Hypocalcaemia Flashcards
What are the main groups of differentials for low Ca?
Low albumin
hypoparathyroidism
Vit D disorders
redistribution
What types of hypoparathyroidism are there?
Primary - either atrophy/ lymphocytic infiltrate of galnd or infarction of an adenoma
Secondary - From sx (normally thyroidectomy), can be from parathyroidectomy. cervical trauma
What vitamin D pathologies are there?
AKI/ CKD
Nutritional secondary hyperparathyroidism - eg. raw food, common in young animals fed diets with inappropriate Ca to phos ratio)
What are the main dzs of redistribution causing low calcium?
Eclampsia Alkalinising treatment Blood transfusions (excess citrate) Feline lower urinary tract obstruction Sodium Phosphate enemas Frusemide Ethylene glycol toxicity Pancreatitis - due to saponification of peripancreatic fat, often subclinical
Compare low calcium with AKI and CKD
AKI - high phos, low Ca. Rapid progression, may see high K, acidosis
CKD - High phos, Ca may be high or low iCa often low to normal
What is eclampsia most common in?
small dogs or cats post whelping, within 3 weeks
Outline nutritional secondary hyperparathyroidism
Unbalanced diet Mineral deficiencies Low Ca Concentration high PTH secretion Bone mobilisation Pain and fractures
On bloods it is rare to see low Ca
What are the main clinical signs of low Ca?
tetany/ seizures facial rubbing/ twitching/ cramps/ stiffness/ fasiculation High temp hehaviour changes - aggression/ increased sensitivity/ disorientation/ Panting Prolapsed TE Increase salivation (cats) Increased HR and arrythmias PUPD
When is treatment for hypocalcaemia not needed?
When no c/s
If cause is low alb, renal, iCa is normal
Outline initial treatment for hypo Ca
IV calcium gluconate. When giving, place ECG, if bradycardia develops, need to stop infusion/ slow as can risk cardiac arrest
Can take 6 hours for signs to disappear
Outline in hospital management of low Ca after initial stabilisation
Ca gluconate as CRI or subcut every 6-8 hours. monitor iCa BID
If giving SC then mix 1:1 saline (can get cutaneous reactions)
Monitor lytes - caution when phos is high as may precipitate together in soft tissues
If MG is low then Hypo Ca can be refractory to tx
When is oral maintenance treatment needed for hypo Ca and how is this done
Needed for hypoarathyroidism
Vit D needed, give oral Ca whilst Vit D taking effect
Normal vit d given is vit D3 - calcitriol - takes 1-4 days for effect
Give Ca carbonate during this time, then very slowly taper
How will the PTH glands respond to different concentrations of calcium?
PTH secretion will dramatically increase when iCa is low;
when iCa is high, PTH secretion will decrease
How does PTH act in the main target organs (kidney, gut, bone)
In the kidney, PTH will increase calcium reabsorption and phosphorus excretion. It also increases the activity of 1α-hydroxylase, the enzyme responsible for converting 25-hydroxyvitamin D (25OHD) to 1,25-dihydroxyvitamin D3 (1,25[OH]2 D3 ) (calcitriol).
Calcitriol then acts on the gastrointestinal tract to increase calcium and phosphorus absorption.
In bone, PTH induces osteoclastic bone resorption, which increases calcium and phosphorus resorption.
How useful are the PTH tests for cats
Not brilliant, can be affected by lots of things. Treat results with caution
