Endocrine Flashcards
How is the corticotropin releasing hormone test (CRHT) performed?
Basal ACTH –> give ovine corticotropin releasing factor –> measure ACTH again 30 min later
JVIM 2021, Tanaka et al
Is the corticotropin releasing hormone test (CRTH) useful to diagnose Cushing’s, differentiate PDHAC vs ADHAC, or both?
Too much overlap ADHAC vs controls for de novo diagnosis. May be useful to differentiate pituitary vs adrenal dependent if already diagnosed with Cushing’s.
JVIM 2021, Tanaka et al
What would the expected post corticotropin releasing hormone test (CRTH) ACTH result be for PDHAC vs ADHAC? (ie, high, low, or the same compared with healthy dogs)
PDHAC – higher
ADHAC – no difference
JVIM 2021, Tanaka et al
Where is ACTH produced in primary bilateral adrenocortical hyperplasia, macro or micronodular (PBMAH)?
ACTH is made in the adrenal. Acts as paracrine rather than endocrine. PBMAH is rare in dogs.
JVIM 2021, Arias et al
Which of the following will be HIGHER in dogs with untreated HAC and why (if known)?
Phos
tCa, iCa
Urinary Ca excretion
PTH
25-(OH)D
Calcitriol
FGF-23
Phos - decr urinary excretion
PTH (adrenal secondary hyper-PTH):
–Multifactorial
–Direct and indirect cortisol effects
–Incr urinary Ca excretion + Phos retention
Urinary Ca excretion – who knows why
JVIM 2021, Corsini et al
Which of the following will be LOWER in dogs with untreated HAC and why (if known)?
Phos
tCa, iCa
Urinary Ca excretion
PTH
25-(OH)D
Calcitriol
FGF-23
25-(OH)D
FGF-23
Who knows why for either one
JVIM 2021, Corsini et al
Which of the following have NO DIFFERENCE in dogs with untreated HAC vs normal dogs?
Phos
tCa, iCa
Urinary Ca excretion
PTH
25-(OH)D
Calcitriol
FGF-23
tCa, iCa
Calcitriol
JVIM 2021, Corsini et al
Which of the following were able to differentiate good vs undercontrolled HAC dogs treated with trilostane?
Endogenous ACTH
Pre-pill cortisol/endogenous ACTH ratio
ACTH Stim
ALT
GGT
Haptoglobin
UCCR
USG
Haptoglobin (best predictor), ALT, GGT. BUT all had overlap between the two groups.
JVIM 2021, Golinelli et al
How does trilostane work and which hormonal endproducts are suppressed?
Competitive inhibitor of 3-beta-hydroxysteroid dehydrogenase –> decr cortisol, aldosterone, testosterone
JVIM 2021, Golinelli et al
What percentage of dogs develop hypernatremia post hypophysectomy? Are there any predisposing factors and does this affect outcome?
46%, no, no
JVIM 2021, Magno et al
What percentage of dogs have central DI >2 weeks post hypophysectomy? Are there predisposing factors?
71%, pituitary macroadenoma
JVIM 2021, Magno et al
What is the effect of hypophysectomy on potassium?
Mild transient increase, but never above reference interval.
JVIM 2021, Magno et al
Fill in the blanks:
A study comparing standard DOCP dose (___ mg/kg) vs low dose (____ mg/kg) q30d found the latter was just as effective and had fewer overtreated dogs.
2.2mg/kg vs 1.1mg/kg q30d
JVIM 2021, Vincent et al
True or false:
If the Na/K is still mild to moderately low after the first DOCP, the dose should be increased for next time.
False – Na/K is higher after 2nd and 3rd doses even when same amount is given, suggesting an initial acclimation period.
JVIM 2021, Vincent et al
How does PCV affect glucometer readings? Does it affect FSL readings?
Glucometer: lower PCV –> more plasma and glu to interact with –> spuriously higher BG
FSL: higher PCV –> higher IG (unknown why)
JVIM 2021, Howard et al
JVIM 2021, Shea et al
For which BGs is FSL less accurate: very high, normal, very low
Very high and very low
JVIM 2021, Shea et al
Do DM dogs tend to have nocturnal HYPER or HYPOglycemia?
HYPERglycemia
JVIM 2021, Shea et al
What two diet strategies may mitigate postprandial hyperglycemia?
High fiber
Low digestible carb
JVIM 2021, Shea et al
Which insulin has lower day to day variability? Which had better overall glycemic control?
Human recombinant insulin (Toujeo, insulin degludec)
Porcine lente insulin
Lower day to day variability - human recombinant
Better overall glycemic control - porcine lente
JVIM 2021, Miller et al
Compare the accuracy of insulin pens vs syringes.
Pens are more accurate. Similar precision pens vs syringes.
JVIM 2021, Malerba et al
Which are most reliable for insulin doses <2U, pens or syringes?
Pens
JVIM 2021, Malerba et al
True or false:
DM dogs tend to have lower TLI, and this correlates with time since DM diagnosis.
False – no difference in TLI in DM vs normal dogs, no correlation with time since dx.
JVIM 2021, Hamilton et al
True or False:
DM dogs frequently have elevated PSL or TLI suggestive of pancreatitis, without any additional supporting evidence.
