GOITRE
Enlargement of thyroid gland.
Classification
• Simple goitre can be; diffuse or nodular. Usually caused by lack of iodine or defects in synthesis of thyroxine hormone
• Toxic goitre; diffuse or nodular. Produces excess thyroxine (T3, T4) and manifests with signs and symptoms of thyrotoxicosis
• Neoplastic goitre; benign or malignant
• Thyroiditis e.g. Hashimoto's disease
• Rare goitres e.g. tuberculosis or syphilitic.
Clinical Features
Most patients are asymptomatic. Pressure symptoms consist of engorged neck veins, dysphagia, stridor, hoarseness. In hyperthyroid patients weight loss, diarrhoea, heat intolerance, sweating, tachycardia, tremors, lid lag, exophthalmos, menstrual disorders may occur.
Investigations
• X-ray neck, thoracic inlet
• Thyroid function tests (levels T3, T4, TSH, etc) in thyrotoxicosis
• Fine needle aspirate and cytology
• Ultrasound of thyroid gland.
Management
• Goitre - Reassure patient:
- smooth non-toxic colloid goitres: thyroxine 50-150 micrograms OD for 6 months
- if no change stop drugs and follow up.
• Toxic Goitre:
- usually managed conservatively with anti-thyroid drugs (carbimazole, methimazole) propranolol and diazepam.
• Thyrotoxicosis
- Aim of treatment is to restore the euthyroid state. Use the pulse rate and thyroid function tests if available to monitor progress
- Antithyroid Drugs: Carbimazole 15-20 mg TDS for 3 to 4 weeks thereafter reduce the dose to maintain euthyroid state, this ranges from 5-30 mg daily. Propranolol 60-240 mg in three divided doses.
Indications for surgery
Toxic goitre
• Failure to control symptoms despite adequate treatment with drugs
• Young subjects
• Adverse reaction to drugs
• Cosmetic.
Non-toxic goitre
• Pressure symptoms - dysphagia, venous obstruction, dyspnoea
• Cosmetic
• Suspicious histology e.g. follicular adenoma
• Solitary thyroid nodule
• Malignancy.
Patients presenting with above should be referred to a specialist.
Complications of thyroidectomy
• Haemorrhage and haematoma
• Dyspnoea - can be due to oedema haematoma or neurological
• Nerve palsy - recurrent laryngeal mainly tends to recover, if "paresis"
• Hypoparathyrodism - leading to tetany and convulsions
• Hypothyroidism - give thyroxine.
Refer If
• Increase in size of the goitre
• Suspicion of malignancy
• Pressure symptoms
• Large goitres for cosmetic reasons
• Thyrotoxic patients who fail to respond to medical treatment
• Goitres in children and male adults.
Prevention
• Iodinisation of salt has helped reduce incidence of endemic goitre.
HYPOTHYROIDISM
Deficiency of thyroid hormone.
Classification
• Congenital failure of thyroid development (complete or partial)
• Endemic cretinism
• Iatrogenic - (after, thyroidectomy, radio-iodine therapy, pituitary ablation, drug induced)
• Auto-immune thyroiditis
• Goitrogens e.g. cabbages
• Pituitary gland damage.
Diagnosis
The deficiency ranges from mild with minimal or unrecognised clinical manifestation to severe mental retardation (cretinism).
Congenital
Most neonates appear normal at birth. Diagnosis should be based on neonatal screening tests and not abnormal physical signs.
Clinical Features
Prolonged jaundice, feeding difficulty, lethargy and somnolence, apnoeic attacks, constipation, large abdomen, umbilical hernia, macroglossia, failure to thrive, delayed physical and mental development.
Investigations
Hormone levels:
• ↓ T4 ↑ ↑ TSH - deficit in thyroid gland (most cases)
• ↓ T4 ↑ TSH - deficit above level of thyroid gland
• ↑ T4 - thyroid hormone unresponsive (goitre is also present in most patients).
Management
• Treat underlying cause
• L-thyroxine sodium 75-100 μg/m2 OD for life
• Neonates and infants 10-15 μg/kg OD PO for life.
NB: Dosage should be adjusted to T4, TSH levels, growth and neuro-development assessments.
Adult Hypothyroidism
Clinical Features
Myxoedema is a very advanced form of hypothyroidism and this is not applicable to the more common milder degrees seen after thyroidectomy or autoimmune thyroiditis. Early symptoms include; tiredness, cold intolerance, menstrual disturbances, carpal tunnel syndrome.
The physical signs include; slow pulse rate, dry skin, sparse and dry hair, periorbital puffiness, hoarse voice. Comparison of facial appearance in a previous photograph is useful.
Investigations
• Serum T4
• TSH levels
• ECG changes: voltage reduced and flattened T-wave
• TRH.
Management
• Replacement with L-thyroxine.
