Endocrine Flashcards
What is the main pancreatic disease?
Diabetes Mellitus (DM)
What are the two types of DM?
- Type 1 (Autoimmune destruction of pancreatic B cells, resulting in lack of insulin secretion).
- Type 2 (decrease in insulin sensitivity).
What is diabetes mellitus?
- Chronic hyperglycaemia due to insulin dysfunction.
- Glucose cannot be moved from bloodstream into cells effectively, leading to them being starved of energy.
What is the clinical presentation of type 1 diabetes?
- Hyperglycaemia
- Polydipsia
- Polyuria
- Weight loss
- Blurred vision
- Nausea and vomiting
- Usually diagnosed in the young.
- Can present with diabetic ketoacidosis.
What is the clinical presentation of type 2 diabetes?
- Usually asymptomatic, and picked up by screening.
- Screening should be carried out when risk factors are present.
What is the pathophysiology of type 1 diabetes?
- Hyperglycaemia due to insulin deficiency.
- Insulin deficiency occurs as a result of pancreatic B-cell destruction (usually caused by autoimmune mechanisms)
- If no evidence of autoimmune destruction, the disease is referred to as idiopathic type 1 DM.
What is the pathophysiology of type 2 diabetes?
- Multifactorial disorder
- Increase in insulin resistance, often accompanied by deficit in insulin secretion.
- Leads to chronic hyperglycaemia.
What is the aetiology of type 1 diabetes?
- HLA-DR3/4 (human leukocyte antigen) is affected in >90% of type 1 diabetic patients.
- This abnormality causes autoimmune disease, often including the attack of islet cells (mainly B cells) of the pancreas.
What is the aetiology of type 2 DM?
- Multifactorial
- There is an element of genetic susceptibility, but not as strong as in type 1 DM.
- No HLA link established.
What is the epidemiology of type 1 DM?
- Onset younger (<30)
- Usually patients will be skinny.
What is the epidemiology of type 2 DM?
- Onset older (>30)
- Patients are usually overweight.
- More common than type 1 DM generally speaking.
What are the diagnostic tests for type 1 DM?
- Plasma glucose test (random, fasted, 2 hour etc.).
- HbA1c. This will provide a measurement of the average plasma glucose over the last 2-3 months.
- C peptide. This will go down in type 1 DM and remain the same/increase in type 2 DM.
What are the diagnostic tests for type 2 DM?
- Plasma glucose test (random, fasted, 2 hours etc.).
- HbA1c. This will provide a measurement of the average plasma glucose over the last 2-3 months to see if it is chronically raised.
What clinical test can be done to tell the difference between type 1 and type 2 DM?
- C peptide test.
- C pep will be low in type 1 DM
- C pep will be normal/raised in type 2 DM.
What is the treatment for type 1 DM?
1st line:
- Basal-bolus insulin
- Pre-meal insulin IF NEEDED
- Metformin (a biguanide) IF NEEDED.
What is the treatment for type 2 DM?
- First line: Diet and exercise changes.
- If no change, prescribe metformin (biguanide).
- Add SGLT2 inhibitor if CV risk is high (canagliflozin)
- Potentially use sulfonylurea (glimepiride) if metformin not tolerated.
- Give aspirin (non-selective COX inhibitor) or clopidogrel (P2Y12 antagonist) to reduce risk of CVD. Both aspirin and clopidogrel are antiplatelet drugs.
What are the potential complications of type 1 and 2 DM?
- Diabetic ketoacidosis (body cannot use glucose as fuel due to lack of insulin, so begins to use lipids and peptides instead. This produces ketones, which are released into the blood. High levels of ketones are toxic.)
- Diabetic nephropathy (chronically high glucose levels do damage to kidneys).
- Diabetic neuropathy (high glucose levels -> neurological damage, causing lack of sensation in feet/hands.)
- Diabetic retinopathy (damage to retinal blood vessels, which if severe enough can lead to vision defects.)
- Hyperosmolar hyperglycaemic nonketotic coma (caused by extremely high glucose levels, similar to ketoacidosis, but with the absence of high ketone levels).
What are the 4 main thyroid disorders I need to be aware of?
- Graves disease
- Hashimoto’s thyroiditis
- Hypothyroidism
- Thyroid cancer/ malignancies.
What is Grave’s disease?
HYPERthyroidism due to the pathological stimulation (immune system disorder) of TSH receptors.
What is the difference between primary and secondary hyperthyroidism?
