Endocrine cases

Question 1

Adrenal case

Interpret these test results:

NAME: Mandie AGE: 13 yr

SPECIES: Canine SEX: FS

BREED: Pomeranian BODY WT: 4.5 kg

SPECIMEN: Urine

CLINICAL SIGNS: PU/PD, hair loss

TEST REQUESTED RESULT NORMALS

URINARY CORTISOL 134

URINARY CREATININE 6.2

CORT:CR Ratio 22 8 – 24

Answer 1

INTERPRETATION:

Hyperadrenocorticism ruled out with a high degree of confidence (high sensitivity test)

Question 2

Adrenal Case

NAME: Timber AGE: 11 yr

SPECIES: Canine SEX: FS

BREED: Golden Retriever BODY WT: 36.3 kg

SPECIMEN: Urine

CLINICAL SIGNS: PU/PD, weight gain, polyphagia, hair loss

TEST REQUESTED RESULT NORMALS

URINARY CORTISOL 522

URINARY CREATININE 8.7

CORT:CR Ratio 60 8 – 24

Answer 2

INTERPRETATION:

Positive test result for hyperadrenocorticism but low specificity test so treat result with healthy skepticism and look for other clinical information to help support the diagnosis. Review for any other findings that would increase possibility that it is a false positive.

Question 3

Adrenal case

NAME: Socks AGE: 12 yr

SPECIES: Canine SEX: FS

BREED: Lhasa Apso BODY WT: 9.5 kg

CLINICAL SIGNS: Panting, PU/PD, elevated ALP and other liver enzymes

TEST REQUESTED RESULT NORMALS

CORTISOL, PRE 286 15 – 110

CORTISOL, POST LOW DEX, 4H 12 < 30 nmol/L

CORTISOL, POST LOW DEX, 8H 9 < 30 nmol/L

Answer 3

INTERPRETATION: Highly sensitive test

Hyperadrenocorticism ruled out with a high degree of confidence (high sensitivity test)

Question 4

Adrenal case

NAME: Sammy AGE: 8 yr

SPECIES: Canine SEX: FS

BREED: Shih Tzu BODY WT: 6.3 kg

CLINICAL SIGNS: Alopecia, PU/PD, Polyphagia, elevated liver enzymes. ALT 395, AST 44, SAP normal at 58. Liver biopsy showed hepatocellular glycogenosis resulting from high levels of endogenous or exogenous corticosteroids.

TEST REQUESTED RESULT NORMALS

CORTISOL, PRE 262 15 – 110

CORTISOL, POST LOW DEX, 4H 71 < 30 nmol/L

CORTISOL, POST LOW DEX, 8H 173 < 30 nmol/L

Answer 4

INTERPRETATION:

Consistent with pituitary dependent hyperadrenocorticism (8hr> cut-off, >50% suppression from baseline). Pituitary because: adrenal dependent would negatively feedback on pituitary and dex would not feedback on pituitary so with adrenal tumours get a flat line on cortisol level. If we have a pituitary mass that’s making too much ACTH and we come in with DEX if that pituitary listens to us at all it’s going to make that ACTH go down a bit. A normal dog would shut down cortisol production in 60% of pituitary cases it won’t shut off cortisol completely will only have 50% suppression. Adrenal tumours would not suppress at all. If flat line it could be ether pituitary or adrenal but if it goes down then it must be pituitary.

Low specificity test so treat result with healthy skepticism and look for other clinical information to help support the diagnosis. History in this case seems to contain a lot of support for hyperadrenocorticism.

Question 5

Adrenal case

NAME: Sigma AGE: 16 yr

SPECIES: Canine SEX: FS

BREED: mix BODY WT: 43 kg

CLINICAL SIGNS: Uncontrolled diabetes mellitus, seborrhea, slight elevation of ALP, PU/PD

TEST REQUESTED RESULT NORMALS

CORTISOL, PRE 251 15 – 110 nmol/L

CORTISOL, POST LOW DEX, 4H 79 < 30 nmol/L

CORTISOL, POST LOW DEX, 8H 177 < 30 nmol/L

Answer 5

INTERPRETATION:

Consistent with pituitary dependent hyperadrenocorticism (8hr> cut-off, >50% suppression from baseline).

