Thyroid Disease in Pregnancy I. Hyperthyroidism II. Subclinical thyotoxicosis III. Hypothyroidism...
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Transcript of Thyroid Disease in Pregnancy I. Hyperthyroidism II. Subclinical thyotoxicosis III. Hypothyroidism...
WILLIAMS 2001
Thyroid Disease in Pregnancy
CONTENTSI. HyperthyroidismII. Subclinical thyotoxicosisIII. HypothyroidismIV. Subclinical hypothyroidismV. Nodular thyroid diseaseVI. Postpartum thyroiditis
INTRODUCTIONSporadic 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:
o GTD thyrotoxicosiso ATA ↑ % of abortiono Hyper/hypothyroidism adverse pregnancy outcome.
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 TRHundetected, fetal TRH detected >20 weeks TSH unchanged (cross react with FSH, LH, hCG)
Early in pregnancy T4 ↑, TSH ↓ ( within normal range).
HYPERTHYROIDISM Thyrotoxicosis and pregnancy Treatment Pregnancy outcome Thyroid storm and heart failure Effects on the neonate Neonatal thyrotoxicosis after
thyroid ablation
= %1 : 2000 of pregnanciesSymptoms in mild cases:
Tachycardia ↑ sleeping pulse rate Thyromegaly Exophthalmos No ↑ weight
Confirm diagnosis by: Free T4 ↑ TSH↓ Rarely T4 is normal, T3 is ↑
% =5 in old women In young women sometimes
excessive thyroxin treatment thyrotoxicosis.
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 .
Side effects:10% leukopenia do not stop ttt0.2% agranulocytosis stop treatment
Any sore throatstop treatment and do CBPDosage in nonpregnant:Propylthiouracil = 100 – 600 mg/dayMethimazole = 10 -- 40 mg/day
Dosage in pregnant: Propylthiouracil = 300 - 450 mg/day Methimazole = 10 - 40 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
Thyroidectomy:Indications:
Cannot adhere to oral ttt Toxicity from oral ttt
Dangers: ↑ vascularity give medical ttt before
surgery
2 % vocal cord palsy 3 % hypoparathyroidism
Pregnancy Outcome ↑ preeclampsia ↑ HFPerinatal mortality: 8 – 12 %
Thyroid storm: Rarely occur in untreated patients
due to a large functioning tumor .
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
Management in ICU :1 - Propylthiouracil:
Initial dose = 1 gm Orally Maintenance dose = 200mg /6hours
2 - After 1 hour Iodide to prevent T3T4
Supersaturated SKI = 5 drops/8hours Lugol solution = 10 drops/8hours
3 - If allergic to Iodine Lithium carbonate = 300 mg/day
Monitor S. lithium = 0.5 - 1.5mmol/L4 - Corticosteroides to further prevent T3T4
Dexamethasone = 2 mg/6 hours I.V 5 - β-blockers for symptoms
6 - Aggressive management of: HTN/infection/anemia
Effects on the neonate:May transient hyperthyroidism/hypothyroidismBoth fetal goiterThiourea drugs
Commonly not used during pregnancy although it extremely small risk (< 3%)
Case : Excessive propylthiouracilfetal hypothyroidism
at 28 weeks confirmed by CBS. Intera-amnionic injection of T4 at 35, 36, 37 weeks recovery.
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 .
SUBCLINICAL THYROTOXICOSIS
GTD
=free T4 normal, TSH ↓ %4 50% due to excessive T4 ttt
50% variable course 40% no thyrotoxicosisLong -term effects:
Cardiac arrhythmia/hypertrophy Osteopenia
If persistent ↓TSH follow up and monitor periodically
HYPOTHYROIDISM
=↓free T4, ↑ TSHRarely become pregnant infertileTreatment:Thyroxine: 50 - 100 μg/dayMonitoring: by TSH/ 4 - 6 weeksAim = T4 ≤ normal ↑↓ by 25 - 50 μgDuring pregnancy monitor: TSH/trimesterStudy: T4 requirement during pregnancy do not ↑ in 80%
SUBCLINICAL HYPOTHYROIDISM
Effects on the fetus and infant Radioiodine treatment Iodine deficiency Congenital hypothyroidism Preterm infants
=normal free T4 + ↑ TSH =5 % in women from 18 - 45 years
10 - 20% of them overt hypothyroidism 1 - 4 years later
Risk factors: TSH > 10 mU/L antimicrosomal antibodies
%↑in type 1 DMPregnancy outcome ↑ PTL + HTN
EFFECT ON THE FETUS AND INFANT:
In the past : no adverse effectsNow:T4 < 10th percentile impaired psychological developmentTSH >99.6th percentile↓school performance ↓ reading recognition
↓I.Q .Most cases are impending thyroid failure .
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
Iodine Deficiency endemic cretinism in endemic areas
20 million people with preventable brain damageIodine unsupplementation:
↑TSH to 19 mIU/mL # 9 ↑Neurological abnormalities to 9% #
3%
Congenital hypothyroidism = 1 : 4000 – 7000 infants
Usually missed Due to:
75 % thyroid agenesis 10 % thyroid hormonoagenesis 10 % transient hypothyroidism
Neonatal screening is mandatoryEarly ttt normal neurological development
Preterm fetuses May develop transient
hypothyroidism .Treatment unnecessary.
NODULAR THYROID DISEASE
-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%
Indications of biopsy of nonfunctioning nodules
<20 weeks: Solid nodule > 2 cm Cystic nodule > 4 cm Growing Lymphadenopathy
Course: indolent surgery can be postponedPregnancy outcome = same as none pregnantThyroidectomy < 24 - 26 weeks no PTL
POSTPARTUM THYROIDITIS
Propensity antedate pregnancyPrecipitated 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
Study : depression = 9 % at 6 months pp %in type I DM = 25%
Risk factors: Previous attach Personal history of autoimmune disease Family “”””””””””””””””””””””””””””””””””” ↓ iodineMany patients have thyroid antibodies before pregnancyPathophysiology:Viral infection immune activation autoantibodies disruption + lymphocytic thyroidites
Thyroid autoantibodies:1 - Microsomal autoantibodies:
% 7-10 early in pregnancy and pp
Study: = 20% < 13 weeks 17% spontaneous abortion
Characteristics : ↓ during pregnancy ↑ 4 - 6 months pp ↓ 10 - 12 months pp
2 - Peroxidase autoantibodies: % ↑of thyroid failure
Both identify women at high risk of thyroid failure
Clinical picture: Hyperthyroidism
Hypothyroidism %4% 2-5%
Occurrence pp 1 - 4 months 4 - 8 monthsSymptoms small painless goiter goiter, fatigue
fatigue, palpitation depression,↓concentration Cause disruption induced thyroid failure
hormone release Treatment β-blockers thyroxin 6-12 monthsFate 2/3 recovery 1/3 thyroid failure
1/3 hypothyroidism