general disease pathology

Question 1

What is a pheochromocytoma?

Answer 1

This is a rare tumour that secretes catecholamines, either originating in the adrenal medulla or extra-adrenal chromaffin tissue (paraganglioma). It presents with
headaches, palpitations and diaphoresis and patients have severe hypertension.
Diagnosis is made via measurement of catecholamines and metanephrines in
plasma (blood) or 24-h urine collection.

Question 2

Explain the pathophysiology of an adrenal crisis.

Answer 2

This is a medical emergency that can be swiftly fatal if left untreated. It is caused
by a deficiency in cortisol and presents with lethargy, hyperkalaemia, hypoglycaemia and hypotension. Treated with hydrocortisone.

Question 3

what are the features of Primary Aldosteronism (Conn’s syndrome)?

Answer 3

• Caused by excess aldosterone production in the glomerulosa.
• Low K+, metabolic alkalosis and increase ECF → hypertension.
• Low plasma renin levels.

Question 4

what are the effects of Adrenal insufficiency – ‘Addison’s disease’

Answer 4

• Caused by primary atrophy (80% autoimmune) or injury (TB, Waterhouse–
Friderichsen syndrome metastatic disease)
• Effects - ↓ ECF, hyponatraemia, hyperkalaemia and mild acidosis, hypoglycaemia,
↑ melanin production (due to MSH sharing same precursor POMC).

Question 5

causes of hypercalcaemia

Answer 5

Hyperparathyroidism
• Malignancy (PTHrP, multiple myeloma, bone metastasis)
• Sarcoidosis (↑ Vitamin D)
• Thiazide diuretics (stimulate Ca2+ reabsorption)
• Thyrotoxicosis
• Paget’s disease

Question 6

causes of hypocalcaemia

Answer 6

Transiently post-op, pancreatitis, prolonged hypoparathyroidism, malabsorption and CRF

CRF
• ↓ renal function → ↑ plasma PO4, ↓ vitamin D production → ↓ ↓ Ca2+
– → 2° hyperparathyroidism → ↑ bone reabsorption with ↑ ALP and ectopic calcification

Effects of parathyroidectomy

Question 7

how many days post parathyroidectomy would hypocalcaemia occur?

Answer 7

2-3 days

Question 8

Name the types of cells found in the islets of Langerhans.

Answer 8

Three types of cells in the islets of Langerhans
Alpha – glucagon (25%);
Beta – insulin and amylin (60%);
Delta – somatostatin (10%).

Question 9

what is the consequence of insulin deficiency?

Answer 9

Diabetes mellitus (reduced entry of glucose into peripheral cells and ↑ plasma
glucose)
– ↑ rate at which amino acids are catabolised
– Protein deficiency and poor resistance to infections
– Ketosis → acidosis → coma

Question 10

what is the role of somatostatin?

Answer 10

Inhibit insulin, glucagon, pancreatic polypeptide and can also inhibit GB contraction (by ↓ CCK release)

Question 11

What is the biochemical consequence of vomiting caused by pyloric stenosis?

Answer 11

Hypochloremic metabolic alkalosis

Question 12

What is achalasia?

Answer 12

It is a disorder characterised by ineffective esophageal parastalsis and ineffectual
lower esophageal relaxation.

Question 13

Explain the pathophysiology of pernicious anaemia.

Answer 13

Pernicious anaemia in gastric atrophy is due to a failure of normal secretion of
intrinsic factor (required for B12 absorption). In the absence of intrinsic factor,
0.02% of vitamin B12 is absorbed → failed maturation of red blood cells.