Paediatrics - Growth, puberty, endocrine (2) Flashcards
What is the definition of short stature?
Height below the second centile (ie. two standard deviations below the mean)
Height velocity is a sensitive indicator of what?
Growth failure
How is height velocity calculated?
2 measurements at least 6 months but preferably a year apart = cm/year
A height velocity of consistently below what centile is abnormal?
25th
How is a child’s genetic target centile for height calculated?
Mean of father and mothers height + 7cm for boy and -7cm for girl.
The 9th-91st centile range of this estimate is given by +- 10cm for boys and +-8.5cm for girls
What percentage of children born with severe IUGR remain short?
33%
Give 6 causes of short stature in children
- Familial short stature or constitutional delay of growth and puberty
- IUGR
- Endocrine
- Nutritional/ chronic illness
- Psychosocial deprivation
- Chromosomal disorder/syndromes
Give 3 endocrine causes of short stature in children
- Hypothyroidism (autoimmune thyroiditis during childhood)
- Growth hormone deficiency (can be secondary to hypopituitarism)
- Corticosteroid excess (Cushing’s syndrome)
Where is IGF-1 produced?
Growth plate and in the liver
Give two causes of growth hormone deficiency
- Craniopharyngioma
2. Laron syndrome
How does a craniopharyngioma often present?
Bitemporal hemianopia
What is Laron syndrome?
Defective growth hormone receptors = high levels of growth hormone and low levels of IGF-1.
Give 3 examples of chronic illnesses that may result in short stature?
- Coeliac disease
- Crohn’s disease
- Chronic renal failure
Give 4 examples of syndromes in which short-stature is seen.
- Down’s syndrome
- Turner’s syndrome
- Noonan syndrome
- Russell-Silver syndrome
Deficiency of which gene on the X chromosome is thought to be linked to short stature and skeletal abnormality
SHOX
How is growth hormone deficiency treated?
Biosynthetic growth hormone, given by subcutaneous injection daily
Give two examples of syndromes or scenarios in which administering daily growth hormone is a treatment.
- Prader-Willi syndrome - improves muscle strength and body composition
- Turner’s syndrome -
- Chronic renal failure
- SHOX deficiency
- IUGR
How do you calculate the ideal weight of children based upon their age?
(age+4) x 2 = weight (kg)
Give the type of fluid that is typically prescribed to older children
0.9%NaCl + 5% glucose +-KCl
Give the fluid requirements per kg for the first four days of life (per day)
Day 1 = 60ml/kg/day
Day 2 = 90ml/kg/day
Day 3 = 120ml/kg/day
Day 4 = 150ml/kg/day
Give the electrolyte requirements per day of sodium, potassium and calcium in neonates
Na = 3mmol/kg/day K = 2mmol/kg/day Ca = 1mmol/kg/day
Give maintenance fluids per day
First 10 kg = 100ml/kg/day
Second 10 kg = 50ml/kg/day
Over 20kg = 20ml/kg/day
Give hourly maintenance fluids
First 10kg = 4ml/kg/hour
Second 10kg = 2ml/kg/hour
Over 20kg = 1ml/kg/hour
Give 5 signs of a dehydrated infant
- Depressed fontanelle
- Cap refill 2-3 s
- Alert/tired
- Reduced urine output
- Dry lips/mucous membranes
How much extra fluid would you give on top of maintenance in a child that was clinically dehydrated? and over how long would you give it?
50ml/kg over 4 hours
How much extra fluid would you give on top of maintenance in a child that was shocked?
100ml/kg + BOLUS
What is the fluid bolus you’d give to a shocked child?
20ml/kg 0.9% NaCl
In what two cases would you not give a 20ml/kg 0.9%NaCl bolus to a shocked child and what would you give instead?
- Trauma
- Diabetic ketoacidosis
Instead give 10
What are the sodium requirements of an older child?
First 10kg - 2-4mmol/kg/day
Second 10kg 1-2mmol/kg/day
Every kg after 20 0.5-1mmol/kg/day
What are the potassium requirements of an older child?
First 10kg 1.5-2.5
Second 10kg 0.5-1.5
Every kg after that 0.2-0.7
Why is a 20ml/kg bolus in a child with diabetic ketoacidosis avoided?
Causes cerebral oedema
Preterm infants may have very low levels of what for the first few weeks of life?
T4 (thyroxine)
What endocrine problem is one of the few preventable causes of severe learning difficulties ?
