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Mikropenis
Last reviewed: 23.04.2024
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Micropenis is the term used to describe the penis, the size of which is less than 2 standard deviations from the norm in the absence of any other visible pathology, accompanied by underdevelopment of the penis (eg, hypospadias, hermaphroditism).
The size of the penis is taken to measure when it is pulled from the base to the tip along the dorsal surface. Normally, the size of the penis in a newborn is about 3.5 cm. The penis is less than 2 cm in the penis (2 SD is less than the norm).
Causes of the micropeniasis
The main growth of a member begins with the second half of the intrauterine period. Therefore, with premature birth in newborn boys, the penis will be shorter than in full-term children, but this does not mean that there is a micropeniasis. Tuladhar et al. (1998) derived a formula for the relationship between penis length and gestational age for children born between the 24th and 36th week of pregnancy:
The length of the penis (cm) = 2.27 + 0.16 x ned pregnancy.
After birth, the dimensions vary slightly until puberty, which is not due to the influence of sex hormones, but to overall somatic growth. The tables of length standards are developed depending on the age.
Intrauterine synthesis of testosterone and its conversion to dihydrotestosterone are necessary for the normal development of the male genital fetus. At the onset of gestation, under the influence of HCG binding to the LH receptor, initial differentiation and development of the genital organs occurs. Approximately from the 14th week, the hypothalamic-pituitary system of the fetus is activated, hence, in the fetus, the fetal tab is normal (t as the main influence on the bookmark is provided by the maternally hCG), but the penis will not grow, the micro penis develops. On the other hand, the violation of the gonad tabs, which occurs on the 7th-10th week of intrauterine development, will also lead to its lack of growth. Thus, the main causes of underdevelopment are as follows:
- hypergonadotropic hypogonadism - impaired gonadal development (anorchism, Klinefelter's syndrome, gonadal dysgenesis, Leipzig cell hypoplasia, consequence of a defect in the LH gene or receptor for LH);
- defects in the biosynthesis of testosterone;
- deficiency of 17.20-lyase activity;
- deficiency of Zeta-hydroxysteroid dehydrogenase (30-HSD);
- deficiency of 17p-hydroxysteroid dehydrogenase;
- defect synthesis of dihydrotestosterone - deficiency of 5a-reductase;
- insensitivity of the receptor to androgens;
- hypogonadotropic hypogonadism (hypopituitarism, Kalmann's syndrome, septo-optic dysplasia, idiopathic hypogonadotropic hypogonadism);
- family form (in men in the genus - a small penis or micropeniasis in the absence of other disorders).
In addition to the above reasons, the micropenis is found in various syndromic diseases and chromosomal defects (Prader-Willi syndrome, Barder-Biedl syndrome, Noonan syndrome, Robinow syndrome, Rud syndrome, CHARGE syndrome).
"False micropeniasis" - in patients with obesity, one can visually determine the shortening of the penis due to the overhanging of the fat fold above its base - the so-called recessed penis.
Symptoms of the micropeniasis
When examining a patient with complaints of underdevelopment or micropeniasis, it is necessary to collect a family history: death in the period of a newborn, short stature in the family, pathology of development of external genital organs among relatives.
Diagnostics of the micropeniasis
Examination and physical examination
Measure the growth of the child and determine the rate of its growth. Exclude any stigma of dysembryogenesis or associated malformations of other systems.
If the micro-penis is combined with hypoglycemia during the period of the newborn and delayed growth at an older age, this requires the exclusion of hypopituitarism. The violation of the sense of smell allows you to suspect Kalman's syndrome (anemia and hypogonadotropic hypogonadism, micropeniasis). The presence of developmental defects or stigma of embryogenesis requires the consultation of a geneticist to exclude chromosomal pathologies and other genetic syndromes.
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Laboratory and instrumental research
Karyotyping and chromosome analysis are indicated for suspected chromosomal pathology and stigma of dysembryogenesis.
Determination of the content of LH and FSH: in the period from 1 to 2 months of life, their concentration corresponds to pubertal, so inflated or underestimated values will indicate hypergonadotropic or hypogonadotropic hypogonadism (respectively). Testosterone, dihydrotestosterone. T / DHT ratio in the sample with chorionic gonadotropin allows to exclude 5a-reductase deficiency.
The content of thyroid hormones, cortisol. IRP-1, glucose-studies are indicated for suspected hypopituitarism, especially if a child with a micropenia had an attack of hypoglycemia.
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Treatment of the micropeniasis
It is proved that testosterone therapy in children with its deficiency is effective and allows to effectively treat the micro penis, to increase the size of the penis to the generally accepted norms. Apply testosterone in various forms (gels, patches, injections). Bin-Abbas (1999) showed that the course of three injections of testosterone 25-50 mg at intervals of 4 weeks to infants allows reaching reference sizes.
Surgical treatment of the micropeniasis
If a true micropeniasis is present, phalloplasty is used.