This document provides a summary of thyroid gland embryology, anatomy, physiology and the assessment of child development. It describes how the thyroid gland develops from an endodermal diverticulum in the neck. It lists the gland's blood supply and drainage. Thyroid hormones are synthesized through iodination and condensation of tyrosine residues. Child development is assessed through history, examination using standardized tools, and calculating the developmental quotient. Both screening tests and definitive tests are used to evaluate development. Factors like environment and genetics also influence a child's development.

1. Thyroid gland embryology and
hormonal physiology
BY DR.ANIRUDH
1ST YEAR JUNIOR RESIDENT
SRMC
NANDYAL

2. THYROID GLAND –BRIEF ANATOMY
.Butterfly or H shaped endocrine gland located in front and sides of neck.
.Lies against C5,C6,C7,C8,T1 cervical vertebrae embracing the upper part of
trachea.
Consists of right and left lobe joined together by isthumus
.Each lobe extends from middle of thyroid cartilage to 4th or 5th tracheal ring.
..A 3rd pyramidal lobe may project upwards from the isthumus(or from one
of the lobes)
.Sometimes a fibrous or muscular band called levator glandulae thyroidae
descends from body of hyoid bone to the isthumus or to the pyramidal lobe.

3. • DIMENSIONS:5X2.5X2.5 Cms and isthumus 1.2x1.2 cms
• Total weight of gland:25 gms
• COVERINGS:
• True capsule
• False capsule

4. • Blood supply:
• Arterial:
• Superior thyroid artery-first anterior branch of ECA
• Inferior thyroid artery-thyrocervical branch of subclavian artery
• VENOUS:
• Superior thyroid vein
• Middle thyroid vein
• Inferior thyroid vein

5. • Sometimes a 4th thyroid vein(kocher’s) may emerge between middle
and inferior thyroid veins.
• LYMPHATIC DRAINAGE:
• Upper part of gland reaches upper deep cervical nodes directly or
through prelaryngeal nodes
• Lower part of gland drains into lower deep cervical nodes through
pretracheal and paratracheal nodes

6. • HISTOLOGY:
• 2 types of secretory cells :
• 1.FOLLICULAR CELLS:
• contain colloid in their lumen, Line the follicles of gland and secrete
two hormones T3 &T4, which stimulate the BMR ,promote somatic
and psychic growth .
• During active phase,lining is columnar and during resting phase lining
is cuboidal.

7. • 2.PARAFOLLICULAR CELLS(C CELLS)
• Fewer in number and lie between the follicles
• Secrete THYROCALCITONIN which promotes deposition of calcium in
skeletal and other tissues thus producing hypocalcemia (opposite to
that of parathormone),formed from ultimobranchial body.

8. DEVELOPMENT OF THYROID:
• Develops from Median endodermal thyroid diverticulum which is
outpouch from primitive foregut in the ventral part of floor of the
primitive pharynx grows down infront of the neck just caudal to
tuberculum impar
• Lower end of diverticulum becomes bifid,enlarge to form the thyroid
gland(8-10 w of GA)
• Rest of the diverticulum remain narrow and is known as
THYROGLOSSAL DUCT
This duct gets obliterates soon after birth

9. • Position of upper end of the duct is marked by FORAMEN CAECUM of
tongue
• Position of lower end of the duct is marked by pyramidal lobe of
thyroid.
• Gland becomes functional during third month (12 w of GA)of
development
• Remanants of thyroglossal duct may form thyroglossal cyst and fistula

10. • Several transcriptional factors like TTF-1/NKX-2.1,TTF-2,NKX2.5 and
PAX8 are important in thyroid gland morphogenesis and
differentiation and also in caudal migration.

13. • HYPOTHALAMO PITUITARY THYROID AXIS:
• TRH synthesized by 6-8 weeks
• Pituitary portal vessel system develop by 8-10 weeks
• TSH secretion occurs by 12 weeks of GA
• Maturation of the axis occurs during second half of gestation but
normal feedback relationships are not mature till 3 months of
postnatal life.

