol leading 17OHP by
these time intervals.
|
Single dose dexamethasone suppression test
In group 1, all patients achieved significant suppression of the 0800 h ACTH concentrations after either dose of dexamethasone. In group 2, three (15.8%) patients did not demonstrate sufficient (<75 pg/ml) suppression of the 0800 h ACTH concentrations after 0.3 mg/m2 dexamethasone, and one (5.3%) did not show sufficient suppression even after administration of the higher dexamethasone dose of 0.5 mg/m2. Two of those patients had extremely high baseline ACTH concentrations (856 and 506 pg/ml).
Discussion
It has long been recognized that patients with CAH due to 21-hydroxylase deficiency demonstrate circadian variation in 17OHP concentrations. Measurement of 17OHP concentrations at 4-h intervals for 24 h before treatment or during inadequate treatment showed that peak concentrations were observed early in the morning, whereas trough concentrations were documented in the evening (16, 17, 18, 19). The circadian variation persists after introduction of glucocorticoid therapy, although the magnitude varies according to the degree of therapeutic control, and is abolished by excessive glucocorticoid treatment.
The present study is the first to delineate in such detail the pattern of 17OHP secretion in patients with classic 21-hydroxylase deficiency and the first to elucidate the relationship between cortisol and 17OHP in these patients. The later is illustrated better in the second group of patients, in whom variations in 17OHP concentrations are observed in relation to circulating cortisol concentrations achieved after the administration of oral hydrocortisone. The extremely high 17OHP concentrations early in the morning gradually declined as cortisol concentrations began to rise and remained low for as long as cortisol concentrations remained elevated, indicating that during daytime (0400–1600 h) cortisol concentrations need to be sufficiently high to result in adequate suppression of the HPA axis activity, as reflected by the magnitude of 17OHP concentrations. On the other hand, mean 17OHP concentrations during the nighttime (1600–0400 h) remained low despite the almost undetectable cortisol concentrations between 1600–2000 h, suggesting a period of decreased activity of the HPA axis. Finally, 17OHP demonstrated a precipitous rise beyond 0400 h, when increased activity of HPA axis is observed and by which time a significant reduction in circulating cortisol concentrations had taken place.
These observations concur with previous reports on the circadian rhythm of 17OHP secretion (16, 17, 18, 19) and indicate that administration of oral hydrocortisone in the evening may only be useful for substitution purposes and should not be expected to contribute significantly toward achieving and/or maintaining adrenocortical suppression. Therefore, it may be more appropriate, although not practical, to administer a dose of hydrocortisone just before the time of the rapid rise in 17OHP concentrations early in the morning (25).
The cross-correlation studies between cortisol and 17OHP showed that maximum suppression of 17OHP concentrations was achieved 1 h after cortisol concentrations reached their peak, and this effect was reversed 6 h, 40 min later. That the peak negative correlation between the two hormones was observed earlier during the nighttime (at lag time 20 min) than during the daytime (at lag time 60 min) suggests that 17OHP suppression is achieved sooner after hydrocortisone administration during the nighttime, and provides further evidence of decreased HPA axis activity between 1600–0400 h. Thus, the pattern of 17OHP secretion and the cortisol-17OHP interrelation along with knowledge of the main pharmacokinetic properties of the oral hydrocortisone formulation used (26, 27) may allow us to make appropriate decisions about the dose and administration schedule of hydrocortisone replacement therapy.
The findings of the present study also provide useful information about the timing of blood sampling for measurement of androgens and androgen precursors, which, along with clinical evaluation and monitoring of the annualized growth velocity and the rate of skeletal maturation, are often performed as part of the assessment of patients with classic 21-hydroxylase deficiency. Given the pattern of 17OHP concentrations described above, single measurements of 17OHP concentrations may be unreliable and can be particularly misleading if blood specimens are obtained beyond 1600 h. Serum androstenedione concentrations, on the other hand, obtained early in the morning and before the administration of oral hydrocortisone, correlate strongly with integrated 17OHP concentrations and can be used as a reliable marker of the adequacy of adrenocortical suppression if a single blood sample is to be obtained. In patients in whom a more detailed assessment is considered necessary, as, for example, in the case of inadequate adrenocortical suppression despite appropriate substitution therapy and adherence to treatment, measurement of cortisol and 17OHP concentrations every hour for the first 4 h after the administration of hydrocortisone and every 2 h thereafter until the next dose is to be given will provide adequate information about the cortisol-17OHP dynamics and will enable physicians to adjust their treatment accordingly. This detailed assessment can also be performed without necessitating admission to hospital, as serial measurements of blood or salivary 17OHP concentrations have been shown to be particularly useful in monitoring patients with classic 21-hydroxylase deficiency and can be obtained easily at home (13, 14, 15, 28, 29, 30).
