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Meded Flashcards 2020 > Bones and Calcium Metabolism > Flashcards

Bones and Calcium Metabolism Flashcards

1
Q

Effect of PTH

  • kidneys
  • bones
  • small intestines
A

Effect of PTH

  • Kidneys
  1. Increased calcium reabsorption
  2. Increased phosphate excretion [Phosphate Sparing Hormone]
  3. [Stimulates 1 alpha hydroxylase enzyme in kidney that makes PTH]
  • Bones
    1. Increased bone resorption
  • Small intestines
  • Increased calcium absorption
  • Increased phosphate absorption
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2
Q

Factors increasing calcium metabolism

A

PTH

Calcitriol/Vit D

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3
Q

Factors decreasing calcium metabolism/blood calcium

A

Calcitonin

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4
Q

Effect of calcitriol/vitamin D on:

Kidneys

Bones

Small intestine

A

Effect of calcitriol/vitamin D on:

Kidneys

  1. Increased calcium reabsorption
  2. Decreased phosphate reabsorption

Bones

  1. Increased bone formation

Small intestine

  1. Increased calcium absorption
  2. Increased phosphate absorption
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5
Q

Which has a bigger effect on increasing blood calcium, PTH or calcitriol?

A

Calcitriol

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6
Q

Overall effect of PTH on blood

A

increased calcium

decreased phosphate

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7
Q

Overall effect of calcitriol on blood

A

Greatly increased calcium

Decreased phosphate

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8
Q

Where is PTH produced?

A

Parathyroid glands

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9
Q

Where is calcitriol produced?

A

Skin {with UV light]

Activated by enzymes in liver [25-hydroxylase] and kidney [1-a-hydroxylase]

[PTH stimulates action of 1-a-hydroxylase]

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10
Q

Where is calcitonin produced?

A

Parafollicular cells in thyroid

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11
Q

Why is UK population deficient in calcitriol

A

Less sunlight/UV

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12
Q

SBA 1

63 y o man, generalised bone pain and muscle weakness

What is the most likely underlying diagnosis?

A Osteomalacia

B Primary hyperparathyroidism

C Paget’s disease

D Osteomyelitis

E Osteoporosis

A

A Osteomalacia

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13
Q

sba 2

A 75 year old woman presents with polyuria, constipation. She admits that her mood has been low over the past few weeks. Her blood results reveal the following:

hypercalcaemia

low phosphate

normal pth

normal glucose

What is the most likely underlying diagnosis?

A Osteomalacia

B Primary hyperparathyroidism

C Paget’s disease

D Osteomyelitis

E Osteoporosis

A

B Primary hyperparathyroidism

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14
Q

Explain the parathyroid axis

A

Low calcium

Stimulates production of PTH and Calcitriol/Vit D

Increases blood calcium

Negative feedback decreases production of PTH and Calcitriol/Vit D

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15
Q

Primary hyperpth

definition

pathophysiology

risk factors

symptoms and signs

investigations

  • blood
  • other

blood results

treatment

A

Primary hyperPTH

Definition

Excess uncontrolled secretion of PTH from parathyroid adenoma

Pathophysiology

Parathyroid adenoma- no negative feedback

Risk factors

MEN one or two a

Hypertension

Symptoms and signs

Often asymptomatic

Hypercalcaemia- stones, bones, thrones, abdominal groans, psychic moans

investigations

- blood

FBC
CRP
U and E
LFT - ALP

Ca

Phosphate

PTH

Vit D

- other

Imaging:

X-ray/CT- bone disease- Pepper pot skull

CT KUB- renal stones

Cervical US- before surgery

blood results

High Ca, PTH, ALP [or normal PTH, ALP]

Low phosphate

Normal Vit D

Treatment

Surgical- first line= total parathyroidectomy

Medical- Cinacalcet [calcimemetic]

If acute hypercalcaemia:

IV fluids

And if still high: bisphophonates

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16
Q

Secondary hyperPTH/Osteomalacia/Rickets

definition

pathophysiology

risk factors

symptoms and signs

treatment

A

Secondary hyperPTH

Definition

Hyperparathyroidism in response to low Ca- due to disorder of bone remodelling

Pathophysiology

Low Ca due to low vit D- osteomalacia- PTH is high due to lack of negative feedback

Risk factors

Vitamin D deficiency

  • poor diet, poor sunlight, malabsorption
  • Chronic kidney disease
  • Liver disease

Symptoms and signs

General

Fractures/bone pain- Looser’s pseudofractures

Fatigue

Hypocalcemia- convulsions, arrthymia, tetany, numbness- CATS go numb

Proximal myopathy

Rickets- only in children

Bowed legs

Rachitic rosary

Knock knees

Bone bossing

Investigations

Same as primaryHPT

  • Bloods for calcium , PTH etc
  • Imaging- X rays, CT KUB, cervical US

Treatment

If acute hypocalcaemia:

