Endocrine Ettinger Flashcards
1
Q
What is primary hyperPTH?
A
Excessive synthesis and secretion of PTH by abnormal, autonomously functioning parathyroid “chief” cells
2
Q
What is the classic biochemical triad of hyperPTH?
A
Hypercalcemia, hypophosphatemia, hyperphosphaturia
3
Q
Which breeds are noted to have hyperPTH?
A
Keeshond (genetic predisposition), Poodles, GSD, Retrievers
4
Q
What does the owner see with hyperPTH?
A
Mild to nothing!
o 42% sought vet care for other reasons when hyperCa found (yearly exams, dental bloodwork)
o 50% urinary signs (urolithiasis, UTIs)
5
Q
What are the hallmarks on a chemistry for hyperPTH?
A
HyperCa!!!!!
Low to normal Phos (PTH inhibits renal tubular resorption of phos - you pee it out!)
6
Q
What are the hallmarks on a chemistry for hyperPTH?
A
HyperCa!!!!!
Low to normal Phos (PTH inhibits renal tubular resorption of phos - you pee it out!)
7
Q
Why are patients with hyperPTH isothenuric?
A
HyperCa = Reversible form of nephrogenic DI (interferes with ADH) = Isosthenuria
8
Q
What % of hyperPTH dogs had UTIS?
A
o Sediments: Hematuria, pyuria, bacteruria, crystalluria (29% with UTIs)
o Uroliths!!! (about 25%)
9
Q
What would you see on a PTH/PTHrp/Vit D panel in hyperPTH?
A
iCa high = PTH should be or approach undetectable!
“Normal” PTH in hyperCa animal = ABNORMAL and considered excessive!
PTHrp - undetectable
Vit D: Normal to increased
10
Q
If the phosphorus is low to normal how does this help with DDx for hyperCa animal?
A
If serum phos low or normal: LESS likely renal failure, Vit D toxicosis, or Addisons; MORE likely primary hyperPTH or malignancy associated hyperCa
11
Q
How many HyperCa have LSA?
A
About 40%, check for mediastinal mass
12
Q
What is recommended for acute hyperCa?
A
saline (0.9%) diuresis +/- Lasix
13
Q
What is recommended for acute hyperCa?
A
- Rehydrate (increased GRF to increased Ca loss in urine)
- saline (0.9%) diuresis (promotes renal loss of Ca, Na competes with Ca for reabsoprtion = Ca lost!)
- +/- Lasix (inhibits Ca reabsorption in thick ascending LOH)
NOTE: Thiazides = Decreased Ca excretion in distal tubule
14
Q
How are steroids helpful for hyperCa?
A
Reduce bone resorption of Ca, decrease intestinal Ca absorption, and increase renal Ca excretion
Cytotoxic to neoplastic lymphocytes, inhibit growth of neoplastic tissue
Counteract effects of Vit D and granulomatous dz
15
Q
What are the major bisphosphonates and how do they work?
A
etidronate, clodronate, pamidronate)
Structurally related to pyrophosphates (metabolic by-product) → Inhibitory effect on osteoclast function and viability
16
Q
What is calcitonin?
A
· Reduces osteoclast activity and formation of new osteoclasts
· Considered to be “weak and short acting” in humans
Salmon calcitonin (Calcimar) = MOST POTENT
17
Q
What is plicamycin?
A
(aka mithramycin)
· Cytotoxic compound = Potent inhibitor of RNA synthesis in osteoclast
Significant Toxicity: Thrombocytopenia, hepatic necrosis, renal damage, hypoCa
Works within 24-48hrs
18
Q
What is plicamycin?
A
(aka mithramycin)
· Cytotoxic compound = Potent inhibitor of RNA synthesis in osteoclast
Significant Toxicity: Thrombocytopenia, hepatic necrosis, renal damage, hypoCa
Works within 24-48hrs
19
Q
How would bicarbonate help with hyperCa?
A
· Ionized fraction of Ca determined by acid-base status
Creating a slight alkalosis (bicarbonate tx) shifts iCa to protein bound fraction (less harmful)
= Mild effect
20
Q
How would a Ca receptor agonist work with hyperCa?
