ENDOCRINE DISORDERS-THYROID DISORDERS 1.2 (AB) Flashcards
What is the primary imaging method for measuring fetal thyroid volume?
Sonography
What are the fetal complications of hypo- or hyperthyroidism?
Hydrops, growth restriction, goiter, and tachycardia
When should umbilical cord sampling be considered for fetal thyroid assessment?
When fetal goiter is present and fetal thyroid status is unclear
What is thyroid storm?
A hypermetabolic, life-threatening condition in pregnancy
What cardiovascular complications are associated with thyrotoxicosis?
Pulmonary hypertension, cardiomyopathy, and heart failure
Why are pregnant women with thyrotoxicosis at risk for cardiac decompensation?
Minimal cardiac reserve, worsened by preeclampsia, anemia, or sepsis
What is hyperthyroidism?
A condition of accelerated thyroid hormone biosynthesis and secretion
What is thyrotoxicosis?
A clinical syndrome caused by elevated free thyroxine (FT4) and/or triiodothyronine (FT3) levels
What is thyroid storm often precipitated by?
Surgery, trauma, or infection
Where should thyroid storm management be carried out?
In an intensive care area within labor and delivery
What are the first-line medications for thyroid storm management?
Beta-blockers (propranolol, labetalol, esmolol), iodine, and corticosteroids
What is gestational transient thyrotoxicosis?
Hyperthyroidism due to TSH-receptor stimulation from hCG
Are antithyroid drugs warranted in gestational transient thyrotoxicosis?
No
What percentage of women with molar pregnancy have elevated T4 levels?
25-65%
What causes hyperthyroidism in gestational trophoblastic disease?
Excess hCG overstimulating the TSH receptor
What happens to serum free T4 levels after molar evacuation?
They rapidly return to normal, paralleling declining hCG concentrations
What laboratory finding defines subclinical hyperthyroidism?
Low TSH with normal T4 levels
What are the long-term effects of persistent subclinical thyrotoxicosis?
Osteoporosis, cardiovascular morbidity, progression to overt thyrotoxicosis
Is subclinical hyperthyroidism associated with adverse pregnancy outcomes?
No
Should subclinical hyperthyroidism be treated in pregnancy?
No, unless periodic surveillance indicates a need
What are common symptoms of hypothyroidism?
Fatigue, constipation, cold intolerance, muscle cramps, weight gain
What are two major causes of hypothyroidism?
Iodine deficiency and Hashimoto’s thyroiditis
What physical exam findings are associated with hypothyroidism?
Enlarged thyroid, edema, dry skin, hair loss, prolonged relaxation phase of DTRs
What defines overt hypothyroidism?
High TSH and low T4 levels
What defines subclinical hypothyroidism?
High TSH with normal T4 levels
What is the most common cause of hypothyroidism in pregnancy?
Hashimoto’s thyroiditis
How does Hashimoto’s thyroiditis cause glandular destruction?
Autoantibodies (anti-TPO) attack the thyroid
What treatment results in post-ablative hypothyroidism?
Radioactive iodine (RAI) ablation or thyroidectomy
How is hypothyroidism treated?
Levothyroxine (LT4) replacement therapy
What is the usual starting dose of levothyroxine in pregnancy?
1-2 µg/kg/day or 100 µg daily
Why do athyreotic patients require higher doses of levothyroxine?
They lack functional thyroid tissue
How often should TSH be monitored in pregnancy?
Every 4 weeks in the first half, once in the third trimester
How should levothyroxine dosing be adjusted in pregnancy?
Increase by 25-50 µg increments to maintain TSH ~2.5 mU/L
How does pregnancy affect levothyroxine requirements?
Estrogen increases demand, requiring higher doses
What are potential complications of overt hypothyroidism in pregnancy?
Infertility, miscarriage, adverse perinatal outcomes
How does iodine deficiency affect fetal thyroid function?
Leads to maternal and fetal hypothyroidism
Can maternal TPO and anti-thyroglobulin antibodies affect fetal thyroid function?
No, they have little to no effect
What is the prevalence of fetal hypothyroidism in mothers with Hashimoto’s thyroiditis?
1 in 80,000 newborns
What factors influence the prevalence of subclinical hypothyroidism?
Age, race, dietary iodine intake, and serum TSH thresholds.
What factors affect the progression of subclinical hypothyroidism to overt thyroid failure?
TSH level, age, diabetes, and presence/concentration of antithyroid antibodies.
What did Diez and Iglesias (2004) find regarding TSH normalization in subclinical hypothyroidism?
Some TSH values became normal over 5 years.
What is the progression rate to overt hypothyroidism for TSH levels between 10-15 mU/L?
19 per 100 patient years.
What is the progression rate to overt hypothyroidism for TSH levels less than 10 mU/L?
2 per 100 patient years.
What initial TSH level predicts overt hypothyroidism within 5 years in nonpregnant patients?
TSH >10 mU/L.
What percentage of women developed thyroid disease in a 20-year follow-up of subclinical hypothyroidism during pregnancy?
0.03
What percentage of women with subclinical hypothyroidism and thyroid antibodies developed thyroid disease in 20 years?
0.17
How likely is the progression of subclinical hypothyroidism to overt hypothyroidism during pregnancy?
