Lectures 11-15 Flashcards by Anon Anon

How many tests would you carry out for diabetes?

In the presence of symptoms, 1 is enough.

Without symptoms, 2 are required

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In type 1 diabetes, what might low insulin levels cause?

High blood glucose levls
increased lipolysis (and hence DKA)
increased protein degradation

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What are the types of insulin? What examples of them might there be?

Meal time insulin - aspart

Longer acting insulin - Zinc

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What allows the body to produce more insulin at mealtimes?

The incretin effect

stimulates endocrine cells, GLP-1 release

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What binds iodine to tyrosine residues in thyroglobulin molecules?

thyroperoxidase

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What enzyme forms T3 from T4?

deiodinase

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How does TSH increase T3 production?

It binds to the TSHR’s on the basolateral membrane of the thyrocytes, causing an increase in Na/I symporters on the membrane, increasing the iodine presence within the cell

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How would you test for thryoid function?

TSH and T4/T3 levels

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What are the 3 main causes of Hyperthyroidism?

Graves’
Toxic nodular goitre
Thyroiditis: inflammation

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What causes Grave’s disease?

pathogenic antibodies bind to TSH receptors on thyrocytes

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What causes neonatal hyperthyroidism?

How is it treated?

TSH-R antibodies cross the placenta.
Antithyroid drugs
Surgical removal of thyroid
radioiodine therapy

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What is the main classification of antithyroid drugs?

Thioamides

they block iodine incorporation through inhibition of thyroperoxidases

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What might be a complication of antithyroid drugs?

Argranulocytosis

Liver disease with propylthiouracil

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What are the complications of a total thyroidectomy?

hypothyroidism
Hypoparathyroidism (- Ca levels)
Recurrent laryngeal nerve damage

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What might cause hypothyroidism?

Hashimoto’s hypothyroidism (autoimmune)
iodine deficiency
silent thyroiditis

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What is cretinism?

congenital hypothyroidism, causing stunted mental and physical growth

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How would the presence of thryoid nodules be investigated?

Serum TSH, T3/T4
Assessment of thyroid size (imaging)
Assessment of thyroid pathology

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How would an ultrasound scan be useful for investigating thyroid pathology?

differentiates between cystic and solid nodules

What are the phases of insulin release?

1 - within 2 minutes of food ingestion, lasts 10-15 minutes

2 - sustained until normoglycaemia restored

What are the subunits of the insulin receptor?

2 alpha (extracellular)
2 beta (transmembrane, tyrosine kinase)

How are pre-diabetic treated?

Nicotinamide (DNA repair)

Who would be prescribed Metformin?

diabetics with a BMI over 25

What are the 3 main dosal regimes of insulin?

Short acting (3x daily) + and intermmediate/long acting one
pre-mixed short + intermmediate insulins 2x daily
continuous infucion

What are the 3 main complications of insulin therapy?

Hypoglycaemia
Allergy
lipodystrophy

What is diabetes type 2 caused by?

A loss of 1st phase insulin secretion, and hence insulin resistance

How does Metformin work?

It is a hypoglycaemic agent. Reduces gluconeogenesis in the liver. Activates AMP-activated protein kinase, decreasing gene expression. Increases Glucose uptake in muscles.

How do sulphonoureas work?

They bind to SUR's on B cells (a part of K(ATP) channels), causing the depolarisation of the membrane, increasing insulin secretion

Who shouldn't be given sulphonoureas?

Pregnant or breastfeeding women

What do thiazolidinediones do?

bind to transcription factors, increasing lipogenesis, decreasing gluconeogenesis and increasing glucose uptake

What are the two forms of drugs based on the incretin effect?

Inhibitors of DP-4 | GLP-1 agonists

How do SGLT2 inhibitors work?

increase glucose and Na+ loss in the proximal tubule

How does PTH increase calcium levels?

Stimulates osteoclasts to release calcium into plasma (and reabsorption in Distal CT) Ultimately activates Vitamin D (via 1-alpha hydroxylase) which causes Ca2+ absorption in the GIT, and reabsorption in the proximal tubule

Where does Vitamin D come from?

UV light converts 7-dehydroxycholesterol in the skin to Vitamin D3, which is then converted into calcidiol in the liver, which is then converted to 1,25 dihydroxy VD3 in the kidney

Which of PTH or Calcitonin is more important?

PTH

What is FGF23?

It is produced by osteocytes, and responds negatively to phosphate, it increases renal excretion of phosphate and suppresses renal synthesis of 1,25D3

What are osteocytes?

Found in the calcified matrix, with long processes contacting other osteocyes and osteoblasts

What are osteoblasts?

bone forming cells

What are osteoclasts?

bone reabsorbing cells attached to bone by integrins They can sometimes dig the Howship's Lacuna

What are the different forms of hyperparathyroidsm caused by?

primary - PT tumour secondary - renal disease, decreased activation of Vitamin D tertiary - PT hyperplasia

What is Rickets caused by?

Vitamin D/Calcium deficiency. lack of mineralisaiton osteoid at growth plates are weak, so the growth plate expands to compensate.

What is the difference between rickets and osteomalacia?

Rickets - affects growing bones | Osteomalacia - affects adult bones

Name 2 types of antithyroid drugs | What enzymes do they target?

Propylthiouracil - deiodinase | Carbimazole - thyroperoxidase

What is the active form of carbimazole?

Methimazole