Calcium Homeostasis and Disorders Flashcards
What is the recommended daily dose of calcium?
700mg
What 4 factors contribute to Calcium homeostasis?
Diet
Gut absorption
PTH
Vit D
Briefly explain the pathway that leads to increased serum calcium.
Ca –> Calcium sensing receptor (CaSR) –> PTH –> resorption of Ca from bone and absorption of Ca from gut –> increased serum calcium
What are sources of Vit D?
Main source from sun exposure
10% from gut absorption
egg yolk, oily fish, fortified cereals and bread
What is the pathway that Vit D is synthesised from sun exposure?
Sun exposure dehydro-cholesterol Cholecalciferol (D3) 25 (OH) Vit D - liver 1, 25 (OH) Vit D - kidneys
In CKD why is there not enough Vit D?
In CKD they lack fine hydorxylation of 25 Vit D so not enough Vit D
What can cause hypercalcaemia?
1y hyperparathyroidism #1 Malignancy #1 Drugs – Vit D, thiazides Granulomatous disease (Sarcoid, TB) Familial Hypocalciuric hypercalcaemia High Ca turnover – Pagets, bedridden, thyrotoxic 3y hyperparathyroidism MEN1 & MEN2
How does hypercalcaemia present acutely?
thirst, dehydration, confusion and polyuria
In chronic hypercalcaemia, what S&S does the patient express?
myopathy, osteopaenia, fractures, depression, HTN, abdo pain (pancreatitis, ulcers, renal stones)
What investigations are required for the diagnosis of primary hypercalcaemia?
1y hypercalcaemia:
Increased serum Calcium
Increased serum PTH (or inappropriately abnormal)
Increased urine calcium excretion
What Ix are required for diagnosing hypercalcaemia associated with malignancy?
Increased serum Ca and ALP
X-ray, CT, MRI
Isotope bone scan
What treatment is required for acute hypercalcaemia?
Acute: Rehydrate 0.9% saline 4-6L in 24hr Consider loop diuretics Bisphosphonates – single dose will lower Ca over 2-3 days, max effect at 1 week Steroids – Prednisolone if Sarcoid
What treatment can be considered in malignant hypercalemia?
Salmon calcitonin – rarely used for malignant hypercalcaemia
Chemo – may reduce Ca in malignant disease (myeloma)
What is familial hypocalcimic hypercalcaemia?
Autosomal dominant inherited condition where there is a deactivating mutation in the calcium sensing receptor
What are the levels of calcium in familial hypocalcimic hypercalcaemia?
low urinary calcium
increased serum calcium
What is the presetation of familial hypocalcimic hypercalcaemia?
Usually benign and assymptomatic
Give the differential diagnosis for the following results: hypercalcaemia albumin normal/low phosphate high ALP low
Myeloma
Vit D excess
Mild-alkali syndrome (thyrotoxicosis, sarcoidosis, raised HCO3)
Give the differential diagnosis for the following results: hypercalcaemia albumin normal/low phosphate high ALP high
Bone metastases
Sarcoidosis
Thyrotoxicosis
What are the most common causes of hypocalcaemia?
Hypoparathyroidism
Vit D deficiency
Chronic renal failure
Give some rare causes of hypocalcaemia.
Pancreatitis
hyperventilation
osteoblastic bone mets
rhabdomyolysis
How does hypocalcaemia present?
Paraesthesia (fingers, toes, perioral) Muscle cramps, tetany Broncho or laryngospasm Muscle weakness Fatigue Fits Chovsteks sign (tap over facial nerve and get facial twitching) Trousseau sign (carpopedal spasm)
What is the treatment for hypocalcaemia?
IV calcium gluconate 10ml 10% over 10 mins (in 50ml dextrose or saline)
Then
Infusion 10ml 10% in 100ml infusate at 50ml/h
What is the deficiency in rickets and osteomalacia?
Vitamin D deficiency
What are the S&S of rickets and osteomalacia?
Proximal myopathy Dental defects (carries, enamel) Bone – tenderness over sternum and shins, rib deformities, limb deformities
What are the causes of rickets and osteomalacia?
Malabsorption Chronic renal failure Lack of sunlight Drugs (anticonvusants) Dietary lack of Vit D
How do you decide between the diagnosis of rickets and osteomalacia?
Rickets occurs before the growth plates fuse
How should you treat chronic Vit D deficiency?
Vit D - Calcitriol or Alfacalcidol
Ca & Vit D – Adcal D3 (elerly with osteoporosis and fractures)
How does Paget’s disease present?
Asymptomatic
Bone pain
Fractures
Nerve compression (deafness, cord compression)
What is the suspected aetiology of Paget’s disease?
Viral trigger in genetically susceptible individual
How should Pagets disease be treated?
Only if symptomatic
analgesia first
orall bisphosphonates - Alendronate
Calcitonin
What causes hypoparathyroidism?
Congenital absence (DiGeorge syndrome) Destruction of gland (surgery, radio, malignancy) AI Hypomagnesaemia Idiopathic
What is the long term management of hypoparathyroidism?
Calcium supplements
Vit D tablets or depot injection
What are the 3 causes of hyperparathyroidsm?
1y – primary over activity of parathyroid e.g. adenoma
2y – physiological response to low Ca
3y – Parathyroid becomes autonomous after many years of 2y
Surgery or nothing are the treatment options for hyperparathyroidism. What are the indications for surgery?
End organ damage
Very high calcium (>2.85 mmol/l)
<60ml/min
In terms of PTH and Ca levels, what would you expect from 1y, 2y and 3y hyperparathyroidism?
1y - increased PTH and increased Ca
2y - increased PTH and low Ca
3y - increased PTH and increased Ca
What drug cna be used for 3y hyperparathyriodism or parathyroid carcinoma?
Cinacalcet
