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Endocrine > Thyroid diseases > Flashcards

Thyroid diseases Flashcards

1
Q

What are some obvious signs of hyperthyroidism?

A
  1. Bruit
  2. Exophthalmos
  3. Opthalmoplegia
  4. Pretibial myxoedema
  5. Thyroid acropachy AKA clubbing, painful finger, toe swelling
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2
Q

What is the 2 most common causes of hyperthyroidism?

A
  1. Graves disease
  2. Plummer’s disease/toxic multinodular goiter
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3
Q

What are the TFT results for hyperthyroidism? Why would hyperthyroidism cause osteoporosis?

A

Low TSH

Low T4

High T3

Because thyrotoxicosis cause excess excretion of Ca2+ and Phosphorus in urine –> resorption of bone

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4
Q

What are the 3 antibodies that could be present in a patient with Grave’s disease.

A
  1. Thyroid stimulating immunoglobulin
    * mimics TSH –> thyroid enlargement
  2. Thyroid growth stimulating immunoglobulin
    * proliferation of thyroid follicular epithelium
  3. Anti-TSH receptor antibodies
    * prevent TSH from binding to receptor
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5
Q

Who is most susceptible to Plummer’s disease?

A
  1. Elderly
  2. Iodine deficienct patient
    * because it causes hyperlasia of thyroid gland –> higher risk of mutation of TSH receptor –> uncontrollable and aurtromonous production of thyroid hormone
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6
Q

What is the treatment for hyperthyroidism?

A
  1. Beta blocker (propanolol) - first line
  2. Antithyroid medication e.g. carbimazole
  • Via titration (dose adjusted)
  • Via block and replace (with levothyroxine)
  1. Radioiodine - damages thyroid cells
  2. Thyroidectomy
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7
Q

What is the function and side effects of carbimazole?

A
  • Prevents thyroid peroxidase enzyme from coupling and iodinating the tyrosine residues on thyroglobulin

SE:

  • Agranulocytosis (low neutrophil –> sepsis)

CI:

  • patient with any form of infection
  • Pregnancy since it crosses placenta
  • Alternative drug is propylthiouracil (but higher risk of liver injury)
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8
Q

What is the side effects and CI of radioiodine?

A

SE:

  • Hypothyroid

CI:

  • Pregnancy
  • Lactation
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9
Q

What are the risks of thyroidectomy?

A
  1. Damage to recurrent laryngeal nerve
  2. Hypothyroidism (require thyroid replacement)
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10
Q

What is the main known risk factor for thyroid eye diseases?

A
  1. Smoking
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11
Q

What is the treatment for thyroid eye diseases e.g. diplopia?

A

Diplopia - fresnel prism behind lens of glasses

More severe cases - high dose steroids to treat inflammation since eye disease are caused by autoabs

Sight threatening diseases - surgical decompression

Opthalmoplegia - Orbital radiotherapy due to its anti-inflammatory effects (little effect on proptosis AKA protrusion of eyes)

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12
Q

What is the TFT results for primary hypothyroidism?

A

High TSH

Low T4

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13
Q

What is the TFT results for secondary hypothyroidism (rare)?

A

Low TSH

Low T4

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14
Q

What other results can we find from a blood test in a patient that has hypothyroidism?

A
  1. Raised cholesterol and triglyceride (thyroxine stimulates fat consumption)
  2. Anaemia (thyroid hormone stimulate RBCs precursors) - common
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15
Q

What are the 2 most common causes of hypothyroidism?

A
  1. Primary atrophic hypothyroidism
  • More common in females 6:1
  • Caused by lymphocytic infiltration into thyroid gland –> atrophy –> no goiter
  1. Hashimoto thyroiditis
  • Common in women aged 60-70yo
  • Goiter due to lymphocytic + plasma cell infiltration –> replace thyroid follicular cells with fibrous tissue
  • High autoantibodies present
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16
Q

Name the targets of autoantibodies produced in Hashimoto’s thyroiditis.

A
  1. Thyroid peroxidase
  2. Thyroglobulin
  3. TSH receptors
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17
Q

What is hashitoxicosis?

