Calcium Flashcards by Zohaa Qaisar

What is the key feature of osteoporosis?

Reduced bone mineral density – the bone structure is normal.

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What are the common presentations of fractures in osteoporosis?

Smith’s fracture (radius fractures forwards, falling onto a flexed wrist)

and Colle’s fracture (radius fractures backward, falling onto an outstretched hand).

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What are the risk factors for osteoporosis? (8)

Cushing’s
steroids
hyperthyroidism
age
immobility
early menopause
alcohol
low BMI.

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What are the blood test findings in osteoporosis patients? (2)

Everything is normal

Decreased bone mineralisation (ALP may be raised if a recent fracture occurred)

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How is osteoporosis managed? (5)

Weight-bearing exercise
Vitamin D

Alendronate (bisphosphonates)

Teriparatide (artificial PTH derivative)

HRT or SERMs (e.g., raloxifene)

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What are the blood test findings in osteomalacia/rickets? (3)

Low calcium and phosphate
High ALP
High PTH

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What are the causes of osteomalacia/rickets? (4)

Poor diet
Malabsorption
Renal failure
Lack of sun exposure

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How does osteomalacia present clinically? (3)

Bone pain

Muscle pain

Increased fracture risk (key feature: pseudofractures, e.g., Looser’s zones)

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What causes primary hyperparathyroidism? (3)

Parathyroid adenoma (most common)

Parathyroid hyperplasia

Parathyroid carcinoma

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What is osteomalacia?

Vitamin D deficiency, impaired bone mineralisation and bone structure is ABnormal

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What are the bone features in primary hyperparathyroidism? (2)

Tends to affect the radius especially

Untreated cases lead to osteitis fibrosa cystica (bony cysts, Brown’s tumors)

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What are the blood test findings in familial hypocalciuric hypercalcemia (FHH)? (5)

High calcium (mild)
Low phosphate
High ALP
Normal/high PTH
Low calcium in urine

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What are the features of secondary hyperparathyroidism? (4)

Low calcium
High phosphate
High ALP
Low PTH

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What are the effects of PTH on calcium and phosphate metabolism?

PTH increases calcium reabsorption and phosphate excretion in the kidneys. It also increases osteoclastic activity and activates 1-alpha-hydroxylase for calcium absorption.

So high PTH will cause low phosphate

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What are the main causes of secondary hyperparathyroidism?

Renal osteodystrophy (renal failure) and Vitamin D deficiency.

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What are the features of tertiary hyperparathyroidism? (2)

No longer sensitive to PTH, so high PTH despite high calcium

Caused by CKD leading to autonomous secretion of PTH

What are the features of Paget’s disease? (5)

Increased bone turnover

Bone pain

Bones may be warm, fractures, cardiac failure

Bowing of the tibia

Hearing loss (both conductive and sensorineural)

What are the blood test findings in Paget’s disease? (2)

Everything is normal except very raised ALP

Also get a rise in osteocalcin

What are the key investigations for Paget’s disease? (2)

X-ray

Technetium Bisphosphonate Scan (aka MDB scan): shows diffuse uptake by one bone (Paget’s) or blotchy uptake (metastatic bone cancer)

How is Paget’s disease managed? (1)

Bisphosphonates (if symptomatic)

What are the complications of lung cancer related to calcium metabolism? (2)

Produces PTHrP

Causes lytic bone lesions and raised ALP

What are the features of pseudohypoparathyroidism? (4)

PTH resistance

Associated with a short 4th & 5th metacarpal

Phenotypic picture like Albright hereditary osteodystrophy (obesity, rounded facies, hypogonadism, mild LD)

Bloods: High PTH, hypocalcaemia, high phosphate

What are the features of pseudopseudohypoparathyroidism? (4)

Normal calcium
Normal PTH
Normal biochemistry

Features of pseudohypoparathyroidism: short stature, brachydactyly, subcutaneous calcification, obesity

What are the features of primary hypoparathyroidism? (3)

Example: secondary to parathyroidectomy (or DiGeorge syndrome)

Low calcium

Low PTH and high phosphate

What are the key points about calcium in general? (5)

Important in causing depolarisation (high calcium → failure of depolarisation; low calcium → irritable nervous system) Normal range: 2.2–2.6 mmol/L 99% stored in the bone; 1% carried in the blood Corrected calcium (takes into account albumin) is important Vitamin D supplements = cholecalciferol (Vitamin D3)

What are the forms of Vitamin D in humans? (2)

Cholecalciferol (Vitamin D3) from UV light Ergocalciferol (Vitamin D2) from plants

What is the pathway for Vitamin D metabolism in the body? (5)

UV light converts 7-dehydrocholesterol in the skin to cholecalciferol (Vitamin D3) Vitamin D3 converted to 25-hydroxycholecalciferol in the liver by 25-hydroxylase 25-hydroxycholecalciferol converted to 1,25-dihydroxycholecalciferol (calcitriol) in the kidneys by 1-alpha hydroxylase Calcitriol increases calcium & phosphate absorption in the gut Vitamin D levels measured in blood = levels of 25-hydroxycholecalciferol

What are the 4 main causes of hypercalcaemia? (4)

Primary hyperparathyroidism (most common) Bone metastases (common in hospitalised patients) Sarcoidosis (rare) Multiple myeloma

What are other causes of hypercalcaemia? (6)

PTHrP release from cancer (e.g., small cell/squamous cell lung cancer) Thyrotoxicosis Hypoadrenalism Thiazide diuretics Excess Vitamin D Sarcoidosis → ectopic 1-alpha hydroxylase (more common in summer; managed with high-dose prednisolone, 40 mg

What are the symptoms of hypercalcaemia? (6)

Bone: Bone pain, fractures Stones: Kidney stones (radioopaque on imaging) Abdominal groans: Diffuse abdominal pain, pancreatitis, constipation Psychic moans: Depression, lethargy, confusion, seizures, coma Polyuria, polydipsia Nephrogenic diabetes insipidus

What are the signs of hypercalcaemia? (5)

Band keratopathy (calcium deposition across the front of the eye) Pepperpot skull Osteitis fibrosa cystica NOTE: Band keratopathy develops only with chronic hypercalcaemia, commonly due to primary hyperparathyroidism

What is the management of hypercalcaemia with calcium levels between 2.6–2.8 mmol/L? (4)

No urgent treatment required Drink lots of water Avoid thiazide diuretics Refer to endocrinology for minimally invasive parathyroidectomy (Sesta MIBI scan and ultrasound used to identify overactive glands)

What is the management of hypercalcaemia with calcium levels >3 mmol/L or if unwell? (5)

Administer 4–6 L of 0.9% IV saline over 24 hours (if liver failure, consider dextrose instead) First litre should be given rapidly within 1 hour If no room for more saline, use furosemide Insert catheter if associated with renal failure If malignancy + bone pain: use bisphosphonates (e.g., pamidronate)

What are the causes of hypocalcaemia? (7)

Chronic renal failure Vitamin D deficiency Subtotal/total thyroidectomy Alkalosis Acute pancreatitis Congenital absence of parathyroids (e.g., DiGeorge syndrome) Magnesium deficiency (involved in PTH regulation)

What are the symptoms of hypocalcaemia? (5)

Mnemonic: CATS go NUMB Convulsions Arrhythmias Tetany Numbness (commonly around the mouth) Other: Chvostek’s sign (facial nerve), Trousseau’s sign (carpopedal spasm), depression

How is hypocalcaemia managed? (1)

Vitamin D (may need to give activated forms in renal failure)