IV calcium gluconate

Medical- if due to simple vit D deficiency

Calcium

Vitamin D- inactive- ergocalciferol

Medical- if due to CKD

Treat CKD

Calcium

Vitamin D- active - alfacalcidol

17
Q

Symptoms of hypocalcaemia

A

CATS go numb

Convulsion

Arrthymia

Tetany

Parasthesia

18
Q

Blood biochemistry in different conditions- summary table

A
19
Q

Characteristic radiological finding in primary hyperPTH

A

Pepper Pot Skull

20
Q

Two radiological findings in secondary hyperPTH

A

Looser’s pseudofractures

Rachitic rosary

21
Q

SBA 3

An 82 year old man sees his GP because of a 3 month history of progressive deafness. Using a 512Hz tuning fork, the doctor performed both Weber’s and Rinne’s test. There was lateralisation of vibration to the left ear, and air was louder than bone conduction in both ears. His blood results were normal apart from increased ALP.

What is the most likely underlying diagnosis?

A Osteomalacia

B Primary hyperparathyroidism

C Paget’s disease

D Osteomyelitis

E Osteoporosis

A

C Paget’s disease

22
Q

SBA 4

A

E Osteoporosis

23
Q

Paget’s disease

Definition

Types

Phases of disease

Aetiology

Risk factors

Symptoms

Signs

Investigations

Blood results

A

Paget’s disease

Definition

Disease of bone remodelling

Aetiology

Genetic factors

Types

monostotic- one bone- 25%

polyostotic- 75%

Phases of disease

Lytic phase - osteoclast- resorption

Mixed phase- osteoblasts compensate

Sclerotic phase- too many osteoblasts- formation of excess woven bone

Risk factors

Elderly

FH

Symptoms

Often asymptomatic

Bone pain- femur, pelvis, skull

Nerve compression- sensorineural deafness, sciatica

Signs

Bone bossing- skull, femure, tibia

Thoracic kyphosis

Warm skin over painful bone

Investigations

Bloods: FBC, U and E, LFT- ALP, Ca, Phosphate, Vit D, PTH

Serum CTX - bone resorption marker

Serum P1NP - bone formation marker

Imaging: X rays, radionucleotide bone scan- Tec

Blood results

24
Q

Osteoporosis

Definition

Aetiology

a- primary causes

b- secondary causes

Symptoms

Signs

Investigations

A

Osteoporosis

Definition

Reduced bone density

Aetiology

Primary causes

Old- over fifty

Post menopausal

Secondary causes

  • Drugs- steroids, thyroxine
  • Endo- Cushing, hyperthyroidism
  • Cancer- multiple myeloma
  • MSK- SLE, RA
  • GI- Coeliac disease, IBD

Symptoms and Signs

Fractures- Neck of femur

Back pain

Thoracic kyphosis

Investigations

Bloods: FBC, CRP, U+E, LFT-ALP, Ca, Vit D, Phosphate, PTH

Imaging:

X ray

DEXA scan

25
Q

What is a DEXA scan?

A

Scan to look at bone mineral density

26
Q

What is a T score in a DEXA scan?

A

Patient’s bone mineral density compared to a young healthy adult

27
Q

What is a Z score in a DEXA scan?

A

Patient’s bone mineral density compared to an age matched bone mineral density

28
Q

When calcium is high, PTH should be…?

A

Low [not normal]

29
Q

Biochem q1

A

E Osteoporosis

30
Q

Biochem q2

A

Osteomalacia [due to vitamin D/calcitriol deficiency]

31
Q

Biochem q 3

A

Osteomalacia [due to CKD]

32
Q

Biochem q4

A

B Primary hyperparathyroidism

33
Q

Biochem q5

A

B Primary hyperparathyroidism

[PTH is inappropriately normal]

34
Q

Biochem q 6

A

C Paget’s disease

35
Q

Endocrine causes of proximal myopathy

A

COT

Cushing’s

Osteomalacia

Thyrotoxicosis

36
Q

Factors predisposing to osteoporosis

A

Primary:

Old age- over fifty

Post menopausal

Secondary:

Endocrine- Cushing, hyperthyroidism

Drugs: Steroids, thyroxine

MSK- SLE, rheumatoid arthritis

GI- coeliac, IBD

Cancer: multiple myeloma

37
Q

Symptoms and signs of Paget’s disease

A

Symptoms:

Bone pain

Sensorineural deafness, sciatica [nerve compression]

Signs

Warm to touch over painful bone

Thoracic kyphosis

Bone bossing- skull, femur tibia

38
Q

Special markers to investigate in Paget’s?

A

Serum CTX- bone resorption

Serum P1NP- bone formation

Meded Flashcards 2020 (36 decks)

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