Page 440 - Medicine and Surgery

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436 Chapter 11: Endocrine system

stroma between them. Spread is mainly to local lymph Prognosis
nodes. Poor: 1-year survival is ∼30%.

Thyroidectomy
Investigations
Calcitonin levels are raised, although serum calcium lev- Hyperthyroid patients must be made euthyroid before
els are normal. Calcitonin is also used for follow-up and thyroid surgery using antithyroid drugs and β-blockers
for screening of relatives. to reduce complications such as cardiac arrhythmias,
excessive sympathetic activity and bleeding.
The thyroid is exposed via a transverse skin-crease
Management
incision above the sternal notch. The lobes of the thy-
Total thyroidectomy and dissection of lymph nodes in
roid are supplied by the superior and inferior artery,
the central neck compartment.
and drained by the middle and inferior veins. These
are dissected out, ligated and divided removing the
desired amount of thyroid tissue. Surrounding struc-
Anaplastic carcinoma
tures that require identification and protection include
Definition the parathyroid glands and the recurrent laryngeal
This is a highly malignant tumour of the thyroid. nerves.
Complications include haemorrhage, leading to tra-

cheal compression; damage to the superior or recur-
Incidence/prevalence
rent laryngeal nerve; damage or excision of parathy-
10–15% of cases of malignant tumours of the thyroid.
roid glands; and scarring. Neuropraxia (temporary
damage) of the recurrent laryngeal nerve occurs in
5% of operations. The ipsilateral vocal cord becomes
Pathophysiology
There is evidence that these are poorly differentiated paralysed and fixed midway between closed and open.
adenocarcinomas derived from thyroid epithelium. Bilateralnerveinjuryisrarebutcausesstridorandmay
They often arise in elderly patients with a long history of subsequently require laryngoplasty or permanent tra-
goitre in whom the gland suddenly enlarges. cheostomy.
Postoperative calcium levels should be monitored to

look for hypocalcaemia, which is usually transient,
Clinical features due to damage to the parathyroid glands. Subsequent
These tumours are rapidly growing and invade local hypothyroidism is treated with lifelong thyroxine
structures early, most patients present with a rapidly en- supplements.
larging neck swelling and complications such as hoarse-
ness, dyspnoea and stridor, dysphagia and Horner’s syn-
drome (miosis, partial ptosis and anhydrosis). Adrenal axis

Corticotrophin releasing hormone (CRH) is secreted
Macroscopy/microscopy
from the hypothalamus in a diurnal pattern. Adrenocor-
Diffusely infiltrative mass, often invading neighbouring
ticotrophichormone(ACTH)issecretedbythepituitary
tissues. Composed of various undifferentiated cells.
in response to CRH that in turn activates the enzyme
desmolaseintheadrenalglandsconvertingcholesterolto
Management pregnenolone. This is the rate-limiting step for the pro-
Resection is rarely possible, but may be carried out for duction of all the adrenocortical hormones. Cortisol is
palliative relief of tracheal compression. Radioactive io- mainly controlled in this way, aldosterone is mainly con-
dine and radiotherapy are ineffective. trolled by the renin-angiotensin system, and androgens