Endocrinology Flashcards
If you have a highly Sensitive test what does this mean?
Highly Sensitive means that anyone that tests negative then that means you can exclude them from further testing as they do not have the disease. Remember SNNOUT
If you have a Highly Specific Test what does this mean?
High Specific means that if they test Positive they have the disease. Remember SPPIN
What is the calculation to work out Sensitivity?
Sn = Tp/Tp+Fn
What is the calculation to work out Specificity?
Sp = Tn/Tn+Fp
What Does a Positive Predictive Value mean?
How like a patient who test positive actually has the disease
What does a Negative Predictive Value mean?
How likely a patient who tested negative actually is negative to the disease
When talking about Hyper and Hypothyroidism Which one is common for Cats and which is common for dogs?
- Dogs - Hypothyroidism
- Cats - Hyperthyroidism
- Where is All circulating T4 produced?
- Talk about T3 production?
- Talk about what signals T4 to be produced
- Produced by the thyroid Glands
- Only 10-40% of T3 is produced by the thyroid glands 60-80% of T3 is generated from T4 in cells throughout the body.
- Hypothalamus -> TRH ->Pituitary gland -> TSH -> Thyroid Glands -> T4 -> fT4 ->fT3 negative feedback loop to hyperthalamus.
What is the difference between T4 and Free T4
T4 is bound to protiens like Thyroid Hormone-Binding globulin (TBG) and to transthyretin, Albumin and apolipoprotiens.
T4 and T3 not bound to plasma protiens are called Free T4, Free T3.
Free hormone concentration is maintained constant by the feeedback regulatory system
Free hormones are the biologically active form.
fT3 is the most metabolically active form (about 3-5 times as potent as fT4)
fT4 enters most cells of the body and is converted to T3
What is Thyroid Hormone Action on :-
- Development
- Growth
- Metabolism
- Development of foetal and neonatal brain
- Necessary for normal growth., Growth-Promoting effect of thyroid hormaones is intimately intertwined with that of GH
- Effect on Basal Metabolic rate
- Increase basla metabolic rate
- Increased heart Rate, Cardiac Contractility, promote vasodialation
- ALtered Mental State
- Reproductive Activity
- Increase basla metabolic rate
- Effects on Lipid Metabolism
- Stimulate fat mobilization
- Enhance oxidation fo fatty acids
- Effects on Carbohydrate metabolism
- Enhancement of insulin-dependent entry of glucose into cells
- increased gluconeogenesis and glycogenolysis to generate free glucose
- In dogs explain Primary, Secondary, and Tertiary Hypothyroidism, How it occurs and why.
- Which is the most common?
- Primary Hypothyroidism
- Caused by a thyroid gland disease
- Aquired: Iorine deficiency (carnivorous diet)
- Lymphocytic Thyroiditis
- Idiopathic Atrophy
- Caused by a thyroid gland disease
- Secondary Hypothyroidism
- Caused by pituitary disease
- Pituitary neoplasia
- Surgical Hypophysectomy
- Caused by pituitary disease
- Tertiary Hypothyroidism
- Caused by hypothalamus disease
- Tumour inflitrating the hypothalamus
- Caused by hypothalamus disease
- Primary is the most Common in Dogs
What Clinicopathological Changes would you see in an animal with Hypothroydism?
- Mild normchromic, normocytic, Non regenerative Anemia
- Decreased T3 and T4 result in decreased matabolic rate and thus a decreased need for O2 in peripheral tissues. The decreased need for O2 leads to decreased EPO production
- Hyperlipemia
- About 75% of dogs with hypothroidism have a fasting hypercholesterolemia, Hypertriglyceridema may or may not present. Due to decreaed exression of hepatic LDL receptors. Decreased activities of hepatic lipase and lipoprotein lipase.
- Increased Fructosamine
- Due to decreased protein turnover
- Increased CK
- Due to hypothyroidism-induce myopathy
WHat is Euthyroid Sick Syndrome?
A condition in which a systemic disease outside of the thyroid hormonal system creates hypothyroxemia (decreased fT4)
What are the 3 Assays availabel to measure T4 and T3?
- RIA (RadioImmunoAssay) Common due to higher sensitivity)
- ELISA (Enzyme-Linked Immune Sorbent Assay)
- CLIA (ChemiLuminescent ImmunoAssay)
All of these are not reliable for canine serum fT4 because the tend to underestimate the canine fT4
To Diagnose Hypothyroidism in dogs what test/s should we use?
Combined Total T4 and cTSH
Where is Insulin and amylin produced?
What is the role of these hormones?
Beta Cells in the Islets of Langerhans -
Reduce Glycaemia
Where is Glucagon produced and what does it do?
alpha cells and it induces hyperglycaemia
What does the hormone Somatostatin do?
Inhibits Growth Hormone Release. Produced in the S-Cells in the Islets of Langerhans
What does Insulin activity do and How?
Insulin activity lowers Blood Glucose by:
- Inhibition of hepatic gluconeogenesis
- Promotion of hepatic glycogen synthesis
- Increased Cellular uptake of glucose by muscles and adipose tissue
What does Glucagone Activity do and how?
Glucagone Activity increased Blood Glucose by:
- Promoting gluconeogenesis in liver and muscles
- Promoting glycogeneolysis in liver and muscles
Where and how can excess glucose be stored in the body?
- Liver as Glycogen
- Muscles as Glycogen
- Adipose as Glucose itself
- Classify the 2 types of Diabetes Mellitus and how it comes about.
- What Animal has type 1 more commonly over Type 2?
- Diabetes Mellitus - group of metabolic disease characterized by hyperglycaemia resulting from defects in insulin secretion, insulin action or both.
Type 1
- Beta Cell destrucgtion leading to lisulin deficiency (Common with dogs)
Type 2
- Impaired insulin secretion/insulin resistance
What Clinical Pathological Changes would you expect with an animal with Diabetes Mellitus?
- Hyperglycaemia - Due to absence of insulin (type1) or impaired insulin actin (insulin resistance type 2)
- Glycosuria - Renal tubular transport maximum for glucose in dogs 9.99-11.1mmol/L in dogs
- Hyperlipemia - increased lipomobilization
- Ketonemia
- Increase Fructosamine - Irreversible, non enzymatic linking of glucose to albumin
- Increase ALP and ALT - due to hepatic lipidosis
- Hyponatremia and Hypochloremia - Osmotic diureses due to glycosuria
- Proteinuria
What is the pathogenesis of Diabetes mellitus type 1
- Multifactorial aetiology
- Characterized by permanend Hypoinsulinemia
- Autoimmune destruction of Beta Cells
- infiltration of lymphocytes into the islets
- antibodies against B-Cell and several islet components (insulin, GAD65, IA2)
- Genetic Susceptibility (Breed predispositin)
- Diabetes in dogs has been associated with major histocompatibility complex class II genes (Dog leukocyte antigen (DLA) -> subgroup of type 1 termed latent autoimmune diabetes LADA