Lecture 3 1/30/25

Question 1

What are the clinical signs of hypercalcemia?

Answer 1

-PUPD
-acute kidney injury
-dehydration
-osteoporosis
-nausea
-vomiting
-constipation
-lethargy
-muscle weakness
-confusion/stupor/coma

Question 2

What are the characteristics of a normal neuron?

Answer 2

-resting state of Na+ channels is stabilized by Ca2+
-Ca2+ prevents spontaneous depolarization

Question 3

What happens to the neuron when there is hypercalcemia?

Answer 3

-Na+ channels are less likely to open
-neuron is harder to depolarize; threshold is increased
-neuron is less excitable
-patient exhibits slower/absent reflexes, slow muscle contraction, and confusion/stupor

Question 4

What effect does hypercalcemia have on the heart?

Answer 4

can cause arrhythmia, such as bradycardia or AV block

Question 5

What effect does hypercalcemia have on the brain?

Answer 5

can cause coma and/or seizures

Question 6

What are the renal effects of hypercalcemia?

Answer 6

-nephrogenic diabetes insipidus
-PUPD
-calcium-oxalate crystals/stones
-AKI

Question 7

What are the characteristics of acute kidney injury associated with hypercalcemia?

Answer 7

-renal vasoconstriction decreases GFR
-worsens with volume depletion
-reversible with volume expansion and lowering of serum Ca

Question 8

How does the cause of hypercalcemia relate to the clinical manifestation?

Answer 8

-PHPTH: animal is not sick to minimally ill
-vitamin D toxicosis: animal is very sick

Question 9

What is the diagnostic approach to hypercalcemia?

Answer 9

-confirm increase with iCa2+ measurement
-history
-physical exam w/ a rectal
-CBC/chem/UA
-PTH, PTHrp, and vit. D conc. measurements
-thoracic and abdominal imaging +/- neck ultrasound
-aspirate peripheral lymph nodes, liver/spleen, and bone marrow

Question 10

What are the characteristics of hypercalcemia treatment?

Answer 10

-treat specific cause
-indications for treatment vary based on clinical signs and acute vs chronic onset
-specific treatment not needed if hypercalcemia is lab identified only and pet is not exhibiting clinical signs

Question 11

Which clinical signs of hypercalcemia are severe and indicate need for immediate treatment?

Answer 11

-dehydration
-azotemia
-arrhythmia
-CNS signs/severe weakness
-tCa x phos > 60-80

Question 12

What needs to be accounted for in the fluid plan for a hypercalcemic patient?

Answer 12

-dehydration %
-maintenance; increased if PUPD
-losses

Question 13

What are the characteristics of fluid diuresis as an emergency treatment for hypercalcemia?

Answer 13

-use 0.9% saline at 2-3x maintenance
-may need to supplement K+
-increases Ca2+ excretion due to filtered Na+ competing with Ca2+ for renal tubular resorption

Question 14

What are the characteristics of loop diuretics as an emergency treatment for hypercalcemia?

Answer 14

-maximize Na+ excretion, leading to calciuresis
-decreases renal Ca2+ reabsorption in thick ascending loop of henle
-patient must be hydrated first

Question 15

What are the characteristics of glucocorticoids as a treatment for hypercalcemia?

Answer 15

-should not give before ruling out neoplasia; makes lymphoma diagnosis difficult due to lymphocyte lysis
-decreases Ca regardless of etiology
-decreases bone and intestinal absorption of Ca
-increases renal Ca excretion

Question 16

What are the characteristics of biphosphonates?

Answer 16

-inhibit osteoclasts and prevent bone resorption
-used IV for emergency use in combination with other treatments
-can be given PO for maintenance in some diseases

Question 17

What are the potential adverse effects of bisphosphonates?

Answer 17

-osteonecrosis of the jaw
-gastrointestinal upset
-esophagitis

Question 18

What are the diseases that cause hypercalcemia?

Answer 18

-hyperparathyroidism
-osteolytic
-granulomatous
-spurious
-idiopathic
-neoplasia
-young animal
-addison’s
-renal
-D vitamin toxicosis

Question 19

What are the mechanisms for hypercalcemia?

Answer 19

-increased PTH or PTH-rp
-increased calcitriol/vitamin D
-unknown
-non-pathologic

Question 20

What are the different ways that increased PTH/PTH-rp and increased calcitriol/vitamin D can lead to hypercalcemia?