A

A state of transient hyperthyroidism due to inflammation associated with hashimoto thyroiditis disturbing thyroid follicles –> excess release of thyroid hormone

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18
Q

What is the other chief cause of hypothyroidism?

A
  1. Iodine deficiency
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19
Q

What are some problems associated with pregnancy for patients with hypothyroidism?

A
  1. Eclampsia (seizures during pregnancy that can lead to coma)
  2. Anaemia
  3. Prematurity
  4. Low birthweight
  5. Still birth
  6. PPH (post partum haemorrhage)
20
Q

What are the treatments for hypothyroidism?

A
  1. Levothyroxine
  • Healthy and young
    • give enough to normalise but not suppress TSH
    • Must check TSH levels 4 weeks later (half life of thyroxine is 7 days)
    • Also prescribe enzyme inducers to increase metabolism of levothyroxine
  • Elderly
    • Be careful with prescription of levothyroxine since it may precipitate angina/MI
  1. Lidothyroixine (T3) but can cause arrythmia
21
Q

Name the 5 most common types of thyroid malignancies in order of prevalence.

A
  1. Papillary Thyroid Carcinoma (follicular cells) - 60%
  • usually <1cm in size
  • spread locally in neck and can compress nerve
  1. Follicular thyroid carcinoma (follicular cells) - 25%
  • May infiltrate neck but most commonly spread to lungs and bones
  • Higher proportion in regions of low iodine
  1. Medullary thyroid carcinoma (c cells) - 5%
  • secrete carcinoembryonic antigen (CEA) and calcitonin
  • test for serum calcitonin
  1. Thyroid lymphomas (intrathyroid lymphoid tissues) - 5%
  • non hodgkin lymphoma (does not happen in the lymphatics)
  • Most women with this disease have Hashimoto thyroiditis
  • Rapidly growing mass in neck
  1. Anaplastic thyroid carcinoma (follicular cells) - 2%
    * large, hard mass invading neck and causing compression –> dyspnoea, cough, vocal cord paralysis, dysphagia and hoarseness
22
Q

What is the most common risk factor for thyroid malignancies.

A
  1. Radiation exposure
23
Q

How to differentiate between non cancerous and cancerous nodules in the thyroid?

A

Cancerous nodule:

  • Hard, fixed and non tender to palpation
  • Firm cervical masses suggest lymph node metastases

Non cancerous nodule:

  • single compressible small lump, not diffuse swelling.
24
Q

Where does malignant thyroid carcinomas usually spread to?

A

Lung (most common)

Bones (second most common)

Liver

Brain

25
Q

How is thyroid cancer diagnosed?

A
  1. Thyroid ultrasound (first line)
  2. Serum calcitonin (diagnose medullary thyroid cancer)
  3. TFT
  4. Fine needle aspiration cytology
  5. Radionuclide imaging (to see uptake of iodine)
26
Q

What are the treatment options for the 5 types of thyroid malignancies?

A
  1. Papillary thyroid carcinoma - thyroidectomy + node excision + radioiodine + give more than normal thyroxine to suppress TSH since TSH may cause remaining thyroid cells to grow
  2. Follicular - thyroidectomy + radioiodine
  3. Medullary - thyroidectomy + node clearance + external beam radiotherapy to prevent regional recurrence
  4. Thyroid lymphomas - thyroidectomy + radioiodine
  5. Anaplastic - thyroidectomy + radiotherapy

Note: For all thyroidectomy, must give thyroxine replacement to prevent hypothyroidism

27
Q

What is the function of parathyroid hormone?

A
  1. Increase osteoclast activity –> increase resorption of bone
  2. Increase production of active vit D
  3. Increase kidney reabsorption of Ca2+ and less phosphate
28
Q

Name 3 most common causes of primary hyperparathyroidism.

A
  1. Solitary adenoma (80%)
  2. Hyperplasia of all glands (20%)
  3. Parathyroid cancer (<0.5%)
29
Q

Name the effects of hyperparathyroidism on the kidneys, GI tract, brain, bones and heart.