14. • Thyroid gland may develop at abnormal sites along the thyroglossal
duct resulting in lingual thyroid or retrosternal thyroids

15. Biosynthesis of thyroid hormones:
• Tyrosine rich proteins and iodine are required for synthesis of thyroid
hormones.
• TSH stimulates all steps of thyroid hormone synthesis and also release
of T4 and T3.

16. STEPS:
• 1.synthesis of thyroglobulin(120 tyrosine units)
• 2.trapping of iodine(RDA of 30 mg/24 hr in infants,90 mcg in
children,150 mcg in adults)
• 3.oxidation of iodine to iodide
• 4.iodination of tyrosine at cell interphase
• 5.oxidative condensation of iodinated tyrosine to yield T3,T4(released
from thyroglobulin by proteases and peptidases)

18. RELEASE OF THYROID HORMONES:
• TRANSPORT OF THYROID HORMONES:
• 1.BOUND FORM
• 2.FREE FORM

19. • BOUND FORM:
Reversible attachament
a)TBG:60% OF THYROXINE BINDS TO GLOBULINS
B)TBPA(TRANSTHYRETIN):BINDS 30% OF THYROXINE
C)TBA:BINDS 10% OF THYROXINE
Of T3,T4, T4 is bound more to plasma protein than T3,
Bound form of thyroid hormones is estimated as protein bound
iodine(PBI),gives a n idea of plasma T3,T4

20. T3 T4
Plasma level is 3-8 mg/dl 1.0-1.5 mg/dl
Precursor of T3 and is solely secreted by the gland Physiologically active form(plasma T3 comes from :
1.Deiodination of T4 in peripheral tissues(80%)
2.Secretion from gland(20%)
Combines less freely with DNA receptor More affinity to DNA receptor
Amount secreted is more(100mcg/day) Amount secreted is less(20mcg/day)
More protein bound Less bound
Slow and sustained action Fast action
Gets metabolised slowly Gets metabolised faster

21. Thyroid hormone into the target cells:
T3,T4 enters the cell
intracellular T3 binds to TH receptor
Activation of THR response element
Messenger RNA & protein synthesis specific for target cells

22. Regulation of thyroid hormone synthesis:

23. • REFERENCES:
• IB SINGH-EMBRYOLOGY
• L.PRAKASHAM REDDY-PHYSIOLOGY
• NELSON
• GOOGLE IMAGES

24. GOAL :
• Generate a diagnosis and also to analyse the patterns of strength and
weaknesses in the child,the family, and available
developmental,educational and social support systems to direct
treatment.

25. INDICATIONS:
• Follow up of high risk neonates for early detection of cerebral palsy
and or mental retardation
• Complete evaluation of children with developmental,chromosomal
and neurological disorders
• Differentiate children with retardation in specific fields of
development as opposed to those with global retardation.

26. PREREQUISITES:
• Should be done in a place free from distractions
• Child should not be-hungry,tired,ill or irritated
• Playful mood with mother around
• Adequate time to make child and family comfortable.
• Carry a development kit

28. DEVELOPMENTAL PREDICTION:WHAT WE
CAN DO AND CANNOT DO:
• WHAT WE CAN DO(BUT NOT NECESSARILY IN THE EARLIEST WEEK) AS
FOLLOWS:
• 1.how far baby has developed in relation to his age and so compare
him with average performance of others of that age,so can say
something about rate of development and developmental potential
• 2.diagnose moderate or severe intellectual disability
• 3.diagnose moderate or severe cerebral palsy
• 4.assess muscle tone
• 5.diagnose moderate or severe deafness

29. • 6.diagnose moderate or severe visual field defects
• 7.diagnose neurological defects in newborn
• 8.giving genetic counselling

30. What we cannot do:
• Cannot draw a narrow dividing line in early infancy,further away from
the average the child is in anything,more likely to be abnormal
• Accurate predictions of future intelligence and achievements cannot
eliminate possibility that the child will undergo intellectual
deterioration in future months or years.
• Cannot come to conclusion with single examination.
• If child is retarded and has no microcephaly,we cannot be sure that
he is a slow starter(delayed maturation)
• Cannot rely on diagnosing mild cerebral palsy in the early weeks.

