Use of the low-dose corticotropin stimulation test for the monitoring of children with asthma treated with inhaled corticosteroids

Partial empty sella syndrome, GH deficiency and transient central adrenal insufficiency in a patient with NF1

PURPOSE

To describe the case of a 9-year-old male patient with neurofibromatosis type 1 (NF1), partial empty sella (PES), transient central adrenal insufficiency (CAI) and growth hormone (GH) deficiency (GHD) treated with recombinant GH (rGH).

METHODS

The diagnosis of GHD was established upon peak GH response <10 ng/mL following glucagon and clonidine stimulation tests. CAI was diagnosed when peak cortisol response was <18 μg/dL following 1 μg Synacthen test (ST) with normal ACTH levels.

RESULTS

The diagnosis of NF1 was made at the age of 1.5 year. The patient first attended our Department at the age of 4.5 years. He presented with short stature (height: 95 cm < 3rd percentile), macrocephaly, frontal bossing, café-au-lait spots and bilateral proptosis. His growth rate (GR) initially was 5.3 cm/year. Brain/pituitary MRI showed T2-hyperintensities typical for NF1 and PES with reduced pituitary gland height (3 mm). The pituitary function tests revealed GHD. During follow-up his imaging findings remained unchanged, while his GR decelerated. He was started on rGH at the age of 8.5 years. Within the following year he grew 8.7 cm in height and could preserve a normal GR thereafter. At the age of 10.3 years, he was diagnosed with CAI (maximum cortisol response post-1 μg ST: 13.1 μg/dL). Ηe received hydrocortisone for 1 year. A repeat 1 μg ST off hydrocortisone showed normal cortisol response. During follow-up, brain MRI findings remained stable, while his pituitary demonstrated normal size and signal intensity.

CONCLUSION

Empty sella and hypopituitarism may occur in the context of NF1. Short stature may be associated with GHD in the absence of intrasellar masses in affected individuals. Lifelong endocrine follow-up is recommended for all NF1 patients.

Adrenal responses to a low-dose short synacthen test in children with asthma

OBJECTIVES

Corticosteroids are known to cause adrenal suppression. The aim of this study was to assess clinical factors affecting responses to a low dose short synacthen test (LDSST) in asthmatic children using corticosteroids.

DESIGN

Patients were recruited from secondary care paediatric asthma populations within the UK.

PATIENTS

Asthmatic children (5-18 years), receiving corticosteroids, underwent a LDSST (n = 525).

MEASUREMENTS

Demographics and corticosteroid doses were tested for association with baseline and peak (stimulated) cortisol concentrations.

RESULTS

Baseline cortisol was significantly associated with age (log baseline increased 0·04 nm per year of age, P < 0·0001), but not with gender or corticosteroid dose. Peak cortisol was significantly associated with total corticosteroid cumulative dose (decreased 0·73 nm per 200 mcg/day, P < 0·001) but not with age, gender inhaled/intranasal corticosteroid cumulative dose or number of courses of rescue corticosteroids. Biochemically impaired response (peak cortisol ≤500 nm) occurred in 37·0% (161/435) overall, including children using GINA low (200-500 mcg/day beclomethasone-CFC equivalent 32%, n = 60), medium (501-1000 mcg/day (33%, n = 57) and high (>1000 mcg/day 40%, n = 13) doses of inhaled corticosteroid (ICS) similarly, and 36·6% of those using fluticasone ICS ≥500 mcg/day (71/194). Impaired response was more frequent in patients on regular oral corticosteroids (66%, n = 27, P < 0·001).

CONCLUSION

Children with asthma can develop biochemical adrenal suppression at similar frequencies for all ICS preparations and doses. The clinical consequence of biochemical suppression needs further study.

A search for variables predicting cortisol response to low-dose corticotropin stimulation following supraphysiological doses of glucocorticoids

OBJECTIVES

To determine which biological or clinical variables may predict cortisol response to low-dose adrenocorticotropic hormone (ACTH) stimulation following supraphysiological doses of glucocorticoids in children.

STUDY DESIGN

This retrospective study included all patients who underwent ACTH testing (1 μg) between October 2008 and June 2010 at the Sainte-Justine University Hospital Center, Montreal, after supraphysiological doses of glucocorticoids.

RESULTS

Data from 103 patients (median age, 8.0 years; range, 0.6-18.5 years; 57 girls) were analyzed, revealing growth deceleration in 37% and excessive weight gain in 33%. Reasons for glucocorticoid treatment included asthma (n = 30) and hematologic (n = 22), dermatologic (n = 19), rheumatologic (n = 16), and miscellaneous (n = 16) disorders. The following information was recorded: duration of glucocorticoid treatment (median, 374 days; range, 5-4226 days); duration of physiological hydrocortisone replacement (median, 118 days; range, 0-1089 days); maximum daily (median, 200 mg/m(2)/day; range, 12-3750 mg/m(2)/day) and cumulative (median, 16 728 mg/m(2); range, 82-178 209 mg/m(2)) doses, in hydrocortisone equivalents; and interval since the last dose (median, 43 days; range, 1-1584 days). Sixty-two patients (58%) exhibited a normal response (ie, peak cortisol >500 nmol/L) to ACTH stimulation. Peak cortisol level was not related to sex, prior morning cortisol level, duration of treatment, or cumulative glucocorticoid dose; 28% of the patients with normal baseline cortisol levels nevertheless demonstrated a subnormal response to ACTH.