A
· Ca sensing receptor on parathyroid cells (down regulates synthesis and secretion of PTH)
Molecules that mimic Ca can activate this receptor and inhibit parathyroid function too
R-5658
21
Q
After sx for hyperPTH, does recurrence happen?
A
Yes, 16/187 dogs
Esp in keehounds (!!! Need to monitor this breed) = 7/187 dogs
22
Q
Besides sx what other options are there for hyperPTH dogs?
A
- Heat Ablation
2. Ethanol Ablation
23
Q
What is the biggest complication with any tx for hyperPTH?
A
Hypocalcemia (post-tx) - Atrophied other parathyroid glands
Risk = Higher pretx Ca, longer duration (Ca >15) = Greater risk of hypoCa NOW study that shows that iCa or PTH levels prior to tx do NOT predict hypoCa after!!!!!
Vit D prior to after did not prevent the decreased in Ca
24
Q
What is used to tx hypoCa after treating hyperPTH?
A
Calcitriol (Vit D)
GOAL: Keep Ca low to low normal (wake up those other parathyroid glands)
25
What is the prognosis for hyperPTH?
Excellent!!!
| After tx 33% will develop hypoCa but treatable!!
26
What is the prognosis for parathyroid carcinomas?
Excision of parathyroid carcinomas = Resolution of hyperCa and Excellent tumor control
27
What are the most common CS in hyperCa cat?
Poor appetite, weight loss, weakness (less common PU/PD)
28
What is different in dogs than cats with hyperPTH?
Cervical mass that CAN be palpated in cats!!! Not true in dogs (need ultrasound)
29
How is primary hypoPTH diagnosed?
Low iCa with low or low normal PTH
30
What is the mechanism of hypoCa in ethylene glycol?
Marked increased in phos = decreased in Ca
31
What can be seen with nutritional HyperPTH?
· Improper diet = Low Ca to Phos ratio (beef heart or liver) → Ca deficiency = transient decrease in serum Ca → Increase in PTH = Reduction in bone mass from Ca mobilization to replace Ca that is lacking in diet
Normally Ca and Phos are in RR (some can have hypoCa)
32
What is considered ER tx for hypoCa?
IV Ca gluconate (slow)
33
What is considered long term tx for hypoCa?
Vitamin D (calcitriol) and Oral Calcium (calcium carbonate)
34
What is seen on histopath for hypoPTH?
Lymphocytic parathyroiditis
35
What is the prognosis for hypoPTH?
Excellent with tx (depends on owner - Lots of monitoring)
36
What are the hallmark CS for hypoPTH?
Seizures (50%), tremors, fasiculations, muscle cramping, stiff gait, tetany
37
What are the major types of primary acquired hypoT4?
· Primary Acquired Hypothyroidism (deficiency of T4/T3):
o 1. Lymphocytic Thyroiditis (50% cases)
§ Multifocal/diffuse infiltrate of lymphocytes, plasma cells, MPs → Fibrosis
§ Immune Mediated (unclear process)
§ Antithyroglobulin antibodies: 36-50% hypoT4 dogs (unclear role); varies with breed
· Association of DLA Class II Haplotype DQA1*00101: Dobermans, English Setters, Rhodesian Ridgebacks
§ Heritable Thyroiditis: Beagle, Borzoi
o 2. Idiopathic Thyroid Atrophy
§ Loss of thyroid tissue, replacement with adipose (may be a final stage of thyroiditis)
o 3. Bilateral Thyroid Neoplasia (thyroid or mets)
§ Remain euthyroid until 75% thyroid destroyed
§ Risk Factor: Lymphocytic thyroiditis
o 4. Reversible from high doses of potentiated sulfonamides
38
What is secondary acquired hypoT4?
(deficiency of TSH) - rare (~5% of cases)
o Pituitary malformation
o Pituitary neoplasia
39
What is tertiary hypoT4?
· Tertiary Hypothyroidism (deficiency of TRH): NOT documented in vet med
40
What is primary congenital hypoT4?
