PITUITARY ANTERIOR
LOBE DEFICIENCY
IN CHILDHOOD AND ADOLESCENCE IN BOYS
The most common deficient hormones in children and adolescents with anterior pituitary failure are the gonadotropins, luteinizing hormone (LH), and follicle-stimulating hormone (FSH). Gonadotropin deficiency may occur in isolation or in concert with other anterior pituitary hormone deficiencies. In the absence of gonadotropins in boys, puberty is delayed, and secondary sex characteristics do not develop (see Plate 4-7). The penis and prostate gland remain small, and the scrotum fails to develop rugae; the larynx fails to enlarge, and the voice maintains the high pitch of childhood. Some pubic hair appears, but it is usually sparse and fine. Axillary hair either does not appear or is sparse. Beard growth is absent.
Lack of androgens leads to prolonged
persistence of open epiphysial plates and in the presence of intact growth
hormone (GH) and insulin like growth factor 1 linear
growth continues for longer than normal. The linear growth is particularly
prominent in the extremities, and the arms and legs become disproportionately
long. Eunuchoid proportions develop; lower body length (from the soles of the
feet to the pubis) exceeds upper body length (from the pubis to the top of the
cranium). In addition, the arm span exceeds the standing height (normally,
these dimensions should be equal). Eventually, the epiphyses close in the third
decade of life, even in untreated eunuchoid men. Administration of testosterone
leads to prompt epiphysial closure. Excessive linear growth is not seen in
adults with anterior pituitary deficiency after epiphysial closure.
The presentation of secondary
hypogonadism in adolescence may be affected by the presence or absence of other
anterior pituitary hormone deficiencies. If GH is also deficient in childhood,
short stature is evident. Short stature occurs when a child is 2 standard
deviations or more below the mean height for children of that gender and
chronologic age typically below the third percentile for height. The three
phases of growth are infantile, childhood, and pubertal. Infantile growth is a
rapid but decelerating growth pattern during the first 2 years of life with an
average growth of 30 cm. A statistically significant and positive correlation
exists between the height at age 2 years and final adult height. The childhood
growth phase progresses at a relatively constant velocity of 5 to 7 cm per
year. The pubertal growth phase refers to the growth spurt of 8 to 14 cm per
year that occurs during puberty. The most common causes of short stature are
genetic short stature and delayed growth. In addition to GH deficiency, the disorders that are most often associated with short stature are renal disease, cancer (and its treatment),
glucocorticoid therapy, pulmonary diseases (e.g., cystic fibrosis), cardiac
disorders (e.g., congenital heart disease), gastrointestinal disorders (e.g.,
celiac disease, inflammatory bowel disease), poorly controlled diabetes
mellitus, vitamin D deficiency, hypothyroidism, and Cushing syndrome.
Additional anterior pituitary
hormone deficiencies may contribute to the clinical presentation. For example, corticotropin deficiency may cause signs
and symptoms of postural hypotension, tachycardia, fatigue, anorexia, weight
loss, hyponatremia, and hypoglycemia. Thyrotropin deficiency may contribute
signs and symptoms of fatigue, cold intolerance, constipation, facial puffiness
with periorbital edema, dry skin, bradycardia, and delayed relaxation phase of
the deep tendon reflexes.
