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Autoimmune disorders
Hashimoto’s Disease
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Mainly affecting women (80% of cases)
Symptoms
o Weight loss associated with lower metabolism
o Formation of goitre
o Difficulty getting pregnant
Caused by autoimmune attack by antibodies against thyroid peroxidase, TSH
receptors, thyroglobulin and Sodium/Iodide importer
Genetically linked disease – cytotoxic T-lymphocyte antigen-4 polymorphism
Diagnosis by blood test for T 4 , TSH and antibodies
Treatment – synthetic replacement of T 3 and T 4 (levothyroxine)

Graves’ disease
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Weight loss, muscle tremors, excessive sweating, bulging eyes, goitre
Hyperthyroidism caused by autoimmune activation by antibodies against thyroid
peroxidase, TSH receptors, thyroglobulin and Sodium/Iodide importer
Genetically linked disease – human leukocyte antigen DR 3 polymorphism
Diagnosis – bulging eyes (exopthalmos), high T 4 , low TSH in blood, antibodies in
blood
Treatment – radioiodine, carbimazole/methimazole (antithyroid drugs – block
coupling of iodides with tyrosines in glands), β-blockers to reduce tachycardia and
other cardiac symptoms

Addison’s disease
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Low blood pressure, sodium and glucose, darkening of the skin
Loss of function of the adrenal glands, low adrenal cortical hormone levels, high
ACTH levels, Adrenal crisis – life threatening loss of function
Genetically linked disorder – genes poorly understood
Antibodies destroy 21β-hydroxylase (enzyme required for biosynthesis of steroid
hormones)
Genetic mutation of ACTH receptor reducing gland response
Tuberculosis induced – in response to rifampicin antibiotic treatment which is
broken down by P 450 s
Causes over activation of cytochrome P 450 CYP 3 A 4 which breaks down steroid
hormones

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Diagnosis by tests for cortisol release response after tetracosactide treatment
(synthetic ACTH) by blood test
Treatments – glucocorticoid hormone replacement, hydrocortisone, prednisone
and prednisolone

Myasthenia Gravis
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Most commonly antibodies target nicotinic acetylcholine receptors at neuromuscular
junction
Less commonly antibodies bind to muscle specific kinase (MuSK)
MuSK is involved in clustering and targeting of nicotinic receptors to the
postsynaptic membrane
Prevents action potentials from causing muscle contraction
Symptoms – mainly eye muscle weakness, also difficulty eating, speaking and in
severe cases respiratory issues
Diagnosis by testing for antibodies, ice test (2mm rinse – acetylcholinesterase
inhibition)
Treatment – acetylcholinesterase inhibitors such as neostigmine and
immunosuppressants such as azathioprine

Lamberton-Eaton myasthenic syndrome
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Antibodies for presynaptic voltage gated calcium channels
Slows/stops release of ACh at neuromuscular junction so no muscle contraction
Usually occurs as a secondary disease to cancer patients
o Hypothesized that the antibody is produced to target calcium channels with
the cancer
Symptoms – muscle weakness in arms, legs and throat, and during late stage
respiratory muscles and coordination issues
Diagnosis – electromyography (EMG) where neurones supplying muscles are
artificially stimulated as well as blood tests for antibody
Treatment – primary treatment for cancer (chemotherapy), steroid prednisolone,
immunosuppressant azathioprine and 3,4 – diaminopyridine
o 3, 4 – diaminopyridine blocks repolarisation at the neuromuscular junction
allowing calcium to accumulate in the presynaptic terminal

Myositis
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Three main types – Polymyositis, Dermatomyositis and inclusion body myositis
Unknown autoantigen attacked by cytotoxic T cells
Difference characterised by symptoms and histology of biopsy
Symptoms – rash for dermatomyositis, muscle weakness for all types, vacuole
formation in inclusion body myositis
Diagnosis – blood test for creatine kinase (CK), EMG and muscle biopsy
Treatments – physical therapy and immunosuppressant such as azathioprine and
methotrexate



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