A

Brain

  • Tired
  • Weak
  • Depressed

Kidneys

  • Kidney stones
  • Biliary stones
  • Thirsty
  • Dehydration
  • Polyuric - due to high charge of tubular fluid

GI tract

  • Abdominal pain (due to stones)
  • Pancreatitis
  • Duodenal and gastric ulcers

Bones

  • Osteoporosis
  • Osteopaenia
  • Fractures

Heart

  • Hypertension
30
Q

Name the test results for primary hyperparathyroidism.

A
  1. Raised plasma Ca2+
  2. Low plasma phosphate
  3. Raised PTH
  4. Raised ALP
31
Q

Name a few other causes of high Ca2+ apart from primary hyperparathyroidism.

A
  1. Consumption of thiazide
  2. Familial hypocalcuric hypercalcaemia –> high Ca2+ and moderately normal or high PTH
  3. Tertiary hyperparathyroidism
32
Q

Name a few other test to identify the effects of hyperparathyroidism.

A
  1. Ultrasound of thyroid to identify adenoma
  2. DEXA T score to measure ostoeporosis
  3. X ray to identify salt and pepper degranulation of skull and subperiostal bone resorption of phalanges
  4. Ultrasound of kidneys to identify kidney stones
33
Q

Name the causes of secondary hyperparathyroidism.

A
  1. Chronic kidney diesease (most common)
  2. Low vit D
34
Q

Name the treatment for secondary hyperparathyroidism.

A
  1. Phosphate binders –> low serum phosphate
  2. Vit D
  3. Calcium supplement
  4. Cinacalet –> low Ca2+, low PTH, raised phosphate
35
Q

Name the traits of patients with tertiary hyperparathyroidism.

A

Long term secondary hyperparathyroidism —> hyperplasia of parathyroid glands, or loss of sensitivity to calcium

Usually patients with end stage kidney disease

36
Q

State the test results for patient with tertiary hyperparathyroidism.

A
  1. High PTH
  2. High calcium (released from bone)
37
Q

State the test results for secondary hyperparathyroidism.

A
  1. Low Ca2+
  2. High PTH
  3. High ALP
38
Q

Explain why in malignant hyperparathyroidism, test results show high Ca2+ but low PTH?

A

In malignant hyperparathyroidism, other types of cancer cells (squamous cell carcinoma, breast carcinoma, renal cell carcinoma) release PTHrp which is structurally similar to PTH but is not picked up by the PTH test.

Hence, it mimics effect of PTH –> high Ca2+

39
Q

List the 4 types of hypoparathyroidism.

A
  1. Primary - problem with gland itself
  2. Secondary - problem not due to gland, but its stimulus
  3. Pseudo - genetic defects, target cells not responsive to PTH
  4. Pseudopseudo - genetic defects, normal biochemistry but same feature as pseudo
40
Q

Name the common causes for primary hypoparathyroidism.

A
  1. Autoimmune disease
  2. Congenital (DiGeorge’s syndrome)
41
Q

State the test results for primary vs secondary hypoparathyroidism.

A

Primary

  • Low PTH
  • Low Ca2+
  • High/normal phosphate
  • Low ALP

Secondary

  • Low PTH
  • High Ca2+
42
Q

Name the treatment for primary hypoparathyroidism.

A
  1. Ca2+ supplements
  2. Calcitriol (vit D) –> can only improve ansorption in intestines not kidneys
  3. Synthetic PTH to enable reabsorption of Ca2+ in kidneys –> prevention of hypercalciuria which is bad for kidneys
43
Q

Name the treatment for secondary hypoparathyroidism.

A
  1. Treat underlying cause
44
Q

Name the causes for secondary hypoparathyroidism.

A
  1. Persistently high Ca2+
  2. Hypomagnesaemia (needed for PTH secretion)
45
Q

Name the features of a patient with pseudohypoparathyroidism

A
  1. Short metacarpals (4th and 5th)
  2. Short stature
  3. Low IQ
  4. Round face
46
Q

State the test results for pseudohypoparathyroidism.

A

High PTH

Low Ca2+

High phosphate

47
Q
A

Endocrine (5 decks)

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