2. Thyroid Disease in Pregnancy
Williams 2001

3. contents Hyperthyroidism Subclinical thyotoxicosis Hypothyroidism
Subclinical hypothyroidism
Nodular thyroid disease
Postpartum thyroiditis

4. introduction Sporadic nontoxic goiter = 5% Hyperthyroidism = 1%
Hypothyroidism = 1%
Postpartum thyroiditis = 1%
Relation of thyroid gland to pregnancy:
Alter thyroid function tests
Drugs used pass to fetal thyroid
Related abnormal conditions:
GTD  thyrotoxicosis
ATA  ↑ % of abortion
Hyper/hypothyroidism adverse pregnancy
outcome.

5. physiology
The thyroid gland moderately enlarge during pregnancy due to ↑ vascularity and hyperplasia. Histologically  active gland. U/S  ↑ volume.
Laboratory investigations:
↑ T3, T4
↑radioactive iodine uptake
↑TBG
TRHundetected, fetal TRH detected >20 weeks
TSH unchanged (cross react with FSH, LH, hCG)
Early in pregnancy T4 ↑, TSH ↓ ( within normal range).

6. hyperthyroidism Thyrotoxicosis and pregnancy Treatment
Pregnancy outcome
Thyroid storm and heart failure
Effects on the neonate
Neonatal thyrotoxicosis after thyroid ablation

7. % = 1 : 2000 of pregnancies
Symptoms in mild cases:
Tachycardia
↑ sleeping pulse rate
Thyromegaly
Exophthalmos
No ↑ weight

8. Confirm diagnosis by:
Free T4 ↑
TSH↓
Rarely T4 is normal, T3 is ↑
= % 5 in old women
In young women sometimes excessive thyroxin treatment  thyrotoxicosis.

9. Thyrotoxicosis and pregnancy
= Graves disease = organ specific autoimmune disease  TSAbs = TSH. Remission occur during pregnancy due to TSBAbs. Recurrence of thyrotoxicosis occur 4 months pp.
Treatment:
Thioamides: propylthiouracil
methimazole
Propylthiouracil:
prevent T3  T4
less placental cross
no aplasia cutis
Compared to methimazole. Both are safe.

10. Side effects: 10% leukopenia  do not stop ttt 0
Side effects: 10% leukopenia  do not stop ttt 0.2% agranulocytosis stop treatment Any sore throatstop treatment and do CBP Dosage in nonpregnant: Propylthiouracil = 100 – 600 mg/day Methimazole = mg/day

11. Dosage in pregnant: Propylthiouracil = mg/day Methimazole = mg/day Median time for normalization = 7-8 weeks Study: Pregnant women treated by 600 mg/day propylthiouracil  50 % remission 33 % require ↑ treatment at delivery 10 % used 150 mg/day Carbimazole  25 % remission

12. Thyroidectomy:
Indications:
Cannot adhere to oral ttt
Toxicity from oral ttt
Dangers:
↑ vascularity  give medical ttt before surgery
2 % vocal cord palsy
3 % hypoparathyroidism

13. Pregnancy Outcome ↑ preeclampsia ↑ HF Perinatal mortality: 8 – 12 %
Thyroid storm:
Rarely occur in untreated patients due
to a large functioning tumor.

14. Preeclampsia Infection anemia Heart failure:
More common than thyroid storm. Due to myocardial effects of T4 = constant exercise
% in untreated cases = 8 %
% in treated cases = 3 %
Precipitated by:
Preeclampsia
Infection
anemia

15. Management in ICU:
1 - Propylthiouracil:
Initial dose = 1 gm Orally
Maintenance dose = 200mg /6hours
2 - After 1 hour  Iodide to prevent T3T4
Supersaturated SKI = 5 drops/8hours
Lugol solution = 10 drops/8hours

16. 3 - If allergic to Iodine  Lithium carbonate = 300 mg/day Monitor S
3 - If allergic to Iodine  Lithium carbonate = 300 mg/day Monitor S. lithium = mmol/L 4 - Corticosteroides to further prevent T3T4 Dexamethasone = 2 mg/6 hours I.V 5 - β-blockers for symptoms 6 - Aggressive management of: HTN/infection/anemia

17. Effects on the neonate: May  transient hyperthyroidism/hypothyroidism Both fetal goiter Thiourea drugs Commonly not used during pregnancy although it  extremely small risk (< 3%) Case: Excessive propylthiouracilfetal hypothyroidism at 28 weeks confirmed by CBS. Intera-amnionic injection of T4 at 35, 36, 37 weeks  recovery.

