What is Adrenal Hypoplasia?

The rare medical condition known as adrenal hypoplasia occurs predominantly in male infants as a result of a genetic abnormality that contributes to the underdevelopment of the adrenal cortex. Symptoms of this potentially lethal disease, which are precipitated by adrenocorticotropic hormone deficiency, usually arise during the first month of life and frequently require hospitalization. Most patients suffering from the disorder mature into adulthood but require ongoing treatment prescribed by an endocrinologist.

The adrenal cortex normally secretes glucocorticoids, mineral corticoids, androgens, estrogens and progestins. Researchers believe that glucocorticoids play an essential role in carbohydrate metabolism. Mineral corticoids primarily affect electrolyte regulation in the blood, whereas androgens, estrogens and progestins contribute to the development of sexual characteristics and are necessary for the reproductive process. Underdevelopment or malformation of the adrenal cortex diminishes hormone production, which may result in dietary deficiencies, metabolic imbalances and a lack of sexual maturity.

Health care providers suggest that 60% of infants born with adrenal hypoplasia experience symptoms within the first month of life but that 40% of patients do not exhibit symptoms until later in childhood. Infants suffering from congenital adrenal hypoplasia often exhibit a failure to thrive. These babies vomit frequently and have trouble feeding. These symptoms may lead to dehydration, dangerously low blood sugar and shock. Along with hypoglycemia, patients often have blood potassium levels that are higher than normal and low sodium levels.

The majority of infants with symptoms of adrenal hypoplasia require admittance to an intensive care unit where medical personnel administer cortisol, glucose and saline. The common treatment for this pediatric condition includes hormone replacement therapy and salt supplements throughout life. Adrenal hypoplasia may delay the onset of puberty or result in the inability to produce male sexual characteristics, and physicians often prescribe testosterone injections for proper physical and secondary sexual characteristic development.

Researchers believe that adrenal hypoplasia stems from a mutation in the nuclear receptor subfamily 0 group B member 1 (NR0B1) gene. When this defect occurs, the gene cannot produce a protein that is vital to normal adrenal cortex development. Scientists have discovered that this anomaly occurs in a recessive gene on the X chromosome of affected women. Carriers may or may not experience symptoms which include varying degrees of muscle cramping and weakness.

Each woman carrying the recessive gene has a 50% chance of passing the disease onto a son, and daughters born to women carrying the defect have a 50% chance of being carriers. Although physicians consider adrenal hypoplasia extremely rare in female infants, girls born with the disorder exhibit the same symptoms and require the same medical treatment as boys.