True. HAC dogs also do this. Some of the DM dogs in the study may have had undiagnosed HAC.
JVIM 2021, Hamilton et al
Name at least 4 patient risk factors for iatrogenic hypothyroidism with I-131, and at least one for persistent hyperthyroidism.
Hypo-T:
–detectable TSH (OR 12)
–higher 24hr % I-131 uptake (OR 3.7)
–female (OR 2.4)
–bilateral thyroid disease esp with homogenous uptake (OR 3.7)
–Older
–Milder severity score
Hyper-T:
–Younger
–Higher severity score (OR 1.9)
–Lower 24hr % I-131 uptake (OR 3.5)
JVIM 2021, Peterson
Which thyroid hormone abnormality becomes more prominent as hyperthyroidism progresses? T4, T3, or TSH
T3
JVIM 2021, Peterson
What proportion of cats are azotemic post I-131 in the following categories: persistent hyper-T, euthyroid, subclinical hypo-T, overt hypo-T
Persistent hyper-T: 0.4%
Euthyroid: 12%
Subclinical hypo-T: 39%
Overt hypo-T: 70%
JVIM 2021, Peterson
In Europe, cats are often hospitalized 2-3 weeks post I-131. Two thirds of cats with T4 elevated at discharge BUT <____ will become euthyroid over time, but if >____ euthyroidism is unlikely.
<7.7, >11.6
JVIM 2021, Mullowney
True or false regarding I-131 treatment failure:
Re-treatment with I-131 and thyroidectomy have similar success rates.
False – re-treatment with I-131 was successful in all cats (incl 2 with carcinoma), thyroidectomy successful in only 1/3 of cats (half had carcinoma).
JVIM 2021, Mullowney
How does oral vs SQ radioactive iodine affect uptake?
Generally similar uptake (but small study – N=7) – 1 cat had 2-fold difference
JVIM 2021, Cosford
In one small study, 64% of patients received more or less I-131 than the prescribed dose?
> 10% less than the prescribed dose – time in syringe, residual left in syringe, syringe material, other
JVIM 2021, Busser
True or false:
Hyperthyroid cats frequently have markers of hypercoagulability, esp if concurrent heart disease.
False – hyperthyroid cats have some altered markers of hemostasis (ex: incr fibrinogen, AT activity, vWB:Ag) which improve post I-131, but did not fulfill criteria for hypercoagulability. Values did not correlate with cardiomyopathy.
JVIM 2021, Keebaugh
How are insulin, GH, IGF-1, and liver related?
Insulin –> incr liver GH receptors –> GH tells liver to make IGF-1 –> neg feedback on GH
JVIM 2021, Zini
Serum IGF-1 is a surrogate for measuring what value?
Represents the previous 24hrs of GH activity
JVIM 2021, Zini
How does overall body weight, weight gain and weight loss affect IGF-1 in cats?
No effect (but small study - N=10 cats)
JVIM 2021, Zini
What is the prevalence of hypersomatotropism (HST) in DM cats?
18-32%
JVIM 2021, Bokhorst
What threshold of IGF-1 is consistent with hypersomatotropism (HST)? Does a normal value rule it out?
IGF-1 >1000 –> HST
Can fluctuate; one normal value does not rule out
JVIM 2021, Bokhorst
Is hypersomatotropism (HST) most frequently caused by pituitary adenoma, adenocarcinoma, or hyperplasia?
Adenoma
JVIM 2021, Bokhorst
What is the cutoff P/B for pituitary enlargement in dogs vs cats?
Cats: >0.40
Dogs: >0.31
JVIM 2021, Bokhorst
What is the most common signalment (breed, sex, age) of cats diagnosed with hypersomatotropism?
DSH (69%), MN (78%), avg 10yrs
JVIM 2021, Bokhorst
JVIM 2021, Fenn
How do the following treatments compare in inducing DM remission in cats with hypersomatotropism? (proportion of cats, how long it takes, durability of remission)
Surgery
Stereotactic radiation
Pasireotide (what is this?)
Surgery: 70-92%, most within 7-10d, 12% relapse
Stereotactic radiation: ~1/3, 4mo, >1/3 relapse
Pasireotide (somatostatin analog): ~1/3 remission, took months, generally durable
JVIM 2021, Bokhorst
JVIM 2021, Fenn
Is IGF-1 helpful to monitor post hypophysectomy for treatment of hypersomatotropism (HST)?
Yes – 80% of cats normalized within 1mo. Cats without DM remission and no improvement in glycemic control maintained high IGF-1 –> tx failure.
JVIM 2021, Fenn
What three supplements do animals need post hypophysectomy?
DDAVP – usually temporary
Corticosteroid
Levothyroxine
JVIM 2021, Fenn
Are neuro deficits post hypophysectomy in cats typically permanent or temporary?
Temporary
JVIM 2021, Fenn
What is the perioperative death rate (within 2mo) for hypersomatotropic cats treated with hypophysectomy?
What are two important causes?
12-15%
Rebound hypoglycemia, bacterial meningitis/sepsis
JVIM 2021, Bokhorst
JVIM 2021, Fenn
What is the threshold for aldosterone to diagnose primary hyperaldosteronism (PHA) due to a functional adrenal tumor?
Ald >1000
JVIM 2021, Langlois