Despite the fact that both groups of patients were receiving similar
hydrocortisone and 9-fludrocortisone doses and displayed similar
24-h cortisol concentrations, there were significant differences in
ACTH, 17OHP, and androstenedione concentrations between them. This
might relate to differences in the severity of salt-wasting CAH and/or
alterations in feedback mechanisms at the hypothalamic/pituitary level.
To investigate the latter, we performed a single dose dexamethasone
suppression test after randomization to two different doses. The
smaller dexamethasone dose of 0.3 mg/m2,
recommended for the single dose dexamethasone suppression test
(31), sufficiently suppressed the 0800 h ACTH
concentrations in all but three patients, who had very elevated
baseline ACTH concentrations and required a higher dose (0.5
mg/m2). Based on those findings, one may suggest
that if a few-day course of dexamethasone is required to achieve
suppression of HPA axis in poorly controlled CAH patients, the dose of
choice should be 0.5 mg/m2 on the first day and
0.3 mg/m2 on subsequent days. This represents the
dose required for overnight suppression of the HPA axis and not the
daily requirements in terms of glucocorticoid substitution. However, it
should be emphasized that longer-term administration of dexamethasone
should be avoided in view of its well documented detrimental effects on
growth and the associated adverse effects of long-acting
glucocorticoids (32, 33, 34, 35).
In summary, in patients with classic 21-hydroxylase deficiency, hydrocortisone replacement therapy should be administered during the period of increased HPA activity, between 0400–1600 h. The biggest hydrocortisone dose should be given in the morning, because circulating cortisol concentrations attained after evening doses are likely to be undetectable by the time of the rapid rise in 17OHP concentrations at 0400 h. Blood investigations performed as part of monitoring of CAH patients should include androstenedione and 17OHP concentrations obtained in the morning before the oral dose of hydrocortisone is given. However, it should be emphasized that blood investigations are only complementary to the overall assessment of these patients, which is primarily based on the evaluation of growth and pubertal progress.
Acknowledgments
We thank Mrs. Brancica Leonard, Ms. Jane Pringle, Ms. Jane McLean, and the staff on Carousel Ward, Middlesex Hospital (London, UK), for their contributions to the successful completion of this study.
Footnotes
Abbreviations: CAH, Congenital adrenal hyperplasia; CV, coefficient of variation; HPA, hypothalamic-pituitary-adrenal; 17OHP, 17-hydroxyprogesterone.
Received December 8, 2000.
Accepted July 18, 2001.
References
This article has been cited by other articles:
 |
|
 |
|
  D. P. Merke Approach to the Adult with Congenital Adrenal Hyperplasia due to 21-Hydroxylase Deficiency J. Clin. Endocrinol. Metab., March 1, 2008; 93(3): 653 - 660. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Pinto, V. Tardy, C. Trivin, C. Thalassinos, S. Lortat-Jacob, C. Nihoul-Fekete, Y. Morel, and R. Brauner Follow-Up of 68 Children with Congenital Adrenal Hyperplasia due to 21-Hydroxylase Deficiency: Relevance of Genotype for Management J. Clin. Endocrinol. Metab., June 1, 2003; 88(6): 2624 - 2633. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. L. Rosenfield Serum Cortisol and 17-Hydroxyprogesterone Concentrations in Children with Classic Congenital Adrenal Hyperplasia J. Clin. Endocrinol. Metab., June 1, 2002; 87(6): 2993 - 2993. [Full Text] [PDF]
|
|
|
|
|
|
E. Charmandari Author's Response: Serum Cortisol and 17-Hydroxyprogesterone Concentrations in Children with Classic Congenital Adrenal Hyperplasia J. Clin. Endocrinol. Metab., June 1, 2002; 87(6): 2993 - 2993. [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Endocrinology | Endocrine Reviews | J. Clin. End. & Metab. |
| Molecular Endocrinology | Recent Prog. Horm. Res. | All Endocrine Journals |
