hypothyroidsm thanks to Dr Riyaz sir SAT Hospital Trivandrum kerala

1. Told by Dr. Riyaz sir

2.  First hormone disease recorded
 There is an axis called hypothalamo-- pituitary --
thyroid axis
 Hypothalamus produces the thyroid releasing
hormone
 Pituitary produces TSH
 And thyroid produces T3, T4

3.  And a part of reverse T3
 T3 is the active form
 Whatever T4 is there is converted to T3
 All the thyroid hormones have got a negative feed back
on TSH
 Whenever there is a deficiency of thyroid hormone ,
TSH will increase

4.  In new born there is a rise and fall of TSH
 That is there is an acute surge of TSH in the immediate
new born period up to 30 min
 It can be as long as 80 min
 So when we take the cord blood and do TSH
 The “call back rate “ of babies will be more
 Which causes more agony to the parents

5.  So people say that it is better to do a filter paper test at
least 48 – 72 hours after birth
 But it depends upon what is the set up we are working
on
 And any method of screening is ok
 One thing is mandatory is that we should do the
screening

6.  And we know that there is a rise in T3 and T4 in the
next 24 hours of life
 And everything gradually decline and come to normal
in the next 2 weeks
 And we know that TSH normalizes earlier than T4
 Because T4 rises a little later

7.  Any TSH > 20
 Any T4 < 6
 At anytime
 In the immediate new born period
 That is something which we have to look again
 That doesn’t mean that u have to start therapy on day 1

8.  There is no hurry of starting the treatment
 The time limit is 14 days of life
 If we start treatment within 14 days of life – the IQ
levels will be equal to normal

9.  It depends
 Mostly TSH > 40
 U can take as 30 , 35 , 40
 According to ur experience
 If less number of deliveries in ur hospitals u can keep
a lower cutoff
 If more no. u can keep a higher cutoff

10.  In SAT hospital trivandrum cut off is 20
 And keep in mind that it’s a screening program
 It is used to find serious cases
 We cannot identify 100% with screening
 Do not believe on lab normalities
 As the TSH normality is different in different age
groups

11.  Infancy T4 mean 10.5
 1—5 years 10.3
 6 – 10 years 9.3

12.  Infancy T4 normal 7.5--- 15.5
 TSH 10 in infancy up to 1 year can be taken as normal
 TSH beyond infancy up to 5 can be taken as normal

13.  In Obs and gynaec
 Tsh cut off 2.5

14.  We do TSH in public health lab trivandrum
 By ELISA technique

15.  TSH – 48.9 in new born period
 Day 21 (reported late)
 Repeat TFT
 T4 -6.2
 TSH ->60
 T3 -0.62
 Diagnosis – Congenital Hypothyroidism

16.  So the baby was examined , there was some subtle
signs of hypothyroidism like icterus
 But no gross features
 Thus the importance of screening
 Wt gain was low
 Child was actually Failing to thrive

17.  So when there is low T4 and T3
 And elevated TSH it is Congenital hypothyroidism
 It can be of 2 types
1. Permanent
2. Transient – normalizes itself

18.  Transient
 Many causes
 Transplacental transfer of antibodies
 Maternal iodine deficiency
 Excess iodine like betadine being painted on child
scalp

19. 1. Thyroid dysgenesis – more common
a. Agenesis –athyriosis
b. Hemi agensis – one lobe is not present
c. Ectopic thyroid-
d. Small dysgenetic gland
1. Thyroid dyshormonogenesis- rare
 Some enzymes are deficient , gland is normal

20.  Enzyme deficiency is never complete
 Produces a little amount of thyroxine
 So later presents

21.  So imaging is needed
 Image thyroid
 So if imaging is abnormal
 That is agenesis or dysgenesis
 Child needs life long treatment

22.  10 – 15 micrgram of thyroxine
 10 for ectopic
 Or hemi agensis
 15 for complete

23.  If imaging is normal
 It is transient or dyshormonogenesis
 That child is worth stopping thyroxin trial a 3 years
 For 4 weeks
 And do TFT

24.  But USG can be misleading too
 Better with Tc scan 99
 Ideally do Iodine 123 with a per chlorate discharge to
know the uptake

25.  High TSH 12.6 at day 6
 T4 = normal
 No need to start as
 Compensated hypothyroidism /
 Sub clinical hypothyroidism is not a problem in
child(unlike in adult)
 In adults subclinical hypo can cause cardiac side effects
 Keep him under follow up…when repeated it was normal
 Baby escaped unnecessary thyroxine

26.  Thyroid is not that much safe too
 It can cause accelerated bone growth
 Will have closed AF early
 And definitely affects total height and weight


27.  If it is a low T4 and normal TSH ?????
 Think about a condition called
 Congenital TBG deficiency

28.  Before starting thyroxine to any child
 U have to do atleast one free T4 value
 Which will be normal in TBG deficiency
 TSH and fT4 will be normal
 And only T4 will be low in this condition

29.  Congenital TBG deficiency needs no treatment
 As the child is euthyroid

30.  Another problem is transient hypothyroxinemia of
new born
 In low birth weight and pre term baby
 As they are keeping the metabolism at a lower rate
 So we need not give thyroxin
 Only thing that u repeat it 2 – 3 weeks

31.  Always keep in mind another condition
 Central hypothyroidism
 Though rare it is there
 TSH – 0.2
 Thought as normal
 But it is low …

32.  Low t4
 And
 Delayed elevation of TSH
 In low birth weight and pre term

33.  So in such cases we cannot identify them if we use
TSH as the screening test
 So repeat screening should be done in preterm and
low birth weight babies if possible

34.  Only 10 % of hypothyroidism can be identified
clinically by 1 month
 At 2 months we can clinically diagnose – 30%
 So we miss huge junk if clinically only
 Start within 2 weeks

35.  1cm growth with Growth Hormone
– costs 10 000
 1 cm growth with thyroxin costs 35

36.  Give it by crushing with mothers milk
 In the early morning
 Non compliance is common

37.  Do not give iron , calcium or soya along with the
thyroid tab
 Repeat T4 and TSH after 4 weeks
 T4 normalizes at 2 weeks and TSH at 4 weeks
 Non compliance is the most common cause for
persistent elevation of TSH


38.  Every 2 months till 6 months
 Every 4 months till 6months to 3 years
 Every 6 months till end of growth
 Hearing evaluation should be done in all cases of
hypothyroidism as there is an entity called pendred
syndrome

39.  Actually no
 Better do only free T4 and TSH
 As all of T4 will be converted to T3
 One clause is that in early phase of hypothyroidism T3
will be normal(and T4 low) which is of no special use

40.  Our aim is to maintain T4 in the upper half of normal
range
 Maintain TSH in the normal range
 Growth , height , weight should be plotted
 And bone age should be noted if any problem
 Development should be assessed