VM527 - Endocrine Exam 2

The first thing you look at when you have a total hypercalcemia (tCa increase) is:

albumin

The first thing you should measure when you have a total hypercalcemia (not fully explained by albumin) is:

iCa

The first thing you should measure when you have a free calcium hypercalcemia (fCa increase) is:

PTH

What is the net effect of PTH on Ca and P?

increase Ca, decrease P

The expected pattern with primary HPTH is:

"normal" (WRI) or high PTH, increase iCa, decrease P

From what you know about normal anatomy, calcium homeostasis, and negative feedback, after effective treatment of primary HPTH, you would be concerned about:

hypocalcemia

Using what you know about PTH and PTHrP in calcium homeostasis, what is the expected pattern in a patient with HHM and +PTHrP?

Suppressed PTH, increased iCa, decreased P

Parathyroid hormone related-protein (PTHrP) is:

highly conserved, with an as-yet unknown function

What is true regarding hypercalcemia of malignancy:

a. PTHrP and PTH are structurally similar, but activate different pathways

b. expected pattern: high total/ionized calcium, high or high-normal PTH

c. Mechanisms include humoral (HHM) or local effects

d. All of the above

mechanisms include humoral (HHM) or local effects

Mineralization is also an immediate concern in primary HPTH:

false: PTH causes increase Ca but decrease P

What are the main organs involved in calcium homeostasis?

bone, kidney, intestine

Calcium is present in different fractions in the blood. Which fraction is the most important biologically?

ionized or free

Critical functions of calcium include the following (check all that apply):

a. Nerve conduction

b. Hormone release

c. Enzymatic reactions

d. Muscle contraction

e. Blood coagulation

all of the above

Which choice reflects the net effect of the specific hormone (iCa = ionized calcium, P = phosphorus)?

a. Parathyroid hormone: increase iCa, decrease P

b. Vitamin D: increase iCa, increase P

c. Calcitonin: decrease iCa, decrease P

d. All of the above

all of the above

Your patient has an increased total calcium concentration. What diagnostic approach is most appropriate (PTH = parathyroid hormone; PTHrP = parathyroid hormone related protein)?

First measure iCa, then PTH, then PTHrP if needed

Which of the following metabolite conversions occurs in the vitamin D metabolism pathway? (Metabolite 1 (acting enzyme) -> Metabolite 2)

a. Cholecalciferol/vitamin D3 (24-hydroxylase) -> 1,24,25(OH)3-vitamin D

b. 25(OH)-vitamin D (1α-hydroxylase) -> calcitriol

c. Calcitriol (25-hydroxylase) -> 24,25(OH)2-vitamin D

d. All of the above occur in the vitamin D metabolism pathway

25(OH)-vitamin D (1α-hydroxylase) -> calcitriol

Choose the most reliable indicator of systemic vitamin D status from the options below:

a. Ionized calcium (because ionized calcium directly parallels vitamin D intake)

b. Ergocalciferol/vitamin D2 (because this is made on the skin in all species)

c. 25-hydroxyvitamin D (because there is little/no feedback control on 25-hydroxylase)

d. Calcitriol (because this is the only endpoint of the vitamin D metabolism pathway)

25-hydroxyvitamin D (because there is little/no feedback control on 25-hydroxylase)

Which of the following combinations is accurate?

a) Cholecalciferol/vitamin D3 - half-life months - lowest bioactivity

b) 25-hydroxyvitamin D - half-life weeks - low bioactivity

c) Calcitriol - half-life hours - very high bioactivity

d) All of the above are correct combinations

All of the above are correct combinations

Which of the following is the most common, and least clinically relevant, cause of a decreased total calcium concentration?

a) Hypoalbuminemia

b) Renal failure

c) Vitamin D deficiency

d) Hypoparathyroidism

Hypoalbuminemia

An expected derangement and its underlying mechanism in primary hypoparathyroidism is:

Hypocalcemia due to increased loss via kidneys

What hormone is the reason we put horses under lights during the winter to help them start cycling sooner?

melatonin

Drug X is a dopamine agonist, what effect does it have on a lactating animal?

reduces lactation

You have a low tCa and you've confirmed fCa is also low. What is the most appropriate next test?

PTH

What is the expected, typical pattern with primary hypoparathyroidism?

