CBL - Thyroid Disease

Question 1

What are the differential diagnoses for hyperthyroidism/thyrotoxicosis? [8]

Answer 1

1. Graves’ disease with thyrotoxicosis,
2. Thyroiditis with thyrotoxicosis,
3. Toxic multi-nodular goitre with thyrotoxicosis ,
4. Transient gestational thyrotoxicosis,
5. Phaeochromocytoma,
6. Carcinoid syndrome,
7. Alcohol dependence/withdrawal
8. Substance misuse

Question 2

Define thyrotoxicosis [1] and hyperthyroidism [1]

Answer 2

1. Thyrotoxicosis:
   
   • syndrome resulting from excessive free thyroxine (fT4) and or free tri-iodothyronine (fT3)
2. Hyperthyroidism:
   
   • refers to thyroid over-activity resulting in thyrotoxicosis

Question 3

What are the symptoms of thyrotoxicosis (of any cause)? [11]

Answer 3

1. weight loss
2. increased appetite
3. tremor
4. oligomenorrhoea
5. polyuria
6. weakness
7. fatigue
8. diarrhoea
9. insomnia
10. anxiety
11. heat intolerance (prefer the cold)

Question 4

What are the symptoms of phaeochromocytoma? [8]

Answer 4

1. episodic sweating
2. heat intolerance
3. pallor
4. feelings of apprehension/anxiety
5. episodic or sustained hypertension
6. palpitations
7. chest pain
8. dyspnoea

Question 5

What are the 2 typical symptoms associated with carcinoid syndrome? [2]

Answer 5

1. flushing
2. diarrhoea

Question 6

What investigations would you do in a patient with possible thyroxtoxicosis? [9]

Answer 6

1. Thyroid function tests
2. Thyroid autoantibodies
   
   • Thyroid receptor Ab
   • Thyroid peroxidase Ab
3. Pregnancy test
4. FBC/ESR (erythrocyte sedimentation rate) → may be elevated in thyroiditis
5. 24hr urine collection for metanephrines → to exclude phaeochromocytoma
6. 24hr urine collection for 5-HIAA (breakdown product of serotonin) → to exclude carcinoid syndrome
7. Liver function tests → abnormal in alcohol excess
8. Urine toxicology → if substance misuse is suspected
9. Thyroid scintigraphy scanning (nuclear imaging)

Question 7

What is the diagnosis based on the thyroid scintigraphy below and how do you know? [2]

Answer 7

Grave’s disease

• diffuse uptake with suppression of background activity

Question 8

What is the diagnosis based on the thyroid scintigraphy below and how do you know? [2]

Answer 8

multi-nodular goitre

• irregular uptake

Question 9

What is the diagnosis based on the thyroid scintigraphy below and how do you know? [2]

Answer 9

toxic adenoma

• hot nodule

Question 10

What is the diagnosis based on the thyroid scintigraphy below and how do you know? [2]

Answer 10

thyroiditis (e.g. viral)

• reduced uptake

Question 11

What are the treatment options for Grave’s disease?

Answer 11

1. Beta blockers (e.g. propranolol)
   
   • can be used to improve symptoms whilst anti-thyroid medication becomes effective
2. Carbimazole or Propylthiouracil
   
   • usually carbimazole is used but PTU used if pregnancy planned or during the 1st trimester
3. radioactive iodine
4. subtotal/total thyroidectomy

Question 12

Describe the 2 types of regimens used in terms of drug therapy for Grave’s disease? [6]

Answer 12

1. Reducing Regimen
   
   • where higher doses are started at initiation of treatment (e.g. 40mg of Carbimazole)
   • then as the patient becomes euthyroid the dose is reduced, maintaining a euthyroid state
2. Block and Replace
   
   • Commence with blocking medication e.g. 4mg of Carbimazole
   • then when patient is euthyroid add in thyroxine.
   • Smoother biochemical control, ideal where there is concern of hypothyroidism with thyroid eye disease.
   • Avoid in pregnancy.

Question 13

What are the potential complications of a sub-total/total thyroidectomy that must be taken into account? [3]

Answer 13

1. hypothyroidism,
2. hypocalcaemia,
3. recurrent laryngeal nerve palsy

Question 14

What are the differential diagnoses for hypothyroidism? [3]

Answer 14

1. anaemia
2. depression
3. hypoadrenalism

Question 15

What are the signs [6] and symptoms [7] of hypothyroidism?

Answer 15

• Symptoms:
  
  1. tiredness,
  2. weight gain,
  3. cold intolerance (prefer warmth),
  4. constipation,
  5. myalgia,
  6. carpal tunnel syndrome
  7. menorrhagia
• Signs:
  
  1. excess weight,
  2. thick coarse facial features,
  3. dry skin,
  4. fine, brittle hair
  5. loss of the outer eyebrows.
  6. delayed relaxation of ankle and other deep tendon reflexes

Question 16

How does anaemia typically present [4] and how would you confirm a diagnosis of anaemia? [1]

Answer 16

1. Presentation:
   
   • fatigue,
   • reduced exercise tolerance
   • feeling cold
   • look pale
2. Confirm diagnosis with blood test (FBC)

Question 17

What investigations would you do in a patient with possible hypothyroidism? [4]

Answer 17

1. Thyroid function tests
2. Thyroid autoantibodies (Ab)
   
   • Thyroid peroxidase (TPO Ab): positive
3. FBC
   
   • rule out anaemia
4. 9am Cortisol
   
   • assess adrenal reserve
   • rule out hypoadrenalism

Question 18

How do you treat hypothyroidism? [1]

Answer 18

1. Thyroid hormone replacement: levothyroxine
   
   • usually starting at 50-100mcg
   • 25mcg where there is a concern of ischaemicheart disease) and titrating in 25mcg increments aiming for a normal TSH