Congenital hypothyroidism
Give four causes of congenital hypothyroidism
- Maldescent of the thyroid and athyrosis
- Dyshormonogenesis
- Iodine deficiency
- Hypothyroidism due to TSH deficiency
What is the commonest cause of sporadic congenital hypothyroidism?
Maldescent of the thyroid and athyrosis
Where does the thyroid migrate from in fetal life?
The base on the tongue (sublingual)
What cause of congenital hypothyroidism is the most common in ethnic groups with consanguineous marriage?
Dyshormonogenesis (an inborn error of thyroid hormone synthesis)
What is the commonest cause of congenital hypothyroidism worldwide? (But rare in UK?)
Iodine deficiency
How is congenital hypothyroidism caused by iodine deficiency prevented?
By iodination of salt in the diet
Give 5 clinical features of congenital hypothyroidism
- FTT
- Feeding probs
- Prolonged jaundice
- Constipation
- Pale, cold, mottled dry skin
- Large tongue
- Goitre
- Umbilical hernia
- Delayed development
(LARGELY ASYMPTOMATIC AND PICKED UP ON SCREENING)
Give 5 clinical features of acquired hypothyroidism
- Short stature or growth failure
- Cold intolerance (cold peripheries)
- Dry skin
- Bradycardia
- Thin, dry hair
- Goitre
- Constipation
- Delayed puberty
- Obesity
- SUFE
- Deterioration in school work/learning difficulties
Why is hypothyroidism due to TSH deficiency rare?
Usually associated with panhypopituitarism which usually manifests with growth hormone, gonadotrophine and ACTH deficiency leading to hypoglycaemia/ micropenis/ undescended testes before the hypothyroidism becomes a problem
What is the term used for the test which detects congenital hypothyroidism?
Guthrie test (routine neonatal screening), detects increased TSH in the blood
How is congenital hypothyroidism managed?
Treatment with thyroxine is started at 2-3 weeks of age and extends lifelong
What kind of congenital hypothyroidism will not be picked up by routine screening (Guthrie test)?
Thyroid disfunction secondary to pituitary abnormality because they will have a low TSH
What is the cause of juvenile hypothyroidism?
Autoimmune thyroiditis
What children are at an increased risk of juvenile hypothyroidism?
Children with Down’s or Turner’s
Give examples of other autoimmune illnesses seen in children with juvenile hypothyroidism
- Vitiligo
- RA
- Diabetes mellitus
- Addisons disease
Which gender is juvenile hypothyroidism more common in ?
Females
How is juvenile hypothyroidism treated?
Thyroxine
What is the most common cause of hyperthyroidism in children?
Graves disease (autoimmune thyroiditis) secondary to the production of thyroid stimulating immunoglobulins (TSI)
Give some clinical features of hyperthyroidism in children?
- Increased appetite
- Sweating
- Diarrhoea
- Weight loss
- Rapid growth
- Advanced bone marturity
- Tachycardia, tremor, warm vasodilated peripheries
- Learning difficulties/behaviour problems
- Psychosis
What symptoms of hyperthyroidism commonly seen in adults are not generally seen in children?
Eye symptoms e.g. exopthalmos, opthalmoplegia, lid retraction, lid lag
What type of patient is hyperthyroidism commonly seen in?
Teenage girls
What markers are elevated or reduced in hyperthyroidism?
T3 and T4 elevated
TSH low
Antithyroid perioxisomal antibodies can be present but may cause hashitoxicosis (hypothyroidism)
What is the first line treatment of hyperthyroidism?
Carbimazole for 2 years
B-blockers for symptomatic relief of tremor and anxiety and tachycardia
What is the risk with anti-thyroid medication?
Neutropenia
What advice should be given to parents of children starting anti-thyroid medication?
Seek help if sore throat and high fever occur starting treatment
What is the treatment of relapsed hyperthyroidism?
Subtotal thyroidectomy (or radioiodine treatment) and thyroxine replacement
What is the function of PTH?
Promotes bone formation via osteoblasts
When calcium low:
- Promotes bone resorption via osteoclasts
- Increases renal uptake of calcium
- Activates metabolism of vit D to promote gut absorption of calcium
What are the electrolyte balances in hypoparathyroidism?
Low serum calcium
Raised serum phosphate
Normal alk phos
PTH low
Give a cause of hypocalcaemia in children
Hypoparathyroidism