Thyroid

Question 1

Congenital hypothyroidism

Answer 1

> 95% asymptomatic

85% is sporadic, usually thyroid dysgenesis (aplasia, hypoplasia, ectopy)

Most preventable cause of potential intellectual disability

Poor feeding
Jaundice
Constipation
Hypotonia
Hoarse cry
Large tongue (macroglossia)
Umbilical hernia
Large ant. Fontanelle

Question 2

Newborn screening for hypothyroidism

Answer 2

Total T4

If fail, repeat it. Start levothyroxine while awaiting results. Prevents ID, clumsiness, fine motor issues.

If fail again, get TSH and free T4

Can’t give levothyroxine with SOY formula (reduces absorption of T4)

Question 3

Teenager on levothyroxine

Answer 3

If lab results inconsistent with treatment think poor compliance

Get TSH and free T4 before adjusting dose

Question 4

Thyroxine binding globulin (TBG) deficiency

Answer 4

Low total T4 on newborn screen

Normal Free T4 (the metabolically active hormone that matters)
Normal TSH

Euthyroid
No Tx needed

Confirm Dx with aTBG level (low)

Question 5

Hashimoto thyroiditis

Answer 5

Most common cause of new hypothyroidism in childhood and of goiter in adolescence

Aka chronic lymphocytic thyroiditis

Autoimmune, more common in female
-Ab to thyroid tissue with lymphocytic infiltration.
-elevated TSH
– T4 can be normal if hypothyroidism is compensated
+anti-thyroglobulin
+anti-thyroid peroxidase
Low-normal radioactive iodine uptake

Common in chromosomal disorders

• Down
• Turner
• Klinefelter

Question 6

Clinical picture of Hashimoto thyroiditis

Answer 6

Kid who is like ADHD all of a sudden

Most are asymptomatic tho, just have a goiter
-if asymptomatic u need to check TSH regularly

Some present as Hashitoxicosis (thyrotoxicosis, hyperthyroidism)

Question 7

Hashimoto thyroiditis treatment

Answer 7

Lifelong levothyroxine

Question 8

Graves disease

Answer 8

Thyroid-stimulating immunoglobulin (IgG)

+radioactive iodine uptake

Bulging eyes (infiltrative ophthalmopathy)
Weight loss 
sleep disturbance 
emotional lability 
heat intolerance 
lid lag 
increased appetite
decreased muscle strength/endurance decreased school performance/hyperactivity itching
tremors
sweating
increase urination at night 
decreased menstrual flow 
decrease frequency of menses

Question 9

Graves disease treatment

Answer 9

Methimazole

-blocks organification of iodide to decrease thyroid hormone synthesis

Question 10

Neonatal thyrotoxicosis

Answer 10

Mom with graves
Ab pass the placenta 
In utero tachycardia, high output
Newborn is tachycardic, tremors, irritable right away! Unlike IEM 
FTT, feeding issues, hyperbili 

Labs: high free T4, low TSH
Need an immediate post-birth thyroid level because of risk of cardiac arrhythmia

Tx: methimazole until mom’s Ab cleared

Question 11

Thyroid nodule

Answer 11

Likely to be malignant in an adolescent compared to an adult

NEED to do FNA
-could do US first if <1 cm, soft, mobile, regular border

History of ionizing radiation
NOT UV radiation