Calcium Flashcards
Calcium distribution in body
Most in bone
Small amount in serum - 50 free (active), 40 albumin bound, 10 bound to calcium / phosphate
Calcium control - 3 paths
Vitamin D + PTH
Low calcium directly stimulates PTH + indirectly stimulates vitamin D through PTH
1. Activates vitamin D (to 1,25 / calcitriol) - GUT calcium + phosphate absorption
2, KIDNEY - calcium absorption, phosphate trashing
3. BONE - calcium + phosphate release from bone
Corrected calcium
Ensures hypocalcaemia not due to low albuin
[Serum Ca + 0.02(40 - serum albumin)] or check blood gas
Normal calcium levels
2.2-2.6
Hypercalcaemia
Approach, causes, Tx
Approach: Hypercalcaemia - is PTH suppressed? (PTH should be suppressed)
Causes:
- High/ normal PTH: PTH = raised Ca (primary hyperparathyroidism - common, 80% parathyroid adenoma [high urinary calcium + stones]; OR familial hypocalciuric hypercalcaemia - rare, CaSR [low urinary calcium + no stones])
- Low PTH: Raised Ca = low PTH (malignancy - either PTHrP e.g. SCLC, bone mets (bone lysis releases - Brs), myeloma); OR non-malignant causes (loads of them e.g. sarcoid, excess vitamin D, thyrotoxicosis, adrenal failure, thiazides)
Tx - FLUIDS, FLUIDS, FLUIDS + Bisphosphonates if malignancy to stop bony pain
Hypercalcaemia symptoms
Stones, bones, abdominal moans, psychic groans, thrones
Hypercalcaemia
Raised / inapp normal PTH
Hypercalciuria + stones
Primary hyperparathyroidism (80% parathyroid adenoma)
Hypercalcaemia
Raised / inapp normal PTH
Hypocalciuria + no stones
Familial hypocalciuric hypercalcaemia
Hypocalcaemia symptoms
Neuro-muscular excitability (Trousseau’s, Chvostek’s)
- Carpopedal spasm when inflating BP cuff (Trousseau’s)
- Twitching of facial muscle when facial nerve tapped (Chvostek’s)
Perioral paraesthesia
Hypocalcaemia
Approach, causes, Tx
Approach - is PTH raised? (PTH should be raised)
Causes:
- Low PTH (low PTH = low calcium) - primary hypoparathyroidism due to surgery (thyroidectomy, AI, Di George, magnesium deficiency)
- High PTH (low calcium = high PTH) - secondary hyperparathyroidism (vitamin D deficiency, CKD) or pseudohyperparathyroidism (PTH resistance)
Tx: If mild oral calcium, if severe iv calcium; if vit D deficiency vitamin D; if CKD alfacalcidiol
CKD
Normal calcium, elevated PTH
Tertiary hyperparathyroidism
Occurs after long period of secondary hyperparathyroidism in CKD - high PTH used to be appropriate to low Ca but once Ca returns to normal no longer appt
Low Ca, raised PTH
Chappati eating, lack of sunlight, dark skin, anti-convulsant use
Looser’s zones, widened epiphysis, costchondral swelling, cupping + fraying of metaphysis
Vitamin D deficiency
Osteomalacia - Adults
Rickets - children
Tx: GIVE VITAMIN D
Looser’s zone
Pseudofractures occurring in vitamin D deficency
Normal bloods
First presentation Colle’s #
Osteoporosis
Raised ALP
Focal pain, warmth, deformity, hearing loss, frontal bossing
Paget’s disease
