SAM - Calcium/Phosphorus

Parathyroid glands are stimulated by

Low calcium or high phosphorus

Parathyroid hormone is inhibited by

Calcitriol

What are the actions of parathyroid hormone?

Increases calcium absorption from bone and kidney

Activates calcitriol.(vit d) -increases calcium and phosphorus absorption from intestine, kidney and bone

Decreases phosphorus resorption from kidney

Vitamin D is primarily attained from

Diet

It is then hydroxyilated in liver

Finally, hydroxylated again in the kidney

Final product is calcitriol

Increases calcium, phosphorus, absorption from bone kidney intestine

What negatively feedback on parathyroid hormone

Calcium

Vitamin D

What is the biologically active form of calcium?

Ionized calcium

34% is protein bound and 10% is bound to other stuff

Clinical signs of hypercalcaemia

PUPD (interferes with ADH)

Lethargy and weakness

G.I. signs (vomiting, diarrhoea anorexia)

Shivering

Constipation

Acute kidney in (due to calcification)

Is one of the biggest concerns of hypercalcaemia in cats

Acute kidney injury due to calcification

Hypercalcaemia (hard ions G)

Hyperparathyroidism

Addison

Renal disease

Vitamin D toxicity

Idiopathic (cat)

Osteolytic lesions

Neoplasia

Spurious

Granulomatous disease (activates vitamin D)

Most common cause of hypercalcaemia in dogs and cats

Dogs = lymphoma

Cats = idiopathic

What is hypercalcaemia of malignancy?

It is when a tumour releases, parathyroid related protein

Act like PTH

How can you determine if an animal is at high risk of classification of tissue, such as kidney

Total calcium times phosphorus

If greater than 70, then they are at high risk of calcifying tissues

How To treat hypercalcaemia

Promote diuresis:

0.9% NACL

Furosemide

Bisphosphonate (inhibit osteoclasts)

Glucocorticoids (hold off until definitive diagnosis because can make causes such as lymphoma harder to diagnose

Primary hyperthyroidism is more common in cats or dogs

Dogs

What's more common carcinoma or adenoma for primary hyperthyroidism?

Adenoma

Average age for primary parathyroidism

Neoplasm so older dogs, average 11 years old

95% or greater than seven years old

(similar to hyperthyroidism and Cushing's)

What is a common presentation you may see in a dog with hyperparathyroidism

Calcium uroliths

(main clinical sign is PUPD)

Most common clinical sign in cats with hyperparathyroidism

Anorexia

Dogs = PUPD

Diagnose hyperparathyroidism CBC is usually unremarkable. What would you find on urinalysis

Dilute urine (calcium impairs ADH)

UTI (29% have bacterial UTI and 10% have cystoliths)

With hyperparathyroidism is hypercalcaemia increases quick overtime or slow overtime

Increases our slow overtime

Are hyper parathyroidism dogs prone to acute kidney injury due to calcification

No

This is because calcium goes up but phosphorus goes down

There is no predisposition to these dogs and kidney disease (azotemia uncommon)

Is the definitive diagnosis for hyperparathyroidism?

Increase PTH and ionized calcium

PTHRP is negative (malignancy can possibly be ruled out)

Can ultrasound help diagnosing hyperparathyroidism

Yes, and adenoma will cause them to be larger

Treatment of choice for hyperparathyroidism

parathyroidectomy

95% cure with one surgery

90% have one abnormal parathyroid gland

Other treatment options for hyperparathyroidism

Percutaneous ultrasound guided ablation (92 percent success rate)

Percutaneous, ultrasound guided ethanol ablation (72-85% success rate). - Risk of leakage outside gland

What do you have to consider post treatment with parathyroid surgery?

The other parathyroid gland have atrophied so you need to supplement with calcitriol

Supplement if total calcium greater than 14 MG/DL

Or ionized calcium greater than 1.7

Occurs with moderate to severe hypercalcaemia

What is hungry bone syndrome?

Usually occurs with parathyroid carcinoma

In this instance, the bone was being severely taken advantage of for calcium

Now the carcinoma is removed, and the bone is taking massive amounts of calcium from the blood, causing prolonged hypocalcaemia

To prevent prolonged calcitriol and calcium supplementation

Rare

Clinical signs with hypocalcaemia

Facial puritus

Seizures (calcium stabilizes, gated sodium channels -reduces threshold)

Muscle fasciculations leading to secondary hyperthermia (eclampsia)

Myalgia and stiff gate

GI signs

Causes of hypocalcaemia

Primary hypoparathyroidism

Eclampsia (most common)

Kidney disease

Acute pancreatitis (saponification of fat)

Intestinal disease (severe infiltrative/male absorptive disease)

Hypomagnesaemia

Hypoproteinaemia total calcium will be decreased, but ionized calcium will be normal. True or false.

True

Emergent treatment of hypocalcaemia

10% calcium gluconate

What causes primary hypoparathyroidism?

Immune mediated destruction of glands (necktrauma, or surgery also possible )

Average age of primary hypothyroidism

4.8 years

If a dog presents with primary hypoparathyroidism and kept hospital for four days what is likely to happen

At initial presentation 50% of dogs have seizures

The longer they stay,, that much more likely chance they will have seizure

Cause his stress related

Note: Secondary hypothermia

What lab findings do you see with hypoparathyroidism

Decreased calcium and increased phosphorus

Definitive diagnosis for hypothyroidism

Low PTH and low ionized calcium

Best way to treat hypothyroidism is PTH supplement. True or false.

False. PTH supplement non existent.

With oral calcitrial and oral calcium

(calcium only first 3 to 4 days because diet will be good source)