Thyroid & Parathyroid Disease Flashcards
Primary disorders of the thyroid are of what origin?
The gland itself
All thyroid diseases are goitrous, true or false?
False
TSH is released by which cells & where?
Thyrotroph cells in the anterior pituitary
T4/T3 represents the majority of thyroid hormone produced?
T4 (80%) AKA “thyroxine”
What are the thyroid-binding plasma proteins? (3)
1) TBG
2) TTR
3) Albumin
True/false: fT3 is the active form of thyroid hormone?
True
T4 or T3 influences a negative feedback loop?
T3
Where is T4 principally converted to T3?
Liver
In primary hypothyroidism, free T3/T4 is what? What is TSH?
Free T3/T4 = low
TSH is high
In secondary hyperparathyrodism, the free T3/T4 is what & what is the TSH?
T3/T4 is high
TSH is inappropriately high or normal
What’s the clinical term for a severe hypothyroid emergency?
Myxoedema
What’s the rare classical skin sign for Graves’ disease?
Pretibial myxodema
What is the TSH and thyroxine profile in subclinical hypothyrodisim?
Thyroxine is just borderline normal while TSH i shigh
Hypothyroidism is more common in African populations than whites? true or false?
False
Iodine uptake positively or negatively correlates with thyroid disease?
Positively (more common in higher uptake areas)
Hashimoto’s thyroiditis is a condition of hypo/hyper-thyroidism? Does it usually cause goitre?
Hypothyroidism & yes goitre present (if not it’s termed atrophic thyroiditis)
Iodine deficiency usually induces a goitrous/non-goitrous form of thyroid disease?
Goitrous
Name 2 drugs which can cause a goitrous hypothyroidism
- Amiodarone
- Lithium
Atrophic thyroiditis is another term for what
Hashimoto’s thyroidits WITHOUT goitre
The most common cause of hypothyroidism in the west is…
Autoimmune hypothyroidism (e.g. Hashimoto’s or atrophic thyroiditis)
Hypothyroidism is more common in women/men?
Women
What are the defining traits of autoimmune hypothyroidism? (2)
1) Antibodies against TPO
2) T-cell infiltrate of thyroid
List the main features of hypothyroidism (8)
1) Coarse, sparse hair
2) Dull, expressionless face
3) Reduced thermogenesis leading to cold intolerance
4) Cardiac dilation
5) Reduced HR
6) Metabolic hyperlipidaemia (xanthelasma)
7) Decrease in appetite but weight gain
8) Megacolon
What neurological signs are associated with hypothyroidism? (3)
1) Decreased intellect and motor activity
2) Depression, psychosis
3) Carpal tunnel syndrome
Hypothyroidism has no influence on reproduction, true or false?
False - causes painful period, can cause hyperprolactinaemia (excess TRH leads to excess PRL)
The cardinal abnormalities in hypothyroidism are (2)
1) Elevated TSH
2) Reduced fT4/T3
Hyponatremia is present in hypothyroidism, true or false?
True (but rare)
Macrocytosis is a feature of hypothyroidism, true or false?
True
TRAb antibodies are present in which % of Graves’ cases?
70-100%
Anti-TPO antibodies are present in which % of autoimmune hypothyroid cases?
95%
Which type of respiratory failure is common in myoxedma coma?
Type 2 (hypoxaemia with hypercapnia)
Myxoedema coma is a complication of longstanding untreated hypothyroidism. How fatal is it with treatment?
60%
How should myoxedema coma be treated (3)?
1) Passive warming
2) Broad-spectrum antibiotics
3) Thyroxine cautiously (but NOT if adrenal failure is present)
Thyrotoxicosis is the condition occurring when tissues are exposed to…
Excessive thyroid hormone
List the major clinical signs & symptoms of thyrotoxicosis (cardiac, sympathetic, GI, vision, repro, muscles, metabolism)
-Cardiac (AF, palpitations)
-Sympathetic (tremor, sweating)
-GI (frequent, loose stools)
Vision (lid retraction, proptosis)
-Repro (lighter bleeding and less frequent periods)
-Muscles (proximal weakness)
-Metabolism (intolerance to heat, weight loss)
Hashitoxicosis refers mostly to what presentation of Hashimoto’s?
The initial presentation, which can give rise to transient hyperthyroidism before hypothyroidism
Thyrotoxicosis is always associated with hyperthyroidism, true or false?
