Thyroid Disease Flashcards
What change in thyroid levels is hyperemesis associated with?
Sub clinical hyperthyroidism
High levels of free T4
Suppressed TSH
This relates to HCG being structurally similar to TSH, and having thyrotopic activity
What is the cause of relative iodine deficiency in pregnancy?
- Increased requirements
- active transport to the fetal-placental unit - Increase excretion in the urine
- increased GFR and decreased renal tubular absorption
How does the thyroid gland respond to iodine deficiency?
Thyroid gland hypertrophied in order to trap a sufficient amount of iodine
What are the clinical features of hyperthyroidism?
Heat intolerance, tachycardia, palpitations, palmar erythema, emotional lability, vomiting, goitre
Discriminatory features in pregnancy
- weight loss, tremor, persistent tachycardia, lid lag, exophthalmos
What is the effect of pregnancy on hyperthyroidism?
T1 - exacerbation due to hCG
T2 and T3 - State of relative immunosuppression
Puerperium - exacerbations due to reversal of the fall in antibody levels
What is a serious adverse effect of Propylthiouracil (PTU) ?
Liver failure
What is a teratogenic effect of carbimazole?
Aplasia cutis - Patches of absent skin, most commonly affecting the scalp
What are side effects of both carbimazole and PTU?
Neutropenia and agranulocyotisis
Women should be advised to report any signs of infection, and have an FBC
What ist he role of beta blockers in hyperthyroidism?
Improve sympathetic symptoms of tachycardia, sweating, tremor
Also reduce peripheral conversion of T4 into T3
What is the best time to perform a thyroidectomy in pregnancy?
What are three indications for such treatment?
Second trimester
Dysphagia or stridor related to a large goitre
Confirmed or suspected carcinoma
Failure of treatment of significant adverse reaction to both anti-thyroid drugs (e.g. agranulocytosis)
What is the risk of radioiodine therapy in pregnancy?
Fetal thyroid ablation and hypothyroidism
As the radioioidine is taken up by the fetal thyroid
What are the clinical features of neonatal / fetal thyrotoxicosis?
Tachycardia, irritability, jitteriness, poor feeding, goitre, hyperexcitability, hepatosplenomegaly, stare and eyelid retraction
Severe cases: congestive cardiac failure
What are clinical features of hypothyroidism?
Weight gain, lethargy, tiredness, Goitre
Hair loss, dry skin, constipation
Carpal tunnel syndrome, fluid retention
Discriminatory features in pregnancy: cold intolerance, slow pulse rate, delayed relaxation of the tendon
What is most common cause of hypothyroidism?
Hashimoto’s thyroiditis
What are the clinical features of cretinism?
What it its cause?
Deaf mutism, spastic motor disorder, hypothyroidism
Severe maternal iodine deficiency causing permanent brain damage
With a thyroid nodule, what are the features indicating malignancy?
Previous history of radiation to the neck or chest in childhood Fixation of the lump Rapid growth of a painless nodule Lymphadenopathy Voice change Horner’s syndrome
Raised thyroglobulin titre is suggestive of malignancy, as 90% of thyroid cancers secrete thyroglobulin
What is the increase in Vitamin D requirements in pregnancy?
50-100%
What are causes of hyperparathyroidism?
Parathyroid adenomas
Hyperplasia
What are clinical features of hyperparathyroidism?
BONES, STONES, GROANS AND PSYCHIATRIC MOANS.
Fatigue, thirst, hyperemesis, abdominal pain, osteopenia and fractures, constipation, depression/confusion,
Hypertension, renal calculi, pancreatitis
What is the fetal risk in hyperparathyroidism?
High maternal calcium levels
Suppress fetal PTH
Tetany and hypocalcaemia
What are the two most common causes of hypoparathyroidism?
- Complication of thyroid surgery
2. Autoimmune
Which women are at increased risk of Vit D deficiency?
Pigmented skin Covered Vegan diet Several pregnancies with short interdelivery interval Obesity Malabsorption AEDs, HAART or Rifampicin Renal or liver disease Alcohol abuse
What are the maternal clinical features of Vit D deficiency?
Bone loss, reduced weight gain Hypocalcaemia Osteomalacia Myopathy GDM HTN, PET SGA Increased risk of CS
What are the fetal risks of Vit D deficiency?
Adverse effect on fetal bone health
Reduced neonatal Ca +/- tetany
Childhood asthma / autopsy
Is screening for sub clinical hypothyroidism or TPO antibodies, and subsequent treatment with thyroxine recommended in pregnancy?
No
For women with a personal history of thyroid disease or symptoms of thyroid disease, what blood tests should they have on booking?
TSH
FT4
How is overt hypothyroidism in pregnancy diagnosed?
TSH above reference range with a decreased T4
OR
TSH > 10mIU / L (regardless of T4)
What physiological change in pregnancy leads to increased iodine clearance?
Increased renal blood flow and glomerular filtration rate
What are the pregnancy specific ranges for TSH?
Locally specific ranges should be used
T1 - 0.5mU less than non-pregnancy range
T2 and T3 - same as non-pregnant range
What are the maternal risks in overt hypothyroidism?
PET
Anaemia
PPH
Anovulation + Miscarriage
How do you identify pregnancies at risk of fetal thyrotoxicosis?
Previous or current maternal Graves’ disease with high TRab titres or levels that do not fall with advancing gestation.
Maternal TRab levels should be performed each trimester and at risk fetuses should undergo serial USS for assessment of fetal growth, fetal heart rate and fetal neck for goitre.
How long should neonatal thyrotoxicosis be treated?
How long should treatment continue for and why?
Neonatal thyrotoxicosis should be treated with anti-thyroid drugs ASAP. These are continued for a few weeks as maternal TRab are cleared the thyrotoxicosis will resolve.
