Calcium disorders Flashcards
what should you check if we see a low total calcium
check for hypoalbuminaemia
If we see high total calcium what should we check
phosphate levels
What will happen if both calcium and phosphorous high in blood
will complex/precipitate
in tissues= mineralisation
this can affect the structure of some organs- and therefore their function
List 6 mechanisms of hypercalcaemia
Increased PTH activity
Activity of PTH-like substances- neoplasia
Increased Vitamin D activity
Osteolysis
Other/unclear mechanism:
- Hypoadrenocorticism
- Feline idiopathic hypercalcaemia
- Raisin toxicity
List the 6 most common causes of total hypercalcaemia in dogs
- Malignancy
- Hypoadrenocorticism
- Primary hyperparathyroidism
- Chronic renal failure
- Vitamin D toxicosis
- Granulomatous diseases
List the 4 most common causes of total hypercalcaemia in cats
- Idiopathic hypercalcaemia
- Renal failure (total mainly, occ iCa)
- Malignancy (lymphoma and squamous cell carcinoma)
- Primary hyperparathyroidism
what age does idiopathic hypercalcaemia affect
youn to middle aged cats
What are the signs of hypercalcaemia
PU/PD
vomiting
anorexia
muscle weakness
dehydration
what age does primary hyperparathyroidism generally affect
middle aged to geriatric disease
If we see hign serum ionised Ca and high serum parathyroid hormone what do we suspect
primary hyperparathyroidism
If we see hig hserum ionised Ca and low serum parathyroid hormone what do we suspect
PTH independent hypercalcaemia (e.e. malignancy, vitamin D toxicity
What is measuring 25 hydroxy vitamin D good indicator of
Excellent indicator of dietary sufficiency and excess
BUT
Will not detect vit D analogues
Describe the generic treatment for hypercalcaemia
Determine urgency by Ca x P
Fluids/diuresis- NaCl and frusomide
Glucocorticoids
Bisphosphanates
Describe the effects of vitamin D on calcium in the body
causes the liver to produce calcidiol, which is turned into calcitriol in the kidneys-which increases Ca absorption from tubules
Describe the effects of PTH on calcium levels
PTH increases calcium turnover in the bone and stimulates the kidneys to release calcitriol, as well as stimulating the kidneys to decrease calcium clearance
what is the function of calcitriol
causes an increase in calcium uptake in gut
If you get hypercalcaemia, what do you need to check
if your patient is abnormal or is your sample abnormal
why is total calcium not as reliable as ionised calcium levels
total calcium can be affected by other things
How does low albumin levels affect toatl calcium values in blood
it will cause a low calcium, as there will be less bound calcium
Describe how phosphorous affects total calcium values
higher phosphate will mean more calcium binding- this creates an increased complexed fraction of calcium
the body responds by increasing PTH due to low ionized calcium- this creates high calcium level
Describe how renal secondary hyperparathyroidism occurs
FGF-23 lowers and this causes decreased calcitriol and reduced calcium absorption, this causes an increased PTH
List 7 causes of vitamin D excess
over-supplementation
incorrect dietary formulation
rodenticide
vitamin D analogues
plants
granulomatous disease
immunological
Describe how hypoadrenocorticism cause hypercalcaemia
The exact mechanism is unknown -but it is suspected that dehydration and an increased protein concentration, combined with decreased renal excretion
What parasite can cause hypercalcaemia in dogs
Angiostrongylus
how can we diagnose a hypercalcaemia caused by PTH on clinical pathology
there will be high calcium and low phosphorous
OR
measure PTH levels
if we have azotaemia and hypercalcaemia, how can we tell which one came first
renal dysfunction will have an elevated total calcium but a low ionized calcium
if calcium has caused renal dysfunction, then the ionized calcium will be high as well as the total calcium
What is ionized calcium levels like in secondary hyperparathyroidism
low-normal
what are ionised calcium levels like in primary hyperparathyroidism
high
What is PTHrP
Parathyroid hormone-related protein
produced in malignant hypercalcaemia cases
where is 25 hydroxy vitamin D produced
in the liver
why would we test calcidiol levels
to look for vitamin D toxicity
why would we test calcitriol levels
to look for renal disease or secondary hyperparathyroidism
why do we give glucocorticoids to hypercalcaemic patients
some tumours may be steroid sensitive
glucocorticoids also promotes calcium losses
why do we give bisphosphanates to hypercalcaemic patients
stops calcium being taken out of bone
why do we have to be careful when removing parathyroid adenomas
all other PTH tissues will be atrophied - the animal won’t have enough PTH of its own and we can get a post surgical hypocalcaemia
what do we have to give post parathyroid adenoma removal
IV calcium and vitamin D therapy
List the 3 categories of hypocalcaemia
parathyroid dependent (primary hypoparathyroidism),
demand exceeds supply or mobilisation,
PTH and calcitriol resistance syndromes
List 10 clinical signs of hypocalcaemia
muscle fasciculation/tremors
face rubbing
biting/licking paws
hypersensitivity
stiff gait
ataxia
tetanic seizures
respiratory arrest
weakness
behavioural changes
Describe how to treat hypocalcaemia
IV calcium- monitor for bradycardia
oral calcium and vit D for long term