Cretinism: Rare in dogs
o Iodine deficiency, thyroid dysgenesis, dyshormonogenesis
o Thyroid peroxidase deficiency: Autosomal recessive Rat terrier, Toy Fox (DNA test for carriers)
41
What is secondary congenital hypoT4?
· Secondary Congenital Hypothyroidism (isolated loss of TSH or TRH deficiency)
o Family of giant Schnauzers and 1 boxer
Feature of panhypopituitarism
42
Which breed are overrepresented with hypoT4?
Goldens and Dobermans
43
What is a myxedma coma?
Profound mental dullness or stupor, with nonpitting edema, hypothermia with lack of shivering, bradycardia, weakness, inappetence
· Deposition of glycosaminoglycans
· Concurrent infection may precipitate hypoT4 crisis
44
What dz is associated with lar par, megaesophagus, Myanthenia gravis, and DCM?
HypoT4
45
What polyendocrinopathies are noted with hypoT4?
Addison's and DM (hypoT4 = insulin resistance)
46
Does T4 supplementation improve survival in euthyroid sick patients?
NO!
47
How is the TSH response test performed?
§ Test of thyroid gland reserve (standard for diagnosis of hypoT4)
§ Protocol: human recombinant TSH (rhTSH): 75-100ug TSH collection in 4-6 hrs
o HypoT4: Pre and post TSH serum T4 below RR ( 2.5 ug/dl and increase at least 1.5X basal T4
§ Can’t be used in dogs on l-thyroxine (thyroid atropy)
o Need to stop for 6-8 wks before testing
48
ow is the TRH response test performed?
§ Dose: 0.01-0.1 mg/kg TRH
§ Protocol: 200 ug TRH/dog IV; collect blood before and 30 mins, then 4 hrs after
o TT4 measured at 0 and 4 hrs; TSH measured at 0 and 30 mins
o Euthyroid: Post TRH TT4 > 2 ug/dl and if relative increased in TSH greater than 100% at 30 mins after TRH administration
o HypoT4: Post TRH TT4
49
What % of hypoT4 dogs have anti-thyroglobulin antibodies?
38-50%
| Can be transiently increased with vaccination
50
Which feline breeds get congenital hypoT4?
DSH and Abyssinians
51
What human disease does hyperT4 resemble?
Human toxic nodular goiter (Grave’s Dz): Autoimmune dz circulating antibodies (thyroid stimulating immunoglobulins (TSIs) bind to throtropin (TSH) receptors and mimic TSH)
BUT TSIs NOT seen in cats
52
Which breeds are at a lower risk of hyperT4?
Siamese and Himalayan, purebred cats
53
What are risk factors of hyperT4?
Entirely canned food (esp flavored
Goitrogenic Compounds
§ Metabolized by glucuronidation (SLOW in cats)
· Goitrogenic soy isoflavones (genistein and daidzein) – In commercial cat food
Living indoors, using cat litter, sleeping on floor = Increase risk
These + eating seafood or fish flavored canned food → Increased exposure to polybrominated diphenyl ethers (PBDEs) = Endocrine disruptors in cats
54
What is the mechanism of intermittent vomiting with hyperT4?
Triggers chemoreceptor trigger zone
55
What is an apathetic hyperT4 cat?
~ 10% of cats, anorexia & depressed; need to r/o CHF and other illness
56
Which counterregulator hormones are the most important for increasing glucose?
Glucagon and catecholamines
57
What molecule is secreted with insulin that in humans and CATS assumes a B-pleated shape?
Islet amyloid polypeptide
58
What are the two big issues with Type 2 DM?
Insulin Resistance
| B Cell Dysfunction (accounts for progressive nature)
59
Which adipokine is anti-inflammatory?
Adiponectin: High levels in lean!
Obesity: Drop in adiponectin and rise in leptin - pro-inflammatory cytokines
60
Have anti-islet antibodies (Type 1 DM) been described in cats?
```
NO! Type I DM is very rare
Lymphocytic infiltration (only in a few cats)
```
61
Which breed of cat is more likely to get DM?
Burmese (4X) higher!
62
How likely are obese cats to get DM?