Primary hyperparathyroidism - Disease is directly within the thyroid, leading to increased T3/T4 secretion (unrelated to TSH levels)
Secondary hyperparathyroidism - Thyroid gland is being overstimulated by excessive TSH hormones.
How will a person with Grave’s syndrome present clinically?
- Rapid heart beat
- Tremor
- Diffuse palpable goitre (swollen thyroid gland).
- Audible bruit over thyroid gland (audible pulse over thyroid due to vascular proliferation).
- Eye problems: Bulging eyes, and lid retraction.
What is the pathophysiology of Grave’s disease?
- Thyroid stimulating immunoglobulins bind to TSH receptors on the thyroid, leading to excess T3 and T4 (thyroxine) production.
- T4 receptors on the pituitary are stimulated due to elevated T4 levels, leading to suppression of TSH secretion.
- Therefore, Grave’s disease causes high thyroid hormone levels, with low TSH.
What is the aetiology of Grave’s disease?
- Unclear.
- There is an element of genetic influence.
- It is an autoimmune disease, and associated with other autoimmune diseases such as parnicious anaemia and myasthenia gravis.
What is the epidemiology of Grave’s disease?
- The most common cause of hyperthyroidism.
What are the diagnostic tests for Grave’s?
- Thyroid hormone tests. High T3 and T4
- TSH test. Lower than normal TSH.
What are the potential treatments for Grave’s disease?
- Antithyroid drugs (carbimazole usually, else propylthiouracil). These will be taken in one of two ways:
- Block and replace. Prolonged treatment using the drug, along with levothyroxine to replace the lost thyroid hormone.
- Titration. Gradual reduction in the dose of anti-thyroid, until the naturally produced thyoid hormones are at the right level again.
- Also give a B blocker (atenolol or propanolol) to treat symptoms such as tachycardia, tremor and anxiety. If contraindicated give CCB (verapamil).
- Thyoidectomy (partial or complete)
- Radioactive iodine. Taken up by thyroid, and will subsequently kill some of the thyroid, reducing hormone production.
What is the most common complication of grave’s disease?
Thyroid storm (same as thyrotoxic crisis).
- This is a hypermetabolic state induced by the presence of excessive thyroid hormones.
Hyperthyroidism can also cause atrial fibrillation, and a subsequent irregularly irregular heartbeat.
What is Hashimoto’s thyroiditis?
HYPOthyroidism due to aggressive destruction of thyroid cells.
How will a person with Hashimoto’s disease present clinically?
- Rapid enlargement of the thyroid gland, which can cause dyspnoea and/or dysphagia due to pressure changes.
- The hypothyroidism will cause fatigue, cold intolerance, slowed movement, decreased sweating. (decreased metabolic activity).
What is the pathophysiology of Hashimoto’s disease?
- Autoimmune disease.
- Causes aggressive destruction of thyroid cells, and thyroid fibrosis.
What is the aetiology of Hashimoto’s disease?
- Unknown
- Autoimmune, with some genetic relation.
- Can be triggered by iodine insufficiency, infection, smoking and stress.
What is the epidemiology of Hashimoto’s disease?
- More common in places with lower iodine intake/ iodine deficiency in diet.
- Approx. 15x more likely in women.
- The most common cause of HYPOthyroidism.
What investigations are required for diagnosis of Hashimoto’s thyroiditis?
- TSH levels will usually be raised (negative feedback).
- Thyroid antibodies will be present.
What treatments are available for Hashimoto’s disease?
- Thyroid hormone replacement (levothyroxine).
- Resection of obstructive goitre to relieve symptoms (dyspnoea and dysphagia.)
What are the potential complications of hypothyroidism?
- Hyperlipidemia. (Blood contains too many lipids, such as cholesterol and triglycerides.). This can increase risk of cardiovascular disease over time.
- Myxoedema coma. A form of endocrine emergency (20-50% mortality), usually caused by extreme (and untreated) hypothyroidism. Treated with thyroid replacement (levothyroxine) and hydrocortisone (to protect against potential adrenal insufficiency).
What is Hashimoto’s encephalopathy?
- Effects brain function
- Associated with Hashimoto’s thyroiditis, but relationship unclear.
Other than Hashimoto’s disease, what are the 3 broad categories of hypothyroid disease?
- Primary
- Secondary
- Transient
What is the clinical presentation of hypothyroidism?
Symptoms relate to reduced metabolic activity.
