The document summarizes thyroid disorders in pregnancy. Some key points:
- Thyroid disorders are among the most common endocrine conditions affecting 1-2% of pregnancies. Proper management is important for pregnancy outcomes.
- Hypothyroidism can cause complications for both mother and fetus like preeclampsia, preterm birth, and developmental delays. Treatment is levothyroxine.
- Hyperthyroidism in pregnancy is usually Graves' disease and may improve during pregnancy due to immunosuppressive effects but often worsens postpartum. Treatment focuses on maintaining normal thyroid levels.
- Postpartum thyroiditis is an autoimmune condition causing transient thyroid dysfunction after delivery
2. Most common endocrine disorder in pregnancy.
1-2% pregnant women.
Pregnancy may modify course of thyroid disease.
Pregnancy outcome can depend on optimal management of thyroid
disorders.
The Himalayan goiter belt - word’s largest belt from Kashmir to
Naga Hills.
3. Thyroid; derived from Greek
word – means shield gland.
Highly vascular organ.
Brownish red, 2 lobes (4x2cm),
one isthmus(2x2cm).
30% have pyramidal lobe.
Weight: 15-20g
5. iodine
reduced iodide
transported Thyroid
in gut to
Iodide
incorporated
into gp
thyroglobulin
MIT DIT
T4 enters circulation by direct glandular secretion.
T3 is produced by mono-deiodination of T4 in periphery.
6. T4 bound to circulating transport proteins –
Thyroxine binding globulin (TBG),
Thyroxine binding prealbumin or transthyretin,
Albumin.
8. Increased thyroxine requirement in pregnancy:
(1) TBG Free thyroid hormones H-P-T axis stimulation
(2) hCG stimulates TSH rp
(3) peripheral metabolism. ?
placental type II deiodinase
T4 T3 (fetus is dependent on type II conversion)
pl type III deiodinase
T4 rT3 3,3’diiodothyronine(T2)
9. PHYSIOLOGIC CHANGE CLINICAL IMPORTANCE
Increased TBG Need for T4 production
TT3 & TT4 levels
Interference with FT4 assay accuracy
Placental de-iodination of T4 T3 & T4 metabolism
Need for T4 production
Increased iodine clearance iodine requirement
(renal clearance and fetal transfer) Risk of maternal and fetal hypothyroidism and goiter
B HCG elevation 1st TM FT4 & TSH
Transient mild thyrotoxicosis
Reduction in TSHRAb during Graves’ disease improvement
pregnancy
Postpartum increase in thyroid Exacerbation of Graves’ disease
antibodies Precipitation of postpartum thyroiditis
10. organization Thyroid screening Goal TSH(mIU/L) Treatment of
with TSH subclinical
hypothyroidism
ACOG Case finding Not specified Not recommended
oct 2007
USPSTF(United Case finding Not specified Not specified
States Preventive
Services Task Force)
TES(The Endocrine Case finding 2.5 in Ist TM Recommended
Society) 3 in IInd &IIIrd TM
AACE( American Routine 0.3-3.0 Recommended
Association of Clinical
Endocrinologists)
BTA(British thyroid Case finding 0.4-2.0 Recommended
association)
11. Sign/symptoms of hypo or hyperthyroidism
Goiter
h/o hyperthyroid or hypothyroid disease, postpartum thyroiditis or thyroid surgery
Previous therapeutic head or neck irradiation
Autoimmune disorder
Family history of thyroid disease
Infertility
History of miscarriage or preterm delivery
Thyroid antibodies
Unexplained anemia or hyponatremia
Increased cholesterol level
12. Events in
fetus
Maternal thyroxine in coelomic fluid 6 weeks
THR gene expression in human brain 8 weeks
Fetal iodine uptake 10-14 weeks
Fetal thyroxine secretion 18 weeks
14. Incidence: 1 - 3 per 1000 pregnancies.
Types:
Primary - inadequate thyroid hormone production despite pituitary
gland stimulation(including iodine deficiency).
Central - insufficient stimulation of the thyroid by the pituitary or
hypothalamus.
Subclinical – Elevated TSH levels normal FT4 in absence of clinical
symptoms.
Overt – increased TSH with low thyroxine levels with clinical
symptoms.