Low specificity test so treat result with healthy skepticism and look for other clinical information to help support the diagnosis.

False positives common in low-dose-dex-suppression and even more common when there is significant non-adrenal illness present. History in this case includes uncontrolled diabetes mellitus so false positive quite likely.

Question 6

While the cortisol test results were pending, Sigma had an excellent response to insulin therapy. The clinician decided to reassess the presence of hyperadrenocorticism. Eight days later another low dose dexamethasone suppression test was performed.

TEST REQUESTED RESULT NORMALS

CORTISOL, PRE 213 15 – 110 nmol/L (don’t pay too much attention to pre as may have been stressed before the test taken)

CORTISOL, POST LOW DEX, 4H 24 < 30 nmol/L

CORTISOL, POST LOW DEX, 8H 18 < 30 nmol/L

Answer 6

INTERPRETATION:

Hyperadrenocorticism ruled out with a high degree of confidence (high sensitivity test). If thinking about making a diagnosis of hyperadrenocorticism in a diabetic, try to treat with insulin first and get some control of diabetes before using a low-dose-dex test.

Question 7

NAME: Zack AGE: 13 yr

SPECIES: Canine SEX: M

BREED: Bichon Frise BODY WT: 10 kg

CLINICAL SIGNS: PU/PD, weight gain, polyphagia, chronic UTI, elevated ALP

TEST REQUESTED RESULT NORMALS

CORTISOL, PRE 196 15 – 110

CORTISOL, POST LOW DEX, 4H 120 < 30

CORTISOL, POST LOW DEX, 8H 125 < 30

Answer 7

INTERPRETATION:

Consistent with hyperadrenocorticism but lack of suppression means can’t differentiate between pituitary and adrenal based disease.

Low specificity test so treat result with healthy skepticism and look for other clinical information to help support the diagnosis.

However, if this result was a false positive and the animal did not have hyperadrenocorticism, it would be “obviously unwell” because of the cortisol concentrations are so high and the response to dex minimal.

Question 8

A sample from Zack was subsequently submitted for endogenous ACTH concentration.

TEST REQUESTED RESULT NORMALS

eACTH 0.0 6.7 – 25.0

Answer 8

INTERPRETATION:

Low ACTH in a dog with hyperadrenocorticism is consistent with adrenal disease (negative feedback of adrenal origin cortisol on pituitary secretion of ACTH)

Question 9

NAME: Copper AGE: 9 yr

SPECIES: Canine SEX: FS

BREED: mix BODY WT: 14.6 kg

CLINICAL SIGNS: History of elevated ALP, increasing lately. Normal ALT. History of mildly low phosphorus; occasional labored breathing, PU/PD.

TEST REQUESTED RESULT NORMALS

CORTISOL, PRE 247 15 – 110

CORTISOL, POST LOW DEX, 4H 213 < 30

CORTISOL, POST LOW DEX, 8H 193 < 30

Answer 9

INTERPRETATION:

Consistent with hyperadrenocorticism. As with all hyperadrenocorticism tests, specificity is not perfect and so positives need to be treated with care (see above). The failure to suppress by at least 50%means that we can’t yet tell if this is pituitary or adrenal disease.

A sample from Copper was subsequently submitted for endogenous ACTH concentration.

TEST REQUESTED RESULT NORMALS

eACTH 19.2 6.7 – 25.0 pmol/L

INTERPRETATION:

The lack of suppression of ACTH means this is not adrenal, therefore it is pituitary hyperadrenocorticism. ACTH does not need to be “high” in pituitary dependent disease

Question 10

NAME: Chopper AGE: 4.5 yr

SPECIES: Canine SEX: MC

BREED: English Bulldog BODY WT: 31.8 kg

CLINICAL SIGNS: Obesity, dermatitis, erythema, papules, plaques, long history of allergic dermatitis and constant steroid therapy. PU/PD, pot-bellied appearance.

TEST REQUESTED RESULT NORMALS

CORTISOL, PRE 3 15 – 110

CORTISOL, POST LOW DEX, 4H 2 < 30

CORTISOL, POST LOW DEX, 8H 7 < 30

Answer 10

INTERPRETATION:

This is what we would get if we used a LDDS test in a case of iatrogenic hyperadrenocorticism. This is why we need to use ACTH stimulation tests in cases that could have iatrogenic Hyperadrenocorticism.

