Chem Path: Calcium metabolism

Question 1

What is normal calcium serum levels?

Answer 1

2.2 to 2.6

Question 2

What is corrected calcium and what is the formula?

Answer 2

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)

Question 3

What are the 3 actions of PTH

Answer 3

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

Question 4

What is PTH’s effect on phosphate

Answer 4

Increases phosphate excretion in kidneys

Question 5

How is Vit D processed in the body?

Answer 5

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

Question 6

What are ergocalciferol and cholecalciferol

Answer 6

Ergo is plant product

Chole is animal product

Question 7

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

Answer 7

Sarcoid lung tissue

Question 8

How does Vit D affect phosphate?

Answer 8

It causes phosphate reabsorption in gut

Question 9

What does Vit D deficiency cause?

Answer 9

Osteomalacia in adults

Rickets in kids

Question 10

How does osteomalacia present?

Answer 10

Loosers zone and pseudo fractures

Question 11

What is the biochem of osteomalacia

Answer 11

Low calcium, low phosphate and high ALP

Question 12

What medication can cause low Vit D?

Answer 12

Anti convulsants

Question 13

What is PTHrp

Answer 13

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

Question 14

What is the biochem of osteoporosis

Answer 14

All normal levels

Question 15

What are t and z scores in DEXA scan

Answer 15

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

Question 16

What drugs to treat osteoporosis

Answer 16

Bisphosphonates - alendronate - take them alone

Teriparatide - PTH analogue

Strontium

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

Question 17

What are symptoms of hypercalcaemia?

Answer 17

Polyuria, polydipsia, constipation, confusion, seizure, coma

Question 18

What can cause primary hyperparathyroidism

Answer 18

Prarathyroid adenoma

Hyperplasia due to MEN1

Question 19

What are the features of primary parathyroidism

Answer 19

Bones, stones, moans, groans

Question 20

What is FHH/FBH

Answer 20

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

Question 21

What drug causes increased PTH and increased calcium

Answer 21

Lithium

Question 22

What are some non PTH driven causes of hypercalcaemia

Answer 22

Sarcoidosis, thyrotoxicosis, hypoadrenalism, thiazide diuretics

Question 23

Acute management for hypercalcaemia?

Answer 23

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

Question 24

How does hypocalcaemia present?

Answer 24

Troussoue’s sign - carpals spam when measuring bp

Chovstek’s sign - increased muscle excitability

Question 25

What is Di George’s syndrome?

Answer 25

Congenital absence of parathyroid

Question 26

Which element is crucial to PTH

Answer 26

Magnesium

Question 27

What is the biochem for secondary hyperparathyroidism

Answer 27

Low calcium, high pth

Question 28

What is raised in Paget’s disease

Answer 28

ALP

Question 29

What is the treatment for Paget’s

Answer 29

Bisphosphonates

Question 30

What is renal osteodystrophy

Answer 30

Due to secondary hyperPTH and retention of aluminium from dialysis fluid

Question 31

What is secondary hyperparathyroidism

Answer 31

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