Low(er) PTH, decrease fCa, ~increase P

Which of the following is not an accurate association regarding development of hypocalcemia?

a. primary hypoparathyroidism: excessive PTH production

b. Eclampsia or milk fever: excessive calcium loss

c. Ethylene glycol: high phosphorus (mass law), chelation (oxalates)

d. Pancreatitis: fat saponification, calcitonin secretion

primary hypoparathyroidism: excessive PTH production

(should be low PTH production)

Which of the following is associated with nutritional secondary HPTH?

a. inadequate sunlight in dogs and cats

b. increased [25-hydroxyvitamin D]

c. Predominant meat or raw food diets

d. All of the above

Predominant meat or raw food diets

Which of the following is true regarding renal secondary HPTH?

a. clinical signs of hypocalcemia are common

b. the pathophysiology involves decreased calcitriol

c. it is well recognized in horses

d. PTH is suppressed, leading to hypocalcemia

the pathophysiology involves decreased calcitriol

What is the diagnosis? (14 yo DSH cat)

•Azotemic, PU/PD

•Good appetite, no GI signs

•Receives commercial renal diet

PTH 42.6 H 0.4 - 2.5 pmol/L

iCa 1.15 1.00 - 1.40 mmol/L

Renal secondary HPTH

(because Ca is within reference range and high PTH)

What would be the next step? (4 mo old bengal)

•Presented for seizures

•Radiographs: low bone density; iStat: ↓iCa

•Diet: exclusively ground chicken

PTH 41.6 H 0.7-3.4 pmol/L

iCa 0.93 L 1.00-1.40 mmol/L

25-hydroxyvitamin D (calcidiol)

What is the most likely diagnosis? (4 mo old bengal)

•Presented for seizures

•Radiographs: low bone density; iStat: ↓iCa

•Diet: exclusively ground chicken

PTH 41.6 H 0.7-3.4 pmol/L

iCa 0.93 L 1.00-1.40 mmol/L

25-hydroxyvitamin D 22 L 127-335 nmol/L

nutritional secondary HPTH - dietary insufficiency

What is the most likely diagnosis? (13 yo pug)

•History of PLE (protein-losing enteropathy)

•↓Ca, ↓Mg, ↓P

PTH 24.90 H 0.5 - 5.8 pmol/L

iCa 1.08 L 1.25 - 1.45 mmol/L

25-OH D 10 L 109 - 423 nmol/L

Nutritional secondary HPTH - malabsorption

What is the diagnosis? (8 mo old border collie)

•Stiff gait, receives raw food diet

•Low Ca, high P

PTH < 0.5 L 1.1 - 10.6 pmol/L

iCa 0.75 L 1.25 - 1.45 mmol/L

primary hypoparathyroidism

Owners tell you their dog probably ingested their vitamin D supplement, what test do you run?

calcidiol (vitamin D 25-OH)

What mechanism(s) account for the persistent increase of 25-hydroxyvitamin D in the blood?

a. continuous reversion of calcitriol to 25-hydroxyvitamin D

b. storage and release of vitamin D3 in the adipose tissue

c. unchecked conversion of vitamin D3 to 25-hydroxyvitamin D

d. B and C

e. all of the above

B and C

What are the 6 classes of nutrients?

•Carbohydrates

•Lipids

•Proteins

•Minerals

•Vitamins

•Water

Water is mostly intracellular, True or False

true

Water in blood, joint spaces and tissues are intracellular. T or F

false (extracellular)

What are the two main classes of carbs?

starch and sugar

Starch is an eg. of what type of carb?

complex

Triglyceride is a type of what?

fat

Eicosanoids are from which nutrient group?

lipid

Arginine is an eg of what type of protein?

essential

Insulin is derived from what class of nutrient?

protein

Name the fat soluble vitamins.

A, D, E, K

What vitamin regulates Ca?

vitamin D

Glycolysis

Breakdown of glucose to pyruvate or lactate

Glycogenesis

Glycogenesis is the process by which the body converts excess glucose into glycogen

Glycogenolysis

glycogen breakdown

Gluconeogenesis

Gluconeogenesis is a metabolic pathway where the body creates glucose from non-carbohydrate sources like lactate, amino acids, and glycerol, primarily in the liver and kidneys, to maintain blood glucose levels, especially during fasting or low carbohydrate intake.

What would be the expected hormone profile in response to hyperglycemia in a normal individual?

Decreased glucagon, increased insulin and amylin

Increased glucagon, decreased insulin and amylin

Increased growth hormone and cortisol

Decreased glucagon, increased insulin and amylin

Assume an individual has consumed a large meal consisting of a hamburger, French fries, and a coke.

What processes would be occurring in this individual immediately after the meal?

