Disorders In Calcium Metabolism Flashcards
What regulates Calcium?
PTH
VitD3
Calcitonin
What state of Calcium do homeostatic mechanisms respond to ?
Ionised
What can cause artefacts in ionised calcium measurements ?
Increases in pH increase protein binding — air, agitation, variation in heparin conc — DECREASE
Lipaemia is increases serum ionised Ca
What should you consider when you see a low total calcium?
Albumin levels
What effect on ions does PTH have?
INCREASE calcium
DECREASE phosphate
What effect on ions does VitD3 have?
INCREASE calcium
INCREASE Phosphate
What should you look at whenever you look at calcium?
PHOSPHATE
ALBUMIN
What happens when you have high calcium and high phosphate?
Produces calcium phosphate which is insoluble and results in irreversible soft tissue calcification.
What clinical signs are associated with hypercalcaemia ?
—PU/PD
—Weakness, lethargy, depression - interferes with neuromuscular transmission
—Inappetence, V+D, Constipation
—facial pruritis and oral discomfort - paraesthesia
— Muscle twitching and fasciculations
—Tachydysrhythmias
— death
How does hypercalcaemia affect renal function?
— interferes with ADH action -> nephrogenic DI
— Impairs NaCl reabsorption in loop - decreases medullary hypertonicity
— if also high phos - Calcium phosphate deposition causes nephron damage
— Vasoconstriction of afferent arterioles -> Reduced GFR and AZOTAEMIA
What clinical pathology is associated with hypercalcaemia?
Hypercalcaemia
+/- phosphate disruption
+/- renal signs - azotaemia and low USG (ICU)
What pathology can cause hypercalcaemia?
Primary hyperparathyroidism
Humoral hypercalcaemia of
malignancy - lymphoma, anal sac adenocarcinoma, multiple myeloma
Non PTH causes
How does the biochem appear in increased PTH Or PTH like activity?
Ionised hypercalcaemia
AND Low or non-elevated phosphate
High PTH-rp measurable for suspect neoplasia
What can cause hypercalcaemia (unrelated to PTH activity)?
Vitamin D toxicity - excessive supplementation - rodenticides, psoriasis creams Granulomatous inflammation HYPOadrenocorticism CKD Grape intoxication Idiopathic Significant osteolysis
What breed/age is predisposed to primary hyperparathyroidism?
Keeshunds
Older dogs - over 6