3.9X more likely
63
What are the risk factors for cats getting DM?
· Old age
· Obesity
o Fat cats are 3.9x more likely to develop DM
o Drop in insulin sensitivity has been documented after weight gain in cats
o GLUT4 expression is lower in muscle and fat of fat cats vs. lean cats
o GLUT1 is unchanged (not insulin sensitive)
o Decreased adiponectin and increased leptin and TNF-a
· Male gender
· Neutered
· Physical inactivity
· Glucocorticoid or progestin administration
64
What is the structure of insulin?
polypeptide chains
§ A chain: 21 aa
§ B chain: 30 aa
o Both chains are connected by 2 disulfide bridges
65
How does insulin differ bwtn species?
o Feline insulin differs from bovine by only 1 aa
o Differs from canine and human in 3 and 4 positions
```
A8 A10 A18 B30
Human Thr Ile Asn Thr
Pig/Dog Thr Ile Asn Ala
Cattle Ala Val Asn Ala
Cat Ala Val His Ala
```
66
Why does oral glucose release more insulin than IV?
o Oral glucose causes more severe insulin release than IV
§ Due to the actions of incretins, release by endocrine cells in the GI tract = Stimulate insulin release
· Glucagon-like-peptide-1 (GLP-1)
Glucose dependent insulinotropic polypeptide (Gastric inhibitory peptide)
67
In which organs is glucose entry not affected by insulin concentration?
brain, kidney, and erythrocytes are not affected by lack of insulin
68
What are lente insulins?
o Based on the fact that insulin effect can be delayed by simply adding zinc in excess
§ Approx 10x the amount in NPH
o Other factor affecting onset of action: physical condition
§ Amorphous
· 1 mm n diameter
· Faster onset and short duration than crystalline zinc
§ Crystalline
o Lente insulins are mixtures of 30% short-acting amorphous with 70% long-acting crystalline
§ Rapid onset
§ Prolonged duration
o Vetsulin/Caninsulin
69
What is a major negative of using sulfonylureas in cats?
Glipizide:
§ may have negative effects on islets and may accelerate β-cell loss
· experiments have documented increased amyloid deposition
o Stimulate secretion of insulin
§ Some b cell function required
o Glipizide should only be used in diabetic cats that are in good physical condition, are nonketotic, and have only mild to moderate signs of diabetes
o Several drawbacks
§ treatment is successful in only about 30% of cats
70
What are in the intrinsic defense and preventative mechanisms in pancreas?
Protect from auto-digestion:
§ Production of proteins as zymogens
§ Segregation from lysosomes
§ Presence of enzymatic inhibitors
o PSTI ( SPINK 1)– pancreatic secretory trypsin inhibitor
§ Unidirectional flow of pancreatic duct
§ Protease inhibition
o α2 macroglobulin – non specific, irreversibly binds, cleared by RES and most important
§ Class specific
o α1 protease inhibitor & α1 antitrypsin – reversible bind, transport to α2 macroglobulin
71
What are 2 circumstances that cTLI would be normal but patient would have EPI?
· Isolated pancreatic lipase deficiency (reported in one dog)
· Obstructed pancreatic duct
72
What is the most common breed with primary hyperPTH in dogs?
Keeshond
73
What is a major difference in cats with hyperPTH compared to dogs?
Cats have a palpable mass (Cervical region)
74
What are bisphosphonates used for idiopathic hyperCa in cats?
Alendronate (erosive esophagitis, osteonecrosos of jaw)
| Zoledronate (more necrosis)
75
What is used ot manage post-op hypoCa in parathyroidectomies?
Calcitriol
76
Which breed has a high incidence of recurrence?
Keeshound! (10%, regardless of path)
| All histopath have similar behavior
77
Can HAC lead to increase in PTH?
Yes, Hypercortisolemia can result in increased PTH BUT NOT increase in total or iCa
Improves with tx of Cushing's dz
78
What is Hungry Bone Syndrome?
HypoCa NOT related to low PTH = Uptake of Ca by bones after longstanding HyperPTH or HyperT4
*calcitriol, but also bisphoshpnates to try to inhibit osteoclasts from taking up Ca
79
What electrolyte is important for PTH secretion?
