There are few things more socially difficult for a teenager than being significantly behind their peers in physical development. At an age when peer comparison is intense and physical maturity carries social meaning, being the smallest in the year group, the last to develop, or the one who still looks much younger than their friends creates real psychological difficulty – even when the underlying cause is entirely benign.
Most children who are late to start puberty fall into the category of constitutional delay of growth and puberty: they are normal, just late, and will catch up. Knowing this – and having a doctor who explains it clearly and takes the social and psychological impact seriously – makes a significant difference to how the young person and family navigate the waiting.
Healthbooq (healthbooq.com/apps/healthbooq-kids) covers growth and puberty in children and teenagers.
Defining Delayed Puberty
Puberty is considered delayed when pubertal development has not begun by an age at least two standard deviations later than the population average. In practice this means: in girls, no breast development (thelarche) by age 13; and in boys, testicular volume below 4ml (Tanner Stage 1) by age 14. These thresholds are population-based and are influenced by ethnicity, geography, and secular trends in pubertal timing.
The normal timing of puberty has shifted earlier over the past century – a trend that continues in many populations and has been documented by Marcia Herman-Giddens at the University of North Carolina and colleagues. This means that what was once considered early puberty is now within the normal range, and the upper end of the normal range for delayed puberty has not correspondingly shifted.
Causes
The causes of delayed puberty divide broadly into three categories.
Constitutional delay of growth and puberty (CDGP) is by far the most common cause overall, accounting for around 60% of cases in boys (the proportion is lower in girls presenting with delayed puberty). CDGP is a normal variant: the hypothalamic-pituitary-gonadal axis activates later than average, puberty eventually occurs normally, and adult height and fertility are normal. A family history of late puberty (a father who was a late developer, a mother with late menarche) is often present and is clinically reassuring. The bone age is typically delayed – younger than chronological age on wrist X-ray – which indicates the child still has growth potential.
Functional hypogonadotropic hypogonadism is caused by a systemic condition suppressing the hypothalamic-pituitary-gonadal axis. The most common cause is poor nutrition or low body weight – extreme leanness, underweight relative to height, or an eating disorder. Other causes include chronic illness (particularly inflammatory bowel disease, coeliac disease, chronic kidney disease), excessive athletic training (especially in female athletes, where the triad of low energy availability, menstrual dysfunction, and low bone density is well recognised), hyperprolactinaemia, hypothyroidism, and other chronic conditions. Treating the underlying condition typically restores pubertal progression.
Hypogonadism (true gonadal or hypothalamic-pituitary failure) is less common. Primary hypogonadism refers to gonadal failure – the gonads themselves are not functioning (due to Turner syndrome in girls, Klinefelter syndrome in boys, or other causes including radiation or chemotherapy damage). Secondary (central) hypogonadism refers to failure at the hypothalamic or pituitary level – including Kallmann syndrome (isolated gonadotropin deficiency associated with anosmia, described by Franz Josef Kallmann in the 1940s), panhypopituitarism, tumours affecting the hypothalamus or pituitary, and congenital abnormalities.
Assessment
A child presenting with delayed puberty requires a careful history (growth pattern, family history of pubertal timing, nutrition, exercise, any systemic symptoms, anosmia), examination (height, weight, BMI, Tanner staging, anosmia testing), and investigations including: LH, FSH, oestradiol or testosterone, thyroid function, prolactin, full blood count, inflammatory markers, coeliac antibodies, and a bone age X-ray. Karyotype is indicated where Turner (45,X or mosaic) or Klinefelter (47,XXY) syndrome is suspected.
MRI of the pituitary and hypothalamus is indicated where central causes are suspected.
Management
CDGP: reassurance, monitoring, and expectant management. Most paediatricians will monitor over 6-month intervals with growth measurements and Tanner staging to confirm progression. For boys with significant psychological distress related to their delayed development, a short course of low-dose testosterone (typically 3-6 months of intramuscular or transdermal testosterone) can initiate pubertal development without significantly compromising adult height. This is an option for boys from around 14 years of age with confirmed CDGP who are experiencing real social or psychological difficulty. For girls with CDGP, very low-dose oestrogen can be considered, though this is less commonly used.
Hypogonadism requiring replacement: sex steroid replacement therapy (testosterone in boys, oestrogen-progesterone in girls) at physiological doses titrated over time to replicate the gradual progression of normal puberty. In girls, oestrogen is commenced at low doses and gradually increased; progesterone is added once breakthrough bleeding occurs. This is managed by a paediatric endocrinologist and requires long-term monitoring.
Functional hypogonadism: treat the underlying cause.
Psychological Impact
The psychological impact of delayed puberty – particularly in boys who have the most visibility of their delayed development relative to peers – is substantial. David Ladd and colleagues at Boston Children's Hospital have documented associations between pubertal delay and poorer self-esteem, increased rates of depression and anxiety, social difficulties, and teasing. The decision about when to intervene pharmacologically should take this impact into account alongside the medical picture.
Key Takeaways
Delayed puberty is defined as the absence of pubertal development by an age two standard deviations later than the population mean – typically, no breast development by age 13 in girls, or testicular volume less than 4ml by age 14 in boys. The most common cause, accounting for around 60% of cases in boys, is constitutional delay of growth and puberty (CDGP) – a normal variant in which puberty is simply late, with no underlying pathology. Other causes include hypogonadism (primary, from the gonads themselves, or secondary, from the pituitary or hypothalamus) and systemic conditions including undernutrition, coeliac disease, inflammatory bowel disease, and other chronic illnesses. Most children with CDGP do not require treatment; those with more significant delay may be offered short courses of low-dose sex steroids.
