Congenital and acquired disorders of the adrenal cortex

Congenital adrenal hyperplasia in pregnancy

The congenital adrenal hyperplasias (CAH) are a group of inherited enzymatic defects of adrenal steroid biosynthesis. Deficiencies of each enzyme required in the steroid biosynthesis pathway are known, and these deficiencies are all inherited as autosomal recessive disorders. During pregnancy, maternal and fetal problems are confined to women who have 21-hydroxylase deficiency (P450c21 deficiency), 11-hydroxylase deficiency (P450c11 deficiency), and 3 beta-hydroxysteroid dehydrogenase deficiency (3 beta HSD deficiency), because other adrenal enzyme deficiencies are not compatible with fertility. The interposition of the placenta on the hypothalamic-pituitary-adrenal axis and other endocrine changes during pregnancy impact considerably on the clinical evaluation of the congenital adrenal hyperplasias. Successful management of CAH in pregnancy requires a firm knowledge of normal adrenal anatomic and endocrine changes that occur during gestation. Women with severe forms of CAH have decreased fertility rates because of oligo-ovulation, and successful conception requires a combination of good therapeutic compliance, careful endocrine monitoring, and often ovulation induction. From a fetal and neonatal standpoint, accurate prenatal diagnosis of 21-hydroxylase deficiency and 11-hydroxylase deficiency is now possible, which allows for prenatal treatment in an attempt to minimize clinical problems in the neonates. Prevention of masculinization of affected female fetuses by corticosteroid suppression has been attempted in both 21-hydroxylase deficiency and 11beta-hydroxylase deficiency CAH, with variable degrees of success. This review provides an overview of the congenital adrenal hyperplasias and their management during pregnancy.

MANAGEMENT OF CONGENITAL ADRENAL HYPERPLASIA DURING PREGNANCY

OBJECTIVE

To provide an overview of the congenital adrenal hyperplasias (CAHs) and their management during pregnancy.

METHODS

Pathways of steroid biosynthesis and inherited deficiencies of required enzymes are reviewed, and applications to prenatal diagnosis and treatment of affected fetuses are discussed.

RESULTS

The CAHs are a group of inherited enzymatic defects of adrenal steroid biosynthesis. During pregnancy, maternal problems are confined to women with 21-hydroxylase deficiency, 11b-hydroxylase deficiency, and 3b-hydroxysteroid dehydrogenase deficiency because other adrenal enzyme deficiencies are incompatible with fertility. The interposition of the placenta on the hypothalamic-pituitary-adrenal axis has a major effect on clinical evaluation of CAH during pregnancy. Women with severe forms of CAH have decreased fertility rates because of oligo-ovulation, and successful conception requires a combination of good therapeutic compliance, careful endocrine monitoring, and often induction of ovulation. 21-Hydroxylase deficiency in the fetus can now be diagnosed accurately prenatally by endocrine testing and molecular genetic techniques. Prenatal diagnosis of 11b-hydroxylase deficiency in the fetus by endocrine testing is not as sensitive. Prevention of masculinization of affected female fetuses by corticosteroid suppression has been attempted in both 21-hydroxylase deficiency and 11b-hydroxylase deficiency CAH, with variable degrees of success. To date, no reports have been published of prenatal diagnosis or treatment of affected female fetuses with 3b-hydroxysteroid dehydrogenase deficiency CAH.

CONCLUSION

Endocrine and genetic studies of CAH during pregnancy have improved the diagnosis and management.

The incidence of non-classical 21-hydroxylase deficiency in hirsute adolescent girls

