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.