Mg!!
80
What is the main defect with primary congenital HypoT4?
Thyroid peroxidase def = Cretinism
81
Which breeds get primary congenital HypoT4?
Rat Terrier, Toy Fox Terrier, Tenterfield terrier
82
What is secondary congenital HypoT4?
Loss of TSH or TRH = Panhypopitutarism
| Seen in Giant Schnauzer, Boxer
83
What can be normal in 13-38% of hypoT4 dogs?
TSH
84
What is the mechanism that sulfonamides results in hypoT4?
Block iodination of thyroglobulin
| Clinical HypoT4 that is reversible
85
Which breeds will have a decreased TT4?
Sighthounds and sled dogs
86
What happens to TT4 in neonates?
3-5X adult for 3 weeks and then decreased
87
Can TSH be increased in euthyroid dogs?
YES, TSH increased in 7-18% euthyroid dogs
88
Which are more common in dogs AntiT3 or AntiT4 antibodies?
AntiT3 - 5.7% dogs with CS, 34% hypoT4 dogs
| AntiT4 - 1.7% dogs with CS, 15% dog hypoT4
89
What is considered the gold standard for testing thyroid function? How is it performed?
TSH response test - thyroid gland reserve
rhTSH 75-100ug (cats 25ug)
If hypoT4: T4 low post TSH!
90
Can the TSH response test be used in dogs on l-thyroxine?
NO!! They have thyroid atrophy
| Need to stop supplementation for 6-8weeks
91
What is the TRH test and how is it performed?
Give TRH (IV) 200ug/dog - samples at 30 mins and 4 hrs for TSH and TT4
If hypoT4 post TSH will be
92
What is the problem with TRH test?
Some dogs fail to respond to TRH!
93
What can transiently affect ATAbs?
Drugs
Viral infection
Vaccination
Nonspecific protein binding
94
Do ATA interfere with thyroid supplementation?
NO!
95
What should be considered in a dog with GI dz that is hypoT4?
Supplementation with T3, but high risk of hyperT4, need to monitor closely
96
What should you consider if there is tx failure in HypoT4 dog?
```
Wrong DX!!
Owner compliance
Inadequate dose
Poor PO absorption
Defective T4 to T3 conversion (but not reported in dogs)
```
97
What would you expect with hypoT4 in cats?
Low TT4/low fT4
Can use K9 TSH test in cats
CS: Inappetant
98
What are causes of hypoT4 in cats?
1. Iatrogenic - I131
2. Congenital HypoT4 - DSH and Abyssinian
3. Lymphocytic thyroiditis
4. Secondary hypoT4 - head trauma
99
If you have normal T4/fT4 and normal TSH.....
Normal dog
| If strong suspicion test more
100
If you have Low/borderline T4/fT4 and normal TSH.....
1. HypoT4
2. Normal variant
3. Concurrent illness
Consider: thyroid ABs, provocative testing, therapeutic trial
101
If you have normal T4/FT4 and HIGH TSH......
1. Early subclinical hypoT4
2. Recovery from illness
Consider rechecking in 1-3 months, or if strong suspicion check for thyroiditis (ATAs)
102
What % of dogs have anti-thyroglobulin ABs?
30-50% hypoT4 dogs
| BUT 10-20% euthyroid dogs do too!!
103
If you have low/borderline T4/fT4 and HIGH TSH....
HYPOT4 - Need supplementation life long :)
104
Why do hyperT4 cats vomit?
Thyroid hormone thought to stimulate CRTZ
105
Why are hyperT4 cats PU/PD?
Thyroid hormone thought to inhibit aquaporins
106
Is there evidence that hyperT4 damages kidneys?
Direct evidence is lacking!
107
What happens with fructosamine with hyperT4?
Decreased!!! dt high protein turnover
108
What % of hyperT4 can have normal TT4?
10% of HyperT4 cats
109
If you have mid-range-high TT4 and increased fT4 in cat.....
HyperT4
110
If you have low TT4 and increased fT4 in cat......
