Hypercalcemia and hypocalcemic disorders in dogs and cats Flashcards Preview

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Flashcards in Hypercalcemia and hypocalcemic disorders in dogs and cats Deck (26):
1

function of calcium in the body

Intracellular second messenger involved in signalling systems
Nerve conduction and neuromuscular transmission
Coagulation
Muscle contraction
Membrane stability

2

3 main hormone systems in control of Ca

parathyroid hormone (PTH)
vitamin D + its metabolites
calcitonin

3

PTH - when is it secreted

secreted by the chief cells of the parathyroid gland in response to decr serum levels of ionised calcium

4

PTH - effects

kidneys - decr Ca excretion and incr calcitriol production
bone - incr Ca resorption
GIT - incr Ca absorption by effects on calcitriol production
incr phosphate excretion through enhanced phosphaturia - hyperparathyroidism tends to develop nephrocalcinosis.

5

PTHrP (parathyroid hormone related peptide)

PTH like factor excreted by some neoplastic cells + causes hypercalcemia with malignancy.

6

Vitamin D and its metabolites

steroid hormone
The biologically active metabolite is calcitriol
Vitamin D synthesised in skin or ingested in the diet
converted in the liver and kidneys to the active for.

7

calcitrol effects

incr serum Ca by incr GI absorption of Ca
facilitates renal reabsoprtion of Ca + mobilises Ca + phosphorus from bone

8

Calcitonin

secreted in response to hypercalcemia by the C cells of the thyroid gland
physiological effects are minor

9

Measurement of calcium

Clinically total serum calcium is most commonly measured parameter
ionised calcium is the physiologically significant value controlled by homeostatic mechanisms

10

measuring Ca with serum albumin conc

common cause of a total hypercalcemia is an incr albumin conce seen with dehydration.
total calcium is incr this is d/t incr in bound fraction + is of no physiological significance
patient with low serum albumin may have a normal total Ca but has incr in ionised calcium that is potentially life-threatening

11

hypercalcaemia - clinical signs

often vague - can be mistaken for natural aging
PU/PD, anorexia, dehydration, weakness/lethargy and vomiting
severe less common signs - facial pruritis, oral discomfort, cardiac arrhythmias, seizures/twitching, acute renal failure and death.

12

hypercalcaemia - effects on kidney

interferes with kidney’s ability to conc urine - patients may be dehydrated with a pre-renal azotaemia but still have urine with a relatively low specific gravity
exacerbated d/t high Ca also causes vasoconstriction of the afferent glomerular arteriole, decr in GFR + azotemia.

13

hypercalcaemia - causes - non pathologic

Young animals
Lab error
Spurious (lipaemia)

14

hypercalcaemia - causes - transient incosequential

Hypoadrenococrticism
Haemoconcentration
Hyperproteinaemia

15

hypercalcaemia - causes - pathologic

Malignancy (esp lymphoma, anal sac adenocarcinoma)
Primary hyperparathyroidism
Renal failure
Hypervitaminosis D
Granulomatous disease (fungal infection, lungworm)
Toxic
Skeletal lesions
Idiopathic (cats)

16

hypercalcaemia - most common causes

neoplasia
primary hyperparathyroidism, chronic renal failure, granulomatous inflammatory disorders and hypoadrenocorticism

17

Primary hyperparathryroidism - cause

parathyroid adenoma of the parathyroid glands
nodule is non-palpable but readily ultrasonographically demonstrable

18

Evaluation of patient with hypercalcemia

PE including rectal examination
Haematology, biochemistry, UA
Aspiration of masses/enlarged lymph nodes
Imaging of thorax and abdomen to assess for neoplasia
Bone marrow aspirate
Ultrasound of neck
ACTH stimulation test
Test for other granulomatous (infectious) disease –dependent on geographical location
PTH/PTHrP levels
Calcitriol measurement

19

hypercalcaemia - treatment of underlying disease

Chemotherapy for some neoplastic diseases
surgery for neoplastic disease and primary hyperparathyroidism
Anti-fungals/antiparastitics in granulomaotus disease

20

hypercalcaemia - treatment without definitive diagnosis

Diuresis with 0.9%NaCl
Bisphosphonates therapy e.g. palmidronate
Calcitonin
Furosemide
Peritoneal dialysis

21

why not to use glucocorticoids`

lower serum Ca but mask underlying disease - diagnosis more difficult

22

long term effect of hyercalcaemia

renal failure secondary to soft tissue mineralisation
more likely if the phosphorus level is also elevated

23

hypocalcaemia - clinical signs

muscle tremors/cramps, stiff gait, behavioural change, panting, hyperthermia tachycardia, hypotension, death

24

hypocalcaemia - causes

Chronic renal failure
Eclampsia (pregnancy disorder)
Acute pancreatitis
Iatrogenic (post thyroidectomy/parathyroidectomy, post blood transfusion)
Ethylene glycol toxicity
Intestinal malabsorption
Primary hypoparathyroidism

25

hypocalcaemia - treatment - acute

IV 10% calcium gluconate

26

hypocalcaemia - treatment - chronic

Oral calcium supplementation
vitamin D metabolite
Ergocalciferol (cheap but long half-life)
Dihydrotachysterol (intermediate price, intermediate half-life
Calctriol (most expensive but shortest half life)