Hypercalcaemia of malignancy (E&M) Flashcards
What different types of hypercalcaemia of malignancy are there? (4)
- humoral hypercalcaemia of malignancy
- local osteolytic hypercalcaemia
- calcitriol-mediated hypercalcaemia
- ectopic hyperparathyroidism (very rare)
What is humoral hypercalcaemia of malignancy?
Tumour secretion of PTH-related peptide (PTHrP)
What cancers does humoral hypercalcaemia of malignancy occur in? (7)
SCC ROBBLE
- SCC (lung, head and neck)
- Renal
- Ovarian
- Bladder
- Breast
- human T-lymphotrophic virus-associated Lymphoma
- Endometrial
What is local osteolytic hypercalcaemia?
Local release of factors, including PTHrP, by bony metastases that promote osteoclast differentiation and function
What cancers does local osteolytic hypercalcaemia occur in? (2)
- multiple myeloma
- breast cancer
What is calcitriol-mediated hypercalcaemia?
Autonomous production of calcitriol (1,25-dihydroxyvitamin D) by lymphoma cells, due to 1-alpha hydroxylase activity in tumour cells
What cancers does calcitriol-mediated hypercalcaemia occur in? (2)
- Hodgkin lymphoma
- Non-Hodgkin lymphoma
- (associated with lymphomas of all types, but also with granulomatous disease e.g. active sarcoidosis or TB)
What are some risk factors for hypercalcaemia of malignancy? (3)
- non-metastatic malignancy (humoral hypercalcaemia of malignancy)
- metastatic skeletal involvement (local osteolytic hypercalcaemia)
- lymphoma (calcitriol-mediated hypercalcaemia)
What medication can cause hypercalcaemia?
Thiazides
What are the clinical features of hypercalcaemia of malignancy?
Stones, Bones, Thrones, Abdominal Groans, Psychic Moans
- Stones (renal)
- Bones (bone pain)
- Thrones (polyuria, polydipsia, poor skin turgor and dry mucous membranes)
- Abdominal Groans (pain, constipation, anorexia, nausea)
- Psychic Moans (confusion, low mood, anxiety)
What are the first-line investigations for hypercalcaemia of malignancy? (6)
- total serum calcium - elevated
- serum ionised calcium elevated
- serum intact PTH - low –> differentiate from PTH-mediated hypercalcaemia e.g. hyperparathyroidism
- PTHrP - elevated in humoral hypercalcaemia of malignancy
- ALP - high in bone metastases –> local osteolytic hypercalcaemia, normal in multiple myeloma
- calcitriol - high in calcitriol-mediated hypercalcaemia
What imaging can we do for hypercalcaemia of malignancy?
- resting ECG - may show shortened QT interval and dysrhythmias
- skeletal survey - may show osteopenia, osteolytic lesions or pathological fractures
- CXR - may show typical findings of lung cancer, TB or sarcoidosis
How can we differentiate between the three main types of hypercalcaemia of malignancy?
- humoral hypercalcaemia of malignancy - high PTHrP
- local osteolytic hypercalcaemia - high ALP (normal in multiple myeloma)
- calcitriol-mediated hypercalcaemia - high calcitriol
What are some differential diagnoses for hypercalcaemia of malignancy? (7)
- primary hyperparathyroidism
- hyperthyroidism
- adrenal insufficiency
- phaeochromocytoma
- sarcoidosis
- medication-related hypercalcaemia (thiazide diuretics, lithium, OTC antacids, large doses vitamin D)
- TB
What do we give as INITIAL management of hypercalcaemia of malignancy?
IV saline (fluids) to reverse dehydration
