Hypercalcaemia Flashcards
What is the typical signalment of primary hyperparathyroidism in cats?
middle aged to older
how do you treat primary hyperparathyroidism?
Normally surgery to remove the affected gland
Use U/S first to see which gland of the 4 is enlarged and guide surgery
What are the clinical signs of hypercalcaemia?
Twitching PUPD constipation Cardiac arrhythmias vomiting anorexia
When is PTHrP high?
In some cases of malignancy induced hypercalcaemia - some cases won’t be high though!
What are the main drugs used to manage hypercalcaemia in cats?
Preds or dexamethasone (only do if have a dx)
Frusemide (ensure hydrated)
alendronate - oral long term management
Calcitonin
How do steroids reduce high Ca?
Glucocorticoids act to reduce bone resorption, decrease intestinal absorption and increase renal excretion of calcium. Their mechanism of action is thought to be through inhibiting prostaglandin E, osteoclastic activating factor and vitamin D production.
How can diet help hypercalcaemia?
in cats with idiopathic hypercalcaemia. High fibre diets can be fed to bind intestinal calcium, thus reducing its absorption. Wet diets can also be helpful in promoting diuresis and generally have a lower calcium content than dry diets. Renal diets may be successful in some cases as these are low in calcium and phosphate, although calcium availability is higher compared with maintenance diets. Renal diets are also more alkalising than normal maintenance diets. However, hypercalcaemia has been noted in cats fed a renal diet and so this diet should be discontinued if hypercalcaemia worsens.
What would bloods show in idiopathic hypercalcaemia?
the total and ionised calcium levels are elevated but phosphate, PTH-rp and vitamin D metabolites are normal. PTH may be normal or decreased due to the suppressive effect of hypercalcaemia.
How can you treat mild idiopathic hypercalcaemia?
Dietary management may be successful in many cases. Feeding a high fibre diet, supplementing with psyllium husks or feeding a wet diet is recommended as an initial first step, particularly in cats with only mild or moderate hypercalcaemia. A renal diet or diet formulated for management of calcium oxalate urolithiasis can be considered as an alternative
What are the calcium results for hypercalcaemic CKD cats?
in cats with early and mid-stage CKD, ionised calcium is normal or low and total calcium is normal or increased. This is the result of increased phosphate concentration associated with reduced renal clearance forming complexes with ionised calcium
What would you see on bloods with primary hyperparathyroidism?
increased total and ionised calcium concentrations, increased PTH concentration, decreased phosphate concentration and normal or increased calcitriol
How does renal secondary hyperparathyroidism work?
results from reduced renal clearance of phosphate in patients with a decreased glomerular filtration rate. The increasing blood phosphate forms complexes with calcium, resulting in a corresponding decrease in calcium concentration and stimulating PTH production.`
Which tumours are most likely to cause hypercalcaemia
2/3 are lymphoma and SCC
Rest is multiple myeloma, bronchocarcinoma, osteosarcoma and fibrosarcoma
What would bloods show with malignancy induced high Ca
Both total and ionised calcium are increased in patients with malignancy-associated hypercalcaemia and, therefore, PTH concentration should be low. PTH-rp can be increased, but can also be normal.
What will bloods show with hypervitaminosis D?
High Ca and Phos
Low PTH
What can cause granulomatous high Ca
mycobacteria, feline infectious peritonitis, toxoplasmosis, Nocardia species, Cryptococcus species and Actinomyces rhinitis in cats.
What adrenal disease can cause high Ca
Addisons
What can cause false Ca levels on bloods?
Contaminants (e.g. oxalate/ citrate/ EDTA) - false decrease haemolysis lipaemia - false decrease High albumin - false high Drugs e.g. paracetemol Inadequate/ excessive sample
How can Ca permenantly affect the body
Mineralisation with phos in the soft tissues
How does Ca affect an ECG?
Prolongation of PR interval
Shortening of the QT interval
Does low USG and azotaemia confirm CKD in hypercalcaemic animals?
no
What are non pathologic reasons for high Ca?
Young animals
lab error
spurious
What are the transient reasons for high Ca?
Hyperparathyroidism Granulomatous disease Skeletal lesions Neoplasia - e.g. thymoma, lymphoproliferative disease Hypervitaminosis D or A Idiopathic (cats) AKI or CKD Thyrotoxicosis Aluminium exposure Over supplementation
What are the most likely dx for high Ca in dogs?
***Neoplasia, often lymphoma or Anal Sac adenocarcinoma
Renal dz
high PTH
Addisons
What are the most likely dx for high Ca in cats
Neoplasia
Renal
Others
What are the main forms of ix in high Ca cases
Bloods
Imaging - survey radiographs, assess bones, check for tumours, US the neck
PTH and PTHrp and vitamin D
Biopsies as needed
What parasite can cause high Ca?
lungowrm
What are the ways neoplasia can cause high Ca?
humoural high Ca of malignancy
Caused by malignancies in bone marrow (may see bone pain/ lucencies)
Or associated with solid tumours, rare, normal to increased phosphate and ALP
What would you see on bloods with PTHrp was high?
High Ca
Low/ normal phos
Outline primary hyperparathyroidism
Older animals High iCa, ALP, low phos, High PTH Oft can feel a PTH gland nodule/ see it on rads Oft see CaO urolithiasis Tx with Sx
Outline addisons as a cause of high Ca
mechanism unknown, appears to correlate with degree of K increase
30% dogs, 10% cats
Resolves with Tx
outline Vitamin D toxicity as a cause of high Ca
Ingestion of psorriasis cream/ jessamine
High Ca occurs approx 24 hours after ingestion
High phos, sometimes azotaemia
Dx - high vitamin D, low PTH, undectable PTHrp
outline granulomatous inflammation as a cause of high Ca
D/t calcitriol synthesis by activated macrophages during inflammation
e.g. unusual bacteria - nocardia/ actinomyces
Granulomatous dermatitis
Fungal dz abroad (e.g. hisotplasmosis)
What do you need to r/o to dx idiopathic disease in cats - care - not even 100% clear this is a dz in the UK, only in US
FIV FeLV -ve Normal t4 normal acid base status imaging clear low normal PTH, undetectable PTHrp Normal vitamin D
How does calcitonin work as a treatment for high Ca
Decreases Ca release from bone
resistance occurs within a couple of days
Can cause v/d, often used as a stop ap
How do bisphosphonates work as tx for high Ca
Decrease osetoclast activity, takes 1-2d
Effective fro many dz
Poss can cause renal injury
How do glucocorticoids work as tx for high Ca
Decrease bone resorption
Increase renal excretion
Decrease intestinal Ca Absorption
Only use when dx is made
What causes of high Ca may respond to steriods?
Addisons many neoplasias idiopathic granulomatous dz Vitamin A and D toxicity
When may bicarb be used as a treatment for hypercalcaemia?
When acidosis is involved
reserved for severe acute high Ca
What is the most common cause of primary hyperparathyroidism in the dog?
Adenoma of the parathyroid gland
Keeshonds over represented
Often over 10