Nonthyroid illness
111
How can you use TSH in cats with hyperT4?
Only 45% success with using canine TSH
| Used to eliminate hyperT4 if TSH is detectable
112
Was there a significant difference in MST in cats that developed azotemia after I131?
NO!!! :)
113
In I131 cats what did decreased survival in azotemic cats?
HypoT4 status!!
114
Can normal housemates eats y/d?
Yes, but they need to even iodine in other food
115
Can cats develop a goiter on y/d?
YES!
116
What are the effects of y/d on I131?
Unknown, stop about 2 weeks ahead
117
Has hypoT4 been reported in cats with hyperT4 and healthy cats on y/d?
NO! When feed 0.3ppm iodine for 1 year
118
What is the critical hormone for DKA?
Increase in glucagon
119
If you have IM insulinitis what are your Abs directed against?
Beta cells and GAD (glutamic acid decarboxylase) - seen in some dogs
120
How many diabetic dogs have uncomplicated ketonuria?
About 66%
121
What % of dogs and cats get EPI with diabetes?
Dogs 25%
| Cats 10%
122
How does kinostat work in DM?
Aldosterone reductase inhibitor that stops cataract formation
123
What is the cut off for Beta hydroxybutyrate in DKA?
Cut off 3.8 but highly specific when >4.8
124
What is HONKDM?
Hyperosmolar nonketotic DM
Extreme hyperglycemia >600
Hyperosmolarity > 350
No ketones - some functioning beta cell remain and thus ketones are not made
125
What are the ranges for fructosamine in dogs?
>500 poor glycemic control
450-500 fair control
400-450 good control
350-400 good control
126
What can falsely lower fructosamine?
```
Hypoalbuminemia
Hyperlipidemia
Azotemia
Room temp
Hypert4
```
127
What is the prognosis for DM in dogs?
2-3 years after sx
128
Is there day to day variation in BG curves?
Yes! When preferred at home vs at hospital there were differences too
60% same decision
40% different decision and in 3% dogs and 8% cats if was contrary decision
129
What are the three mains factors resulting in DKA?
1. Absolute or relative lack of insulin= hyperglycemia
2. Increased glucagon
3. Increase EPI, cortisol, GH
130
What are the four main outcomes of DKA?
Increased hepatic glycogenolysis and gluconeogensis
Decreased peripheral use of glucose
Increased lipolysis
Increased hepatic ketogenesis
131
What is the prognosis for DKA?
Guarded
Mortality
Dogs 29%
Cats 26%
132
What are the goals for insulin tx in DKA?
Decrease bg by 50-70 mg/Dl/hr
Above 250 for first 4-6 hrs
Once lower than 250 add dextrose
133
What are the insulin cri rates in dogs and cats?
Dog 0.09 u/kg/hr
| Cat 0.045 u/kg/hr
134
Are fat cats at risk of DM?
Yes 3.9x more likely to get DM
Decrease in insulin sensitivity
Decrease GLUT4 Muscle and fat
Decreased apidonectin and increased leptin and TNFa
135
What are the risk factors for DM in cats?
Obesity
Male
Neutered
136
What % cats go into remission with glargine and high protein,low carb diet?
> 80-90%
137
What is key to diabetic remission in cats?
Need functioning beta cells
138
What type of diet is ideal for cats with DM for remission?
Low carb and high protein
139
What were remission rates in cats with DM?
>80-90% with glargine and diet
60% with PZI
20-30% diet alone
140
What factors make remission in DM unlikely?
Increased cholesterol
Plantigrade stance
Increased insulin dose
141
What is insulin resistance?
> 1.5 u/kg q 12hrs
142
How long can somogyi response last?
Release of EPI, glucagon
Can last 24-72hrs
Marked hyperglycemia > 400
143
What is considered Whipple's triad?
Related to insulinoma
144
In what disease can a glucagon cri be used?
With an insulinoma
145
What % of insulinoma develop DM after sx?
About 10%
146
What are medical management options of insulinoma?
