Thyroid Disease

Question 1

What change in thyroid levels is hyperemesis associated with?

Answer 1

Sub clinical hyperthyroidism

High levels of free T4
Suppressed TSH

This relates to HCG being structurally similar to TSH, and having thyrotopic activity

Question 2

What is the cause of relative iodine deficiency in pregnancy?

Answer 2

1. Increased requirements
   - active transport to the fetal-placental unit
2. Increase excretion in the urine
   - increased GFR and decreased renal tubular absorption

Question 3

How does the thyroid gland respond to iodine deficiency?

Answer 3

Thyroid gland hypertrophied in order to trap a sufficient amount of iodine

Question 4

What are the clinical features of hyperthyroidism?

Answer 4

Heat intolerance, tachycardia, palpitations, palmar erythema, emotional lability, vomiting, goitre

Discriminatory features in pregnancy
- weight loss, tremor, persistent tachycardia, lid lag, exophthalmos

Question 5

What is the effect of pregnancy on hyperthyroidism?

Answer 5

T1 - exacerbation due to hCG
T2 and T3 - State of relative immunosuppression
Puerperium - exacerbations due to reversal of the fall in antibody levels

Question 6

What is a serious adverse effect of Propylthiouracil (PTU) ?

Answer 6

Liver failure

Question 7

What is a teratogenic effect of carbimazole?

Answer 7

Aplasia cutis - Patches of absent skin, most commonly affecting the scalp

Question 8

What are side effects of both carbimazole and PTU?

Answer 8

Neutropenia and agranulocyotisis

Women should be advised to report any signs of infection, and have an FBC

Question 9

What ist he role of beta blockers in hyperthyroidism?

Answer 9

Improve sympathetic symptoms of tachycardia, sweating, tremor

Also reduce peripheral conversion of T4 into T3

Question 10

What is the best time to perform a thyroidectomy in pregnancy?

What are three indications for such treatment?

Answer 10

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)

Question 11

What is the risk of radioiodine therapy in pregnancy?

Answer 11

Fetal thyroid ablation and hypothyroidism

As the radioioidine is taken up by the fetal thyroid

Question 12

What are the clinical features of neonatal / fetal thyrotoxicosis?

Answer 12

Tachycardia, irritability, jitteriness, poor feeding, goitre, hyperexcitability, hepatosplenomegaly, stare and eyelid retraction
Severe cases: congestive cardiac failure

Question 13

What are clinical features of hypothyroidism?

Answer 13

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

Question 14

What is most common cause of hypothyroidism?

Answer 14

Hashimoto’s thyroiditis

Question 15

What are the clinical features of cretinism?

What it its cause?

Answer 15

Deaf mutism, spastic motor disorder, hypothyroidism

Severe maternal iodine deficiency causing permanent brain damage

Question 16

With a thyroid nodule, what are the features indicating malignancy?

Answer 16

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

Question 17

What is the increase in Vitamin D requirements in pregnancy?

Answer 17

50-100%

Question 18

What are causes of hyperparathyroidism?

Answer 18

Parathyroid adenomas

Hyperplasia

Question 19

What are clinical features of hyperparathyroidism?

Answer 19

BONES, STONES, GROANS AND PSYCHIATRIC MOANS.
Fatigue, thirst, hyperemesis, abdominal pain, osteopenia and fractures, constipation, depression/confusion,
Hypertension, renal calculi, pancreatitis

Question 20

What is the fetal risk in hyperparathyroidism?

Answer 20

High maternal calcium levels
Suppress fetal PTH
Tetany and hypocalcaemia

Question 21

What are the two most common causes of hypoparathyroidism?

Answer 21

1. Complication of thyroid surgery

2. Autoimmune

Question 22

Which women are at increased risk of Vit D deficiency?

Answer 22

Pigmented skin
Covered
Vegan diet
Several pregnancies with short interdelivery interval
Obesity
Malabsorption
AEDs, HAART or Rifampicin 
Renal or liver disease
Alcohol abuse

Question 23

What are the maternal clinical features of Vit D deficiency?

Answer 23

Bone loss, reduced weight gain
Hypocalcaemia
Osteomalacia
Myopathy
GDM
HTN, PET
SGA
Increased risk of CS

Question 24

What are the fetal risks of Vit D deficiency?

Answer 24

Adverse effect on fetal bone health
Reduced neonatal Ca +/- tetany
Childhood asthma / autopsy

Question 25

Is screening for sub clinical hypothyroidism or TPO antibodies, and subsequent treatment with thyroxine recommended in pregnancy?

Answer 25

No

Question 26

For women with a personal history of thyroid disease or symptoms of thyroid disease, what blood tests should they have on booking?

Answer 26

TSH

FT4

Question 27

How is overt hypothyroidism in pregnancy diagnosed?

Answer 27

TSH above reference range with a decreased T4
OR
TSH > 10mIU / L (regardless of T4)

Question 28

What physiological change in pregnancy leads to increased iodine clearance?

Answer 28

Increased renal blood flow and glomerular filtration rate

Question 29

What are the pregnancy specific ranges for TSH?

Answer 29

Locally specific ranges should be used

T1 - 0.5mU less than non-pregnancy range
T2 and T3 - same as non-pregnant range

Question 30

What are the maternal risks in overt hypothyroidism?

Answer 30

PET
Anaemia
PPH

Anovulation + Miscarriage

Question 31

How do you identify pregnancies at risk of fetal thyrotoxicosis?

Answer 31

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.

Question 32

How long should neonatal thyrotoxicosis be treated?

How long should treatment continue for and why?

Answer 32

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.