18. Subacute granulomatous thyroiditis Subacute lymphocytic thyroiditis
Transient hyperthyroidism
Transient hypothyroidism
90% 10%
recover persistent goiter
Lasts 4-6 weeks; may be 9 months
Differentiated from Graves disease by lack of radioiodine uptake on
thyroid scan
Symptomatic treatment.
19. Leading cause of preventable mental retardation worldwide.
Mean IQ loss of 13.5 points.
Iodine sufficiency determined through measuring median Urinary
Iodine excretion.
Insufficient urinary iodine:
Pregnancy : <150mcg/L
Lactation : <100mcg/L
renal clearance
Iodine needs increase in pregnancy
fetal and placental uptake
20. Recommended iodine Excessive iodine (μg/d)
intake (μg/d)
Pregnant women 250 500
Lactating women 250 500
Children 0-5 years 90 180
6 to 12 years 120 180
>12 years 150 180
21. Iodised salt : 46–76 mg/kg
Shrimp (85 grams) : 35mcg
Egg, boiled : 12mcg
Navy beans, cooked – ½ cup : 32mcg
Potato with peel, baked – 1 medium : 60mcg
Seaweed (7 grams) dried – 4,500mcg (highest).
Iodine should be added after cooking of food. ?
22. Secondary hypothyroidism
Pituitary necrosis from vascular hypoperfusion
Spectrum varies from failure of lactation or resume menses to acute
panhypopituitarism
90% develop secondary hypothyroidism.
23. Secondary hypothyroidism
Peripartum period
Autoimmune disorder
Anterior pituitary destruction
Panhypopituitarism to single hormone deficiency
Imaging: enhancing sella turcica mass
Mass effects (headache and visual field changes)
24. TSH ; N FT4 & FT3
Prevalence in pregnancy- 2-5%
31% +ve for TPO antibodies.
More commonly seen with autoimmune diseases
Associated with gestational hypertension, preterm
delivery, stillbirths, abruption.
25. N TSH FT4
Prevalence: 1-2% of pregnancies.
No adverse affects on pregnancy outcome
No benefit of levothyroxine treatment.
29. Goal
To return thyroid hormone levels to within the
reference range. ?
30. Euthyroidism at the time of conception.
If on treatment- delay pregnancy until TSH is normal.
do not take levothyroxine and multivitamins at the same time
(interference with absorption of thyroxine)
adequate iodine intake (250mcg/d).
Dietary goitrogens : cabbage, cauliflower, broccoli and even water
purifying agents should be avoided. Boiled water is recommended.
31. >/=1 risk Euthyroid:no
factor for S.TSH 0.08-<3 further work
thyroid ds up
Repeat TSH,FT4, TPO
>/=3 Levothyroxine
started
TSH>/=3
Normal TSH>/=3 Low FT4
results N FT4, +/-TPO
+/- TPO
SUBCLINICAL HYPOTHYROIDISM HYPOTHYROIDISM
EUTHYROID:
Stop
levothyroxine
32. Levothyroxine sodium - most widely prescribed treatment
Safe for both mother and fetus. Category A.
Available dosages - 25–300 mcg.
Dose : 30% increase from non pregnant value, if already
hypothyroid.
If newly diagnosed in pregnancy : 1.0–2.0 mcg/kg/day or
approximately 100 – 150 mcg of levothyroxine daily.
TSH measured 4-6 weeks following dose change with TSH goal
between 0.5-2.5mIU/L
Once stable, TSH checked every 8 weeks.
33. Bioavailability affected by medications or food: taken empty
stomach.
Absorption: Carafate, cholestyramine, ferous sulphate & calcium
carbonate.
Clearance: phenytoin, carbamazepine.
Postpartum:
Decrease dose by 30% (diagnosed in pregnancy)
Prepregnancy dose (hypothyroid before pregnancy)
TSH reassessed 6 week postpartum.
34. ON MOTHER ON FETUS
Related to Overtreatment smaller head circumference
and LBW.
hyperthyroidism.
transient hair loss.
BMD
35. Women should be clinically and biochemically euthyroid
prior to labor.
Obstetric complications including increased risk of
stillbirth, preterm delivery, pre-eclampsia and placental
abruption should be kept in mind.
37. In utero therapy:
Fetus effectively absorbs T4 from amniotic fluid.
