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Congenital adrenal hyperplasia
The heel test or neonatal screening is a test that is performed on newborns to confirm the presence of certain diseases, such as congenital adrenal hyperplasia.
What is congenital adrenal hyperplasia?
It is an autosomal recessive enzyme alteration, which means that both parents must have the defective gene for the disease to be expressed in their generation.
In addition, the deficiency of the enzyme results in little or no production of hormones called cortisol and aldosterone, but an excessive biosynthesis of male hormones.
At the same time, as it is a metabolic pathway, the lack of an enzyme can give rise to different disorders, for this reason, the disease has multiple variants, specifically, 7 variants.
The most frequent variable is congenital adrenal hyperplasia due to a deficiency of the 21beta-hydroxylase enzyme, since it is the cause of 95% of the cases registered.
Forms of presentation of the disease
It is worth mentioning that depending on the age of presentation, the expression of the disease may be milder or more severe, regardless of the variant.
In this way, any of the 7 variants can have a severe or classical form and a moderate or non-classical form.
The first refers to the fact that the enzyme deficiency is complete, which means that your body does not produce it.
For this reason, the expression of the defect is in earlier ages, mainly, in the fetal or neonatal stage.
It is very different when it is the non-classical form, the enzyme deficiency is partial, whose clinical manifestations are later, that is, during childhood and adolescence.
Thus, the most frequent form of presentation is serious or classic.
What Causes Congenital Adrenal Hyperplasia?
The cause is genetic. Also, it has been associated with children of parents who share consanguinity.
However, each clinical variant is affected by a specific chromosome and gene.
21 beta-hydroxylase deficiency
This is the most common variant, characterized by deficiency of the enzyme 21 beta-hydroxylase.
Consequently, the neonate develops adrenal gland insufficiency and hyperandrogenism, the latter being the elevation of male hormones.
The hormone 21 beta -hydroxylase has the function of transforming 17 hydroxyprogesterone into 11 hydroxydesoxycortisol, the end product of which is the hormone cortisol.
Therefore, in the absence of 21 beta-hydroxylase, the body cannot synthesize cortisol, a hormone that is involved in the metabolism of glucose.
In addition to this, 17 hydroxyprogesterone accumulates, which deviates from the metabolic pathway and, the end result is the excessive production of testosterone, the male hormone.
In the same way, it occurs with the synthesis of aldosterone, a hormone whose function is to absorb water in the tubules of the kidney.
In the case of aldosterone, progesterone cannot be converted to 11-deoxycorticoesterone, because the enzyme 21 beta-hydroxylase is missing.
Clinical variants of 21 beta-hydroxylase deficiency
In turn, this deficit can be divided into two clinical variants. A classic or salt- wasting form, a virilizing classic variety, and a non-classic variety.
Classic clinical variants
Both variants have different clinical manifestations in both sexes, although the enzyme deficiency is complete or low.
First, the fetus is exposed in utero to high concentrations of male hormones, leading to hyperandrogenism.
Thus, in the virilizing clinical variant, female newborns will have masculinized female external genitalia, which is known as virilization. Besides, there is sexual ambiguity.
On the contrary, male newborns, what can be seen are highly developed external genitalia.
As for the classic salt-losing variant, it is the most frequent and has a poor prognosis.
The expression of the disease is severe, as there is a complete deficiency of the enzyme, therefore, your body does not produce cortisol or aldosterone. The age of presentation is in the neonatal stage.
In relation to the above, the newborn begins the picture with vomiting episodes, does not gain weight and has severe dehydration.
Non-classical clinical variant
The number of cases is limited, because it is the less frequent variant, but the one with the best prognosis. Symptoms usually appear in childhood or during adulthood.
However, there are consequences of excess male hormones. Some manifestations in girls are.
Early puberty
Signs of hyperandrogenism (acne, hirsutism)
Alterations in the menstrual cycle
On the contrary, in children some of the symptoms that can be observed are.
Very large and dark external genitalia
Acne
How is the diagnosis of congenital adrenal hyperplasia made?
The diagnosis is based on 4 pillars, signs and symptoms, karyotype, laboratory tests and neonatal screening.
In short, the deficit of 21 beta-hydroxylase is confirmed by the elevation of the blood concentrations of 17-hydroxyprogesterone.
If it is elevated, it means that there is no enzyme that makes it the next product in the metabolic pathway.
Also, the karyotype is available, but it is a very expensive study and the result takes weeks to deliver.
For its part, neonatal screening or neonatal screening or heel testing is a key element to avoid unfavorable scenarios.
This test consists of the analysis of the concentrations of 17-hydroxyprogesterone in the blood of the newborn, which is obtained from the heel stick.
Additionally, it allows a correct assignment of sex in girls who have sexual ambiguity.
Treatment of congenital adrenal hyperplasia
Treatment depends on the context in which the symptoms began, but generally, treatment is hormone replacement with glucocorticoids.
In relation to masculinized female genitalia, according to each case, one of the options is surgery and, of course, psychological support.
Follow-up of children with congenital adrenal hyperplasia
The follow-up consists of the periodic evaluation of the symptoms and the analysis of the hormonal values.
In addition to this, monitoring growth and paying attention to the consequences that can appear such as obesity and osteoporosis.
Another aspect that should be monitored is sexual function and fertility, both in girls and in boys.
In short, it is a disease that can be diagnosed during pregnancy, but if it goes unnoticed, this is where the neonatal screening plays a fundamental role in its early diagnosis.
