• Girls:
o Sequence: thelarche (breast development) → pubarche (pubic/axillary hair) → menarche
• Boys:
o Sequence: testicular enlargement → pubarche
• Normal onset:
o Girls: 8–13 years
o Boys: 9–14 years
• Girls: no breast development by age 13 or no menarche by 15
• Boys: no testicular enlargement by age 14
• Most common cause: constitutional delay
• Must exclude hypogonadism:
o Hypergonadotropic: e.g. Turner’s (45,XO), Klinefelter’s (47,XXY)
o Hypogonadotropic: e.g. Kallmann syndrome, chronic illness, pituitary disease
• Investigation: FSH/LH, oestradiol/testosterone, bone age, MRI if central cause suspected
• Girls: <8 years; Boys: <9 years
• Central (GnRH-dependent):
o Early activation of HPG axis
o Causes: idiopathic (common in girls), CNS lesions (boys), hypothalamic hamartoma
• Peripheral (GnRH-independent):
o Causes: adrenal tumours, CAH, exogenous sex steroids, McCune–Albright syndrome
• Diagnosis: LH/FSH, bone age, GnRH stimulation test, imaging if central cause suspected
• Treatment: GnRH analogues (central), address underlying cause (peripheral)
• Defined as height <2 SD below the mean for age and sex
• Causes:
o Normal variants: familial short stature, constitutional delay
o Pathological:
GH deficiency (congenital or acquired)
Turner’s syndrome (females with XO karyotype – short stature, webbed neck, shield chest)
Chronic illness, hypothyroidism, skeletal dysplasia
• Investigation: growth chart, bone age, IGF-1, karyotype (girls), MRI (if GH deficiency suspected)
• Common endocrine disorder in women of reproductive age
• Features: hirsutism, irregular menstruation, acne, obesity, subfertility
• Rotterdam criteria (any 2 of 3):
o Oligo-/anovulation
o Clinical/biochemical hyperandrogenism
o Polycystic ovaries on ultrasound
• Hormonal profile: ↑ LH:FSH ratio, ↑ androgens, insulin resistance
• Management:
o Lifestyle: weight loss improves ovulation
o COCP: regulates cycle, reduces hirsutism
o Metformin: improves insulin sensitivity
o Anti-androgens (e.g. spironolactone) if needed
• Congenital conditions with discordance between chromosomal, gonadal, or phenotypic sex
• Categories:
o 46,XX DSD: usually virilisation due to CAH (↑ androgens)
o 46,XY DSD: testicular tissue but undervirilised phenotype (e.g. androgen insensitivity syndrome)
o Ovotesticular DSD: rare, both ovarian and testicular tissue
• Investigation: karyotype, hormonal panel (testosterone, DHT, 17-OHP), pelvic imaging
• Management: multidisciplinary – endocrinology, urology, psychology, genetics
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Author & Educational Disclaimer
Author:
Dr Phillip Cockrell BM FRCP DipClinEd
Dr Phillip Cockrell is a UK Consultant Physician in Internal Medicine, currently working at Queen Alexandra Hospital, Portsmouth University Hospitals NHS Trust. He has previously worked as a registrar across Intensive Care Medicine, Gastroenterology, Cardiology, Stroke Medicine, Acute Medicine, and Respiratory Medicine.
He has held senior leadership roles including Associate Clinical Director of the Acute Medical Unit, Clinical Director of Internal Medicine, and Chief of Medicine. Dr Cockrell has over 15 years’ experience in postgraduate medical education, having lectured extensively across the MRCP syllabus and contributed to MRCP revision teaching and course development.
Dr Cockrell holds a Bachelor of Medicine (BM), Fellowship of the Royal College of Physicians (FRCP), and a Diploma in Clinical Education (DipClinEd). His teaching approach is based on structured consolidation of complex medical topics to support efficient and effective revision for postgraduate examinations.
Purpose of this content:
The material on this page is intended solely for educational purposes to support revision for the MRCP (UK) Part 1 examination. It reflects examination-relevant principles of internal medicine and is designed to aid learning and pattern recognition.
Medical disclaimer:
This content is designed for postgraduate medical examination revision and does not constitute medical advice, diagnosis, or treatment guidance and must not be used as a substitute for professional clinical judgement, local guidelines, or specialist consultation. Clinical decisions should always be made in the context of individual patient circumstances and current national guidance.
