Page 438 - Medicine and Surgery

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434 Chapter 11: Endocrine system

Sex Prognosis
F > M Myxoedema coma has a poor prognosis, particularly as
it tends to occur in elderly patients who have little respi-
ratory and cardiological functional reserve.
Aetiology
Mayoccur in any patient with hypothyroidism (see page
432). Myxoedema coma may be precipitated by inter- Malignant tumours of the thyroid
current illness or disorder, such as heart failure, perhaps Papillary adenocarcinoma
following a myocardial infarction, stroke, pneumonia;
iatrogenic causes include water overload and sedative or
Definition
opiate drugs.
A slow-growing, well-differentiated primary thyroid tu-
mour arising from the thyroid epithelium.
Pathophysiology
Thyroid hormones maintain many metabolic processes Incidence/prevalence
in the body. Severe and chronic lack of these hormones 50% of malignant tumours of the thyroid.
without adequate exogenous replacement leads to
respiratory failure with CO 2 retention and hypoxia, Age

water intoxication due to the syndrome of inappropri- Rare after the age of 40 years. Occurs in young adults.

ate antidiuretic hormone (SIADH) and hypothermia
and
Sex
adrenal insufficiency.

F > M
Clinical features Clinical features
There may be a history of previous thyroid disease, Presentsasasolitaryormultifocalswellingofthethyroid.
followed by gradual onset of symptoms from lethargy Lymph nodes are palpable in one-third of patients, and
through stupor to coma. The patient appears obese with may be the only sign when there is a microscopic pri-
hypothermia,yellowishdryskin,thinnedhair,puffyeyes mary. Papillary tumours spread via lymphatics within
and has a slow pulse, respiration and reduced reflexes. the thyroid resulting in multifocal lesions and to neck
nodes. Widespread metastases are rare.

Investigations
Macroscopy/microscopy
Diagnosis may be made clinically, but is supported by
Non-encapsulated mass in contrast to adenomas, which
alow free thyroxine (T 4 ) and a high TSH. Thyroid au-
have a capsule. There is often infiltration into the sur-
toantibodies, blood gases, blood sugar, ECG, CXR are
rounding tissue with associated fibrosis.
also required.
Investigations
Management Patients may be identified during investigation for a soli-
Myxoedema coma requires admission to intensive care. tary thyroid nodule (see page 430). Definitive diagnosis
Respiratory failure requires support and may necessi-
is by histology, although cytology from fine needle aspi-
tate ventilation. ration may indicate malignancy.
Thyroxine replacement is essential either orally or in-

travenously. Management
Corticosteroids must be given if adrenal insufficiency Total thyroidectomy with excision of involved neck

is present. lymphnodesandpreservationoftheparathyroidglands.
Patients also require gradual re-warming and dextrose Radical neck dissection is not necessary. Metastases may

support to prevent hypoglycaemia. be treated by resection. Radioactive iodine therapy may