Normal puberty and adolescent development — formative SAQs

SAQ 1 — Pubertal assessment and counselling (10 marks)

A 14-year-old boy is brought in because he is the smallest boy in his class and "hasn't started puberty." His father reached his final adult height at 19 years. On examination his testicular volumes are 3 mL bilaterally, his height tracks along the 3rd centile at a normal velocity, and his bone age reads two years behind his chronological age. [4] [6]

Questions

1. What is the most likely diagnosis, and give the three features of the diagnostic pattern? (4 marks) [4] [6]
2. State the normal age range for puberty onset in boys and the threshold for defining delayed puberty. (2 marks) [4]
3. Outline your management and counselling of the young person and family, including when you would refer. (4 marks) [6] [8]

Model answer

Diagnosis and pattern (4). Constitutional delay of growth and puberty — the most common cause of delayed puberty in boys (over 60 per cent). The three features are: (1) a family history of late maturation; (2) a delayed bone age that equals the height age, both behind the chronological age; and (3) a normal growth velocity with the child short for the family. [4] [6]

Normal range and threshold (2). The normal age range for puberty onset in boys is 9 to 14 years, with testicular enlargement to at least 4 mL as the first sign. Delayed puberty is defined as no testicular growth by 14 years, or a gap of more than five years from onset to completion. [4]

Management and counselling (4). Reassure the young person and family that the pattern is a recognised normal variant with a normal final adult height for the family. Explain the sequence of male puberty and that he will enter it later. Monitor height, weight and pubertal stage every 6 to 12 months, re-plotting the trajectory, until puberty begins and progresses. Address the psychosocial impact (bullying, withdrawal, sport and identity) and involve a psychologist or school if needed. For significant distress, discuss a short low-dose testosterone course with endocrine input. Refer to paediatric endocrinology if there is no testicular growth by 14 years, if growth velocity falls, or if any red flag appears. [6] [8]

SAQ 2 — Recognising the abnormal (10 marks)

A 7-year-old girl is referred with progressive breast development over 4 months, a height velocity of 9 cm per year, and a bone age advanced by 3 years. Separately, you review a 13-year-old girl with no breast development at all. [3] [5] [4]

Questions

1. For the 7-year-old: what is the likely diagnosis, what first-line investigations are indicated, and what neuroimaging principle applies? (5 marks) [3] [5]
2. For the 13-year-old: what is the threshold for defining delayed puberty in girls, and outline your initial assessment and first-line investigations. (5 marks) [4] [6]

Model answer

Case 1 — precocious puberty (5). The likely diagnosis is central precocious puberty (signs before 8 years in girls with progressive development, accelerated growth and a markedly advanced bone age). First-line investigations: bone age (already advanced), basal LH and FSH with oestradiol, and a GnRH- or agonist-stimulation test to confirm a pubertal LH response. Neuroimaging principle: all boys with central precocious puberty warrant brain MRI because of a higher yield of central nervous system causes; girls under 6 years, and any child with neurological signs, also warrant MRI. Girls between 6 and 8 years with isolated, slowly progressive central precocious puberty may be managed without immediate imaging, but this girl's rapid progression warrants full evaluation. [3] [5]

Case 2 — delayed puberty (5). The threshold for delayed puberty in girls is no breast development by 13 years (or more than five years from onset to completion). Initial assessment: a focused puberty history (onset, sequence, tempo, family timing, growth, general health, neurological symptoms), Tanner staging with palpation to distinguish true thelarche, height and weight with height velocity plotted on a growth chart, and a targeted examination for chronic disease and red flags (visual fields, skin, thyroid, anosmia). First-line investigations: bone age and basal gonadotropins (LH, FSH) with oestradiol, plus screening for chronic disease (full blood count, coeliac serology, thyroid function, inflammatory markers, renal function). Refer to paediatric endocrinology. [4] [6]