Endocrinology 2 Flashcards
(719 cards)
what are metabolic changes in pregnancy?
- increased erythropoietin, cortisol, noradrenaline
- high cardiac output
- plasma volume expansion
- high cholesterol and triglycerides
- pro thrombotic and inflammatory state
- insulin resistance
what are gestational syndromes of pregnancy?
- pre-eclampsia
- gestational diabetes
- obstetric cholestasis
- gestational thyrotoxicosis
- transient diabetes insipidus
- lipid disorders
- postnatal depression
- postpartum thyroiditis
- postnatal autoimmune disease
- paternal disease
what is the embryological development of the thyroid gland?
- fetal thyroid follicles and thyroxine synthesis occurs at 10 weeks
- axis matures at 15-20 weeks
- maternal T4 0-12 weeks regulates neurogenesis, migration and differentiation of fetal T4
what are glycoprotein hormones involved in thyroid/pregnancy?
- glycoprotein hormones contain two subunits, a common alpha subunit and a distinct beta subunit
- TSH, LH, FSH and hCG
what happens with thyroid hormone levels in the first trimester of pregnancy?
- increase in thyroxine and triiodothyronine, which results in inhibition of TSH due to a high hCG level that stimulates the TSH receptor due to partial structural similarity
- increased TBG
- increase then decrease in hCG
- increase then decrease in free T4
- decrease tehn increase in thyrotropin
what are levels of thyroid hormones like in the fetus throughout pregnancy?
increased TBG, total T4, thyrotropin, free T4, total T3, free T3 (in order of most increased to least increased levels)
what is responsible for higher thyroxine requirements in pregnancy?
- large plasma volume and thus an altered distribution of thyroid hormone
- increased thyroid hormone metabolism
- increased renal clearance of iodide
- higher levels of hepatic production of TBG in the hyperestrogenic state of pregnancy
what produces thyroxine binding globulin (TBG)?
liver
what is the incidence of hypothyroidism in pregnancy?
- 2-3%
- overt hypothyroidism 0.3-0.5% in pregnancy
- subclinical hypothyroidism 2-3%
what are symptoms of hypothyroidism in pregnancy?
weight gain, cold intolerance, poor concentration, poor sleep pattern, dry skin, constipation, tiredness
what are the ATA guidelines for TSH levels during the pregnancy?
1st trimester: 0.1-2.5mIU/L 2nd trimester: 0.2-3.0mIU/L 3rd trimester: 0.3-3.0mIU/L - 4 weekly for 20 weeks gestation - again 26-32 weeks
25-30% increase if miss period and no recent test
urgent blood test and review
ATA 2017 ULL ~4.0mIU/L
how does hypothyroidism affect pregnancy?
- inadequate treatment
- gestational hypertension
- placental abruption
- post partum haemorrhage
- low birth weight
- preterm delivery
- neonatal goitre and respiratory distress
what is the treatment for hypothyroidism in pregnancy?
- preconception counselling; ideal preconception TSH <2.5mIU/L
- increase dose by 30%
- arrange TFT early pregnancy and titrate
- women require a dose increase in their thyroxine during pregnancy
- if overt in pregnancy, aim to normalise asap
- commence at 50-100mcg, measure TFT at 4-6 weeks
when is targeted screening done for thyroid problems in pregnancy?
- age >30
- BMI >40
- miscarriage preterm labour
- personal or family history
- goitre
- anti TPO
- T1DM
- head and neck irradiation
- amiodarone, lithium or contrast use
what is the prevalence of hyperthyroidism in pregnancy? what are some causes?
0.1-0.4% prevalence
female population 2%
85-90% due to Graves’
less common causes: MNG, gestational thyrotoxicosis, toxic adenoma, trophoblastic neoplasia, TSHoma
how does hyperthyroidism affect pregnancy?
- IUGR
- low birth weight
- preeclampsia
- preterm delivery
- risk of stillbirth
- risk of miscarriage
how does pregnancy affect hyperthyroidism?
- tends to worsen in first trimester
- improves latter half of pregnancy
what is the management of hyperthyroidism in pregnancy?
- symptomatic treatment; beta blockers
- anti-thyroid medications
- PTU/carbimazole
- radioactive iodine is contraindicated
- surgical interventions; optimal timing is 2nd trimester
what are effects of carbimazole and propylthiouracil on pregnancy?
carbimazole
- increased risk of congenital abnormalities
- aplasia cutis
- choanal atresia
- intestinal anomalies
propylthiouracil
- rare hepatotoxicity
what is fetal thyrotoxicosis?
transplacental crossover of TSH-R antibodies
- 0.01% of cases
- anti-thyroid medications
what is fetal thyrotoxicosis associated with?
- IUGR
- fetal goitre
- fetal tachycardia
- fetal hydrops
- preterm delivery
- fetal demise
what are the causes of gestational thyrotoxicosis?
- limited to first half of the pregnancy
- raised T4, low/suppressed TSH
- absence of thyroid autoimmunity
- associated with hyperemesis gravidarum
- 5-10 cases/1000 pregnancies
- multiple gestation
- hydatidaform mole
- hyperplacentosis
- choriocarcinoma
what are the issues of gestational thyrotoxicosis?
- benefits of treating
- hyperemesis gravidum
- extreme; Wernicke’s encephalopathy
- thyrotoxicosis risks
what is the prevalence of post-partum thyroiditis?
7%