Endocrine - Exam 2: Giving me Hypertension and Hypomotivation

What is the role of PTH?

Increase serum calcium and decreased serum phosphate (eliminate through urine)

What is the role of calcitriol (vitamin D)?

Increased calcium (and phosphate) absorption from GI tract

What is the role of calcitonin?

Lower blood calcium by sending it to bone

What is the role of PTHrP?

Tumor hormone that mimics PTH locally

What activates vitamin D to the active form, calcitriol?

PTH

What inhibits PTH?

Increased serum calcium

Excess vitamin D will lead to what imbalances?

Hypercalcemia and hyperphosphatemia

Excess of PTH will lead to what imbalances?

Hypercalcemia (possible hypophosphatemia)

So the only hormone that increases serum phosphorous is what?

Vitamin D

What four systems are affected by hypercalcemia?

Cardiovascular, CNS, GI, and kidneys

A calcium-phosphorous product greater than what will lead to dystrophic mineralization?

70

What is the number one sign of hypercalcemia in dogs?

PU/PD

What is the number one sign of hypercalcemia in cats?

Vomiting

What two things in a blood sample can mess with calcium diagnostics?

Lipemia (make sure to fast) and hemoglobinemia

While 99% of calcium is in bone, what are the three forms of the other 1%?

Ionized (active) (50%)

Albumin bound (40%)

Bound to something else (10%)

How would hypoalbuminemia affect calcium?

Total calcium will be low, but ionized should be normal

What are the differentials for hypercalcemia, and what are the four most common? (Sorry, y'all know I hate a long answer)

Granulomatous

Osteolysis

Spurious (lab error)

HyperPT

vit D toxicity

Addison's

Renal (2nd)

Neoplasia (1st)

Idiopathic (cats)

Toxicity (grape)

GOSH DARNIT, ARNI!

How does granulomatous disease cause hypercalcemia?

Macrophages activate vitamin D

How does Addison's disease cause hypercalcemia?

Increases GI absorption and decreases renal excretion

If renal function is okay, then a high calcium and a high phosphorous indicates what?

Increased vitamin D

If renal function is okay, then a high calcium and a normal to low phosphorous indicates what?

HyperPTH or PTHrP

What is the most likely cause of hypercalcemia in dogs?

Neoplasia (LSA, AGASACA, MM)

What is the most likely cause of hypercalcemia in cats?

Idiopathic hypercalcemia

When ionized calcium is high, what level should PTH be?

Below normal

When should you treat acute hypercalcemia directly?

Unknown cause

Severe hypercalcemia

Showing signs

What is the first step in treating hypercalcemia?

Fluid therapy

What is the preferred diuretic for hypercalcemia?

Furosemide

When should you avoid giving glucocorticoids to treat hypercalcemia?

If the diagnosis is unknown (GC messes with diagnostics)

What is the MOA of bisphosphonates?

Osteoclast inhibition

What are the three treatments of idiopathic hypercalcemia?

Diet (avoid acidifying, add fiber)

Predniso(lo)ne

Alendronate (bisphosphonate)

What is the most common form of hyperPTH?

Benign adenoma or hyperplasia

What is the preferred treatment of hyperPTH?

Surgery

What is a possible post-op complication for treating hyperPTH?

Hypocalcemia

What are the differentials for hypocalcemia?

HypoPTH

Acute pancreatitis

Measured with EDTA

PLE

Eclampsia

Renal failure

Hypoalbuminemia

Ethylene glycol

Lab error

Phosphate enema

HAMPER HELP

What is the emergency treatment of hypocalcemia?

Calcium gluconate

What is the preferred form of calcium supplementation?

Calcium carbonate

Glucocorticoids have the opposite action of what?

Insulin (GC increases gluconeogenesis and glycogen storage)

What is the vascular effect of GC?

Maintain normal blood pressure

What are the two forms of spontaneous HAC?

Pituitary dependent (PDH) and functional tumors (FAT)

What is more likely, PDH or adrenal tumors?

PDH (85%)

Of the PDH, are they more likely to have micro or macroadenoma?

Micro (85%)

What are the odds of adrenal tumors being malignant?

50%

What is the signalment of PDH dogs?

Middle aged/older small dogs

What is the signalment of FAT dogs?

Middle aged/older big dogs (cuz their fat)

What are the five P's of HAC?

Polydipsia

Polyuria

Polyphagia

Pot-bellied

Panting

T/F: Dog's with HAC usually feel fine

True

Why do dogs with HAC have hepatomegaly and increased intra-abdominal fat?