31. • Finally it must be remembered that there are many aspects of
ability,verbal,numerical,spatial,perceptual,memorising,reasoning,
mechanical and imaginative qualities.
• Hard that these tests detect development with high degree of
reliability.

32. EQUIPMENT FOR DEVELOPMENTAL
ASSESSMENT:
Equipment for development asessment
RED ring (diameter 6-7 cm)tied to a string
Nine red cubes
Paper pellets
Spoon
Cup with handle
Book with thick pages
Picture book
Red pencil,paper
Doll and mirror

34. STEPS:
HISTORY:
• (i) determining the details of probable risk factors affecting
development,
• (ii) evaluation of rate of acquisition of skills and differentiating
between delay and regression
• (iii) forming a gross impression about the development age of the
child. This helps to choose the appropriate tools for further
evaluation and confirmation

35. Examination:
• (i) assess physical growth and head circumference,
• (ii) do a physical assessment, particularly for dysmorphism, stigmata
of intrauterine infections and signs of hypothyroidism,
• (iii) screen for vision and hearing, and
• (iv) conduct neurological examination and examine for primitive
reflexes (if required).
• Adequate time should be spent in observing the baby especially
social responsiveness, alertness, concentration, interest and
distractibility.

36. - assess vision and hearing at the outset so that further observations
are not confounded by lack of sensory stimuli.
• The annoying maneuvers, including assessment of reflexes, head
circumference, ventral suspension and pull to sit should be done at
the end.
• It is preferable to perform the developmental assessment before the
systemic examination so that the child's cooperation is good

37. • .By the end of the evaluation one should be able to arrive at a
conclusion whether the neurological status and cognitive status are
within normal range or not.
Significant delay on screening is an indication for a detailed
assessment of development status.

38. Developmental quotient:
average age of attainment/observed age of attainmentx100
-DQ below 70% -delay and requires detailed evaluation.
-several tests to assess,each test having its own psychometric
properties.
Gives overall scores for development and also subscores for gross
motor,fine motor,visual perception,receptive language and expressive
language.

39. INTERPRETATION:
• Corrected age
• Wide variations in normalcy
• Retardation not to be diagnosed on a single feature
• dissociation

41. UPPER LIMIT FOR A MILESTONE

42. Developmental screening:
• Brief assessment procedure designed to identify children who should
recieve more intensive diagnosis or evaluation further.
• Aids in early intervention methods.
• LIMITATIONS:
• Asessors need to trained for appropriate interpretation and scoring
• Cannot be used to make diagnosis
• One cannot stop with screening.

43. Reasons for not practising developmental
screening in india:
• Unawareness of parents
• Health care seeking is prioritised for acute illness
• If parents express cocerns,they are given false assurance.

44. Selection of screening tool:
• PSYCHOMETRICS:sensitivity and specificity atleast 70-80%
• Time/staffing required
• Cost
• Parent completed vs directly administered
• Cultural and linguistic sensitivity.

