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Clinical Pathology Exam 3 > Lecture 5 > Flashcards

Lecture 5 Flashcards

1
Q

What type of calcium is active in the body?

A

Ionized free form

Makes up about 50% of total calcium

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2
Q

Which calcium is provided on your serum biochemical profile?

A

Total calcium i.e. protein bound (40%), ionized (50%), and complexed (10%)

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3
Q

What are five functions of calcium?

A

Cell signaling, muscle contraction/nerve conduction, gene transcription, calcium mediated excitation, voltage dependent ion channgels

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4
Q

What does calcium concentrations depend on?

A

Dietary intake
Absorption by small intestine
Skeletal release

Renal reabsorption and excretion

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5
Q

What increases small intestinal absorption?

Decreases?

A

Increased by calcitriol (vit D), lactation, growing animals, acid in diet

Decreased by malabsorption, cortisol/steroids, thyroxin, chronic acidosis

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6
Q

What modifies the skeletal release of calcium?

A

PTH, calcitonin, age, osteolytic disease

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7
Q

What dictates renal excretion of calcium?

A

PTH, calcitriol, and calitonin action on distal tubules

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8
Q

What is the main endocrine organ involved in Ca/P metabolism?

Where does it come from?

What does it do?

A

PTH from chief cells of parathyroid gland

Increases Ca and decreases P

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9
Q

Where is calcitriol made?

What is it stimulated by?

What does it do?

A

Made in kidneys

Stimulated by PTH

Increases GI absorption of Ca and P, increases bone release, increases renal reabsorption
Basically increases both Ca and P

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10
Q

Where does calcitonin come from?

What does it do?

A

Produced by C cells of thyroid gland

Decreases serum Ca and P by inhibiting PTH

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11
Q

What protein is 40% of ca bound to?

A

Albumin

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12
Q

What is the most common cause of hypocalcemia of total calcium in all species?

A

Hypalbuminemia

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13
Q

Hypcalcemia caused by hypoalbuminemia affects which pool of Ca?

Is this serious?

A

Total calcium

Ionized calcium stays the same

*this is benign

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14
Q

What can cause hypoalbuminemia?

A

Increased loss or decreased production

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15
Q

When you can’t measure it directly, what can you use to infer ionized calcium concentration?

A

Total calcium concentration
Albumin concentration
Acid base status

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16
Q

If you need ionized calcium, should you use correction formula?

A

No! Measure directly because the correction formula is very faulty

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17
Q

How does acidosis affect ionized calcium?

Alkalosis?

A

Acidosis increases ionized calcium while alkalosis decreases ionized calcium

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18
Q

What are causes of hypocalcemia?

A 
Hypoparathyroidism
Hypoalbuminemia
Renal disease (not horses)
Pancreatitis
Intestinal malabsorption
Spurious/artifact
Alkalosis
Lactation
Ethylene glycol
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19
Q

When do clinical signs of hypocalcemia occur?

Why do these signs occur?

A

Only when ionized ca is low

Signs occur due to increased neuron excitability

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20
Q

What are clinical signs of hypocalcemia?

A 
Nervousness
Trembling
Excessive panting
Muscle fasciculation and/or cramping
Stiff pelvic gait
Cats:facial rubbing and paw licking and tetanic paralysis
Cows: flaccid paralysis
21
Q

Which causes of hypocalcemia are most common besides hypoalbuminemia

A

Renal disease (not horses)
Pancreatitis
Eclampsia/milk fever

22
Q

How does kidney disease cause hypocalcemia?

A

Decreased calcitriol formation by the kidney

Ionized calcium is low more often than total calcium

23
Q

Describe hypocalcemia from eclampsia (common presentation, treatment, etc)

A

1-3 weeks post partum in small breed dogs
Seizures, trembling, twitching, shaking, stiffness
Treat via IV calcium gluconate but watch the heart

24
Q

Describe hypocalcemia due to milk fiver

A

Dairy cows- flaccid paralysis

Classic S-shape curve in neck

25
Q

What are clinical signs of hypercalcemia?

