Doença tiroideia e gravidez

Question 1

TSH

Answer 1

• TSH (Thyroid Stimulating Hormone), synthesised by the adenohypophysis, promotes the synthesis of thyroid hormones T3 (Triiodothyronine) and T4 (Thyroxine)
• T4 and T3 are carried in the blood mostly bound to TBG (Thyroxine Binding Globulin), with < 1% circulating freely
• Thyroid hormones interfere with cell metabolism and affect almost every physiological process in the body

Question 2

Patologia tiroideia gravidez

Answer 2

• 2nd most common endocrine pathology in Pregnancy

- In the fetus, thyroid hormones are fundamental for neurocognitive development

Question 3

Fisiologia placentar

Answer 3

• Thyroid hormones are required for brain and CNS development in the fetus.
• During the 1st T it relies on maternal thyroid hormones
• From 12 weeks on, the fetal thyroid gland starts functioning but it remains dependent upon maternal ingestion of iodine
• Placenta:
  o Impermeable to maternal TSH
  o Slightly permeable to maternal hormones T4 and T3
  o Permeable to iodine, drugs, and antibodies

Question 4

Alt fisio materna

Answer 4

• Aum prod de TBG (devido a estrogénio)
• TBG aum -> aum concentração total de T4
• Prod aum hCG (tem função TSH-like)-> Inibe secreção materna de TSH e o nível de T4 fica inalterado
• Increase in thyroid size due to gland hyperplasia and increased vascularization.

Question 5

Iodo e Gravidez

Answer 5

• Decreased plasma levels due to:
  1. Greater consumption-> increased synthesis of thyroid hormones
  2. Greater losses due to:
  o Increased renal clearance
  o Increased utilization by the fetus – autonomous production
• Spot urinary iodine levels are used most frequently for determination of iodine status populations
  o Normal: 149-249microg/l
• Só 17% mulheres em PT tem niveis normais

Suplemento:

1. Supplementation with recommended daily dose of 150μg/day
2. Usar na PRECONCEÇÃO (150), GRAVIDEZ (250), AMAMENTAÇÃO (250)
3. Food items with iodine: fish, shellfish, fruits and vegetables, milk and its derivatives, eggs, bread

Question 6

Avaliação função tiroideia

Answer 6

Plasma T4 and T3 aum na 1ª metade da gravidez-> plateau nas 20 sem

• Aum TBG (estrogenios no figado) -> Aum T4 e T3

Question 7

Desafios dx na gravidez

Answer 7

• Higher plasma levels of thyroid hormones
• Increased thyroid size
• Overlapping symptoms:

o Tiredness, asthenia, increased body weight, constipation (Hypo)
o Intolerance to heat, greater appetite, sweating, tachycardia (Hyper)

Question 8

LAB

Answer 8

• Hipotiroidismo: TSH aum, T4 livre baixa
• Hipo subclinico: TSH aum, T4 livre N
• Hipertiroidismo: TSH baixa, T4 livre aum
• Hiper subclinico: TSH baixa, T4 livre N

Niveis normais TSH:
o 1 trim:0,1-2,5 mU/L
o 2 trim: 0,2-3 mU/L
o 3 trim: 0,3-3 mU/L

Question 9

Hipotiroidismo

Answer 9

• Prevalence 2-3%
• Clinical hypothyroidism: 0,3 to 0,5%
• Subclinical hypothyroidism: 2 to 3% gestations
• MAIOR NAS MULHERES GRAVIDAS COM DM INSULINO DEP
• Causas:
  o Hashimoto’s thyroiditis or chronic autoimmune (antithyroid antibodies)
  o Previous gland removal and insufficient compensation

- Sinais e sintomas:
o Asthenia 
o Somnolence 
o Constipation 
o Cramps
o Paraesthesia 
o Intolerance to cold
o Body weight increase 
o Dry skin and hair loss

• Sinais e sintomas parecidos com gravidez normal
• Tx:
  o Levothyroxine with dose adjusted according to TSH levels (follow-up endocrino)

o Between 50 and 85% of LT4 - treated hypothyroid women need to increase exogenous levothyroxine during pregnancy
o Previous therapy – increase of 30-50%
o The requirements increase from 20 weeks
o After delivery – dose re-evaluation after 6 weeks

• Inappropriate therapy -> greater risk for the mother and the fetus:
  o Abortion or fetal death
  o Pre-eclampsia, Placental abruption
  o Fetal growth restriction
  o Prematurity and low birth weight
  o Congenital defect
  o Cognitive deficit – mental retardation - cretinism

Question 10

Hipertiroidismo

Answer 10

• Prevalence: 0,1-0,4% of gestations

- Causas:
o Graves’ disease (≈ 95%)
o Thyrotoxicosis induced by hCG 
o Transitional gestational hyperthyroidism (1st half pregnancy; T4l #)
o Hyperthyroidism associated with tumours of trophoblast 
o Bocio (uni/multinodular)
o Toxic adenoma 
o Subacute thyroiditis 
o Hyperthyroidism induced by iodine 
o Carcinoma (rare)

- Sintomas:
o Asthenia 
o Anxiety/palpitations 
o Heat intolerance 
o Diaphoresis 
o Weight loss/lack of weight gain 
o Exophthalmia/edema pre-tibial (rare)
- Difficult diagnosis because signs and symptoms overlap with those of pregnancy itself

• It is recommended a normal state of the thyroid (euthyroid) 3 months before pregnancy -> Pregnancy should be postponed until a stable, euthyroid state is reached
  o 2 sets of thyroid function test within the reference range, at least 1 month apart, and with no change in therapy between tests
• DX:
  o TSH <0,1 e T4/T3 L aum ou N (subclinico)
  o Anticorpos estimuladores tiroide pos (Graves)
• TX:
  o Keep mother’s disease under control
  o No interference upon normal development of fetal thyroid
• Graves’ disease - medical therapy (1st line therapy)
  o Raro cirurgia (2 trim)
  o Objetivo manter T4L no limite superior ou um pouco acima
• Inibidores hormona tiroideia
  o Propylthiouracil – in the 1st T (risk of hepatotoxicity)
  o Methimazole – from the 2nd T (several types of congenital malformations)
• EA para o feto tx:
  o Cutaneous rash, hepatitis, thrombocytopenia, agranulocytosis
  o Transitional hypothyroidism or neonatal goiter
  o Aplasia cutis- ausencia de uma porção de pele (methimazole)
• RECOMENDAÇÕES:
  o Use the smallest dose possible (acts upon thyroids of both mother and fetus)
  o Avoid overmedication
  o In the 2nd and 3rd T usually Dim dose (sintomas atenuados)
  o Symptomatic therapy with beta blockers.

Question 11

Tiroidite pos parto

Answer 11

• Prevalence: 5-10% (1,1-16,7%)
• Higher prevalence in DM1, Antibody antiperoxidase +
• High recurrence (80%) in future pregnancies
• Hx natural
  o Thyroid dysfunction, excluding Graves’ disease, in the first postpartum year in women who were euthyroid prior to pregnancy -> Variable outcome in 1st year after delivery
  o 25% Classical form -> Transient thyrotoxicosis -> transient hypoT -> euthyroid state
  o 25% Isolated thyrotoxicosis
  o 50% Isolated hypothyroidi
• TX:
  o Sintomatico
• Follow-up
  o Post partum thyroid risk ↑ in future gestations
  o Potential conversion into Hypothyroidism
  o Women with a prior history of PPT should have TSH testing annually to evaluate the risk of permanent hypothyroidism