Diet increased freq high protein
Prednisone
Diazoxide inhibits stop and blocks insulin secretion
Octerotide somatostatin analog that inhibits insulin secretion
147
What cat breed gets insulinomas?
Siamese
148
What should be considered if concurrent pituitary and adrenals rumors noted?
Transition from adrenal hyperplasia to adrenal nodular hyperplasia
149
Which part of the pituitary makes ACTH?
Pars distalis mainly
| Little from beta cells in pars intermedia
150
Since it is recommended to perform pituitary imaging in all dogs with PDH, what could be used to help?
POMC and pro ACTH levels to determine if imaging needed
151
Is there a correlation of ALP with severity of HAC?
No!
152
Can you have an abnormal bile acids in dogs with HAC?
Yes they can be increased
153
What % of HAC dogs have proteinuria?
60-80%
| It does not always normalize with tx
154
What effects does HAC have on thyroid status?
HAC can decrease TSH leading to low TT4 in 20-57%
155
What is the protocol for ACTH stim?
Cosyntropin at 5ug/Kg
156
Which HAC screening test is very affected by systemic disease ?
UCCR
| LDDST
157
What is the protocol for LDDST in dogs?
0.01 mg/kg dex sp IV
158
What many HAC are dexamethasone resistant?
40% PDH
| 100% adrenal tumors
159
What is the protocol for HDDST in dogs?
0.1 mg/kg dec sp iv
160
How many cases will be differentiated with HDDST?
Only 12% of PDH cases, in general FAT and 15-50% PDH esp large tumors do not suppress!
161
What is the name of the syndrome that described progression of neurological signs in dogs that have HAC with treatment?
Nelsons syndrome
162
Is there a difference btwn trilostane and mitotane?
No! Trilostane 662 days and mitotane 708 days
163
What the MST difference with q12 vs q24 dosing of trilostane?
Q12 900 days vs q24 662 days
164
What electrolyte change can be seen with trilostane?
Mild increase in K
165
What % dogs relapse on mitotane?
50% relapse within 12 months
166
How does selegiline work?
Increased Dopamine which inhibits secretion of ACTH from pars intermedius
167
What % of dogs that underwent radiation tx for PDH needed medical management?
30-60%
168
In FAT cases is there a difference btwn trilostane and mitotane?
No significant difference btwn MST
169
What is ectopic ACTH syndrome?
Marked increase in ACTH
hypokalemia- severe cortisol activated mineralocorticoid receptors
No suppression even with HDDST
No evidence of pituitary tumor
170
Which dog breeds have ectopic ACTH syndrome been seen?
Dachshunds
| GSD with pancreatic and hepatic masses
171
How do you do ectopic ACTH syndrome?
Give CRH, if PDH ACTH and cortisol will increase
| If ectopic no change
172
What is food dependent glucocorticoid excess?
When gastric inhibitory polypeptide (GIP) from duodenum activated ectopic GIP receptors on adrenal glands
High cortisol with bilateral adrenomegaly
Low ACTH
173
What is the tx for food dependent glucocorticoid excess?
Octerotide to down regulate somatostatin receptors on GIP cells
Trilostane
Mitotane
174
What are the dynamic thyroid function tests to consider in hyperT4 cats?
Used when CS of hyperT4 but TT4 equivocal and fT4 not helpful
1. TSH response test (give TSH and measure TT4 = BUT abnormal thyroid gland can respond too)
2. TRH Response Test (give and measure TT4) = BUT indistinguishable btwn sick euthyroid and hyperT4 with illness)
3. T3 suppression Test (give liothyronine for 7 doses and then check TT4 and TT3) - In hyperT4 additional T4 does NOT change TT4 since already decreased TSH; if euthyroid >50% suppression
Test is more useful to confirm euthyroid (rule out hyperT4)
175
What is the most reliable to confirm hyperT4 in sick cats?
Thyroid scintigraphy, may even help prior to increase in TT4
176
Is it known in hyperT4 cats if anti-thyroid drugs affect uptake for thyroid scintigraphy?
Unknown, but in healthy cats methimazole can alter uptake
177
Do thyroid nodules continue to grow on methimazole?
