endocrinology Flashcards
Give 5 causes of thyrotoxicosis.
Thyrotoxicosis - excess thyroid hormone due to any cause:
1. Increased production e.g. Grave’s, toxic adenoma.
- Leakage of T3/4 due to follicular damage.
- Ingestion of excess hormone.
- Thyroiditis (de quervain’s).
- Drug induced.
Grave’s disease vs gestational thyrotoxicosis?
- Grave’s: symptoms predate pregnancy; symptoms are severe during pregnancy; goitre and TSH-R antibodies present.
- Gestational thyrotoxicosis: symptoms do not predate pregnancy; lots of N/V - hyperemesis gravidarum associated. No goitre or TSH-R antibodies.
epidemiology of thyroid disorders?
Commonest endocrine disorder
Females (5-10x more)>males
Hyperthyroidism 2.5% prevalence
Hypothyroidism 5%
Most common clinical presentation of thyroid disease is Goitre 5-15%
2% of women will get Graves’ disease or autoimmune hypothyroidism (5-10 times the frequency in men)
5% will have postpartum thyroiditis and up to 20% will have positive thyroid antibodies
causes of hyperthyroidism?
(get main 2)
- Grave’s disease.
- Toxic adenoma. (benign) (causes 5% of cases of hyperthyroidism)
- Toxic multi nodular goitre (nodules that secrete thyroid hormones, seen in elderly and in iodine-deficient areas)
- Ectopic thyroid tissue (metastases)
- Exogenous (iodine/T4 excess) - * eg w amiodarone medication (used to treat hypothyroidism)* bc its iodine rich
- De quervain’s thyroiditis (post-viral)
(hCG can activate TSH receptors (bc HCG and TSH are glycoprotein hormones with very similar structure) and cause hyperthyroidism)
Give 5 causes of hypothyroidism.
- Autoimmune thyroiditis e.g. Hashimoto’s and atrophic thyroiditis.
- Post-partum thyroiditis.
- Iatrogenic - thyroidectomy.
- Drug induced e.g. drug induced eg anti thyroid drugs (carbimazole, amiodarone, lithium.) or amiodarone (its used to treat hyperthyroidism)
- Iodine deficiency.
- hypopituitarism
primary hypothyroidism vs secondary hypothyroidism?
Primary hypothyroidism: thyroid gland itself producing LESS/reduced T4 and thus T3
Secondary hypothyroidism:
ANTERIOR PITUITARY is releasing LESS TSH
reduced TSH from anterior pituitary:
Thus not wnough T3 and T4
Hypopituitarism
Hypothyroidism: name 3 anti-bodies that may be present in the serum in someone with autoimmune thyroiditis.
- TPO (thyroid peroxidase).
- Thyroglobulin.
- TSH receptor.
What is the treatment for thyroid hypopituitarism?
Levothyroxine.
Give 5 symptoms of hypothyroidism.
- Menorrhagia – heavy bleeding.
- Obesity/weight gain.
- Malar flush.
- Tiredness.
- Intolerance to cold.
- Energy levels fall/eyebrow loss.
- Depression/dry skin and hair.
- GOITRE!
Give 5 signs of hypothyroidism.
- Mental slowness.
- Dry thin hair.
- Bradycardia. (mnemonic in oxford handbook)
- Anaemia.
- Hypertension.
- Loss of eyebrows.
- Cold peripheries.
- Carpal tunnel syndrome.
What 1st line investigation might you do in someone who you suspect has hypothyroidism?
- TFT’s - serum TSH will be raised and T3/T4 will be low in primary hypothyroidism.
- Thyroid antibodies.
in the 1st line investigation of suspected primary hypothyroidism - what are the results of the TFTs?
and why (pathophysiology)
TFT’s - serum TSH will be raised and T3/T4 will be low.
- Less T4 and T3 are produced due to the thyroid’s reduced capacity to produce hormone or respond to TSH.
- As a result, there is reduced negative feedback on the pituitary and hypothalamus.
- The reduction in negative feedback results in increased production of TRH (which we don’t typically measure) and TSH.
- The end result is low T4 and T3 and a raised TSH.
in the 1st line investigation of suspected secondary hypothyroidism - what are the results of the TFTs?
and why (pathophysiology)
Normal/low TSH: due to a lack of production.
