Hypercalcaemia- Endo Flashcards
What are the two conditions that account for 90% of cases of hypercalcaemia?
- Primary hyperparathyroidism
- Malignancy
What is the commonest cause of hypercalcaemia in non-hospitalised patients?
Primary hyperparathyroidism
What is the commonest cause of hypercalcaemia in hospitalised patients?
Malignancy
List the processes through which malignancy can cause hypercalcaemia.
- PTHrP from the tumour (e.g. squamous cell lung cancer)
- Bone metastases
- Myeloma due to increased osteoclastic bone resorption
What is the key investigation for patients with hypercalcaemia?
Measuring parathyroid hormone levels
Name some other causes of hypercalcaemia.
- Sarcoidosis
- Granulomas (e.g. tuberculosis, histoplasmosis)
- Vitamin D intoxication
- Acromegaly
- Thyrotoxicosis
- Milk-alkali syndrome
- Drugs (e.g. thiazides, calcium-containing antacids)
- Dehydration
- Addison’s disease
- Paget’s disease of bone
What role does magnesium play in relation to parathyroid hormone (PTH)?
Magnesium is required for both PTH secretion and its action on target tissues
What effect does hypomagnesaemia have on calcium levels and treatment response?
It may cause hypocalcaemia and render patients unresponsive to treatment with calcium and vitamin D supplementation
How much magnesium is contained in the body?
1000mmol
Where is half of the body’s magnesium stored?
In bone
What other locations in the body contain magnesium?
- Muscle
- Soft tissues
- Extracellular fluid
Is there a specific hormonal control of magnesium?
No, various hormones including PTH and aldosterone affect renal handling of magnesium
How do magnesium and calcium interact at a cellular level?
Decreased magnesium affects the permeability of cellular membranes to calcium, resulting in hyperexcitability
What are the two conditions that account for 90% of cases of hypercalcaemia?
- Primary hyperparathyroidism
- Malignancy
What is the commonest cause of hypercalcaemia in non-hospitalised patients?
Primary hyperparathyroidism
What is the commonest cause of hypercalcaemia in hospitalised patients?
Malignancy
List the processes through which malignancy can cause hypercalcaemia.
- PTHrP from the tumour (e.g. squamous cell lung cancer)
- Bone metastases
- Myeloma due to increased osteoclastic bone resorption
What is the key investigation for patients with hypercalcaemia?
Measuring parathyroid hormone levels
Name some other causes of hypercalcaemia.
- Sarcoidosis
- Granulomas (e.g. tuberculosis, histoplasmosis)
- Vitamin D intoxication
- Acromegaly
- Thyrotoxicosis
- Milk-alkali syndrome
- Drugs (e.g. thiazides, calcium-containing antacids)
- Dehydration
- Addison’s disease
- Paget’s disease of bone
What role does magnesium play in relation to parathyroid hormone (PTH)?
Magnesium is required for both PTH secretion and its action on target tissues
What effect does hypomagnesaemia have on calcium levels and treatment response?
It may cause hypocalcaemia and render patients unresponsive to treatment with calcium and vitamin D supplementation
How much magnesium is contained in the body?
1000mmol
Where is half of the body’s magnesium stored?
In bone
What other locations in the body contain magnesium?
- Muscle
- Soft tissues
- Extracellular fluid