Glycogenolysis, gluconeogenesis, lipolysis

Glycogenolysis, gluconeogenesis, lipogenesis

Glycogenesis, inhibition of gluconeogenesis, lipolysis

Glycogenesis, inhibition of gluconeogenesis, lipogenesis

Glycogenesis, inhibition of gluconeogenesis (not making glycogen cause you just ate a lot), lipogenesis

Carbohydrates are broken down into glucose, fructose, and galactose, with about 80% being glucose. T or F

true

What organ converts fructose and galactose into glucose?

liver

What increases facilitated diffusion of glucose into cells?

insulin

The drug diazepam is given orally. It is a weak base with a pKa of 3. Assume the stomach has a pH of 3 and the small intestine has a pH of 6. Choose all explanations that account for variation in the absorption of Diazepam in the stomach and small intestine.

a. Ratio of unionized/ionized in the small intestine=1000/1

b. Ratio of ionized/unionized in the small intestine = 1000/1

c. GI tract has largest surface area to enhance absorption

d. Ratio of unionized/ionized in the stomach=1/1

e. Ratio of ionized/unionized in the small intestine = 3/1

a. Ratio of unionized/ionized in the small intestine=1000/1

c. GI tract has largest surface area to enhance absorption

d. Ratio of unionized/ionized in the stomach=1/1

What hormones are secreted by the pancreas?

insulin, somatostatin, glucagon

Hyperglycemia stimulates the alpha cells in the pancreas to secrete insulin. T or F

false

What compound activates the Krebs Cycle?

Acetyl CoA

What effect does insulin have on movement of potassium and phosphate ions?

	a)  Phosphate moves into the cell in exchange for potassium, which moves out of the cell
	b)  Both phosphate and potassium move into the cell
	c)  Both phosphate and potassium move out of the cell
	d)  Potassium moves into the cell in exchange for phosphate, which moves out of the cell

Both phosphate and potassium move into the cell

Which of the following is true regarding insulin effects on glucose?

a) Insulin promotes rapid movement (within minutes) of intracellular glucose to extracellular spaces.

b) Insulin results in a delayed movement (within 2-4 hours) of intracellular glucose to extracellular spaces.

c) Insulin promotes rapid cellular uptake (within minutes) of glucose

d) Insulin results in a delayed cellular uptake (within 2-4 hours) of glucose

c) Insulin promotes rapid cellular uptake (within minutes) of glucose

In general, which of the following would be true of a drug that is a weak base (pKa = 8.4)?

a. This drug would be predominately unionized at rumen pH (5.5-6.5)

b. This drug would be predominately unionized in milk (pH 6.5-6.8)

c. This drug would be predominately ionized at physiologic pH (approximately 7.4)

d. This drug would be predominately ionized in saliva (pH 8.1-8.4)

c. This drug would be predominately ionized at physiologic pH (approximately 7.4)

In a hay analysis, the most important factor for insulin and glucose dynamics is:

	Crude Protein
	NSC content
	Ca: Phos ratio
	Ash

NSC content (non-structural carbohydrates)

Co-secretion of amylin is something that can contribute to development of diabetes in both dogs and cats. True or False?

false

In obese cats, you can rule out an underlying condition of insulin resistance by documenting a normal blood glucose value. True or False

false

Somatostatin's effect on insulin and glucagon release from the pancreas is:

inhibits glucagon, increases insulin

inhibits glucagon, inhibits insulin

increases glucagon, decreases insulin

increases glucagon, increases insulin

inhibits glucagon, inhibits insulin

How much should 1000# horse eat a day?

2% of BW

What hay characteristic would indicate a risk of impaction colic?

a. NDF >65%

b. ECS + starch >10% (Ethanol soluble carbohydrates)

c. WSC <12% (water soluble carbohydrates)

d. Ca:P of 1

e. ADF >45

NDF >65% (really dry and bulky)

What hay characteristic would indicate a risk for horses prone to laminitis?

NSC should be less than 10% (more mature = lower NSC)

Insulin is considered a/an _____________ hormone

anabolic

What is the mechanism by which pancreatic beta cells are stimulated to release insulin?

They detect a rise in extracellular glucose via entrance of glucose through insulin-independent GLUT-2 transporters

It is important to centrifuge and separate red cells from serum in a timely manner because:

Red blood cells in contact with serum continue to utilize serum glucose due to their GLUT-1 transporters.

What is not true with regard to amylin?

It also plays no role in regulation of glucose.

Which statements are true of glucagon?

A. A lack of binding of glucose on the pancreatic alpha cells (via GLUT-2) is a main stimulus for glucagon release.

B. The actions of glucagon chiefly take place in the liver, where it is also quickly metabolized and inactivated.

C. Glucagon acts in opposition to insulin

D. It serves to prevent hypoglycemia

E. All of the above are true.

all of the above

The main thing to remember about Somatostatin is that:

It comes from delta cells, and inhibitory effects serve to extend the time for nutrient absorption.