Low T4: due to the absence of any positive feedback from TSH.
- Decreased production or secretion of TRH and TSH results in decreased stimulation of the thyroid gland.
- The thyroid gland, therefore, produces less T3 and T4.
- The low T3 and T4 would normally stimulate the pituitary and hypothalamic glands to increase TRH and TSH production, however, they are unable to increase production.
- The end result is low T4 and T3 and a normal/low TSH.
Give 3 potential consequences of untreated hypothyroidism in pregnancy.
- Gestational hypertension.
- Placental abruption.
- Post partum haemorrhage,
- Low birth weight.
- Neonatal goitre.
What is the effect of hyperthyroidism on TSH and T4 levels?
TSH will be low.T4 will be high.
Symptoms/signs of hyperthyroidism? COMPLETE THIS
- Palpitations
- Diarrhoea
- Weight loss & increase appetite
- Oligomenorrhea (infrequent periods) +/- infertility
- Heat intolerance i.e. sweating a lot
- Irritability/behavioural change
- Tremor
- Hyperkinesis muscle spasm
- Warm - vasodilator peripheries
- Proximal myopathy & muscle wasting
- Lymphadenopathy and splenomegaly can occur
- Anxiety
- Hands:
- Palmar erythema, warm moist skin and fine tremor
- Diffuse goitre
- Lid lag & ‘stare’ can occur in any hyperthyroidism
- Elderly:
- Atrial fibrillation
- **Other tachycardias and/or heart failure
- Children:
- Excessive height or excessive growth rate
- Behavioural problems like hyperactivity
Investigations of hyperthyroidism?
TFTs
- low serum TSH
- raised T3 and T4
And autoantibody status
management of hyperthyroidism?
- carbimazole 2. propylthiouracil
(+ radioactive iodine)
(+also beta blockers!!!!)
First-line pharmacological management of thyrotoxicosis involves the use of ablock (carbimazole) and replace (levothyroxine) regime. Anti-thyroid drugs
Beta-blockers(e.g. propranolol) are used to manage the adrenergic clinical features of thyrotoxicosis (e.g. tachycardia, tremor).
Other management options includeradioiodineandthyroidectomy.
complications of hyperthyroidism?
Main side effect is AGRANULOCYTOSIS (with carbimazole) - results in a severely low white blood cell count (leukopenia) - most commonly neutropenia:
- If they get sore throat, mouth ulcers and fevers then STOP DRUG
ASAP
- Other S/E; rash (common), arthralgia, hepatitis and vasculitis (in bold less common)
thyroid storm
Aka thyrotoxic crisis - excessive adrenergic activity secondary to thyrotoxicosis. Rapid T4 increase
- Management
Treated with LARGE DOSES of:
- ORAL CARBIMAZOLE
- ORAL PROPRANOLOL
- ORAL POTASSIUM IODIDE (to block acutely the release of thyroid hormone from gland)
- IV HYDROCORTISONE (to inhibits peripheral conversion of T4 to T3)
Thyroid storm is associated with high mortality.
grave’s disease: pathophysiology?
circulating IgG autoantibodies (aka TSH receptor stimulating antibodies TSHR-Ab) binding to and activating G-protein-coupled thyrotropin receptors, (TSH receptors in thyroid) which cause smooth thyroid enlargement and increased hormone production (esp. T3),
aka Autoimmune disease. TSH receptor antibodies stimulate thyroid hormone production -> hyperthyroidism.
grave’s disease: aetiology?
- FEMALE - biggest risk factor (onset is common postpartum)
- Genetic - association with HLA-B8, DR3 & DR2
- E.coli and other gram-NEGATIVE organisms contain TSH-binding sites so may initiate pathogenesis via ‘molecular mimicry’
- Smoking
- Stress
- High iodine intake
- Autoimmune disease:
- Vitiligo (pale white patches on skin)
- Addison’s disease
- Pernicious anaemia
- Myasthenia gravis
- Type 1 DM
Give 5 signs of Grave’s disease that don’t include opthalmopathy signs.
- Tachycardia.
- Arrhythmias e.g. AF.
- Warm peripheries.
- Muscle spasm.
- Pre-tibial myxoedema (raised purple lesions over the shins).
- Thyroid acropachy (clubbing and swollen fingers).
Give 5 symptoms of Grave’s disease that don’t include opthalmopathy signs.