Question 11

NAME: Lady Gizmo AGE: 14 yr

SPECIES: Canine SEX: FS

BREED: Pekingese BODY WT: 4.2 kg

CLINICAL SIGNS: Pruritus, recent chemistry panel showed elevated hepatic enzymes and decreased Na/K ratio (25). Rule out hypoadrenocorticism.

TEST REQUESTED RESULT NORMALS

CORTISOL, PRE 379 15 –110

CORTISOL, POST ACTH 1 hr 793 220 – 550

Answer 11

INTERPRETATION:

Hypoadrenocorticism is ruled out. This is where you should normally stop as exaggerated responses are common in sick dogs (even without HAC) and many dog that you will be testing because for suspected HYPO-adrenocorticism will be “sick”.

Question 12

NAME: Cocoa AGE: 3 yr

SPECIES: Canine SEX: FS

BREED: Springer Spaniel BODY WT: 16.5 kg

CLINICAL SIGNS: Not eating well, negative fecal, diarrhea, normal urinalysis, BUN and Cr within normal limits. Na/K ratio < 23, weak.

TEST REQUESTED RESULT NORMALS

CORTISOL, PRE 7 15 –110

CORTISOL, POST ACTH 1 hr 9 220 – 550

ALDOSTERONE, PRE 0 14 – 957

ALDOSTERONE, POST ACTH 1 hr 0 197 – 2103

Answer 12

INTERPRETATION:

Consistent with primary hypoadrenocorticism – adrenal cortex destruction – both glucocorticoid and mineralocorticoid are affected. You could not create this pattern of response with exogenous steroids

Question 13

NAME: Koko AGE: 9 yr

SPECIES: Canine SEX: M

BREED: mixed BODY WT: 16 kg

CLINICAL SIGNS: Weight loss, lethargy, anorexia, dehydration, Na 120, K 7.73

TEST REQUESTED RESULT NORMALS

ALDOSTERONE, baseline 768 14 – 957

Answer 13

INTERPRETATION:

Primary hypoadrenocorticism is ruled out. Mineralocorticoid function is normal. It’s able to make aldosterone so that cant be why it has sodium potassium problem so negative for addisons disease.

Question 14

NAME: Cholo AGE: 12 yr

SPECIES: Canine SEX: M

BREED: West Highland White Terrier BODY WT: 14 kg

CLINICAL SIGNS: long history of PU/PD, weakness, lethargy

TEST REQUESTED RESULT NORMALS

INTACT PARATHORMONE 71.8 2 – 13

IONIZED CALCIUM 1.71 1.25 – 1.45

PARATHORMONE

RELATED PROTEIN 0.4 < 1.0

Answer 14

INTERPRETATION:

Primary hyperparathyroidism

Question 15

NAME: Taylor AGE: 8 yr

SPECIES: Canine SEX: FS

BREED: Springer Spaniel BODY WT: 17.7 kg

CLINICAL SIGNS: Weight loss, anorexia, total calcium 18.6 mg/dL, phosphorus 1.7 mg/dL.

TEST REQUESTED RESULT NORMALS

INTACT PARATHORMONE 0.7 2 – 13

IONIZED CALCIUM 2.41 1.25 – 1.45

PARATHORMONE

RELATED PROTEIN 3.8 < 1.0

Answer 15

INTERPRETATION:

Humoral hypercalcaemia of malignancy. There is parathyroid-independent hypercalcaemia. The PTHrP identifies the origin of this parathyroid-independent hypercalcaemia as malignancy

Question 16

NAME: Fat Kitty AGE: 12 yr

SPECIES: Feline SEX: FS

BREED: DSH

CLINICAL SIGNS: Chronic weight loss, poor hair coat, normal renal function.

TEST REQUESTED RESULT NORMALS

INTACT PARATHORMONE 0.7 0 – 4

IONIZED CALCIUM 1.53 1.0 – 1.4 7

PARATHORMONE

RELATED PROTEIN 0.0 < 1.0

Answer 16

INTERPRETATION:

There is no support for primary hyperparathyroidism. Parathyroid-independent hypercalcaemia is likely – the most common in cats is probably idiopathic hypercalcaemia but you would want to rule out other causes of parathyroid-independent hypercalcaemia such as PTHrP negative neoplasia, granulomatous disease, Vit D intoxication, raisin toxicity etc.

