Session 9 - Disorders Of Calcium Metabolism And Metabolic Bone Disease

Question 1

Chronic Hypercalcaemia

What are the clinical signs of this?

Answer 1

“Stones, moans(depression), groans(abdominal pain), bones(muscle aches)”

• renal calculi (stones)
• kidney damage
• constipation
• dehydration
• tiredness
• depression

Question 2

Hypocalcaemia

What are the symptoms of this?

Answer 2

Hyper-excitability of NMJ

Sensory symptoms

• pins and needles
• tingling around mouth and fingers

Motor symptoms

• tetany (muscle spasms)
• carpopedal spasm
• paralysis
• convulsions

Question 3

Hypocalcaemia

When is this mostly seen in patient ?

Answer 3

Post-thyroidectomy patients because of inadvertent removal/ischaemia of parathyroid glands

Serum calcium < 2.10 mmol/L

Question 5

Hypocalcaemia

How does it lead to a hyper-excitability of NMJ?

Answer 5

Lower serum calcium causes an increase in sodium entry into neurones, leading to depolarisation and increase likelihood of AP

Question 6

Hypercalcaemia

What is the reference range for which this is diagnosed?

Answer 6

Serum calcium > 3mmol/L

Question 7

Hypercalcaemia

What are the symptoms of this?

Answer 7

• Polyuria
• Dehydration
• Lethargy
• Weakness
• Confusion
• Coma
• Renal failure

Question 8

Hypercalcaemia

State the two main mechanisms by which malignancy can cause Hypercalcaemia

Answer 8

• Haematological malignancies (myeloma) and those that metastasise to bone produce local factors that act in a paracrine manner to activate osteoclasts
• Squamous tumour of the lung, head and neck produces a hormone, Parathyroid hormone-related peptide (PTHrp) that cats on parathyroid hormone receptors

Question 9

Hypercalacaemia

Name the 4 common types of cancer that metastasise to bone causing osteolytic lesion

Answer 9

• Breast
• Lung
• Renal
• Thyroid

Question 10

Hypercalcaemia

Though prostate cancer is a common cause of bone metastasise, why doesn’t it cause Hypercalcaemia ?

Answer 10

It causes osteoblastic(building of bone) metastasis therefore calcium not released thus Hypercalcaemia not occurring

Question 11

Hypercalcaemia

Give examples of common sites for bone metastasis in the axial skeleton

Answer 11

• vetebrae
• pelvis
• ribs
• skull

Question 12

Hypercalcaemia

Give examples of common sites for bone metastasis in the appendicular skeleton

Answer 12

• proximal part of the femur

- proximal part of the humerus

Question 13

Hypercalcaemia

Name the effects of Parathyroid hormone related peptide on parathyroid hormone receptors

Answer 13

Mimics some of the effects of parathyroid hormone on bone and kidneys but not on intestine to produce vitamin D

Question 14

Hyperparathyroidism

What is the primary cause of this?

Answer 14

One of the 4 parathyroid glands develops an adenoma and secretes excessive parathyroid hormone

Question 15

Hyperparathyroidism

Why does the primary cause of it lead to an increase in serum calcium and decrease in serum phosphate?

Answer 15

Parathyroid hormone acts on the bones and kidneys

Bones
- increases number and activity of osteoclasts therefore calcium and phosphate released into blood stream

Kidneys
- increases reabsorption of calcium
- increases excretion of phosphate
(Net loss of phosphate because more of it is lost from urine than gained from bones)

Question 16

Hyperparathyroidism

What is the secondary cause of this ?

Answer 16

All 4 parathyroid glands become hyperplastic

Question 17

Hyperparathyroidism

When is secondary hyperparathyroidism seen in patient ?

Answer 17

• with vitamin d deficiency (why)

- Chronic renal failure (why)

Question 18

What is the difference between osteomalacia and osteoporosis?

Answer 18

Osteomalacia - vitamin d deficiency so bone is not mineralised

Osteoporosis - increased osteoclast activity or reduced osteoblasts function therefore bone is not being laid down enough or bone resorption increases

Question 19

Osteomalacia

Signs and Symptoms

Answer 19

• bone pain
• muscle weakness
• deformity of bone

Question 20

Primary Hyperparathyroidism

What are the symptoms of this?

Answer 20

• Stones: kidney stones, polyuria due to impaired sodium and water reabsorption
• Moans : tired, exhausted, depressed
• Groans : constipation, peptic ulcers, pancreatitis
• Bones : bones and muscle aches

Question 21

Rickets

Signs and Symptoms

Answer 21

• Soft bones
• weakened bone development
• shortened height and stature
• painful to walk

Question 22

Rickets

What may cause this is children ?

Answer 22

• diet
• environment
• chronic renal disease: renal osteodystrophy

Question 23

What is osteomalacia in children called ?

Answer 23

Rickets