Hyper/Hypo - Calcaemia Flashcards
What is the normal serum level of calcium?
2.2 - 2.6 mmol/L
What does PTH do and how does it work?
- Raises serum calcium
1. Increases osteoclast activity to raise calcium and phosphate
2. Increase calcium resorption and increase phosphate secretion at the kidney
3. Increases activation of vitamin D which leads to more uptake from the GI tract
What cells secrete PTH?
Chief cells
How does calcitriol form and what does it do?
- Formed from the skin in sunlight or absorbed in the gut bound to protein in blood
- Hydroxylation at the liver and then the kidney, calcitriol is the active form of vitamin D3.
- Same function as PTH
How does calcitonin form and what does it do?
- Made in the C cells of the thyroid gland
- Lowers serum calcium and phosphate but role is unclear
What is the relationship of magnesium to calcium?
- Low magnesium prevents PTH release, which may cause hypocalcaemia
What are the signs and symptoms of hypercalcaemia?
Bones - Osteitis fibrosa cystica, fragility fractures
Stones - Renal calciuli
Thrones - Polyuria, constipation
Abdominal groans - Abdominal pain, N+V, pancreatitis
Psychic moans - Mood disturbance, depression, fatigue, psychosis
How can cancer cause hypercalcaemia?
- PTHrP released from tumours (prostate, breast, myeloma)
- Malignant osteolytic bone metastases (breast, lung, thyroid, kidney, prostate, ovary, colon)
What are other causes of hypercalcaemia?
- Primary hyperparathyroidism
- Sarcoidosis
- Vitamin D intoxication
- Thyrotoxicosis
- HIV
How would you investigate hypercalcaemia?
- You need to distinguish between malignancy and primary hyperparathyroidism
Malignancy - Low albumin, low chloride, alkalosis, high potassium, high phosphate, high ALP
Parathyoid - High PTH - Bone profile, U+E (Mg esp), vit D, PTH
- ECG
What would require treatment in hypercalcaemia?
- If Ca2+ is >3.5mmol/L
- Symptomatic
What is the treatment for acute hypercalcaemia?
- Correct dehydration
- Bisphosphonates - Prevent bone resorption by inhibiting osteoclast activity.
- Chemotherapy in malignancy. Steroids in sarcoidosis. Eg treat underlying cause
What are the causes of ectopic calcification?
PARATHORMONE
P - Parathormone (high PTH or other causes of high calcium eg sarcoidosis A - Amyloidosis R - Renal failure A - Addison's disease T - TB Nodes, Toxoplasmosis H - Histoplasmosis O - Overdose of vitamin D R - Raynaud's associated diseases M - Muscle primaries/leiomyosarcomas O - Ossifying metastases (osteosarcoma, ovarian mets) N - Nephrocalcinosis E - Endocrine tumours (gastrinoma)
What are the features of hypocalcaemia?
SPASMODIC
S - Spasms (carpopedal spasm) P - Perioral paraesthesiae A - Anxious, irritable, irrational S - Seizures M - Muscle tone increased in smooth muscle (colic, wheeze, dysphagia) O - Orientation impaired and confusion D - Dermatitis I - Impetigo herpetiformis C - Cataracts, cardiomyopathy
What would an ECG show in hypercalcaemia?
- Decreased QT interval