Question 17

NAME: Danny AGE: 4 yr

SPECIES: Feline SEX: MC

BREED: Persian BODY WT: 6.2 kg

CLINICAL SIGNS: Currently no symptoms, had calcium oxalate crystals in urine in the past

TEST REQUESTED RESULT NORMALS

INTACT PARATHORMONE 0.8 0 – 4

IONIZED CALCIUM 1.60 1.0 – 1.4

Answer 17

INTERPRETATION:

There is not support for primary hyperparathyroidism. Parathyroid-independent hypercalcaemia is likely – the most common in cats is probably idiopathic hypercalcaemia but you would want to rule out other causes of parathyroid-independent hypercalcaemia such as PTHrP negative neoplasia, granulomatous disease, Vit D intoxication, raisin toxicity etc. Calcium oxalate crystalluria has been reported in idiopathic hypercalcaemia

Question 18

NAME: Holly AGE: 12 yr

SPECIES: Canine SEX: FS

BREED: Maltese BODY WT: 2.7 kg

CLINICAL SIGNS: Two days ago began sneezing and rubbing face which progressed to anorexia and lethargy. Low total calcium (1.24mmol/l). Ataxia, seizures.

TEST REQUESTED RESULT NORMALS

INTACT PARATHORMONE 1.7 2 – 13 pmol/L

IONIZED CALCIUM 0.72 1.25 – 1.45 mmol/L

Answer 18

INTERPRETATION:

Primary hypoparathyroidism

Question 19

NAME: Bear AGE: 12 yr

SPECIES: Canine SEX: MC

BREED: German Shepherd BODY WT: 35.4 kg

CLINICAL SIGNS: PU/PD, dilute urine, elevated urea, Creatinine, P, and total calcium

TEST REQUESTED RESULT NORMALS

INTACT PARATHORMONE 86.4 2 – 13 pmol/L

IONIZED CALCIUM 1.18 1.25 – 1.45 mmol/L

25-OH VITAMIN D 89 60 – 215

Answer 19

INTERPRETATION:

Secondary renal hyperparathyroidism

Chronic kidney failure is the most common cause of secondary hyperparathyroidism. Failing kidneys do not convert enough vitamin D to its active form, and they do not adequately excrete phosphate. When this happens, insoluble calcium phosphate forms in the body and removes calcium from the circulation. Both processes lead to hypocalcemia and hence secondary hyperparathyroidism.

Question 20

NAME: Zeus AGE: 4 yr

SPECIES: Reptile SEX: F

BREED: Iguana

CLINICAL SIGNS: Iguana was lethargic and off its feed for 1 week prior to presentation. Lab work: blood calcium level was low; phosphorus level was high.

TEST REQUESTED RESULT NORMALS

IONIZED CALCIUM 0.73 mmol/L

25-OH VITAMIN D 13 nmol/L

Answer 20

INTERPRETATION:

Vitamin D deficiency (poor UV light exposure)

Question 21

NAME: Barton AGE: 8 yr

SPECIES: Canine SEX: MC

BREED: Golden Retriever BODY WT: 34.0 kg

SPECIMEN: Serum

CLINICAL SIGNS: This dog presents with poor hair growth on rump, hyperpigmentation on abdominal skin, erythema of both ears and previous Staph dermatitis.

TEST REQUESTED RESULT NORMALS

Total thyroxine 48 15 – 67

Total triiodothyronine 1.0 1.0 – 2.5

Free (unbound) T4 (FT4) 12 8 – 26

Free (unbound) T3 (FT3) 4.6 4.5 – 12.0

T4 Autoantibody 7 < 20

T3 Autoantibody 2 < 10

Thyroid Stimulating Hormone 12 0 – 37

Thyroglobulin Autoantibody 95 < 200 % No evidence of inflammation.

Answer 21

INTERPRETATION:

Thyroid pathology and dysfunction conclusively ruled out with a high degree of confidence. Whatever is causes this other presentation is nothing to do with thyroids can be very confident about this.

