thyroid gland

2. PREGNANCY IS A NATURAL STRESS
TEST FOR THYROID GLAND
ESTROGENS INCREASE TBG 2-3 FOLD—INCREASE IN TOTAL T3 ,T4
PRODUCTION OF T3,T4 INCREASED BY 50%
THUS TOTAL T3,T4 INCREASED BUT FREET4 REMAINS NORMAL
HCG MIMICS TSH --- LOW TSH FROM PITUITARY
NON FUNCTIONING FETAL THYROID 10-12 WKS –
HIGH DEMAND OF T3, T4
INCREASED PERIPHERAL METAB OF THYROID HORMONE –
LOW FT3 & FT4
INCREASED PLASMA VOL. & INCREASED RENAL FLOW –
INCREASED RENAL CLEARANCE OF IODIDES

3. SUBCLINICAL/BIOCHEMICAL
HYPOTHYROIDISM
• ELEVATED TSH LEVEL WITH NORMAL FREE T4 IN ASYMPTOMATIC
WOMEN
• 5-10% OF THESE MAY PROGRESS TO OVERT HYPOTHYROIDISM
DURING PREGNANCY OR LATER IN LIFE
• INCREASED RISK OF PRETERM LABOUR OR PLACENTAL ABRUPTION
• NEWBORN MAY HAVE SUBNORMAL MENTAL DEVELOPMENT LOW
IQ,PSYCHOMOTOR DYSFUNCTION
• IN SUCH CASES TPO Ab. TEST TO BE DONE & POSITIVE CASES
TREATED WITH LOW DOSE THYROXINE STARTING WITH 25-50 mcg
TO MAINTAIN TSH BELOW 2.5mU/L
& TSH EVERY 4 wks TILL 20 wks THEN AT 30 wks.

4. MANAGEMENT OF AUTO-IMMUNE
HASHIMOTOS THYROIDITIS
• TPO Ab. MAY LEAD TO ABORTIONS DUE TO CROSS REACTIVITY OF TPO
WITH HCG RECEPTORS
• TPO Ab. BLOCKS THE HCG RECEPTORS ON ZONA PELLUCIDA & PLACENTA
BECAUSE OF WHICH THE CONCEPTUS BECOMES MORE PRONE FOR
ANTIGEN ANTIBODY REACTION
• EUTHYROID PREGNANCY WITH TPO POSITIVE WITH H/O OF RPL START
WITH 25-50mcg. OF LT & REPEAT TSH EVERY 4wks. TILL MID PREGNANCY
• THEN REPEAT TSH AT 30-32 WEEKS.
• STEROIDS & Igs ARE NOT RECOMMENDED IN TPO +ve

7. WHAT IS THYROID PEROXIDASE?
• PRIMARY ENZYME PRODUCED IN ER OF THYROCYTE
WHICH OXIDIZES IODINE TO FORM THYROXIN.
• TPO- Ab. ARE AUTO ANTIBODIES , SO SHOULD BE
TESTED IN PTS WITH RPL ,PTL IN PAST , TYPE 1
DIABETES, H/O ARTHRITIS ,UVEITIS ,CROHN’S , FAMILY
H/O THYROID DISEASES,INFERTILITY,ART
• CROSS REACTION OF TPO-Ab. WITH HCG RECEPTORS
ON ZONA PELLUCIDA , INTERFERE WITH
IMPLANTATION AND OPTIMAL HCG SECRETION .
• TPO-Ab. ASSOCIATED WITH RECURRENT ABORTIONS
AND PRETERM LABOUR .

8. MONITORING DURING PREGNANCY
TSH IS THE BEST INITIAL TEST
SERUM TSH LEVEL ANTIBODY NEGATIVE ANTIBODY POSITIVE
<2.5mU/L NO FURTHER
EVALUATION
REPEAT TSH EACH
TRIMESTER &
POSTPARTUM
2.5-4mU/L REPEAT TSH AFTER 6-8
wks.
TREAT WITH
LEVOTHYROXINE
>4mU/L TREAT WITH
LEVOTHYROXINE
TREAT WITH
LEVOTHYROXINE

9. AUTOANTIBODIES IN PREGNANCY
 ANTI TPO ANTIBODIES & ANTITHYROGLOBULIN ANTIBODIES PRESENT IN
30- 60% OF OVERT HYPOTHYROIDISM
 TPO ANTIBODIES CAN CROSS THE PLACENTA BUT THESE ARE NOT
ASSOCIATED WITH FETAL THYROID DYSFUNCTION
 HIGH RISH TARGETED SCREENING FOR TPO ANTIBODIES:-
 Pts WITH AID LIKE RA,CROHNS,UVEITIS ETC.
 WOMEN WITH INFERTILITY,
 RPL
 DEPRESSION
 TYPE 1 DIABETES
 ELDERLY >35
 OBESE (BMI>29)

10. CLINICAL HYPOTHYROIDISM/OVERT
HIGH TSH WITH LOW FREE T4 LEVELS
PRIMARY HYPOTHYROIDISM
HASHIMOTO THYROIDITIS IODINE DEFICIENCY
 TPO ANTIBODIES+(30-60%) SURGICAL EXCISION
 ASSOCIATED WITH INFERTILITY RADIOIODINE ABLATION
 PREGNANCY COMPLICATIONS LYMPHOMA
• ABORTION GOITROGENS FOUND IN LEGUMES,
AMIODARONE ,LITHIUM 27,BROCCOLI,
• ANAEMIA ,MYOPATHY CAULI FLOWER , TURNIP ,CABBAGE,CANOLA,
PEACHES ,PEANUTS ,RED WINE ,MUSTARD
ASPARTAME ,KALE …ETC
THESE INTERFERE WITH IODINE UPTAKE WHEN TAKEN IN R
RAW FORM OR RAW JUICE.
PREECLAMPSIA -3X
• PLACENTAL ABRUPTION-3X ENDEMIC IODINE DEFICIENCY
• HIMACHAL, HIMALAYAN BELT ,
• PRETERM LABOUR I
• FGR LOW IODINE CONTENT OF THE SOIL
• PPH
• POST PARTUM BLUES