False
DeQuervain’s Thyroiditis is a condition of resulting from what factor?
X = thyrotoxicosis
Resulting from viral infection. Often self-limiting - but can indicate progression
Thyroiditis may be caused by amiodarone, true or false?
True
Thyrotoxicosis factitia describes what clinical case?
Self or deliberate poisoning
Struma ovarii is a condition of what
Ovary teratoma containing thyroid tissue
Overtreatment of levothyroxine can lead to thyrotoxicosis, true or false?
True
What % of HLA genes determines the risk of developing Graves?
70%
The cardinal abnormalities of Graves (biochemistry)
Low TSH, high fT4/T3
Hypercalcaemia is present in Graves, true or false?
True - it’s a cause of osteoporosis
Thyroid acropachy is a sign of which condition?
Graves’ Disease
What’s a goitre sign specific to Graves?
Thyroid bruit
Graves’ goitre is always bilateral, true or false?
False - can be unilateral
Nodular thyroid goitre tends to be symmetrical, true or false?
False
Thyroid storm is a medical emergency characterised by…
Severe untreated hyperthyroidism
The end-stage manifestation of thyrotoxicosis is…
Thyroid storm
How is thyroid storm treated (4)
1) Lugol’s iodine
2) Steroids
3) PTU
4) Beta-blockers
What’s the 1st line treatment for nodular thyroid disease & relapsing Graves?
Radioiodine
Radiodine increases risk of thyroid cancer, true or false?
False
Radiodine is contraindicated in (2)
Pregnancy & active thyroid disease
Which nerve is at risk in thyroidectomy?
Recurrent laryngeal
Sub-acute thyroiditis usually progresses to clinical disease, true or false?
False - usually self-limiting
Subclinical hypothyroidism does not need to be treated in pregnancy, true or false?
False
What’s the biochemical profile of subclinical hyperthyroidism?(2)
Low TSH, normal fT4/T3
Subclinical thyroiditis is assoicated with which 2 conditions?
Osteoporosis, AF
Amiodarone only induces hypothyroidism, true or false?
False - can cause hyperthyroidism as well
Amiodarone works how?
Inhibiting DIO1
Sick euthyroid syndrome is a rare/common condition in the acutely unwell. It generally needs treated, true or false?
Common - does not often need treatment
Spot diagnosis:
- 68 year old female
- TATT, weight gain, goitre, slowness.
- Lab results: high TSH, fT4 low.
- DX: ?
-DX: Primary hypothyroidism
Spot diagnosis:
- 68 year old female
- TATT, goitre. FH of thyroid disease.
- Lab results: TSH high, fT4 normal, TPO antibodies present.
- DX: ?
-DX: Subclinical hypothyroidism (as fT4 is normal but TSH is high)
Spot diagnosis:
- 52 year old male
- Headache, visual field defect, dizziness, poor libido.
- Lab results: TSH low, fT4 low.
- DX: ?
-DX: Secondary hypothyroidism (secondary to a pituitary tumour - notice the lack of sexual characteristics)
Spot diagnosis:
- 32 year old female
- Weight loss, tremor, TATT, sleep disturbance.
- Lab results: TSH very low, fT4 very high.
- DX: ?
-DX: Graves Disease (not secondary as the TSH would be high in this case, indicating the gland is working)
Spot diagnosis:
- 70 year old female.
- Diagnosed with AF
- No symptoms
- Lab results: TSH low, fT4 high.
- DX: ?
-DX: Toxic multi-nodular goitre (associated with AF, TSH will be low but the nodules keep producing T4)
Spot diagnosis:
- 32 year old female.
- Sore throat & febrile illness. Weight loss, poor sleep.
- Lab results: TSH low, fT4 high.
- Six weeks later lab results change to TSH high, fT4 low.
- DX: ?
-DX: Subacute thyroiditis (DeQuervain’s; can present with initial hyperthyroidism then transient hypothyroidism).
Principle symptoms of hypothyroidism (4)
1) Reduced BMR, puts on weight easy
2) Slow pulse
3) Fatigue, lethargy
4) Cold intolerance
In adults, hypothyroidism may lead to…
Myxoedema (puffy facial appearance)
Principle symptoms of hyperthyroidism (5)
1) increased BMR
2) Very fast pulse
3) Emotional lability
4) Sweating & heat intolerance
5) Exopthalmos
Which 3 signs are specific to Graves’ disease?