18. Neonatal thyrotoxicosis after maternal thyroid ablation by surgery /radiation
Thyroid ablation in women with Graves disease does not remove maternal TSAbs in her blood which cross the placenta to the fetus and may fetal HF and death ( non-immune hydrops from fetal thyrotoxicosis ).
Fetal thyrotoxicosis can be diagnosed
By ↑ FHS and CBS.

19. Subclinical thyrotoxicosis
GTD

20. = free T4 normal, TSH ↓
% 4  50% due to excessive T4 ttt
50% variable course 40% no thyrotoxicosis
Long -term effects:
Cardiac arrhythmia/hypertrophy
Osteopenia
If persistent ↓TSH  follow up and monitor periodically

21. hypothyroidism

22. = ↓ free T4, ↑ TSH Rarely become pregnant infertile Treatment: Thyroxine: μg/day Monitoring: by TSH/ weeks Aim = T4 ≤ normal  ↑↓ by μg During pregnancy monitor: TSH/trimester Study: T4 requirement during pregnancy do not ↑ in 80%

23. Subclinical hypothyroidism
Effects on the fetus and infant
Radioiodine treatment
Iodine deficiency
Congenital hypothyroidism
Preterm infants

24. antimicrosomal antibodies
= normal free T4 + ↑ TSH
= 5 % in women from years
% of them  overt hypothyroidism
1 - 4 years later
Risk factors:
TSH > 10 mU/L
antimicrosomal antibodies
% ↑ in type 1 DM
Pregnancy outcome  ↑ PTL + HTN

25. Effect on the fetus and infant:
In the past : no adverse effects
Now:
T4 < 10th percentile impaired psychological development
TSH >99.6th percentile↓school performance ↓ reading recognition
↓ I.Q.
Most cases are impending thyroid failure.

26. Radioiodine therapy: destruction of fetal thyroid Exposed fetuses:
Evaluate
Give prophylactic thyroid hormone
Consider abortion
Congenital anomalies:
2 studies  no ↑
1 study  1 : 73
No pregnancy for 1 year after treatment

27. Iodine Deficiency  endemic cretinism in endemic areas
 20 million people with preventable brain damage
Iodine unsupplementation:
↑ TSH to mIU/mL # 9
↑ Neurological abnormalities to 9% # 3%

28. Congenital hypothyroidism
= 1 : – infants
Usually missed
Due to:
75 % thyroid agenesis
10 % thyroid hormonoagenesis
10 % transient hypothyroidism
Neonatal screening is mandatory
Early ttt  normal neurological development

29. Preterm fetuses May develop transient hypothyroidism.
Treatment unnecessary.

30. Nodular thyroid disease

31. - Evaluation and management depend on GA
- Evaluation and management depend on GA. - Malignant nodules = 5 – 30 % mostly low malignant tumors. - Radioiodine scanning is commonly not used although it has minimal effect on the fetus. - U/S can detect > 0.5 cm nodules. - FNA is an excellent method during pregnancy - Study : malignancy by FNA = 40%

32. Indications of biopsy of nonfunctioning nodules
< 20 weeks:
Solid nodule > 2 cm
Cystic nodule > 4 cm
Growing
Lymphadenopathy
Course: indolent surgery can be postponed
Pregnancy outcome = same as none pregnant
Thyroidectomy < weeks  no PTL

33. Postpartum thyroiditis

34. Propensity antedate pregnancy
Precipitated by:
- Viral infection
- Others as Chernobyl disaster
Characterized by :
- transient pp hypothyroidism
- transient pp hyperthyroidism
% by carful evaluation = 7 – 10 %
Usually missed because symptoms are nonspecific as:
Depression
Carelessness
↓ memory

35. Study : depression = 9 % at 6 months pp
% in type I DM = 25 %
Risk factors:
Previous attach
Personal history of autoimmune disease
Family “””””””””””””””””””””””””””””””””””
↓ iodine
Many patients have thyroid antibodies before pregnancy
Pathophysiology:
Viral infection  immune activation  autoantibodies  disruption + lymphocytic thyroidites

36. Thyroid autoantibodies:
1 - Microsomal autoantibodies:
% 7-10 early in pregnancy and pp
Study: = 20% < 13 weeks 17% spontaneous abortion
Characteristics:
↓ during pregnancy
↑ months pp
↓ months pp
2 - Peroxidase autoantibodies:
↑ % of thyroid failure
Both identify women at high risk of thyroid failure

37. Clinical picture: Hyperthyroidism Hypothyroidism % 4% 2-5%
% % %
Occurrence pp months months
Symptoms small painless goiter goiter, fatigue
fatigue, palpitation depression,↓concentration
Cause disruption induced thyroid failure
hormone release
Treatment β-blockers thyroxin 6-12 months
Fate /3 recovery /3 thyroid failure
1/3 hypothyroidism