A

PU/PD
Lethargy, weakness, constipation
Mineralization of soft tissue
Calcium containing uroliths

26
Q

Causes of hypercalcemia

A 
Granulomatous disease
Osteolysis
Spurious/iatrogenic
Primary hyperparathyroidism
Vitamin D toxicosis
Addison’s disease
Renal disease
Neoplasia
Idiopathic (cats)
Hypothermia
27
Q

Primary hyperparathyroidism causing hypercalcemia

A

Increases total calcium, ionized calcium, PTH, and calcitriol (or may be normal)

Decreases phosphorus (or may be normal)

28
Q

Hypervitaminosis D causing hypercalcemia

Causes?

A

Can be from oversupplementation, rodenticides, Vitamin D containing medications, plants containing Vit D precursors, granulomatous disease (activation of macrophages releases vitamin D

29
Q

What does hypervitaminosis D do?

A

Increases Ca release from bone, Ca absorption in the intestine, phosphorus absorption

*so patients will have high calcium and high phosphorus

30
Q

What is the second most common cause of hypercalcemia in dogs?

A

Addison’s disease

31
Q

What does Addison’s do to calcium?

A

Increases total and ionized calcium

Physiology not known

32
Q

What does renal disease do in horses?

A

Causes hypercalcemia

33
Q

What does renal disease do in small animals?

A

Usually causes hypocalcemia

HOWEVER, hypercalcemia in small animals can lead to renal disease

34
Q

What is the most common cause of hypercalcemia?

A

Hypercalcemia of malignancy

35
Q

What tumors can cause hypercalcemia

A

Lymphoma, apocrine gland adenocarcinoma of anal sac, multiple myeloma

*usually associated with PTHrP production

36
Q

Where is most of your phosphorus?

A

In your bones and teeth

The other small percentage is in high energy bonds

37
Q

How does PTH, calciltonin, vit D, and growth hormone affect phosphorus?

A

PTH and calcitonin decrease P

Vit D and growth hormone increase P

38
Q

What does hyperphosphatemia cause?

A

Induces bone resorption

Can cause soft tissue mineralization if also have high Ca

39
Q

What is the number 1 cause of hyperphosphatemia?

A

Decreased renal excretion from decreased GFR from prerenal azotemia or renal disease

40
Q

What are other causes of hyperphosphatemia?

A 
Disorders of Ca homeostasis
Growing animals (bone remodeling)
Shifts from intracellular to extracellular fluid
Iatrogenic
Spurious
41
Q

Causes of hypophosphatemia

A 
Disorders of Ca homeostasis
Shifts from ECF to ICF
Equine renal disease
Milk fever
Iatrogenic
42
Q

Differentials for hypophosphatemia

A 
Primary hyperparathyroidism
Hypercalcemia of malignancy
Vit D deficiency
Respiratory alkalosis
Decreased intestinal absorption of P
Renal tubular defects
Chronic renal disease in horses
43
Q

What signs may occur with hypophosphatemia?

A

Iv hemolysis

Neuromuscular signs

44
Q

What does magnesium do?

A

Has a role in PTH synthesis and release
Facilitates Na/K ATPase activity
Bone formation
Neuromuscular function

45
Q

How is mg controlled?

A

Mainly through renal excretion

46
Q

What clinical signs will you see with hypomagnesemia

A

Those associated with electrolyte abnormalities

Neuromuscular and cardiac abnormalities

47
Q

What are some causes of low mg

A

Increased loss- most common cause in small animals (renal or GI)
Decreased intake- most common cause in ruminants

48
Q

Manifestations of hypomagnesemia

A

Secondary hypokalemia due to renal wasting of K

Impaired PTH production leading to secondary hypocalcemia

Clinical Pathology Exam 3 (8 decks)

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