- Insidious (slow) onset.
- Tiredness/ lethargy
- Intolerance of cold
- goitre (swelling of thyroid gland)
- Slowing of intellectual activity.
- Constipation
- Deep hoarse voice
- Puffy face, hands and feet.
What do the different classifications of thyroid disease mean?
- Primary. Means disease directly associated with the thyroid gland.
- Secondary. Means disease associated with the pituitary or hypothalamus.
- Transient. Means it is temporary hypothyroidism (eg after birth, or after withdrawing from treatment for a short time.)
What is the pathophysiology of primary hypothyroidism?
- Aggressive destruction of the thyroid cells due to cellular/antibody mediated immune processes.
- Antibodies bind and block TSH receptors on thyroid, leading to inadequate T3/4 production and secretion.
What is the pathophysiology of secondary hypothyroidism?
- Reduced release or production of TSH due to issues with either the hypothalamus (TRH) or the pituitary (TSH).
- This results in reduced T3/4 release from the thyroid.
What is the pathophysiology of transient hypothyroidism?
- Sudden deficit of T3/4 leading to raised TSH levels (-ve feedback) as the thyroid tries to re-establish normal T3/4 levels.
What is the aetiology of hypothyroidism?
Primary:
- Hashimotos thyroiditis (autoimmune)
- Iodine deficiency
- Congenital defects
Secondary:
- Isolated TSH deficiency
- Hypopituitarism (due to neoplastic infection/tumour of pituitary).
- Hypothalamic disorder (neoplasm, severe head trauma).
Transient:
- Caused by withdrawal from thyroid therapies., such as iodine supplementation withdrawal.
What are the diagnostic tests used to diagnose hypothyroidism?
- Low free serum T4 levels.
- TSH will be normal/high in primary hypothyroidism.
- TSH will be low in secondary hypothyroidism.
What treatments are given for primary and secondary hypothyroidism?
Primary - Thyroid hormone replacement therapy (Levothyroxine), and potential resection of the obstructive goitre.
Secondary - Still give thyroid hormone replacement (levothyroxine) but also treat the underlying cause.
Transient - Will often resolve on its own. If due to treatment withdrawal, consider restarting treatment/ re-establishing a higher dose.
What are the 5 common classifications of thyroid cancer?
- Papillary
- Follicular
- Anaplastic
- Lymphoma
- Medullary
What thyroid cancers usually present as asymptomatic thyroid nodules (hard and fixed)?
- Papillary thyroid cancer
- Follicular thyroid cancer
- Anaplastic thyroid cancer
What thyroid cancer presents as a rapidly growing mass in the neck?
- Thyroid lymphoma
What thyroid cancer causes diarrhoea, flushing episodes and itching?
- Medullary thyroid cancer.
What is a papillary thyroid cancer?
- A cancer of the thyroid gland which exhibits papillae (small rounded processes) amongst it’s cells histologically.
What is a follicular thyroid cancer?
- Cancer of the follicular cells of the thyroid (cells responsible for T3/4 production and secretion.
What is an anaplastic thyroid cancer?
- A very aggressive, rapidly proliferating cancer.
- Consists of cells that have little to no resemblance to normal cells.
What is a thyroid lymphoma?
Cancer of the thyroid originating from leukocytic cells.
What is a medullary thyroid cancer?
Cancer that starts in the “C” cells of the thyroid. These are the cells that produce calcitonin (related to calcium management in the body).
What is the pathophysiology of a papillary thyroid cancer?
- Tends to spread locally within the neck.
- Could compress the trachea.
What is the pathophysiology of a follicular thyroid cancer?
- Greater likelihood to metastasise and spread to the lungs and bones than a papillary thyroid cancer.
- Still may infiltrate neck
What is the pathophysiology of an anaplastic thyroid cancer?
- Dedifferentiation of follicular thyroid cells, and rapid proliferation of those cells.
- Dedifferentiation means that these cancer cells no longer uptake iodine or contribute to T3/4 synthesis.
What is the pathophysiology of thyroid lymphoma?
- Originates from leukocytic cells.
- Almost always will be non-hodgkins (Reed-Sternberg cells are NOT present in non-hodgkins).
What is the pathophysiology of medullary thyroid cancer?
- Cancer of the parafollicular calcitonin producing cells (“C-cells”).
- Medullary cancer results in large amounts of calcitonin production (affects calcium regulation - hypocalcaemia).