14. MANAGEMENT OF OVERT
HYPOTHYROIDISM IN PREGNANCY
 TO ACHIEVE TSH 0.5-2.5 mU/L
DOC –LEVOTHYROXINE SODIUM
 HYPOTHYROID ISM -IF DETECTED DURING PREGNANCY START 1.6-2 mcg / kg /day
IF TAKING BEFORE PREGNANCY ,THEN THYROXINE
DOSE TO BE INCREASED BY 25-30%
OR
INCREASE 2 TABLETS WEEKLY(9/WEEK)
 TSH MEASURED EVERY 4- 6 WEEKS AND THEN 30-32wks
 HIGH RISH TARGETED SCREENING FOR TPO Ab
 IN ART/IVF-ICSI PTS -THYROXINE TO BE GIVEN TO SCH CASES EVEN IF TPO –Ab
NEGATIVE TO ACHIEVE TSH BELOW 2.5 mIU/L
 FT4 TO BE DONE IN THE TRANSITION PHASE BECAUSE IT TAKES 6 wks TO
EQUILIBRATE TSH

15. WHAT ARE THE RISKS OF
HYPOTHYROIDISM TO THE MOTHER
• UNTREATED OR INADEQUATELY TREATED
HYPOTHYROIDISM HAS INCREASED RISK OF
• MATERNAL ANAEMIA
• MISCARRIAGE
• MYOPATHY
• CHF & CARDIOMYOPATHY
• PRE-ECLAMPSIA
• PLACENTAL ABRUPTION & ABNORMALITIES
• PPH
• PP BLUES
• HIGHER IN WOMEN WITH TPO-Ab +ve

16. FETAL RISKS OF IODINE DEFICIENCY OR
HYPOTHYROIDISM DURING PREGNANCY
• MATERNAL TSH DOESN’T CROSS PLACENTA BUT TRH DOES
CROSS
• IN FIRST TRIMESTER FETUS DEPENDS ON MOTHER FOR
THYROXINE
• AT 10-12 wks FETAL THYROID STARTS MAKING THYROXINE
FROM IODINE RECEIVED THROUGH PLACENTA + 30% OF
T4 LEVELS IN CORD BLOOD IS OF MATERNAL ORIGIN
• T4 REQUIRED FOR BRAIN DEVELOPMENT, NEURONAL
MULTIPLICATION ,MIGRATION DURING 1st HALF OF
PREGNANCY IS OF MATERNAL ORIGIN SO OPTIMUM
IODINE METABOLISM & ADEQUATE THYROXINE LEVELS
HAVE TO BE MAINTAINED IN MOTHER.
• IN 3rd TRIMESTER GLIAL CELL MULTIPLICATION,
MIGRATION & MYELINIZATION IS BY FETAL T4 .

17. FOLLOWING CONDITIONS MAY BE SEEN IN THE
NEWBORN:-
• FGR
• PREMATURE BIRTH
• CARDIAC DYSFUNCTION
• CEREBRAL PALSY,SPASTIC DIPLEGIA
• NEUROLOGIAL OR MYXEDEMATOUS CRETINISM
• NEONATAL HYPOTHYROIDISM
• RETARDED PHYSICAL,NEUROMOTOR ,COGNITIVE
DEVELOPMENT

18. DRUG INTERACTIONS WITH LEVOTHYROXINE:-
• IRON TABLETS
• ANTACIDS
• CHOLESTYRAMINE
• PHENYTOIN
• CARBAMAZEPINE
• DRUGS INTERFERING WITH TFTs :ESTROGENS
BIOTIN
SUPPLEMENTS FOR HAIR
( HAVE TO BE STOPPED 2 DAYS
PRIOR TO BLOOD TEST )

19. FOLLOW UP AFTER CHILD BIRTH
• THYROXINE IS NOT CONTRAINDICATED DURING
BREASTFEEDING
• TSH REPEATED AFTER 6 wks PP TO TITRATE THE
DOSAGE
• NEONATE TO BE SCREENED AFTER 2 DAYS FOR TSH
LEVELS
• ANNUAL SCREENING OF MATERNAL TSH

20. TAKE HOME MESSAGES
• TSH OF ALL SEEKING INFERTILITY TREATMENT
• TSH IN FIRST TRIMESTER
• T3 IS RARELY HELPFUL IN HYPOTHYROID PT. SINCE IT IS THE LAST TEST TO BECOME ABN.
• LT4 TO BE GIVEN IF TSH > 4mIU/ L
• LT4 TO GIVEN IN PATIENTS HAVING TSH 2.5-4mIU/L
WITH POSITIVE ANTIBODY OR ART/IVF-ICSI CASES OR BOH
• TPO TO BE DONE IN INFERTILE PTS. & ALL PTS HAVING
 H/O PREGNANCY LOSS , PTL,IUD,STILLBIRTH
 FAMILY H/O THYROID DISEASE,TYPE 1 DM
 AID LIKE RA,CROHNS
• RECOMMENDED UPPER LIMIT OF TSH :-
 PREGNANCY 2.5 mIU/L
 NON PREGNANT 4.5mIU/L
• FREE T4 SHOULD BE 0.7-1.8ng/dL