TESTIS FAILURE V: DELAYED
PUBERTY
Puberty in the male occurs in progressive stages, most commonly identified by the classification into five stages by Tanner (see Plate 1-6). In addition to rapid development of sexual organs and other characteristics, during the later Tanner stages, the testes produce sperm capable of fertility. Adolescence is the period of further development following puberty that ends when full maturity is reached. Prior to the onset of puberty (i.e., the prepubertal period), the testes are immature and quiescent as pituitary gonadotropins are released in only subthreshold amounts. As such, it is not possible to evaluate hypogonadism in prepubertal boys. It is also true that variations in male genitalia or stature during this period may not be due to absent or defective testes but may be ascribed to other factors, including those related to heredity, pituitary, thyroid, adrenal, growth hormone, or nutritional issues.
The real physical changes
associated with puberty occur in response to the secretion of luteinizing
hormone (LH) from the anterior pituitary gland. LH stimulates Leydig cells
within the testis interstitium to produce androgens from cholesterol
precursors. The age of onset and the rate at which it proceeds exhibit wide
variation, lending tremendous variation in the length and degree of pubertal
development in boys of any particular age.
Care providers are often
called upon by parents to prognosticate regarding the sexual development of
peripubertal boys, especially if the average age for pubertal onset has passed
without genital growth. However, it is difficult to make an absolute diagnosis
of hypogonadism during pubescence. A testicular biopsy is likely to reveal
findings consistent with infantile testes, indicating only a lack of
gonadotropic stimulation. Hormone assays for gonadotropins are more accurate
but may change rapidly during this developmental period. The consistency of the
testes, when soft and small, may possibly indicate true hypogonadism over time.
Temporary breast development is normal during early male pubescence. Assessing
linear growth or observing disproportionate bone growth can provide evidence of
growth disorders such as dwarfism.
If there is real concern
about pubertal development, a diagnostic and therapeutic challenge with human
chorionic gonadotropin (hCG, 500-700 IU three times weekly for 3 weeks) can
evaluate potential gonadal and pituitary factors. An increase in testis
consistency or serum testosterone implies that the testis Leydig cells are
normal. This in turn suggests that there may only be a delay in the onset of
puberty, although the existence of a permanent pituitary defect is still a
possibility.
Obesity and delayed genital
development frequently coexist, but obesity in the vast majority of the cases
is based on nonendocrine causes (see Plate 3-18). Careful examination of most
obese boys with alleged genital underdevelopment reveals no evidence of delayed
puberty. A thorough examination of suspected micropenis that
involves retraction of the pendulous abdomen and excessive mons pubic fat most
commonly exposes a “hidden” penis and testes that are within the limits of
normal for age.
The management of most boys
with delayed puberty and persistently infantile genitalia remains watchful
waiting. Although the onset of puberty may be delayed, full genital and linear
growth usually ensues with time. Indeed, weight loss from diet management in
cases of obesity may hasten the onset of puberty.
Regular medical follow-up with anthropometric measurements can help with the
early detection of true pubertal abnormalities resulting from hypogonadism or
dwarfism. Treatment with gonadotropins or androgens may be considered when the
lack of sexual development affects other quality-of-life issues such as school
performance, athletic development, or concerns regarding socialization.
