Parotid gland and hyperparathyroid, endocrine conditions Flashcards
Causes of parotid swelling: unilateral and bilateral
Unilateral
-Tumouir
-Blocked duct e.g. calculus
Bilateral:
Sjogrens
Mumps
TB
Alcoholism/liver cirrhosis
Diabetes
Sarcoidosis
Drugs (diuretics)
What are the causes of unilateral parotid swelling?
Duct obstruction – salivary calculus, external ductal compression
Neoplasia – benign or malignant
Infective - mumps (although bilateral swelling is more common), parotitis
What symptoms are associated with sialolisthiasis as a cause for unilateral parotid swelling?
Intense pain with an associated intermittent parotid swelling during mealtimes.
N.B. Symptoms can be re-produced with lemon juice.
Are salivary calculi more common in the submandibular or parotid glands and why?
Submandibular glands.
{80% Submandibular, 18% parotid, 2% sublingual}
Submandibular sialolithiasis is more common because its saliva is more alkaline
-higher mucous content
-increased concentration of calcium and phosphate than `saliva of the parotid and sublingual glands.
Do you know any ways in which parotid and submandibular calculi differ?
Parotid calculi tend to be multiple, smaller and 50% are within the gland
Submandibular calculi tend to be single, larger and intraductal
What is the pathogenesis of salivary calculus formation?
-Saliva is rich in calcium.
-Salivary flow is slow and the intermittent stasis of flow predisposes to stones.
-Stones are mainly formed of calcium phosphate and hydroxyapatite
What percentage of salivary calculi are radio-opaque?
80%
What type of tumours are found in the parotid?
85% are benign – pleomorphic adenoma (70%) and Warthin’s tumour
15% are malignant - mucoepidermoid carcinoma and adenoid cystic carcinoma.
Which worrying clinical sign may point towards malignancy in parotid tumours?
Ipsilateral facial nerve palsy. This is extremely uncommon in benign tumours.
What are the post operative complications of parotidectomy?
VIIth nerve palsy
Frey’s Syndrome
Salivary fistula
Greater auricular nerve damage - numbness to earlobe
What is Frey’s Syndrome?
-Gustatory sweating and facial flushing
-Caused by misdirected autonomic nerve regeneration
-Injury to auriculotemporal nerve, which then reattaches to sweat glands in skin rather than removed salivary gland
-Via sympathetic receptors
-Stimulation that normally causes salivation causes erythema and sweathing
Where is parathyroid hormone produced and what does it do? Same question for calcitonin
-Secreted by chief cells of parathyroid glands
-Increases concentration of ca in blood
-Calcitonin (produced by parafollicular C cells) reduces calcium concentration in blood
Parathyroid hormone (PTH) is secreted by the chief cells of the parathyroid glands. It acts to
increase the concentration of calcium (Ca2+) in the blood, whereas calcitonin (a hormone
produced by the parafollicular cells (C cells) of the thyroid gland) acts to decrease calcium
concentration
What are the causes of primary hyperparathyroidism?
85% are due to a single adenoma
< 1% are due to carcinoma (occasionally as part of MEN 1 and 2a syndrome)
What are the causes of secondary hyperparathyroidism?
-Secondary hyperparathyroidism is the parathyroid glands’ response to hypocalcaemia,
-usually due to chronic renal failure:
What is the mechanism behind secondary hyperparathyroidism?
-decreased levels conversion of 25 hydroxy-vitamin D to 1,25 dihydroxy-vitamin D in the kidneys.
-Reduced levels of active vitamin D therefore result in hypocalcaemia.
What are the actions of 1,25 dihydroxy-vitamin D?
(1) increasing the uptake of calcium from the GI tract
(2) increasing the release of calcium from bone
(3) decreasing the renal excretion of calcium
Describe tertiary hyperparathyroidism. What causes it?
-Chronic stimulation of the parathyroid glands by secondary hyperparathyroidism
-leads to disregulation and over activation of the parathyroid glan
- resulting in hypercalcaemia.
Renal transplant
What are the clinical manifestations of hypercalcaemia?
Clinical manifestations of hypercalcaemia can be remembered with the following:
BONES: Bone pain
STONES: Renal
MOANS AND GROANS: Abdominal pain, constipation, acute pancreatitis and gallstones
THRONES: Polyuria i.e. sitting on the throne!
PSYCHIATRIC OVERTONES: Psychosis, depression
Where are parathyroid glands found and what is their embryological origin?
The parathyroid glands, of which there are 4 (2 superior and 2 inferior), develop from the 3rd and 4th pharyngeal pouches and generally lie immediately posterior to the thyroid gland.
Where can the parathyroid glands atypically be found?
As the thymus also develops from the 3rd pharyngeal pouch, occasionally the thymus may
drag the inferior glands down into the mediastinum
What are frozen sections and why are these carried out during parathyroidectomy?
It is a pathological laboratory procedure to perform rapid microscopic analysis of a specimen
The reason for using frozen section during parathyroidectomy is to ensure that the surgeon
has actually removed parathyroid tissue as they are small and occasionally hard to recognise.
What is the difference between primary, secondary and tertiary hyperparathyroidism?
Primary hyperparathyroidism: due to excess parathyroid hormone secretion from
parathyroid adenomas, hyperplasia, or carcinoma.
Secondary hyperparathyroidism: Increase in parathyroid hormone in response to low plasma
ionised calcium secondary to renal disease or malabsorption.
Tertiary hyperparathyroidism: development of autonomous hyperplastic parathyroid glands
in a patient with secondary hyperparathyroidism resulting in profound hypercalcaemia.
What are the causes of hypoparathyroidism?
Post-thyroidectomy
Idiopathic (autoimmune)
After radioactive iodine therapy for Graves
Which part of the adrenal gland secretes corticosteroids & mineralocorticoids, and which
secretes catecholamines?
Corticosteroids & mineralocorticoids: adrenal cortex
Catecholamines: adrenal medulla