Non-classical adrenal hyperplasia due to 21-hydroxylase enzyme deficiency (NC21OHD) causes hirsutism, acne and menstrual irregularities in women. Clinically, patients with NC21OHD may be indistinguishable from other hyperandrogenic women, as they all present with similar symptoms. An elevated response of cortisol precursors like 17 alpha-hydroxyprogesterone (17-OHP) to ACTH stimulation is a valuable diagnostic criteria. In this study, 32 hirsute adolescent girls, aged 13-19 years, underwent i.v. adrenocorticotrophic hormone (ACTH) (Synacthen 0.25 mg) stimulation test. The results were compared with those of the controls. The plasma levels of 17 alpha-hydroxyprogesterone, cortisol, dehydroepiandrosterone sulphate (DHEA-S), androstenedione, testosterone, follicle stimulating hormone (FSH), luteinizing hormone (LH) and prolactin were established before, and 60 min after the infusion of ACTH to both patients and controls. Six patients demonstrated an increase in both the 17 alpha-hydroxyprogesterone levels and the 17 alpha-hydroxyprogesterone/cortisol ratio on ACTH stimulation, almost twice that of the mean +/- 2SD in the control group and ten times that in one patient. Six patients with abnormal elevation of 17 alpha-hydroxyprogesterone were considered heterozygotes for 21-hydroxylase enzyme deficiency, and one patient was presumed to have NC21OHD. Human leukocyte antigen (HLA) analysis supported these diagnoses. In this study, the incidence of NC21OHD in hirsute adolescent girls in our population was investigated, and NC21OHD was found in only one of 32 patients.

Loss of therapeutic control in congenital adrenal hyperplasia due to interaction between dexamethasone and primidone

A 14-year-old girl with congenital adrenal hyperplasia showed rapid conversion from undertreatment to overtreatment when primidone, used to treat coexistent epilepsy, was withdrawn while on a constant steroid dose. In addition to signs of hypercortisolism and a decrease in random measurements of plasma testosterone and 170H-progesterone concentrations, the deterioration in control was also illustrated by changes in the pattern of blood spot steroid profiles. Adequate control was achieved only after a 3-fold reduction in steroid dose. The decrease in dose requirement was probably the result of a reversal of liver enzyme induction consequent upon the withdrawal of primidone.

Prevalence of congenital adrenal hyperplasia in Kuwait

Between 1978 and 1988 congenital adrenal hyperplasia (CAH) was diagnosed in 60 children in Kuwait with an estimated prevalence of 1:9,000 livebirths, which is higher than that reported from Europe and Canada. In addition, there was presumptive evidence of CAH resulting in the death of 20 other children, giving a prevalence figure of 1:7000. There were 41 girls (68%) and 19 boys (32%). Thirty-one of the girls (75.6%) and 11 of the boys (57.9%) were saltlosers. Fifty-four patients (90%) were diagnosed as 21-hydroxylase deficient, 3 patients (5%) had a deficiency of the 3 beta-hydroxy-steroid dehydrogenase enzyme, and 3 patients (5%) showed a deficiency of 11 beta-hydroxylase.

A review of the rational use of corticosteroids

Understanding of the use of corticosteroids has been aided by knowledge of their effect on cellular protein synthesis and by an appreciation of how modification of their molecular structure alters their pharmacological action. Their ability to modulate the immune response and to diminish inflammation make them useful in rheumatology, respiratory diseases, allergies, endocrine and metabolic disorders, blood disorders, gastro-intestinal diseases, neurological and muscular diseases, renal diseases, cardiovascular disorders and skin diseases. They have been widely tried empirically and, sometimes, they have proved unequivocally effective. Often there has been a need for cooperative clinical trials to establish their efficacy, and initial enthusiasm for corticosteroids has been tempered by a better appreciation of their limitations, especially in infections and ophthalmology. Those areas where either controlled trials or other persuasive evidence has established a place for their use are reviewed.

Value of selective screening for congenital adrenal hyperplasia in Hungary

Measurement of the 17-hydroxyprogesterone concentration in blood spots was used to identify cases of congenital adrenal hyperplasia among patients with inappropriate virilisation, or salt wasting, or both. Between 1978 and 1986 61 were identified among 707 patients (278 neonates, 204 infants, and 225 children). The incidence of classic congenital adrenal hyperplasia was calculated for a seven year prospective trial period using the blood spot 17-hydroxyprogesterone method in selective screening. There were 38 salt losers and 14 simple virilisers in 968,303 live births, an incidence of congenital adrenal hyperplasia of 1:18,000 in the Hungarian population. Selective screening led to earlier diagnosis of congenital adrenal hyperplasia and a pronounced decrease in mortality. A central laboratory to measure the blood spot 17-hydroxyprogesterone concentrations is valuable for the investigation of patients at risk for congenital adrenal hyperplasia in countries where blood steroid assays are not readily available.