GC increase storage

What is the main cutaneous change with HAC?

Symmetrical alopecia

When will a dog with HAC be anorexic?

With macroadenoma

What CBC findings are consistent with HAC?

Stress leukogram (SMILED)

What is the most common abnormality of HAC on chem?

Elevated ALP (due to excess glycogen storage?)

T/F: HAC urine is often concentrated

False, dilute

What is a common systemic complication of HAC?

Hypertension

T/F: You should not test a dog for HAC that has a concurrent illness

True, false positive

What is the single best test to screen for HAC due to high sensitivity?

Low Dose Dexamethasone Suppression Test (LDDST)

What part of the LDDST do you look at to determine if it is HAC?

8-hour greater than 30 nmol/L (if less, not HAC)

If 8-hour is greater than 30, what criteria determine that it is PDH?

If the LDDST never falls below 50%, then is it PDH or FAT?

Can't tell

Your 4-hour sample is 35 and 8-hour sample is 27. What is it?

Not HAC, I'll tell you that (8-hour < 30)

What is the test of choice of iatrogenic HAC or when there is a concurrent ilness?

ACTH stim

What value of cortisol after ACTH stim indicates HAC?

Above normal range after 1 hour

ACTH stim test, at 1-hour it is above RR. What type is it?

HAC, can never tell type

If the urine cortisol:creatinine ratio is WNL, what can you tell about HAC?

HAC is unlikely

If the patient is above the RR with the urine cortisol:creatinine ratio, what are the odds the patient has HAC?

20% (high false positive rate)

What does bilateral adrenomegaly indicate?

PDH

What percent of dogs with PDH will suppress with a high DDST?

75%

What responses of the HDDST are consistent with PDH?

Less that 50% or 30 nmol at any time

What level of ACTH would you expect in PDH?

Elevated

What level of ACTH would you expect in FAT?

Decreased

T/F: You should only treat clinical dogs

True

How do you treat FAT?

Surgery

How do you treat PDH?

Trilostane (blocks steroidogenesis) and Mitotane (necrosis of zona F and R)

T/F: The goal is normal cortisol concentration when treating PDH

False, just better

T/F: Iatrogenic HAC can be caused by topical GC

True

T/F: All GC have the same potency

False

How do you diagnose iatrogenic HAC?

ACTH test with little response

What physical sign is indicative of HAC in a cat?

Thin/friable skin

How do you screen for HAC in a cat?

LDDS

What is a common sign of HAC in a cat, but not a dog?

Glucosuria

What layer is most often affected in Addison's?

Fasciculata

T/F: Hypoglycemia, anorexia, and hypotension are all consequences of GC deficiency

True

How are electrolytes affected by a mineralocorticoid deficiency?

Hyponatremia and hyperkalemia (lack of aldosterone)

What is the most common cause of Addison's?

Adrenal failure (primary) due to immune mediated disease

What differentiates typical from atypical Addison's?

Aldosterone deficient, with hyponatremia and hyperkalemia, is typical. If normal, then atypical

T/F: Typical Addison's is always primary

True, only primary can cause aldosterone deficiency

What can you expect the heart rate of an Addison's patient to be?

Bradycardic due to hyperkalemia

If a dog is bradycardic, what form is most likely?

Primary, because hyperkalemia indicates typical, which must be primary

Why do Addison patients have waxing and waning signs?

They have enough cortisol in unstressed states, but not in stressed states

T/F: Addison's has a grave prognosis

False, good if you diagnose it

T/F: Atypical primary Addison's can be typical

True, but never typical to atypical

What does a CBC of Addison's look like?

Lack of stress leukogram (opposite of SMILED (frowned?))

What changes on a chem profile are due to a lack of mineralocorticoids in Addison's?

Hyperkalemia

Hyponatremia

Azotemia

USG < 1.030

What changes on a chem profile are due to a lack of glucocorticoids in Addison's?

Hypoalbuminemia

Hypocholesterolemia

Hypercalcemia

Hypoglycemia

How do you diagnose Addison's?

ACTH stim

What steroid will not cross react with a cortisol assay?

Dexamethasone

What does the baseline cortisol test tell you?

If greater than 55, then NOT Addison's

If a dog's cortisol remains unchanged after ACTH stim, does it have adrenal or pituitary failure?

Can't tell, just know that it is Addison's

What is the first treatment of an Addisonian crisis?

Fluid therapy

What glucocorticoids can you provide a dog in Addisonian crisis?

Dexamethasone since it won't interfere with ACTH

What is the most life threatening electrolyte imbalance?

Hyperkalemia