3rd trimester fetal T4 requirement : 6 ug / kg /day.
Intraamniotic administration of 250 – 500 ug of thyroxine done at 7 –
10 days interval.
In term infants :
Requirement : 10 – 15 ug /kg /day.
TSH levels kept below 5 mU /l and T4 levels at 10-16 ug /dl.
Tab thyroxine crushed and fed directly to the infant.
38. Thyroid antibodies:
directed towards cytoplasmic antigens-
thyroid peroxidase (TPOAb) and
thyroglobulin (TgAb) antibodies.
directed to the TSH receptor-
TSH receptor antibody (TSHRAb).
TPOAB present in 10-15% normal population.
39. Thyroid autoimmunity increased miscarriage rates.
Causes :
subtle maternal thyroid dysfunction
autoimmune imbalance; rejection of the fetus
thyroid antibodies affecting fetal thyroid gland ; fetal loss
Associated increased maternal age
40. Trophoblast secrete immunosuppressant factors
antibody titers
graves disease improvement
antibody titer post partum
postpartum flare up
postpartum thyroiditis.
41. Incidence: 0.1 to 0.4 %
Types:
Subclinical hyperthyroidism-suppressed TSH, normal FT4 and FT3
Overt-suppressed TSH and elevated FT4 and/or FT3
Gestational- detected in pregnancy.
43. Cause: cross reactivity between hcg and TSH at thyroid receptor
Nausea and vomiting leading to dehydration, electrolyte
imbalance and weight loss.
Spontaneous resolution by 18 weeks.
Antithyroid medications avoided.
44. Autoimmune disorder.
Incidence: 0.5%
Most common cause of hyperthyroidism in pregnancy
Symptoms antecedent pregnancy
Physiology: antibodies stimulate thyroid receptors; thyroid
hypertrophy and hyperfunction.
Antibodies:
TPO
Thyroglobulin
Microsomal
Thyroid receptor antibodies.
47. 1st and 2nd trimester
Previous radio-active iodine or thyroidectormy for Graves’ disease
New-onset thyrotoxicosis to differentiate Graves’ disease from
gestational thyrotoxicosis
Previous pregnancy complicated by fetal or neonatal
hyperthyroidism
3rd trimester
Woman requiring antithyroid drugs for Graves’ disease into third
trimester
48. Nervousness,Agitation,Fatigue Eye signs (distinct from
Graves’ ophthalmopathy)
Tachycardia/palpitations
Heat intolerance Lid lag
Increased appetite, Weight loss Lid retraction
Change in bowel habits
Proptotis
Skin/hair/nail changes; Skin is soft
and moist
Onycholysis (separation of the distal
nail from its bed)
Hair soft, fine and thin
49. Graves' orbitopathy:
Chemosis (swelling of the conjunctiva),
Proptosis (exophthalmos or bulging orbit),
Dysconjugate gaze (double vision on looking to the extremes of the visual
field)
Pretibial myxedema ( thyroid dermopathy)
bilateral, firm, nonpitting, asymmetric plaques or nodules, most often
confined to the pretibial area ; may occur anywhere
Thyroid bruit
Clubbing
51. Hyperthyroidism can be diagnosed on the basis of
Clinical presentation
Thyroid examination
Thyroid function tests
Thyroid antibody tests
52. Graves disease- a diffuse, symmetric, soft goiter, which
may have an audible bruit.
Nodular thyroid disease- A palpable nodule (usually 3 cm)
Subacute thyroiditis- generalized thyroid tenderness.
53. Goals
To normalize thyroid hormone levels(keeping FT4 in upper normal
range <0.85-1.9ng/dl),
To treat bothersome adrenergic symptoms of hyperthyroidism.
54. Clinical situations:
Hyperthyroidism under treatment
Potential side effects of antithyroid drugs on the fetus discussed.
wait 6 months after radioablation.
euthyroid at the time of conception.
Previous ablation treatment for Graves' disease
The dose of thyroid replacement therapy needs to be increased soon after conception.
In spite of euthyroidism, high maternal titers for TSI may be present; fetus at risk.
Previous treatment for thyroid carcinoma
wait 1 year after completion of radioactive treatment before conception.
Inadequately treated hyperthyroidism
impaired maturation of the fetal hypothalamic-pituitary-thyroid axis - central congenital
hypothyroidism in the infant.
