Clin path Flashcards

Question

hypercalcemia causes

Answer 1

Young, growing animals Hyperparathyroidism Humoral hypercalcemia of malignancy Vitamin D toxicity others

Answer 2

Parathyroid adenoma **secretes PTH** **increased Ca** **P may be decreased or WRI**

Answer 3

Secretion of PTH-like hormone, **PTHrP** **Increased Ca** **P may be decreased or WRI** Most common neoplasms are **lymphoma and apocrine gland anal sac adenocarcinoma (AGASACA)** Others also possible

Answer 4

rodenticides, supplements, some plants Vit D: **Increase serum Ca and P** mineralization of tissues > death * if Ca x P >80 mineralization

Answer 5

Hypoparathyroidism Decreased GFR for any reason Vitamin D toxicosis Shift of PO4 from ICF to ECF

Answer 6

Equine renal failure Prolonged anorexia Milk fever

Answer 7

Serum protein concentration GI absorption * Rumen in ruminants * Distal SI and colon in monogastrics * Enhanced by Vit D * Inhibited by dietary Ca and PO4 Excretion * Fecal * Kidneys * Mammary gland

Answer 8

Decreased urinary excretion * Renal failure and other causes of decreased GFR (herbivores) Shift from ICF to ECF * In vivo hemolysis or delayed RBC separation from serum (except cattle) **Increased PTH: Milk fever**

Answer 9

Hypoproteinemia Inadequate GI absorption * Prolonged anorexia * Calves on whole milk diet * **Grass tetany**

Answer 10

Lush pasture with low Mg Mg needed for PTH function ↓Mg and ↓PTH May lead to hypocalcemia Hypocalcemia may not respond to treatment until hypomagnesemia is corrected

Answer 11

Clinical signs: PU/PD, Polyphagia, Muscle weakness, pendulous abdomen, Alopecia, thin skin, Hepatomegaly, Panting Clin path abnormalities: * **Elevated ALP** (dogs) * **Stress leukogram** * Isosthenuria/hyposthenuria * **Hypercholesterolemia** * Recurring urinary and skin infections * **Hyperglycemia/concurrent DM** | Cushings

Answer 12

Pituitary dependent (secondary HAC) * 80% of canine HAC * Pituitary microadenoma Adrenal dependent (primary HAC) * 20% of canine HAC * Adrenocortical adenoma or adenocarcinoma * May produce cortisol precursors (17-hydroxyprogesterone) instead of cortisol Iatrogenic * Exogenous glucocorticoid administration

Answer 13

80% of canine HAC Pituitary microadenoma

Answer 14

20% of canine HAC Adrenocortical adenoma or adenocarcinoma May produce cortisol precursors (17-hydroxyprogesterone) instead of cortisol

Answer 15

Exogenous glucocorticoid administration

Answer 16

Urine cortisol-creatinine ratio (UCCR) Low-dose dexamethasone suppression test (LDDST) ACTH stimulation test

Answer 17

Endogenous ACTH (eACTH) Low-dose dexamethasone suppression test LDDST High-dose dexamethasone suppression test (HDDST) Abdominal ultrasound Head and abdominal CT/MRI

Answer 18

Collect urine in the morning at home and measure cortisol and creatinine Positives * Very sensitive * 90% of dogs with HAC will have elevated UCCR * **Easy and inexpensive** * Owners can collect urine at home = less stress to patient Negatives * Poor specificity * 20% specificity * **80% false positive rate** * Use primarily in patients with only a few signs of HAC * **Use to rule HAC OUT, DO NOT USE to rule HAC in**

Answer 19

Baseline cortisol measured, dexamethasone administered, cortisol measured again at 4h and 8h * Use the 8h value to rule in/out HAC * Use the 4h value to differentiate PDH from AT Positives: * **Cheaper** than ACTH stimulation test * May differentiate PDH from AT * **High sensitivity** Negatives: * Lower specificity than ACTH stim test * **High false positive rate** * Best to use with patients who have classic clinical and CBC/chem features of HAC

Answer 20

Measure baseline cortisol, give ACTH, measure cortisol again in 1-2h Positives * Highest specificity (**low false positive rate**) * Does not require all-day hospitalization (test done in 1-2h) * May be less stressful to patient * **Can identify iatrogenic HAC** Negatives * **Less sensitive** than LDDST * **More expensive** than LDDST Use to screen patients that are not the classic presentation * Less likely to get false positive than with LDDST Also used to monitor therapy

