Calcium Homeostasis and Disorders Flashcards
(36 cards)
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