55. PROPYLTHIOURACIL (PTU)
Inhibits conversion of T4 to T3
Crosses placenta less readily. Improvement seen in 3-4
Dose- 300-450mg in 3 divided weeks; full response 8 weeks.
doses of 100-150mg each.
Category D ? Tapered as pregnancy
progresses.
Side effects:
Iatrogenic fetal hypothyroidism
Transient leukopenia (10%)
Agranulocytosis (0.3-0.4%)
Hepatotoxicity (0.1-0.2%)
Vasculitis
56. METHIMAZOLE Side effects:
Dose- 5–20 mg b.i.d
Crosses placenta more readily.
Transient leukopenia (10%)
Category D
Agranulocytosis (0.3-0.4%)
Methimazole embryopathy – Hepatotoxicity (0.1-0.2%)
Esophageal atresia Vasculitis
Choanal atresia
Cutis aplasia.
Dose monitored with 3-4 weekly FT4 or FT4I levels.
Improvement seen in 3-4 weeks; full response 8 weeks.
Tapered as pregnancy progresses.
58. Routine fetal blood sampling for thyroid indices is recommended if –
previous I131 ablation,
Abnormal TSIs or TBII,
FGR, heart failure or goiter, with or without tachycardia.
59. Other drugs in hyperthyroidism
Beta adrenergic blockers: propranolol.
inhibits
MOA: T4 T3
20-40mg orally every 8-12 hours
60. Management
Antithyroid medications,
beta-blockers and
Supportive Care.
fetal thyrotoxicosis suspected in labor aggressive treatment of
maternal thyrotoxicosis
fetus with a large goiter consideration of the best route of delivery
Elective cesarean to avoid dystocia
management of the fetal airway.
61. ex utero intrapartum treatment (EXIT) procedure
Candidates: Fetuses with neck masses large enough to cause airway
obstruction ; to manage airway obstruction after fetal surgery.
It involves securing the neonatal airway (usually with endotracheal
intubation often guided by laryngoscopy or bronchoscopy) while the
umbilical cord and maternal-fetal circulation remain intact in the
hopes of avoiding difficult emergency intubations in the delivery
room.
Usually perfomed with cesarean deliveries; described with vaginal
deliveries too.
62. Most commonly diagnosed endocrine malignancy.
Incidence: 14 / 1,00,000 pregnant women.
Histologic types: papillary, follicular, medullary, Hurthle cell, anaplastic
Papillary thyroid cancer : most common type in pregnancy.
Excellent long term prognosis
Surgey delayed postpartum; depending upon histology.
S.thyroglobulin : predictive of recurrent disease.
Postsurgical I131 whole body scintigraphy and radioiodine remnant
ablation : contraindicated in pregnancy & lactation.
64. STEP 1. START THIONAMIDES & CONTROL HEART RATE
beta-blockers - control tachycardia (maintain
THIONAMIDES- 1 g PTU (orally or through HR<90bpm)- propranolol 1-2 mg i/v over 5 min to total
NG tube) 200 mg every 6 hours of 6-10mg 60–80 mg every 4 hours orally or
NG tube.
STEP 2.CORTICOSTEROIDS
Dexamethasone 1-2mg PO/IV/IM 6 hourly
Or
Hydrocortisone 100mg IV 8 hourly
Or
Prednisone 60mg PO a day
STEP 3.IODINE(after 1-2 hour of thionamide therapy.)
SSKI 5 drops orally 8 hourly.
Or
500-1000mg sodium iodide i.v. 8 hourly
Or
Lugol’s solution 10 drops orally 8 hourly
Or
Lithium carbonate 300mg PO 6 hourly
Or
Iodinated radiocontrast agents iopodate and iopanoic acid
0.5–1.0 g orally daily.
65. immunosuppression postpartum relapse(70%)
disappears (within first 3 months)
TSH and free T4 done 6 weeks post partum.
T4 levels must be controlled prior to the next pregnancy.
Drugs in lactating mother:
Both PTU and methimazole excreted in breast milk; PTU is largely protein bound;
does not seem to pose a significant risk to the breastfed infant.
Methimazole safe only at low doses (10–20 mg/day).