Answer 21

UCCR * High sensitivity * **High negative predictive value** * **Poor specificity** ACTH stimulation test * **Most specific test** * High positive predictive value * **Not as sensitive** as the others LDDST * **High sensitivity** * High negative predictive value * Reliable if clinical signs and clin path data are supportive of HAC * **Specificity is poor** if there is non-adrenal illness

Answer 22

Used to help **differentiate PDH from ADH** Only about 14% of the dogs with PDH that don’t suppress at 8h on the LDDST will suppress at 8h on the HDDST | dont really use

Answer 23

Used to help **differentiate PDH from ADH** Only about 14% of the dogs with PDH that don’t suppress at 8h on the LDDST will suppress at 8h on the HDDST | dont really use

Answer 24

Single time-point measurement of ACTH Very sensitive to specimen handling, consult lab for best procedure Positives * Good at **differentiating PDH from AT** Negatives * ACTH is very unstable > prone to **pre-analytical error and falsely decreased values** * Some assays have a poor detection limit * Misclassification of HAC type in 15-25% of cases Use to **differentiate PDH from AT ONLY after HAC is ruled in** Do NOT use to screen for HAC

Answer 25

Addisons Cause: * >90% Primary: lymphocytic adrenalitis > **destruction of all three layers of adrenal cortex** > **lack of aldosterone and cortisol**; “atypical Addison’s disease” is a lack of cortisol only * Secondary: lack of ACTH > lack of cortisol * Iatrogenic: **chronic corticosteroid treatment** > atrophy of pituitary and adrenal glands Clinical signs: * Occurs most commonly in** young to middle-aged dogs;** rare in cats * Lethargy, weakness, **vomiting, diarrhea,** abdominal pain, anorexia; often **intermittent** * Bradycardia, collapse, shock, hypovolemia

Answer 26

Addisons Cause: * >90% Primary: lymphocytic adrenalitis > **destruction of all three layers of adrenal cortex** > **lack of aldosterone and cortisol**; “atypical Addison’s disease” is a lack of cortisol only * Secondary: lack of ACTH > lack of cortisol * Iatrogenic: **chronic corticosteroid treatment** > atrophy of pituitary and adrenal glands Clinical signs: * Occurs most commonly in** young to middle-aged dogs;** rare in cats * Lethargy, weakness, **vomiting, diarrhea,** abdominal pain, anorexia; often **intermittent** * Bradycardia, collapse, shock, hypovolemia

Answer 27

**Azotemia**, hyperphosphatemia, inadequately concentrated urine Hyponatremia, hyperkalemia, **Na:K ratio <27** Absence of stress leukogram +/- hypoglycemia, anemia, hypercalcemia

Answer 28

Baseline cortisol * Use to **rule OUT hypoadrenocorticism** * Use when there is less suspicion of Addison’s * A normal baseline cortisol rules out Addison’s * Decreased baseline cortisol does NOT confirm hypoadrenocorticism ACTH stimulation test * **Confirmatory test** * Use when there is high suspicion of Addison’s * Addisonian animals will have a flat ACTH response

Answer 29

1. TRH stims release of TSH from pituitary 2. TSH stims thyroid to secrete T4 (and some T3) 3. T4 has negative feedback on hypothalamus and pituitary

Answer 30

hyperthyroid: TT4, fT4 hypo: TT4, fT4, TSH

Answer 31

Cause: Thyroid adenoma (primary hyperthyroidism) Generally occurs in middle-aged to older cats Clinical signs: * Hyperactivity * **weight loss** despite normal appetite or polyphagia * +/- PU/PD, tachycardia, vomiting, patchy alopecia, unkempt haircoat, Clin path abnormalities: * mild to moderate **increase in ALP**, mild **increases in ALT, AST** * **hypocalcemia and hyperphosphatemia** * +/- azotemia, mild polycythemia, stress leukogram

Answer 32

total T4 **Increased TT4 = hyperthyroidism** * TT4 in **upper half of the reference interval > gray zone** (10% of hyperthyroid cats will fall in this area) * TT4 secretion is pulsatile, can be variable in hyperthyroid cats * Non-thyroidal illness can falsely decrease values Use as a screening test to **rule out hypothyroidism** * **95% hypothyroid dogs will have ↓TT4** * 20% dogs without hypothyroidism may have ↓TT4 – “euthyroid sick” **(false positives for hypothyroid)** * Rarely, autoantibodies may falsely increase TT4

