Paediatrics: Growth, Endocrine + Development

Question 1

In whom is delayed puberty more common?

Answer 1

Males

Question 2

What is the definition of delayed puberty?

Answer 2

Delayed activation and progression of pubertal development > +2SD of the average age of onset (females > 14; males > 16)

Question 3

What are the 2 main categories of precocious puberty? What are the key causes for both?

Answer 3

Central PP - due to early activation of the pituitary-gonadal axis –> early puberty

1. Idiopathic
2. Intracranial pituitary tumour
3. CNS lesion in hydrocephalus

Peripheral PP - due to end/exogenous source of androgens (sex steroids)

1. gonadal cause - testicular or ovarian tumour/cyst or McCune albright synd
2. adrenal cause - CAH, adrenal tumour

Question 4

In whom is precocious puberty more worrying? males or females? What are the features of each?

Answer 4

Males

Male CP (usually onset at <9yo)

• B/L enlarged testis - suggest central PP
• U/L enlarged testis - gonadal tumour (peripheral)
• small testis - suggests adrenal cause e.g. CAH (peripheral)
• Premature pubarche

Female CP (usually onset < 8yo)

• Virilisation (male appearance of genetalia) suggests adrenal cause (peripheral)
• premature thelarche
• premature pubarche

Question 5

What is the treatment for central and peripheral PP?

Answer 5

Central = GnRH will suppress the adrenal-pituitary gonadal axis

Peripheral = androgen antagonists

Question 6

What is the main cause of ambiguous genatalia?

Answer 6

Congenital adrenal hyperplasia (CAH) typically a 21-hydroxylase enzyme deficiency (90%)

Question 7

What are the effects of 21-HED (CAH)? Explain mechanism?

Answer 7

Ambiguous genatlia

deficiency in cortisol + aldosterone –> reduced Na+ reabsorption, increased K+ retention, decreased ACTH –> Increased adrenal hyperplasia –> adrenal crisis

Males - pigmented scrotum, enlarged penis
Females - virilisation, variable fusion of labia, clitoromegaly

Question 8

what are the key investigative finding of 21HED (CAH) caused ambiguous genatalia?

Answer 8

1. Low Na+, High K+
2. 17a-hydroxyprogesterone
3. Metabolic acidosis
4. Hypoglycaemia

Question 9

What is the treatment for 21-HED ambiguous genatlia?

Answer 9

1. Life long glucocorticoids (prednisolone)

2. Corrective surgery before sexual intercourse

Question 10

What is the main cause of congenital hypothyroidism

Answer 10

Thyroid dysgenesis (85%) –> low TH + TSH secretion –> thyroid aplasia/hyplasia or ectopics

Question 11

What are the key features (symptoms, signs) of congenital hypothyroidism?

Answer 11

Typically non-specific combination of:

1. Umbilical hernia
2. Prolonged jaundice
3. Constipation
4. Dry skin
5. Hoarse cry
6. Hypotonia
7. Coarse faeces
8. Poor feeding
9. Excessive sleeping

Question 12

What is the treatment of congenital hypothyroidism?

Answer 12

Levothyroxine

Question 13

What is phenylketonuria?

Answer 13

A deficiency in phenylalanine hydroxylase –> inability to breakdown phenylalanine –> accumulation –> characterised by delayed brain development –> mental retardation + seizures

Question 14

What is the investigative diagnosis and findings for phenylketonuria?

Answer 14

Guthrie card (1 week of life) diagnosis disease

Urinalysis shows ketones (due to phenylalanine accumulation breaking down to phenylketones in urine)

Question 15

What is the treatment of phenylketonuria?

Answer 15

Dietary control

1. Avoid foods high in protein (meat, eggs, fish, peanuts etc)
   - adherence reduces risk of mental retardation + seizures

Question 16

What are the symptoms and signs of phenylketonuria?

Answer 16

1. Musty odour
2. Blonde hair blue eyes
3. Eczema

Late - seizures, mental retardation