DIABETES, ENDO, CLINCIAL BIOCHEMISTRY

Question 1

Myasthenia Gravis

What cancer can Myasthenia Gravis cause?

Answer 1

Thymomas

Question 2

Myasthenia Gravis

Describe what is Myasthenia Gravis and the key features?

Answer 2

1. Myasthenia gravis is an autoimmune disorder resulting in insufficient functioning acetylcholine receptors. Antibodies to acetylcholine receptors are seen in 85-90% of cases*
2. More common in women
   Key Features:
3. muscle fatigability - muscles become progressively weaker during periods of activity and slowly improve after periods of rest:
   * 2. extraocular muscle weakness: diplopia
   * proximal muscle weakness: face, neck, limb girdle
   * ptosis
   * dysphagia

Question 3

Myasthenia Gravis

Describe other clinical associations with Myasthenia Gravis and what investigations would be carried out?

Answer 3

1. Thymoma in 15%
2. Autoimmune disorders: Pernicous Anaemia, Rheumathoid, SLE, Autoimmune thyroid disorders
   Investigations:
3. single fibre electromyography: high sensitivity (92-100%)
4. CT thorax to exclude thymoma
5. CK normal
6. antibodies to acetylcholine receptors
   positive in around 85-90% of patients (remaining patients: + for anti-muscle-specific tyrosine kinase antibodies)
7. Tensilon Test: IV endrophonium reduces muscle weakness temporarily (Not commonly used-risk of arrhythmia)

Question 4

Myasthenia Gravis

Describe the management process for Myasthenia Gravis and a Myasthenic Crisis?

Answer 4

1. Long-Acting Acetylcholinesterase Inhibitors (PYRIDOSTIGMINE-1st line)
2. Immunosuppression: not at start of diagnosis- eventually required in addition to long-acting acetylcholinesterase inhibitors» PREDNISOLONE initially» azathioprine, cyclosporine and mycophenolate mofetil maybe used
3. Thymectomy
   Myasthenic Crisis:
4. Plasmapheresis
5. IV Immunoglobulins