Answer 20

-increased absorption in the gut
-increased reabsorption in the kidneys
-increased resorption of bone
-decreased excretion in the kidneys

Question 21

What are the characteristics of hyperparathyroidism?

Answer 21

-parathyroid-dependent mechanism of hypercalcemia
-can be primary
-can be secondary with renal or nutritional components

Question 22

What are the characteristics of primary hyperparathyroidism?

Answer 22

-abnormal gland produces PTH
-chief cells function autonomously and do not respond to feedback from increased Ca
-can occur with solitary adenoma or hyperplasia
-normal glands atrophy

Question 23

What is the result of excessive PTH due to primary hyperparathyroidism?

Answer 23

-increased Ca
-decreased P

Question 24

How is primary hyperparathyroidism diagnosed?

Answer 24

PTH is inappropriately increased in the face of hypercalcemia; high-end normal or inc. PTH in the face of increased iCA

Question 25

What is the signalment for primary hyperparathyroidism?

Answer 25

-uncommon in dogs -typically occurs in middle to older age dogs -keeshond dog breed has autosomal dominant PHPTH -rare in cats

Question 26

What are the clinical signs of PHPTH?

Answer 26

-possibly asymptomatic -slow onset -PUPD -lower urinary tract signs -weakness/hyporexia

Question 27

What is the diagnostic workup for PHPTH?

Answer 27

-physical exam -minimum database -iCa and PTH/PTH-rp measurements -neck ultrasound -possible thoracic and abdominal radiographs

Question 28

What is seen on a neck ultrasound in patients with PHPTH?

Answer 28

-one large, abnormal gland -other normal glands atrophied

Question 29

What is the treatment for PHPTH?

Answer 29

cervical exploratory surgery and parathyroidectomy; must leave 1 remaining gland to prevent hypoparathyroidism

Question 30

What is important in post-op parathyroidectomy patients?

Answer 30

-monitor iCa -supplement patients with calcitriol +/- calcium carbonate as needed until atrophied glands return to function

Question 31

What is the prognosis of PHPTH?

Answer 31

-excellent prognosis following surgery -poor prognosis if disease caused by malignancy or patient is in renal failure -low recurrence rate in all breeds except Keeshond breed

Question 32

What are alternative treatment options for PHPTH?

Answer 32

-ultrasound-guided ethanol or heat ablation -medical management with PO bisphosphonates

Question 33

What are the characteristics of secondary hyperparathyroidism?

Answer 33

-involves renal or nutritional abnormalities -hypertrophy of all four parathyroid glands

Question 34

What are the characteristics of renal secondary HPTH?

Answer 34

-driven by decreased calcitriol/vit. D in early stages -driven by increased phosphorus in late stages -can lead to renal disease progression -can cause bone demineralization/fibrous osteodystrophy -can lead to other non-specific, non-skeletal effects

Question 35

What are the characteristics of calcium levels in renal disease?

Answer 35

-typically mild abnormalities -tCa can be increased due to binding of inorganic ions or dehydration -iCa can be increased, decreased, or normal -iCa can change with changes in renal reabsorption/secretion or with decreased vit. D

Question 36

What is nutritional secondary HPTH?

Answer 36

imbalanced diet with low calcium, low vitamin D, and/or high phosphorus leads to increased PTH secretion

Question 37

What are the characteristics of neoplasia as a cause of hypercalcemia?

Answer 37

-most common cause of hypercalcemia in the adult dog -third most common cause in cats

Question 38

What are the neoplastic mechanisms of hypercalcemia?

Answer 38

-humoral hypercalcemia of malignancy/production of PTH-rp by tumor -osteolysis -other/ectopic production of PTH

Question 39

Which cancer types can result in paraneoplastic hypercalcemia?

Answer 39

-apocrine gland anal sac adenocarcinoma -lymphoma -multiple myeloma -carcinomas

Question 40

How does neoplasia impact clin path measurements of calcium, phosphorus, and PTH?

Answer 40

-tCa increases -iCa increases -phos decreases or is low-normal -PTH is 0 to low-normal -PTH-rp is sometimes increased, sometimes normal

Question 41

What is important about PTH-rp as a diagnostic tool?

Answer 41

-presence of PTH-rp indicates neoplasia -PTH-rp reading of 0 does NOT rule out neoplasia; not all tumors produce it