Question 22

NAME: Pepper AGE: 15 yr

SPECIES: Canine SEX: MC

BREED: Rat Terrier BODY WT: 8.1 kg

CLINICAL SIGNS: Alopecia, dog has easily epilated hair

TEST REQUESTED RESULT NORMALS

Total thyroxine 2 15 – 67

Total triiodothyronine 0.9 1.0 – 2.5

Free (unbound) T4 (FT4) 4 8 – 26 (can sometimes be due to sick and stress in this case not case because TSH is up)

Free (unbound) T3 (FT3) 3.8 4.5 – 12.0

T4 Autoantibody 2 < 20

T3 Autoantibody 1 < 10

Thyroid Stimulating Hormone 48 0 – 37

Thyroglobulin Autoantibody 82 < 200 % (indicates inflammation)

Answer 22

INTERPRETATION:

Primary hypothyroidism is confirmed with a high degree of confidence. TgAA is negative classifying this hypothyroidism as “idiopathic follicular atrophy”.

Question 23

NAME: Mollie AGE: 6.5 yr

SPECIES: Canine SEX: F

BREED: Beagle BODY WT: 22.2 kg

CLINICAL SIGNS: Obese and lethargic for a long time, diets are not helping. Hair loss on tail (“rat tail”).

TEST REQUESTED RESULT NORMALS

Total thyroxine 3 15 – 67

Total triiodothyronine 0.0 1.0 – 2.5

Free T4 by dialysis (FT4d) 4 6 – 42

Free (unbound) T3 (FT3) 3.2 4.5 – 12.0

T4 Autoantibody 6 < 20

T3 Autoantibody 3 < 10

Thyroid Stimulating Hormone 109 0 – 37

Thyroglobulin Autoantibody 491 < 200 %

Answer 23

INTERPRETATION:

Primary hypothyroidism is confirmed with a high degree of confidence. TgAA is high classifying this hypothyroidism as “immune mediated thyroiditis”.

Question 24

NAME: Max AGE: 4 yr

SPECIES: Canine SEX: MC

BREED: Mixed breed BODY WT: 17.3 kg

CLINICAL SIGNS: Thin hair coat, alopecia, obesity.

TEST REQUESTED RESULT NORMALS

Total thyroxine 4 15 – 67

Total triiodothyronine 0.0 1.0 – 2.5

Free (unbound) T4 (FT4) 2 8 – 26

Free (unbound) T3 (FT3) > 22.7 4.5 – 12.0

T4 Autoantibody 13 < 20

T3 Autoantibody 36 < 10

Thyroid Stimulating Hormone 55 0 – 37

Thyroglobulin Autoantibody 226 < 200 %

Answer 24

INTERPRETATION:

Primary hypothyroidism is confirmed with a high degree of confidence. TgAA is high classifying this hypothyroidism as “immune mediated thyroiditis”. The T3 cross reacting form of TgAA has interfered with TT3 and FT3 analysis to cause false results.

Question 25

NAME: Murphy AGE: 4 yr

SPECIES: Canine SEX: M

BREED: Golden Retriever BODY WT: 30 kg

CLINICAL SIGNS: Dull, dry haircoat

TEST REQUESTED RESULT NORMALS

Total thyroxine 21 15 – 67

Total triiodothyronine 1.2 1.0 – 2.5

Free T4 by dialysis (FT4d) 25 6 – 42

Free (unbound) T3 (FT3) 9.3 4.5 – 12.0

T4 Autoantibody 7 < 20

T3 Autoantibody 0 < 10

Thyroid Stimulating Hormone 5 0 – 37

Thyroglobulin Autoantibody 305 < 200 %

Answer 25

INTERPRETATION:

TgAA is positive. There is thyroiditis but it has not destroyed sufficient thyroid volume to cause thyroid dysfunction.

Question 26

NAME: Webster AGE: 1.5 yr

SPECIES: Canine SEX: MC

BREED: Mixed breed BODY WT: 44.5 kg

CLINICAL SIGNS: weight gain, change in haircoat

TEST REQUESTED RESULT NORMALS

Total thyroxine 45 15 – 67

Total triiodothyronine 0.0 1.0 – 2.5

Free T4 by dialysis (FT4d) 24 6 – 42

Free (unbound) T3 (FT3) > 22.7 4.5 – 12.0

T4 Autoantibody 9 < 20

T3 Autoantibody 85 < 10

Thyroid Stimulating Hormone 20 0 – 37

Thyroglobulin Autoantibody 595 < 200 %

Answer 26

INTERPRETATION:

TgAA is positive. There is thyroiditis but it has not destroyed sufficient thyroid volume to cause thyroid dysfunction. The T3 cross reacting form of TgAA has interfered with TT3 and FT3 analysis to cause false results.