45. SCREENING TESTS FOR INDIAN INFANTS:
• 1.Phataks baroda screening test-by Dr.Promila Phatak,best known
,indian adaptation of bayley developmental scale
• 2.Trivandrum development screening test.
• 3.ICMR scales
• 4.Denver II (0-60 m) scales
• 5.goodenough harris drawing test (4-14 y)
• 6.CAR/CLAMS(clinical adaptive test/clinical linguistic and auditory
milestone scale)
• 8.NIMHANS Bengaluru learning disability test (5-15 y)

46. FACTORS BARODA SCREENING TEST TRIVANDRUM DEVELOPMENTAL
CHART
ICMR PSYCHOSOCIAL CHART
DEVELOPED FROM Bayley scale of infant development Bayley scale of infant
development
Programme for estimating
age related centiles using
piece wise polynomials
AGE 0-30 MONTHS 0-6 Y 0-6 MONTHS
FORMAT 54 ITEMS 51 ITEMS PARENTS INTERVIEW
64 ITEMS
DOMAINS MOTOR &COGNITIVE MENTAL & MOTOR GROSS ,FINE
MOTORMOTOR,VISION,HEARI
NG,SOCIAL
SCORING /RESULT Age equivalent &development
quotient calculated
Within age range 3rd,5th,25th,50th,75th ,95th
&97th centile. Significant
delay in <3rd centile(2SD)
TIME TAKEN 10 MIN 10 MIN MINIMAL
PSYCHOMETRICS Sn-65-93%
Sp-77-94%
66.8%
78.8%
Not given
COST Inexpensive inexpensive free

48. Goodenough harris drawing test:Non verbal intelligence test
Requires pencil /pen &white unruled paper
Asked to draw a man in best possible manner & points given for each
detail which the child draws.

51. SCREENING TESTS OF INTERNATIONAL
INFANTS:
FACTORS DENVER II BAYLEY INFANT
NEURODEVELOPMENTAL
SCREENING TEST
PARENTS EVALUATION OF
DEVELOPMENTAL
STATUS(PEDS)
AGE FORMAT 0-6Y,directly administered 3-24 m,directly administered 0-8 y,parent reported
SCREENS/DOMAI
NS
Expressive&receptive,
language,gross motor,fine motor,
social
Neurological
process,expressive
&receptive ,cognitive
Cognitive,expressive,
receptive ,language,fine
,gross motor,social,emotional
,behavioural
ITEMS 125 11-13 10
SCORING/RESULT N/ABN High/low/moderate Low/med/high
TIME 10-20 min 10 min 2-10 min
PSYCHOMETRICS Sn-40-90
Sp-43-80%
Sn-75-86%
Sp-75-86%
Sn-74-79%
Sp-70-80%

52. • AGES & STAGES QUESTIONNAIRE (ASQ):
• Age based
• Parent completed questionairre
• 1m-66 months
• Communication,grossmotor ,fine motor,problem solving personal
skills are tested 30 items per questionnaire
• Takes 10-15 min to complete,2-3 min to score.

53. DEFINITIVE TESTS:
• Done when screening tests are abnormal
• For accurately determining impairments in both degree and sphere

54. DEFINITIVE TESTS:
SCALE AGEGROUP TIME TAKEN COMMENTS
BAYLEY SCALE FOR
INFANT
DEVELOPMENT II
1M-3.5Y 30-60 MIN Mental development index &psychomotor
development index and other domains
WECHSLER SCALE
IV
6-17 Y 65-80 MIN Verbal and performance skills,full scale IQ,working
memory and speed
STANFORD
BINNET SCALE
2-85 Y 50-60 min Full scale IQ,verbal IQ

55. WECHSLER SCALE

57. • SEGUINE FORM BOARD TEST:
• Based on single factor of intelligence,
• measures speed and accuracy
• Evaluating handeye coordination,shape concept,visual
perception,cognitive ability
• Child is asked to copy 10 geometrical figures containing wooden
blocks and large form board with recessed corresponding shapes.

58. SEGUINE BOARD TEST

59. Developmental survellaince:
• Dynamic process & repeated observation
• Physician need to use standardised screening tool that is practical and
easy to use.
• 5 components:
• Eliciting and attending parents concern about their child development
• Documenting and maintaining developmental history
• Making accurate observations about child
• Identify risk and protective factors
• Maintaining accurate record

60. THANK YOU!!!