AAP and WHO support compatibility of breatfeeding and all antithyroid
medications
66. Postpartum Rebound in thyroid autoimmunity
lymphocytic infiltration of the thyroid gland
The likelihood of developing postpartum thyroidis is related to serum levels of
thyroid autoantibodies.
Anti-TPO antibodies are present in 90% of women with PPT.
Women with high antibody titers in early pregnancy have 40–50% chance of
developing PPT.
Women with type 1 diabetes have a significantly higher incidence, ranging from
18% to 25% due to the high prevalence of TPO antibodies.
67. HYPERTHYROID PHASE HYPOTHYROID PHASE
Autoimmune destruction of the immune destruction loss of
gland - release of stored hormone functioning thyrocytes
1 - 4 months postpartum 3 - 8 months postpartum (usually at 6
months)
self-limiting (1–2 months).
lasts much longer (4–6 months)
Abrupt onset
fatigue, palpitations, sleep fatigue, weight gain, loss of
deprivation, nervousness / irritability. concentration, depression
small, painless goiter may be
present.
Antithyroid medications not
beneficial.
68. Patients identified with PPT should be screened regularly since 20–
50% of women will develop permanent hypothyroidism within 2–10
years.
A TSH level should be done annually and prior to conception.
69. EVALUATION OF THYROID NODULE IN PREGNANCY
Abnormal TSH
Work up N
& treat
Solid lesion>2cm USG
Cystic lesion>4cm Solid lesion<2cm
Cystic lesion<4cm
<24
weeks
>24
weeks
FNAC Postpartum
Levothyroxine follow up
Non
malignant malignant
surgery
Hinweis der Redaktion
Thyroid hormone is produced by iodination of tyrosine residues in thyroglobulin to form mono or diiodo tyrosine
Estrogen acts on liver to produce TBGstimulatory effect of hCG on the TSH thyroid receptor identical alpha subunit10,000 IU/L increment in circulating hCG corresponds to a mean T4 increment of 0.1 ng/dl, and in turn to a lowering of TSH of 0.1 mU/L.
Overt: 0.61%s/c: 5.48%
Lithium causes hypothyroidism by inhibiting thyroid hormone releaseAmiodarone: iodine containg drug may also cause hypothyroidism
Four inorganic compounds are used as iodide sources, depending on the producer: potassium iodate, potassium iodide, sodium iodate, and sodium iodide.
Serum TSH is more sensitive than free T4 for detecting hypothyroidism and for following effectiveness of replacement therapy. If the TSH is abnormal, then evaluation of free T4 is recommended. The presence of antithyroid antibodies identify a population of women at particular risk for pregnancy complications(miscarriage), postpartum thyroid dysfunction.Free T4 index:TT4*Resin T3 uptake
Pregnancy is associated with a decrease in antibody titers due to trophoblast secretion of immunosuppressant factors
long-acting thyroid-stimulating antibody (LATS) TSI
In c/o previousthyroidectomy or ra I tt patient may be euthyroid but antibodies may still be present
Lid lag (elicited by having the patient follow your finger as you move it from the top to the bottom of their visual field. Lid lag is present if the upper lid is slow to follow the eye on downward movement and white sclera becomes exposed above the iris)Lid retraction and stare (the white sclera abovethe iris is visible at rest. The orbit appears prominentbut is not actually bulging (proptotic))
Clubbing (individuals without clubbing display a diamond-shaped window at the base of the nailbeds when two fingers from opposite hands areopposed dorsally. The distal angle between thetwo opposed nails should be minimal. In individualswith digital clubbing, the diamond window isobliterated and the distal angle between the nailsincreases with increasing severity of clubbing)
Block and replace therapy not adviced as antithyroid medications cross placenta but levothyroxine does not. Leading to fetal hypothyroidism.
Cesarean to avoid dystocia in extremely large fetal goiter.
Intervention on behalf of fetus should not be undertaken until mother is stabilized as vaginal or c sn may exacerbate thyroid storm
distinguished from postpartum Graves’ disease by an I123 uptake and scan (low or normal uptake in PPT compared to a diffusely increased uptake consistent with Graves’).However, this requires interruption of the woman’s breastfeeding.In Graves’ disease, hyperthyroidism will persist, whereas in PPT the hyperthyroid phase will spontaneously resolve.