Question 27

NAME: Chelsea AGE: 2 yr

SPECIES: Canine SEX: FS

BREED: Golden Retriever BODY WT: 64.5 kg

CLINICAL SIGNS: Gaining weight, less active

TEST REQUESTED RESULT NORMALS

Total thyroxine > 156 15 – 67

Total triiodothyronine 0.0 1.0 – 2.5

Free (unbound) T4 (FT4) 15 8 – 26

Free (unbound) T3 (FT3) 12.7 4.5 – 12.0

T4 Autoantibody 49 < 20

T3 Autoantibody 28 < 10

Thyroid Stimulating Hormone 123 0 – 37

Thyroglobulin Autoantibody 1492 < 200 %

Answer 27

INTERPRETATION:

Positive TgAA and high TSH indicate thyroid pathology (thyroiditis) and thyroid dysfunction (loss of negative feedback on TSH) but the other results may be causing confusion. The T3 and T4 cross reacting forms of TgAA have interfered with TT4, TT3, FT4 and FT3 analyses to cause false results.

Further testing was done on Chelsea.

TEST REQUESTED RESULT NORMALS

FREE T4 BY DIALYSIS 2 6-42 pmol/L

INTERPRETATION:

Low FT4 by dialysis (which is free from interference from T4AA) in combination with the TgAA and TSH results above confirms primary hypothyroidism due to immune mediated thyroiditis with a high degree of confidence

Question 28

NAME: Tatum AGE: 10 yr

SPECIES: Canine SEX: F

BREED: Mixed breed BODY WT: 36 kg

CLINICAL SIGNS: Weight loss, hair loss, lethargic, dull attitude

TEST REQUESTED RESULT NORMALS

Total thyroxine 3 15 – 67

Total triiodothyronine 0.4 1.0 – 2.5

Free (unbound) T4 (FT4) 3 8 – 26

Free (unbound) T3 (FT3) 3.8 4.5 – 12.0

T4 Autoantibody 11 < 20

T3 Autoantibody 4 < 10

Thyroid Stimulating Hormone 12 0 – 37

Thyroglobulin Autoantibody 116 < 200 %

Answer 28

INTERPRETATION:

There are low concentrations of thyroid hormones but not an elevation in TSH. This may be one of the 15% or so of hypothyroid dogs that have normal TSH or it may be a dog that has non-thyroidal illness syndrome (euthyroid sick) as an explanation for its low thyroid hormone status. In cases like these when TgAA is normal you have to re-evaluate all the clinical and medication history and consider re-testing at a later date (particularly after any other illness has been stabilized or medications withdrawn). The addition of Free T4 by dialysis may be helpful because it is less commonly and less severely decreased by non-thyroidal illness

Question 29

NAME: Buddy AGE: 8 yr

SPECIES: Canine SEX: MC

BREED: Labrador Retriever BODY WT: 32 kg

CLINICAL SIGNS: Weight loss, panting, polydipsia

THERAPY: None

TEST REQUESTED RESULT NORMALS

Total thyroxine 99 15 – 67

Total triiodothyronine 3.7 1.0 – 2.5

Free (unbound) T4 (FT4) 76 8 – 26

Free (unbound) T3 (FT3) 12.4 4.5 – 12.0

T4 Autoantibody 0 < 20

T3 Autoantibody 1 < 10

Thyroid Stimulating Hormone 0 0 – 37

Thyroglobulin Autoantibody 64 < 200 %

Answer 29

INTERPRETATION:

An uncommon but genuine case of canine hyperthyroidism. The clinical signs are also consistent with this diagnosis. The negative TgAA (including negative T4AA) tells us we can believe our TT4 results (unlike T7). Clinical examination and history will help determine if functional thyroid tumour vs ingested thyroid glands or thyroid medication.