YES
178
What is the ideal dosing with methimazole?
2.5 mg PO q12hrs (87%) compared to 5 mg PO q24hrs (54%) in 2 wks
179
Why are B-blockers used in hyperT4?
In humans inhibit peripheral T4 to T3 conversion
180
In I131, what results in damage and tissue destruction?
Beta rays!
181
How many cats are euthyroid with one dose of I131?
90%!!
182
How many are hypoT4 after I131 tx?
About 30% > 3 months post I131, but tx not needed in all
183
What is the relapse rate after I131?
Rare,
184
What can be given prior to I131 that has the potential to decrease dose by 30%?
rhTSH (25ug/cat)
185
What are the guidelines for adrenal insufficiency or critical illness related corticosteroid insufficiency in dogs?
1. Normal or elevated cortisol but ACTH cortisol
186
What can decreased renin?
Aging and neutering
187
Why would you perform a fludrocortisone test for hyperaldosteronism?
Rule out false + from Screening tests (aldosterone:renin), idea that it should decreased aldosterone production (based on urine aldosterone: creatinine ratio)
188
What disease result in secondary hyperaldosteronism?
When increased renin and increased aldosterone
Renal Disease
Cardiac disease
Liver Failure
189
What is medical management of primary hyperaldosteronism?
Spironolactone
K supplementation
Hypertension tx (amlodipine)
190
What are two main differences of feline and canine cushing's?
Cats have no increased in ALP and No LOW USG
191
What are the main effects of steroids that result in insulin resistance?
1. Decreased GLUT4
2. Decrease insulin secretion from B cells
3. Increased hepatic gluconeogenesis
192
What is different about UCCR in cats?
Higher RR than dogs
193
How is the LDDST different in cats than dogs?
Higher dose of steroids given (0.1 mg/kg dex sp)
Really just looking at 8 hr (unknown if 4 hr is helpful to detect PDH)
Can combined LDDST with UCCR after 2-3 days of dex PO
194
IN which type of cushigns are ACTH precursors high in cats?
PDH has increased POMC and proACTH
195
How is the HDDST performed in cats?
1 mg/kg Dex SP - Like a coin toss, only 50% PDH cats will suppress
196
What % of cats with PDH have normal head CT scans?
45% - microadenomas
197
What drug inhibits 11-B hydroxylase and has been used in cats with HAC prior to adrenalectomy?
Metyrapone
198
Is mitotane good in cats with cushings?
no, cats appear to be resistant
199
Why is ACTH stim not good in cushing cats?
low sensitivity - 2/3 cats within RR with Cushings
200
What are the major forms of acromegaly in dogs?
Luteal phase/exogenous progestins (GH from mammary tissue)
HypoT4
Primary somatotroph adenoma (rare)
201
What radiation for acromegaly o the GH and IGF-1 return to normal?
NO! Even in animals that care clinically improved
| contrast to sx
202
What is pasierotide?
Somatostatin that resulted in decreased IGF-1 and decreased insulin needs (2 cats DM remission) in acromgealy cats
203
In acromegaly cat why can you have a false - IGF-1?
Based on insulin duration, since insulin needed to make IFG-1 in liver - Need to be on insulin for 6-8 weeks
204
What are the IGF-1 and GH ranges that diagnose Acromegaly?
IGF-1> 1000 ng/ml
GH > 10 ng/ml
Best when combined
205
How do you diagnose pituitary dwarfism?
Since normal animals can have decreased GH need stim test
GHRH or alpha adrenergic (xylazine) - Pre GH and 20-30 post GH
Ghrelin Stim
206
What breed gets congenital nephrogenic DI?
Huskies
207
What are major comlications with hyperlipidemia?
Increased LEs
Insulin resistance
Pancreatitis
Renal injury
208
What is the profile of idiopathic hyperlidpidemia in Mini Schnazuers?
Excessive VLDL +/- hyperchylomicronemia
| Mild increased in cholesterol
209
What are the main stays in tx of hyperlipidemia?
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Low fat and moderate protein diet
Fish OIl (omega 3)
Niacin (B3)
Gemfibrozil
(statins)
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