Which of the following are true with regard to Pancreatic Polypeptide:

A. It comes from F cells in the pancreas

B. It has inhibitory effects on gastric and pancreatic secretions

C. It plays a role in satiety

D. All of the above.

all of the above

Insulin directs amino acids into most tissues, but not into the liver. Why?

A. Because insulin is anabolic, and the anabolic path for amino acids is to be directed toward protein synthesis in muscles

B. Because shunting AA into the liver is considered a catabolic activity (readying nutrients to release).

C. Because when insulin predominates, glucose is plentiful, so we do not need to make any more from amino acids.

D. All of the above

all of the above

How does cortisol help maintain glucose in a fasted state?

A. It promotes gluconeogenesis

B. It suppresses glucose utilization in peripheral tissues

C. It facilitates breakdown of fats and proteins

D. All of the above

all of the above

Which Hormones Play a Significant Role in Maintaining Glucose in the Fasted State?

glucagon, catecholamines, leptin, ghrelin, growth hormone, cortisol

What hormone is predominant when glucose is too low to measure?

glucagon

What Accounts for Signs of PU/PD with Diabetes Mellitus?

Osmotic diuresis: Glucose in excess of capacity for renal threshold for resorption in the proximal renal tubules.

What is the generally agreed upon renal threshold for glucose in dogs?

180-220 mg/dl

What clinical signs do you expect with Diabetes Mellitus?

Increase in appetite, Lethargy, Increase in urination, Weakness, Compensatory increase in thirst, Neuropathy, Weight loss, Cataracts (dogs), Muscle wasting, Recurrent infections, poor wound healing

What Factors May Contribute to developing Diabetes Mellitus in Dogs?

A. Genetic Predisposition

B. Chronic, recurrent pancreatitis

C. Immune mediated disease process

D. All of the above

all of the above

A good test in horses to assess insulin and glucose would be:

Oral Sugar Test

Equine Metabolic Syndrome is a cluster of which of the following (select all that apply)?

a. muscle wasting

b. regional adiposity

c. insulin dysregulation

d. dyslipidemia

regional adiposity

insulin dysregulation

dyslipidemia

Which of the following is true regarding insulin effects on glucose?

a) Insulin results in a delayed movement (within 2-4 hours) of intracellular glucose to extracellular spaces.

b) Insulin results in a delayed cellular uptake (within 2-4 hours) of glucose

c) Insulin promotes rapid movement (within minutes) of intracellular glucose to extracellular spaces.

d) Insulin promotes rapid cellular uptake (within minutes) of glucose

d) Insulin promotes rapid cellular uptake (within minutes) of glucose

What would happen to the concentration of ACTH in a normal dog that is administered a corticosteroid like dexamethasone?

	It will not change
	It will increase
	It will decrease

it will decrease

You are working for a large pharmaceutical company and are designing a new therapeutic for treating migraines (to be given orally). What physicochemical properties would increase bioavailability of the drug? Choose all that apply:

a. Increased lipid solubility

b. Increased water solubility

c. Hydrophobicity

d. Lipophobicity

increased lipid solubility and hydrophobicity

What is secreted by the adrenal cortex?

	Norepinephrine and corticosterone
	Epinephrine and aldosterone
	Norepinephrine and epinephrine
	Cortisol and aldosterone

Cortisol and aldosterone

Which of the following is true regarding glucocorticoids?

a. They promote protein synthesis

b. They stimulate hepatic gluconeogenesis

c. They decrease blood sugar levels

d. None of the above

They stimulate hepatic gluconeogenesis

What clinically significant affect could incretins have on an OST?

increase peak insulin

increase peak glucose

decrease peak insulin

decrease peak glucose

increase peak insulin

What is the normal function of adipose tissue?

Protection, conserve heat, temperature control, insulation, release energy

What hormone does adipose tissue produce?

Leptin, adiponectin, inflammatory cytokines, aromatase (sex hormone metabolism)

What stimulates adipose tissue?

Glucose, high dietary caloric meals, low exercise, increasing insulin

What inhibits adipose tissue?

Ghrelin, exercise, hypoglycemia, starvation/fasting, glucagon, epinephrine, cortisol, GH, ACTH, caffeine, calcium

What is stored in the colloid?

thyroglobulin

What is produced by parafollicular cells (aka C-cells)?

Calcitonin, tones blood Ca

What organs does PTH act on and what does this hormone do?

Acts on kidney, bones, intestines and increases blood calcium

What do chromaffin cells produce?

epinephrine and norepinephrine

What do alpha cells in pancreas secrete?

glucagon (increases glucose)