231- A 15-year-old boy presented with delayed puberty. His height was 156 cm (at
3 rd percentile, with target height of 173 cm, 25th percentile) and he had a tes-
ticular volume of 2 ml bilaterally, pubic hair Tanner stage P 2 , and no axillary
hair. Systemic examination was normal. His bone age was 11 years, and rou-
tine investigations, thyroid function tests, and celiac serology were normal.
His LH was 0.1 μIU/ml and testosterone was 0.3 nmol/L. What is the
diagnosis?
The differential diagnosis in this scenario includes CDGP and isolated hypo-
gonadotropic hypogonadism, and it is difficult to differentiate between these
two disorders either clinically or biochemically. However, on prospective
follow- up, if the child does not enter into puberty by the age of 18 years, the
diagnosis of isolated hypogonadotropic hypogonadism is almost certain. The
cutoff of 18 years is based on the fact that 97.5 % of normal children com-
plete their pubertal development (B 2 to menarche in girls and G 2 to G 5 in
boys) within 5 years after the onset of puberty (i.e., thelarche 8–13 years,
testicular enlargement 9–14 years). The probability of CDGP is more likely
in the index patient as he is short and his father had a history of delayed
puberty. Further, triptorelin stimulation test was performed to differentiate
between CDGP and IHH, and LH response of 16 mIU/ml was observed
which excluded IHH. - What is CDGP?
CDGP is a normal variant of growth and puberty which is characterized by a
decline in growth velocity between 2 and 3 years of age, followed by normal
height velocity during prepubertal period (along the third percentile) and
delayed but spontaneous pubertal growth and development before the age of
18 years. It is accompanied by delay in skeletal maturation (BA < CA); how-
ever, the bone age correlates with height age. CDGP is the most common cause
of delayed puberty and is more common in boys. A family history of delayed
puberty is present in 50–80 % of these individuals. The final adult height is usu-
ally within the target height range and fertility is normal. The exact cause for
initial decline in height velocity and delay in onset of puberty remains elusive,
but the possible mechanisms include transient dysfunction of GHRH–GH–
IGF1-axis and delayed reactivation of HPG-axis, respectively (“lazy pituitary
syndrome”) (Fig. 7.12).7 Delayed Puberty