Unlikely in otherwise healthy women.
What did 1999 studies by Haddow and Pop highlight?
Maternal thyroid dysfunction impacts fetal neuropsychological development.
What pregnancy complications are associated with subclinical hypothyroidism (Casey et al., 2005)?
Preterm birth, placental abruption, NICU admissions.
What did Cleary-Goldman et al. (2008) conclude about subclinical hypothyroidism and pregnancy outcomes?
No significant association with adverse outcomes.
What risks are linked to subclinical thyroid dysfunction (Chen, 2017; Maraka, 2016)?
Adverse pregnancy outcomes.
What increased risk was found in 24,883 women with subclinical hypothyroidism (Wilson et al., 2012)?
2x greater risk of severe preeclampsia.
How does rising TSH affect gestational diabetes risk (Tudela et al., 2012)?
Increases the risk.
What adverse outcomes are linked to subclinical hypothyroidism (Nelson et al., 2014)?
Increased risks of diabetes and stillbirth.
What did the CATS Study (Lazarus et al., 2012) conclude about prenatal thyroid screening?
No improvement in offspring IQ at ages 3 and 9.
What did the MFMU Network study (Casey et al., 2017) conclude about thyroxine therapy for subclinical hypothyroidism?
No difference in pregnancy outcomes or child cognitive development.
What is the current recommendation for routine prenatal thyroid screening?
Not recommended for all women, only for high-risk women.
What conditions warrant thyroid screening in pregnancy?
Personal/family history of thyroid disease, thyroid dysfunction symptoms, autoimmune disorders.
How is isolated maternal hypothyroxinemia (IMH) defined?
Low free T4 with normal TSH levels during pregnancy.
What is the incidence of IMH in large trials?
1.3%–2.1%.
How does IMH differ from subclinical hypothyroidism?
IMH has a low prevalence of antithyroid antibodies.
What early findings suggested neurodevelopmental impacts of IMH?
Cognitive and developmental delays (Pop, 1999, 2003; Li, 2010; Levie, 2018).
What did Casey et al. (2007) find about IMH and perinatal risks?
No significant increase in perinatal risks compared to euthyroid women.
What did the Consortium on Thyroid and Pregnancy (2019) find about IMH?
Higher risk of preterm birth.
What did the CATS Study (Lazarus et al., 2012; Hales et al., 2018) conclude about thyroxine treatment in pregnancy?
No improvement in neurodevelopmental outcomes in children.
What did the MFMU Network study (Casey et al., 2017) find regarding IMH treatment?
No benefit in pregnancy outcomes or child cognitive development.
What is the consensus on treating IMH during pregnancy?
Routine treatment is not recommended.
What organizations recommend targeted thyroid screening in pregnancy?
American Thyroid Association (2017), Endocrine Society (2017), ACOG (2020).
What is euthyroid autoimmune disease?
Autoimmune attack on thyroid with normal thyroid function.
What antibodies are associated with euthyroid autoimmune disease?
Anti-TPO and Anti-Tg antibodies.
What pregnancy risks are linked to euthyroid autoimmune disease?
Early pregnancy loss, preterm birth.
What did Negro (2006) find about levothyroxine in euthyroid autoimmune disease?
Reduced preterm birth risk from 22% to 7%.
What iodine deficiency risks exist during pregnancy?
Lower fetal IQ, thyroid dysfunction.
What are the recommended daily iodine intake levels during pregnancy?
220–250 µg/day.
What percentage of Filipinos have thyroid dysfunction?
8.53% (higher in women, ratio 1.6:1).
What is the primary cause of congenital hypothyroidism?
Thyroid gland developmental disorders (agenesis, hypoplasia).
What is the key treatment for congenital hypothyroidism?
Early aggressive thyroxine replacement.
What is postpartum thyroiditis?
Transient autoimmune thyroiditis occurring within the first year postpartum.
What phases occur in postpartum thyroiditis?
Thyrotoxicosis (early) and hypothyroidism (late).
What is the risk of permanent hypothyroidism after postpartum thyroiditis?
20%-30%.
What is nodular thyroid disease?
Thyroid mass without hyper- or hypothyroidism.
What is the malignancy risk of solitary thyroid nodules?
90-95% are benign.
What imaging is used to evaluate thyroid nodules in pregnancy?
Ultrasound.
When is thyroidectomy recommended for malignancy in pregnancy?
Second trimester or postpartum if non-aggressive.
What is the function of parathyroid hormone?
Regulates serum calcium levels.
What is the main cause of hyperparathyroidism in pregnancy?
Parathyroid adenoma.
What symptoms indicate hyperparathyroidism?
Weakness, renal calculi, psychiatric issues.
What is the treatment for symptomatic hyperparathyroidism in pregnancy?
Surgical removal of adenoma.
What is hypoparathyroidism?
Deficiency of parathyroid hormone leading to hypocalcemia.
What symptoms occur in hypoparathyroidism?
Tetany, muscle cramps, seizures.
What is the main treatment for hypoparathyroidism?
Calcium and vitamin D supplementation.
What is pregnancy-associated osteoporosis?
Bone loss during pregnancy leading to fractures.
What factors increase the risk of pregnancy-associated osteoporosis?
Low BMI, multiple pregnancies, breastfeeding.