CONCLUSION

Given the absence of clinical or biological predictors of the cortisol response to ACTH after suppressive doses of glucocorticoids, physicians have only 2 options: (1) empirically advocate glucocorticoid stress coverage during 18 months after cessation of high-dose glucocorticoid treatment; or (2) perform serial ACTH testing in all such patients until a normal peak cortisol level is attained.

Lack of sensitivity of the 1-μg low-dose ACTH stimulation test in a paediatric population with suboptimal cortisol responses to insulin-induced hypoglycaemia

CONTEXT

The insulin-tolerance test (ITT) is the gold standard for evaluation of the hypothalamic-pituitary-adrenal (HPA) axis. The low-dose ACTH stimulation test is increasingly used for evaluation of secondary adrenal insufficiency as several studies performed in adults have demonstrated high sensitivity and specificity when compared to the ITT. Whether the ACTH stimulation test demonstrates similar sensitivity in a paediatric and adolescent population compared with the gold standard is unclear.

OBJECTIVE

To compare the sensitivity of the low-dose (1-μg) Synacthen(™) test (LDSST) and the gold-standard ITT in a paediatric and adolescent population.

DESIGN AND PATIENTS

A retrospective review of 42 consecutive LDSSTs in children and adolescents with suboptimal cortisol responses (peak <500 nm) on ITT.

RESULTS

Thirty-one patients (74%) had an adequate cortisol response to low-dose Synacthen(™) (sensitivity 26%). Patients had a higher cortisol increment with the LDSST than ITT (median Δ cortisol 294 vs 168 nm, P < 0.0001) and correspondingly a higher cortisol peak (median peak cortisol 572 vs 396 nm, P < 0.0001). Patients who had a suboptimal peak cortisol both on ITT and on LDSST had a lower baseline cortisol on ITT (median 178 vs 227 nm, P = 0.04). Peak cortisol on ITT was significantly higher in patients who had a subsequent normal LDSST than those that did not (median 417 vs 300 nm, P = 0.0005).

CONCLUSIONS

The 1-μg LDSST lacks sensitivity in detection of secondary adrenal insufficiency in children when compared to the gold-standard ITT.

Low-dose and high-dose adrenocorticotropin testing: indications and shortcomings

PURPOSE OF REVIEW

The 250 microg adrenocorticotropin test (high-dose test) is the most commonly used adrenal stimulation test, though the use of physiologic doses (1.0 microg or 0.5 microg/1.73 m) (low-dose test) has recently gained wider acceptance. These variants and the use of adrenocorticotropin test in the ICU, however, remain controversial. The validity of the low-dose test and the parameters for evaluation of high- and low-dose tests in different situations need reevaluation.

RECENT FINDINGS

In the last few years, numerous studies have used the low-dose test as a single test following previous findings that it is more sensitive and accurate than the high-dose test. It is used mainly in secondary adrenal insufficiency and after treatment with therapeutic glucocorticosteroids to define hypothalamo-pituitary-adrenal suppression. Unless there is a very recent onset of disease, the results are interpreted by most researchers as diagnostic. The treatment of relative adrenal insufficiency, based on delta cortisol, has not yielded proof of correlation between this diagnosis and better prognosis with glucocorticoid treatment.

SUMMARY

For interpretation of an adrenocorticotropin test, only peak - and not delta - cortisol should be used. The use of 240-300 mg of hydrocortisone daily in ICU patients, including septic shock, should be considered as pharmacologic, rather than as a replacement dose. Using the low-dose test for this purpose will lead to further misdiagnosis.

Adrenal function in children with severe asthma treated with high-dose inhaled glucocorticoids: recommended screening tests in outpatient conditions

BACKGROUND

A number of previous studies have suggested that adrenal suppression occurs in asthmatic children treated with high-doses of inhaled glucocorticoids (IGC). This study was designed to determine the frequency of adrenal suppression in children with severe asthma treated with recommended doses of IGC: namely 500-1,000 microg/day of fluticasone propionate or the equivalent of budesonide (1,000-2,000 microg/day) for a period of at least 12 months.

METHODS

Early morning cortisol (F) and ACTH serum levels were measured in 27 severe asthmatics aged 6-16 years old. The children underwent a low dose ACTH test (1 microg/1.73 m2) with a parallel glucose measurement. Twenty-four hour urine collection was performed before examination for free F (UfF) and creatinine levels. There were no clinical manifestations of adrenal hypofunction in the analyzed children.

RESULTS

Of the 27 patients, 22 had normal basal and post-stimulatory levels of F and normal UfF, and the other five (18.5%) had basal serum F levels of <400 nmol/l. Four of the five also had normal post-stimulatory levels of F and normal UfF. One child had a subnormal peak F value of 484 nmol/l during the ACTH test. None of the patients had a suppressed serum ACTH level, but an elevated ACTH level was found in four children. This study provided biochemical evidence of suboptimal adrenal function in one child in the examined group (3.7%) and a good response to stimulation in all the others, even in those with slightly reduced basal cortisol levels.

CONCLUSION

This study showed that the use of fluticasone in doses of up to 1,000 microg/day (or the equivalent of budesonide) as long-term treatment of children with severe asthma did not substantially affect their adrenal function.