Chempath 20: Clinical Chemistry CPC Flashcards Preview

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Flashcards in Chempath 20: Clinical Chemistry CPC Deck (20)
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1
Q

Which fracture is most likely if you slip and fall on outstretched hands ?

A

Cole’s fracture

Radius fractures backwards away from the palm side

2
Q

What fracture is caused by falling on a flexed wrist ?

A

Smith’s fracture

3
Q

List 3 causes of hypercalcaemia ?

A

Primary hyperparathyroidism
Cancer
Sarcoidosis

4
Q

How can you differentiate Primary hyperparathyroidism from cancer causing hypercalcaemia ?

A

Plasma PTH

0 in cancer and high in primary hyperparathyroidism

5
Q

What is PTHrP ?

Give 2 locations where its produced ?

A

PTH related peptide

Produced by the placenta (so mothers calcium increases and baby can steal some)
produced by breast and secreted into breast milk

6
Q

Why is PTHrP activation in cancer a bad prognostic feature ?

A

PTHrP stimulates cancer invasion of bone by turning on osteoclasts.

7
Q

Which enzyme activates Vitamin D in the kidneys ?

A

1-alpha hydroxylase

8
Q

How does vitamin D affect the kidneys ?

A

Activated vitamin D (calcitriol) causes increased reabsorption of calcium

9
Q

Which tumours are featured in MEN1 ?

A

Pituitary tumour
Parathyroid tumour
Pancreas - islet cell tumour

10
Q

What symptoms do you get with hypercalcaemia ?

A

Moans- depression, psychosis, coma
Groans- constipation, abdominal pain,
Bones- fractures, bone pain (osteitis fibrosa cystica)
Stones- renal colic (calcium oxalate stones)

Polydipsia and polyuria (nephrogenic diabetes insipidus)

11
Q

Which organism causes recurrent UTIs in patients with calcium stones ?

A

Proteus mirabilis

12
Q

Why are patients so dehydrated with Hypercalcaemia ?

A

Calcium acts like mannitol, it causes water to move with it into the urine causing a diuresis

13
Q

How do you treat hypercalcaemia ?

A
  • Saline fluids (to rehydrate)
  • Furusamide (causes calcium loss in the urine)
  • IV pamidronate (a bisphosphonate that stops bone resorption by causing osteoclast apoptosis. Only use in very high calcium)
14
Q

Why is giving saline to hypercalcaemia patients with liver failure contraindicated ?

What do you give instead ?

A

They retain salt so can cause hypernatraemia

Dextrose Fluids

15
Q

Which diuretics should be avoided in hypercalcaemia ?

A

Thiazides

They cause increased calcium reabsorption into the blood.

16
Q

Which feature of Osteitis fibrosa cystica is described by this histology:

“Multinucleate giant cells in the bone”

A

Brown tumours

Giant cells are the activated osteoclasts

17
Q

A lady is noted to have hypercalcaemia, her chest X ray shows bilateral hilar lymphadenopathy.

What is the most likely diagnosis ?

A

Sarcoidosis

18
Q

A histology specimen of a patient with hypercalcaemia shows “non-caseating granuloma”.

What is the most likely diagnosis ?

A

Sarcoidosis

19
Q

What is the mainstay of treatment for sarcoidosis ?

A

Steroids

20
Q

How does sarcoidosis cause Hypercalcaemia ?

A
  • Macrophages in the lungs of people with sarcoidosis express 1-alpha-hydroxylase.
  • This causes increased activation of vitamin D (especially in the summer)
  • Activated Vitamin D causes increased calcium reabsorption from the kidneys and G.I tract

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