1) Thyroid bruits
2) Pretibial myxoedema
3) Thyroid acropachy
Lactotroph cells (LH secretors) are under short/long-loop control & what’s the mechanism of feedback?
Short loop negative feedback w/ dopamine
IGF-1 works on which organ?
Liver
No / low cortisol leads to an…
Addisonian Crisis
Cabergoline is what kind of drug & what is it used to treat?
Dopamine agonist - used to treat prolactinoma
Prolactinomas often require surgical excision, T/F?
False - drugs like cabergoline (dopamine agonists) usually control it well
Hypothyroidism can be a cause of raised prolactin, T/F?
True
Hypertension is an important feature of acromegaly, T/F?
True
The headache in acromegaly is usually treatable with drugs, T/F?
False - it’s vascular in origin
Acromegaly is diagnosed using which test?
OGTT (looks for IGF-1, which should be suppressed as GH is a counter-regulatory hormone which is released in hypoglycaemia)
The first-line therapy for acromegaly is surgical/medical?
Surgical
Medical therapies for acromegaly include (3)
1) Dopamine agonists (cabergoline)
2) Somatostatin analogues (octreotide) - advantageous as they also treat headache
3) GH antagonist (Pegvisomant)
Pegvisomant (a GH-receptor antagonist) reduces tumour size, T/F?
False
Side-effects of somatostatin analogues include (3)
1) Local stinging
2) Flatulence
3) Diarrhoea
What drug can be used pre-operatively to improve outcome in GH-tumour surgery?
Somatostatin analogue (e.g. sandostatin) as they will reduce the tumour size
Common causes of hypocalcaemia (3)
Hypoparathyroidism, vitamin D deficiency, pseudohypopoarathyroidism
What is psuedohypoparathyroidism?
A mutation in GNAS causing a peripheral resistance to parathyroid hormone, giving elevated PTH
What is psuedo-psuedo-hypoparathyroidism?
Mutation in GNAS gene (AD) causing lack of peripheral action of PTH, but no resistance (unlike 1 psuedo) - often with normal calcium
Describe “CATS go numb” in hypocalcaemia
Convulsions Arrhythmia Tetany Spasms Numbness
All hypocalcaemia should be treated with IV calcium, T/F?
False - only severe. Mild/moderate can be treated with calcium supplements
What effect does PTH have? (3)
1) Bone resorption
2) Decreased calcium loss in urine
3) Enhanced calcium absorption from GI tract
Where does vitamin D production occur? (3)
Skin, liver and kidney
Where does the final step of vitamin D production occur?
Kidney
Which form of vitamin D is made by the kidney?
1, 25-OH vitamin D
What are the symptoms of hypercalcaemia?
Fractures (osteitis fibrosa cystica), renal stones, pancreatitis (and nausea& vomiting) and depression.
Painful Bones, Renal Stones, Abdominal Groans and Psychic Moans
What’s the primary investigation for hyperglycaemia?
ALK-P (if high suggests bony mets, if low myeloma)
Causes of hypercalcaemia include (3)
Primary hyperparathyroidism, malignancy, certain drugs (e.g. Vitamin D, thiazides)
Treatment of acute hyperglycaemia is with (2)
1) Fluids and ONCE rehydrated 2) loop diuretics (not thiazides)
How long do bisphosphonates take to work & what condition are they useful in?
1 week and hypercalcaemia
Primary hypercalcaemia is often medically managed, T/F?
False - usually surgical excision required
Secondary hyperparathyroidism is a response to…
Low calcium (a physiological)
Tertiary hyperparathyroidism develops due to
Multiple years of secondary (parathyroid becomes autonomous)
If patient is hypercalcaemic & albumin is raised, what is the likely diagnosis?
Dehydration
Cinacalcet is useful in which condition?
Tertiary hyperparathyroidism
Hypocalciuric hypocalcaemia is inherited how? What’s the defect?
AD and a defect in the calcium sensor (often benign & incidental)
Is calcium elevated in Paget’s? What about PTH?
No (only ALK-P is elevated)
Looser’s Zones is a classical X-ray sign of what disease?
Osteomalacia
Vitamin-D resistant Rickets is a genetic condition with which association?
X-linked hypophosphataemia (due to PHEX / FGF23 gene mutation)
FGF23 is secreted by which cell?
Osteocyte
