Clinical Significance Of The Abnormalities Of Sex Hormones Caused By Adrenocortical Lesions
Sex Hormones In Action
A General Overview
Anatomy: Adrenals are paired glands each weighing about 4-7g. Section shows an outer cortex and inner medulla. The arterial supply is derived from several branches of the phrenic, renal and ovarian or spermatic arteries and aorta. Venous drainage on the left is into the left renal vein and inferior vena cava on the right. Histologically, three zones are visible- the zona glomerulosa, zona fasciculate and zona reticularis from without inwards.
Embryology: Adrenal cortex in the fetus is formed during the fourth to sixth weeks of gestation from the celomic mesoderm of the posterior abdominal wall. The permanent adrenal cortex is formed from the small basophilic cells which appear five weeks later. The adrenal medulla develops in the seventh week from sympathogonia which migrate from the neural crest into the fetal adrenal cortex. The adrenals are relatively bigger at birth, but with the passage of time, the size reduces since the inner zone of acidophilic cells undergo involution.
Physiology: Several hormones are produced by the adrenal cortex. It synthesizes cholesterol and also takes cholesterol from the circulation for the production of its hormones. Synthesis of hormones take place in several steps.
The adrenal cortical Hormones
Secretory rate in mg/24 hours
Adrenocorticotropic hormone (ACTH) secreted by the anterior pituitary stimulates secretion of adrenal cortical hormones (glucocroticoids) and sex hormones) by acting on specific receptors present on the adrenal cortex through the mechanism of c-AMP.
Adrenal cortex may secrete excess of androgens if it is the seat of tumour or congenital enzyme defects. The final clinical picture is determined by the sex of the patient, age of onset of the disorder and its severity. The condition may remain unnoticed in adult males. Women develop virilisation. Male children show precocious puberty. Female children develop clitoromegaly and other signs of hyperandrogenism.
Drake Congenital Adrenal Hyperplasia
Adrenogenital syndrome (Congenital Adrenal Hyperplasia)
This rare disorder is characterized by virilisation in female and precocious puberty in male children. The underlying defect is congenital deficiency of enzymes leading to metabolic block in hormone synthesis. This results in the accumulation of intermediary metabolites with androgenic activity. Deficient synthesis of glucocorticoids and mineralocorticoids results in functional adrenocortical deficiency.
Etiology: The enzyme defect is transmitted as an autosomal recessive disorder, with clinical expression in the homozygous state. Females are affected more than males. The severity of enzyme defect determines the age of manifestation. Severe defects manifest earlier in life. At least six different enzyme defects are known, but four of these are more frequent. These are C-21-hydroxylase defect, C-11 hydroxylase defect, 3-beta hydroxydehydrogenase defect and C-18 dehydrogenase defect. In each type, slight differences are recognizable.
Clinical features: In some cases, the newborn female infants show pseudohermaphrodism due to androgen effect on the genitalia. Male infants show precocious sexual development after birth. Manifestations of adrenal insufficiency are failure to thrive, vomiting, hyponatremia and hypotension. Death may occur due to adrenal insufficiency unless the condition is recognized and treated.
Milder cases manifest as virilisation in girls and sexual precocity in boys. Due to the premature fusion of epiphyses, growth is stunted. Hyperandrogenisms causes testicular atrophy and infertility in adult males.
Diagnosis: Adrenogenital syndrome should be considered in the differential diagnosis of all cases of hermaphroditism or ambigious sexual development. Diagnosis is confirmed by estimation of the products of androgens in urine.
Treatment: Deficiency of glucorcoticoids and mineralocorticoids should be corrected by supplementation. Liberal intake of salt helps in mild cases. Fluodrocortisone in a daily dose of 0.05 to 0.1mg orally is given to replace mineralocorticoids. Prednisolone in a dose of 5 mg/day serves to overcome glucocorticoid deficiency. Surgery may be required for cosmetic correction of the genitalia. In those cases in whom adrenal tumours or hyperplastic glands are demonstrable, surgical removal is indicated.
© 2014 Funom Theophilus Makama