Answer 33

free T4 Use when there is clinical suspicion of hyperthyroidism, but TT4 is in the upper half of the reference interval Non-thyroidal illness can cause **false increases** **DO NOT USE fT4 ALONE FOR DIAGNOSIS OF HYPERTHYROIDISM** Use equilibrium dialysis fT4 test > not affected by non-thyroidal illness

Answer 34

Cause: * 95% **Primary: lymphocytic thyroiditis** > follicular destruction * ≤5% Secondary: structural or biochemical lesion in the pituitary: pituitary tumor/cyst, pituitary hypoplasia, TSH deficiency in giant schnauzers Clinical signs * **Weight gain** without increase in food intake * Lethargy * Cold intolerance, heat-seeking behavior * **Dull haircoat, alopecia**, hyperpigmentation – without pruritus * +/- secondary skin disorders: seborrhea, dry coat, pyoderma Clin path abnormalities * **Hypercholesterolemia** (80%) and hypertriglyceridemia * Mild **non-regenerative anemia** (30%) or hct in low end of RI * +/- Increased liver enzymes, increased CK

Answer 35

**Hypothyroidism in dogs** Clinical signs develop **gradually** over years Lymphocytes and plasma cells produce **antibodies directed at thyroglobulin** (most common), colloid, TT3, TT4

Answer 36

Theoretically, dogs with primary hypoparathyroidism should have elevated TSH **Only about 2/3 hypothyroid dogs have elevated TSH** Some of these may have secondary hypothyroidism (↓TSH> ↓T4)

Answer 37

Clinical signs: * PU/PD * Weight loss despite normal or increased appetite * Decreased appetite * +/- diabetic cataracts (dogs), recurring skin and urinary infections Clin path abnormalities * **Dehydration**: erythrocytosis, increased Pi, azotemia * Isosthenuric or minimally concentrated urine, **glucosuria, ketonuria** * Hyponatremia, hypochloremia, +/- hypokalemia, +/- hypophosphatemia * Hypercholesterolemia, hypertriglyceridemia * **Acidosis, increased anion gap (ketoacidosis)** * Hyperosmolality * Increased hepatic and pancreatic enzyme activities

Answer 38

Differentiate from other causes of hyperglycemia **Severity of hyperglycemia** * DM typically **>250 mg/dL** * Stress/excitement in cats can be >300 mg/dL * Fast small animals for 12h before blood collection Urine glucose/ketones * **Glucosuri**a expected with DM * Glucosuria possible but unlikely with transient increases * Ketonuria may be present with DM, but is not expected with stress/excitement **Fructosamine** * Estimate of glucose concentrations over the previous 2-3 weeks * Will not be increased with stress/excitement

Answer 39

Monitoring of insulin therapy **Marked elevation with poor control** **Mild elevation with good control** Considerable variability regardless of control Single blood draw – easier on owner and patient than glucose curve

Answer 40

Monitor glucose concentration over an 8, 12, or 24h period – document time and dose of insulin administration and meals Will **detect Somoygi effect** with insulin overdosing **Time-consuming, difficult** for owner to do, stressful for patients in-hospital > accuracy?

Answer 41

* **Insulin overdose** * Extreme **exertion** – hunting dogs, endurance horses * Glycogen storage diseases – rare * **Hepatic insufficiency** – should see hypoalbuminemia, decrased BUN, and increased serum bile acids * Neonatal (all species)/juvenile (toy breed puppies <6 mo) – fasting or other stressors * Bovine ketosis/lactational hypoglycemia * Pregnancy – dogs and sheep * **Sepsis** * **Xylitol** toxicosis in dogs * Insulinoma – dogs, cats, ferrets

Answer 42

insulin overdosing with rebound hyperglycemia

Answer 43

**Beta cell tumor > secretes insulin > hypoglycemia** Patients with insulinomas may be euglycemic Measure serum insulin at a time when patient is hypoglycemic Increased insulin or insulin WRI with concurrent hypoglycemia > insulinoma Hypokalemia is also frequently associated with hyperinsulinism