Chem Path: Calcium metabolism Flashcards

1
Q

What is normal calcium serum levels?

A

2.2 to 2.6

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2
Q

What is corrected calcium and what is the formula?

A

It is corrected for albumin levels

It tells you what calcium would have been if albumin is normal

serum calcium + 0.02(40-serum albumin)

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3
Q

What are the 3 actions of PTH

A

Turn on osteoclasts to break down bone

Increased renal calcium reabsorption

Increases 1 alpha hydroxylation of vit D and vit D causes calcium reabsorption in the gut

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4
Q

What is PTH’s effect on phosphate

A

Increases phosphate excretion in kidneys

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5
Q

How is Vit D processed in the body?

A

Cholecalciferol is 25 hydroxylased in the liver, and is 1 alpha hydrxylased in the kidneys

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6
Q

What are ergocalciferol and cholecalciferol

A

Ergo is plant product

Chole is animal product

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7
Q

Other than the kidney, what else can produce 1 alpha hydroxylase

A

Sarcoid lung tissue

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8
Q

How does Vit D affect phosphate?

A

It causes phosphate reabsorption in gut

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9
Q

What does Vit D deficiency cause?

A

Osteomalacia in adults

Rickets in kids

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10
Q

How does osteomalacia present?

A

Loosers zone and pseudo fractures

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11
Q

What is the biochem of osteomalacia

A

Low calcium, low phosphate and high ALP

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12
Q

What medication can cause low Vit D?

A

Anti convulsants

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13
Q

What is PTHrp

A

Produced by placenta to steal calcium from mother. Also expressed in cancer patients

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14
Q

What is the biochem of osteoporosis

A

All normal levels

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15
Q

What are t and z scores in DEXA scan

A

T score compared to young people - below 2.5 is osteoporosis
z score compared to your age

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16
Q

What drugs to treat osteoporosis

A

Bisphosphonates - alendronate - take them alone

Teriparatide - PTH analogue

Strontium

SERM - Raloxifene and tamoxifen (antagonist in breast but agonist in bone and uterus)

17
Q

What are symptoms of hypercalcaemia?

A

Polyuria, polydipsia, constipation, confusion, seizure, coma

18
Q

What can cause primary hyperparathyroidism

A

Prarathyroid adenoma

Hyperplasia due to MEN1

19
Q

What are the features of primary parathyroidism

A

Bones, stones, moans, groans

20
Q

What is FHH/FBH

A

Raised calcium levels due to mutation in CaSR. Higher threshold for PTH release

21
Q

What drug causes increased PTH and increased calcium

A

Lithium

22
Q

What are some non PTH driven causes of hypercalcaemia

A

Sarcoidosis, thyrotoxicosis, hypoadrenalism, thiazide diuretics

23
Q

Acute management for hypercalcaemia?

A

Fluids - 0.9% saline - 1L over an hour or 500ml per hour

24
Q

How does hypocalcaemia present?

A

Troussoue’s sign - carpals spam when measuring bp

Chovstek’s sign - increased muscle excitability

25
Q

What is Di George’s syndrome?

A

Congenital absence of parathyroid

26
Q

Which element is crucial to PTH

A

Magnesium

27
Q

What is the biochem for secondary hyperparathyroidism

A

Low calcium, high pth

28
Q

What is raised in Paget’s disease

A

ALP

29
Q

What is the treatment for Paget’s

A

Bisphosphonates

30
Q

What is renal osteodystrophy

A

Due to secondary hyperPTH and retention of aluminium from dialysis fluid

31
Q

What is secondary hyperparathyroidism

A

Anything that causes PTH glands to be more active and produce more PTH. Like CKD for example