Malignant Hypercalcaemia

Question 1

What is malignant hypercalcaemia?

Answer 1

Serum calcium > 2.6mmol/L

Question 2

What are the most common cancers causing hypercalcaemia?

Answer 2

Breast cancer
Multiple myeloma
Lymphoma
Lung cancer

Question 3

How must serum calcium be corrected?

Answer 3

In reference to albumin levels

Protein binding of calcium is affected by pH

Acidosis reduces calcium binding with albumin and vive.

Question 4

What are the three main mechanisms of malignant hypercalcaemia?

Answer 4

• Osteolytic metastasis
• PTH-related protein secretion (PTH-rP)
• Increased 1,25-dihydroxyvitamin D production

Question 5

What does PTHrP secretion lead to?

Answer 5

Released from tumour cells

Increased bone resorption
Increased absorption of calcium
Decreased excretion of phosphate

Question 6

How do you explain PTHrP secretion to a patient?

Answer 6

So, your cancer has started to release a hormone, which is a special type of chemical, into your blood

This chemical then causes your bones to break down and release calcium

Does everything I’ve said make sense so far?

Perfect so, this increased bone break down has caused the raised levels of calcium, which is causing your symptoms like the constipation etc

So what we need to do, is bring these levels of calcium back down, now there’s a few ways we can do this, but before we go on to that I just want to make sure I’ve explained everything properly

Question 7

What happens in osteolytic metastasis?

Answer 7

Metastasis to the bone

This leads to increased bone resorption

Question 8

How do you explain osteolytic metastasis to a patient?

Answer 8

Hi again, how are you?

Okay so I know you’ve had some tests, but just so we’re on the same page, would you mind telling me what you’ve had done

Yeah, that’s exactly right, and do you know what they were looking for?

Has anyone come to explain the test results to you so far?

Okay would you like for me to go through your results with you today?

Before I start, sometimes patients find it really helpful to have a family member or friend to sit with them while I go through results to help them absorb some of what I’m saying and to ask some questions that might not come to mind straight away. Is there anyone you’d like in the room with you?

Okay, so because of the symptoms you were mentioning, we wanted to have a closer look, to try understand what’s going on.

The scan did show some abnormalities which do explain the symptoms you have been experiencing.

Are you okay for me to continue?

The scan has shown that your lung cancer has spread to your bones.

Pause

etc etc.

Because your cancer has spread to your bones, they have been breaking down and releasing calcium which is what is causing your symptoms

Question 9

What does increased 1,25-Dixydroxyvitamin D lead to?

Answer 9

Increased absorption of calcium from the gut

Most common cause of hypercalcaemia in Hodgkin’s lymphoma

Question 10

How does malignant hypercalcaemia present?

Answer 10

Mild

• Polyuria
• Polydipsia
• Mild cognitive impairment
• Dyspepsia

Moderate

• All of the above
• Constipation
• Weakness
• Fatigue
• Nausea
• Dehydration

Severe

• All of the above
• Abdominal pain
• Vomiting
• Arrhythmias
• Pancreatitis
• Coma

Question 11

What investigations do you do for hypercalcaemia?

Answer 11

Bedside
ECG - arrhythmias
Abdominal exam
Neurological exam - signs of confusion etc

Bloods
Metabolic panel including, calcium levels and phosphate levels
PTH
PTHrP
Vitamin D levels

Imaging
CT CAP- Looking for any metastases
I would consider a PET-CT to look for any lymph node and further spread

Question 12

How is hypercalcaemia managed?

Answer 12

IV rehydration - restores normal volume and increases calcium diuresis

Calcitonin - promotes urinary excretion and inhibits bone resorption

Bisphosphonates - Zoledronic acid, inhibits bone breakdown