Prenatal diagnosis of congenital adrenal hyperplasia: reliability of amniotic fluid steroid analysis

The concentration of 170H-progesterone was measured in amniotic fluid samples collected from 55 mothers who had previously had a child with congenital adrenal hyperplasia due to 21-hydroxylase deficiency. In eight pregnancies the levels of 170H-progesterone were raised; the parents elected to terminate in four and examinations of the fetus confirmed the diagnosis of congenital adrenal hyperplasia. In each case, the affected sib was a salt loser. The remaining four affected pregnancies proceeded to term and each infant had salt losing 21-hydroxylase deficiency. All 47 infants predicted to be unaffected were normal at birth. However, an increased plasma concentration of 170H-progesterone was documented in a male non-salt loser at three months of age. Prenatal diagnosis of congenital adrenal hyperplasia by amniotic fluid steroid analysis is reliable only for the salt losing variant of 21-hydroxylase deficiency. Of the affected sibs in this study, 20% died during infancy in a salt losing crisis. This simple and rapid prenatal test is sufficiently reliable to predict the group of infants most at risk in early infancy.

Clinical aspects of congenital adrenal hyperplasia: early diagnosis and prognosis

The neonatal presentation of congenital adrenal hyperplasia is either virilization of females or salt loss in both sexes. Early diagnosis is based on the rapid measurement of plasma 17 alpha-hydroxyprogesterone. Milder forms of congenital adrenal hyperplasia can present later in life with abnormalities of somatic or sexual development. The majority of cases of congenital adrenal hyperplasia are clinically diagnosable in the first 2-3 weeks of life: the need for screening for the remaining missed cases and the late onset types remains to be established.

Single dose dexamethasone suppression test in children: dose relationship to body size

We have performed an overnight single dose dexamethasone suppression test in 15 children at different dosages to determine the minimum dose required to suppress the 0800 h serum cortisol level. With a dexamethasone dose of 0.1 mg/m2 two of seven children showed suppression. When the dose was increased to 0.3 mg/m2 all of six patients showed suppression as did three given dexamethasone 0.5 mg/m2. We recommend that doses of dexamethasone should be calculated in terms of body surface area when assessing the hypothalamo-pituitary axis in children and that a dose of 0.3 mg/m2 should be used for suppression tests.

The hypothalamic-pituitary-adrenal axis

Anterior pituitary corticotrophin cells secrete ACTH as part of a larger precursor molecule, pro-opiomelanocortin. Post-translational cleavage of this precursor yields three major peptides: ACTH, beta-LPH and N-POMC. Experiments both in vivo and in vitro suggest that N-POMC may act as a prohormone amplifier for ACTH-induced adrenal steroidogenesis and as regulator of adrenocortical cell growth. The secretion of POMC is under the control of CRF. These findings are discussed in relation to the pathophysiology of corticotrophinoma. The primary defect in this condition appears to reside at the level of the anterior pituitary cell and is readily amenable to treatment by trans-sphenoidal microsurgery. The estimation of plasma ACTH concentrations is proving useful in the monitoring of various clinical conditions including Addison's disease and congenital adrenal hyperplasia.

Cold stress and congenital adrenal hyperplasia heterozygotes

Congenital adrenal hyperplasia due to 21-hydroxylase deficiency is common in certain regions of the world characterised by cold winters. The persistence of this potentially lethal recessively inherited disease suggests that an evolutionary advantage is conferred upon the partially affected heterozygotes. Profound hypothermia following acute cold exposure in normal subjects carries a considerable mortality especially from cardiac arrhythmias and dehydration. A hypothesis is proposed to suggest that the incomplete block at the 21-hydroxylase step of steroid biosynthesis decreases stress-induced steroid responses, especially in the younger heterozygote and clinically non-salt-losing homozygote; glucocorticoid and mineralocorticoid insufficiency reduces the severity of cold-induced water diuresis; prevention of severe dehydration contributes towards the ability to survive profound hypothermia. Studies into the salt and water metabolism of the congenital adrenal hyperplasia heterozygote at various ages as well as examination of antidiuretic hormone and steroid hormone interactions upon the renal tubule in cold-exposed normal individuals are merited.