9- Paediatric Endocrinology (2/2) Flashcards
hypothyroidism background
- Can be:
o Congenital
o Acquired - Thyroid hormones are essential for development and functioning of the brain and body
o Undiagnosed: neurodevelopment and intellectual disability - Used to be known as cretinism
pathophysiology of congenital hypothyroidism
Where child is born with underactive thyroid gland
- 1 in 3000
Cause:
- Underdevelopment of gland (agenesis) or fully developed gland which doesn’t produce enough hormone (dysgenesis) - primary
- Iodine deficiency
- Rarely a problem with pituitary (secondary) or hypothalamus (tertiary)
RF
- Female
- Down syndrome
Diagnosis: Newborn blood spot screening test (day Presentation
- Prolonged neonatal jaundice
- Poor feeding
- Constipation
- Abdominal swelling
- Umbilical hernia
- Enlarged protruding tongue
- Increased sleeping
- Reduced activity
- Slow growth and development
- Developmental delay/ learning difficulties
Acquired hypothyroidism
Acquired hypothyroidism is where a child or adolescent develops an underactive thyroid gland when previously it was functioning normally
Cause
- Autoimmune thyroiditis (Hashimoto’s)
- Associated with anti-TPO antibodies and antithyroglobulin antibodies
- Associated with type 1 diabetes and coeliac disease
- Iodine deficiency in infancy
Presentation
- Fatigue and low energy
- Poor growth
- Weight gain
- Poor school performance
- Constipation
- Dry skin and hair loss
Investigations
- TFTs (TSH freeT4)
- Thyroid US
- Thyroid antibodies
thyroid hormonal axis
- The hypothalamus secretes Thyrotropin Releasing Hormone (TRH) which stimulates the anterior pituitary gland to release Thyroid Stimulating Hormone (TSH).
- TSH then binds to the TSH receptor (TSH-R) on the thyroid gland, stimulating the release of thyroid hormones T4 (thyroxine) and T3 (tri-iodothyronine) from the thyroid gland.
- To control the levels of circulating thyroid hormones, negative feedback is exerted by T4 and T3 onto the pituitary and hypothalamus, thus reducing the secretion of TRH and TSH.
managment of hypothyroidism
Management – DIAGNOSE AS EARLY AS POSSSIBLE
- If preterm will need new born screening repeat at 28 days of life
- Screen for congenital heart problems
- Levothyroxine taken once a day orally (start within 2 weeks of burtg)
- Doses titrated based on TFT
Hyperthyroidism
Background
- Hyperthyroidism: excess production and secretion of thyroid hormones by the thyroid gland.
- Thyrotoxicosis: the clinical manifestation of excess circulating thyroid hormones caused by hyperthyroidism or other causes (e.g. increased release of stored hormones from thyroiditis)
- Relatively uncommon in children
- Neonatal thyrotoxicosis affects 1-2% of babies born to mothers with autoimmune hyperthyroidism e.g. graves
Risk factors hyperthyroidism
- Girls
- Increases with age
- Family history
- Increased iodine intake
- Smoking
Pathophysiology of hyperthyroidism
- Primary hyperthyroidism- problem with thyroid gland
- Secondary- problem with pituitary gland
Specific causes
- Autoimmune e.g. Graves disease -> TSH receptor antibodies which mimic TSH
- Toxic multinodular goitre
- Thyroids cancer
- Neonatal hyperthyroidism
- Functioning pituitary adenoma
investigations of for hyperthyroidism
Examination
- Remember thyroid moves with swallowing
Blood tests
- TSH and free T4
- Free T3 too with hyper
- TPO antibodies
Neonatal thyrotoxicosis: if mother has Graves disease the baby will have TFTs done between day 5-14 to check their thyroid levels
Imaging
- US
- Radionuclide thyroid scan
Presentation
Symptoms of hyperthyroidism
- Weight loss / failure to thrive
- Increased appetite
- Rapid growth in height
- Sweating
- Heat intolerance
- Fatigue
- Anxiety, restlessness, irritability
- Diarrhoea
- Palpitations
- Warm, vasodilated peripheries
- Dyspnoea
- Insomnia
- Learning difficulties, behavioural problems, decreased concentration
- Deteriorating school performance
- Psychosis
- Delayed or accelerated puberty; oligo or amenorrhoea
presentation
signs of hyperthryoidism
- Goitre (bruit) that will move on swallowing but not on tongue protrusion (Figure 3)
- Fine tremor
- Hyperreflexia
- Moist, warm skin
- Tachycardia (rarely SVT), wide pulse pressure
- Proximal muscle wasting
- Hair loss
- Signs of thyroid eye disease – exophthalmos, ophthalmoplegia, lid retraction, lid lag (can cause dry eyes)
- Pretibial myxoedema – indicative of Graves’ disease
initial management of graves
Anti-thyroid drugs e.g. Carbimazole or propylthiouracil
- 2 methods of ATD admin
1) Titration
2) Block and replace i.e. completely suppress thyroid and replace with thyroxine
- Side effects:rashes, nausea, headache, agranulocytosis, hepatitis
Symptom relief: propranolol
Thyroid eye- ophthalmologist
management of neonatal hyperthyroidism
self-limiting within 1-3 months
management of transient thyroidtoxicosis
without hyperthyroidism (only need supportive management with beta-blockers)
definitive management of hyperthyroidism
1) radioiodine therapy
2) surgery
Radioiodine therapy
- Given as a tablet or drink
- Iodine taken up by thyroid gland and radiation kills the cells- need to avoid school due to radiation risk for a few weeks
- Will require lifelong levothyroxine
- Not recommend ed <6 or those with uncontrolled disease
surgery for hyperthyroidism
- Total thyroidectomy
- Will need lifelong levothyroxine
- Good for very young children, goitre, nodule, poorly controlled hyperthyroidism
- Damage to parathyroid or recurrent laryngeal nerves causing hoarseness