- Weight loss.
- Increased appetite.
- Irritable.
- Tremor.
- Palpitations.
- Goitre.
- Diarrhoea.
- Heat intolerance.
- Malaise.
- Vomiting.
With what disease would you associated pre-tibial myxoedema and thyroid acropachy?
Grave’s disease.
Describe the treatment for Grave’s disease.
- Anti-thyroid drugs e.g. carbimazole. (blocks so targets thyroid peroxidase and so prevents the formation of T3/4.)
- Radioiodine drugs. ((blocks so targets thyroid peroxidase and so prevents the formation of T3/4.)
- Surgery - partial thyroidectomy.
De Quervain’s thyroiditis:
definition?
signs?
treatment?
Transient hyperthyroidism sometimes results from acute inflammation of the thyroid gland, probably due to viral infection
Usually accompanied by fever, malaise and pain in the neck
Treat with aspirin and only give prednisolone for severely symptomatic cases
Amiodarone:
function?
side-effects?
anti-arrythmia drug
can cause hypo/hyperthyroidism because it is iodine rich.
(can cause hypothyroidism alongside lithium and carbimazole)
Hashimoto’s thyroiditis
key presentation?
management of this?
Produces atrophic changes with regeneration that results in GOITRE FORMATION due to lymphocytic and plasma cell infiltration
LEVOTHYROXINE THERAPY may shrink the goitre, even when the patient is not hypothyroid
thyroid cancer:
risk factor?
pathophysiology?
radiation
Over 90% secrete thyroglobulin which can be used as a tumour marker after thyroid ablation
thyroid cancer:
key presentations?
- In 90% they present as thyroid nodules
- Occasionally (5%) they present with cervical lymphadenopathy or with lung, cerebral, hepatic or bone metastases
If thyroid gland increases in size, becomes hard and is irregular in shape - think carcinoma
Patients may complain of dysphagia or hoarseness of voice due to tumour compression on surrounding structures i.e. oesophagus and laryngeal nerve
thyroid cancer:
investigations?
- Fine needle aspiration cytology biopsy:
- **To distinguish between benign or malignant nodules
- Blood test to check TFTs (TSH, T4 & T3):
- To check if hyperthyroid or hypothyroid needs to be treated before carcinoma surgery
- Ultrasound of thyroid:
- Can differentiate between benign or malignant
management of thyroid cancer?
- Thyroid LOVES iodine so will readily take up radioactive iodine which in turn
will locally irradiate and destroy cancer - providing very little radiation damage to other surrounding structures
- Administer lots of LEVOTHYROXINE (T4) to keep TSH reduced as this is a
growth factor for the cancer!
extra or treatments for each diff type of thyroid carcinoma → kp
hypothyroidism: management?
levothyroxine for adults, children and young people with primary hypothyroidism.
(am on empty stomach)
Give 5 metabolic changes that occur in pregnancy.
- Increased EPO, cortisol and NAd.
- High CO.
- High cholesterol and triglycerides.
- Pro thrombotic and inflammatory state.
- Insulin resistance.
Is hypothyroidism or thyrotoxicosis more common in pregnancy?
Hypothyroidism is more common in pregnancy.
Give 3 potential consequences of untreated hypothyroidism in pregnancy.
Give 3 potential consequences of untreated hyperthyroidism in pregnancy.
- Gestational hypertension.
- Placental abruption.
- Post partum haemorrhage,
- Low birth weight.
- Neonatal goitre.
- Intra-uterine growth restriction.
- Low birth weight.
- Pre-eclampsia.
- Risk of still birth/miscarriage.
Give 5 signs and symptoms of diabetes insipidus.
- Excessive urine production (>3L/24h).
- Very dilute urine - <300 mOsmol/Kg.
- Severe thirst.
- Hypernatraemia.
- Dehydration.
(6. incontinence [secondary to chronic bladder distension).)
What investigations might you do to determine whether someone has diabetes insipidus?
- Measure 24-hour urine volume - >3L/24h = suggests DI.
- Plasma biochemisty - hypernatraemia.
- Water deprivation test - urine will not concentrate when asked not to drink.
Treatment for cranial DI vs nephrogenic DI
cranial DI = Desmopressin. (man-made form of ADH)
nephrogenic = treat the cause
Give 4 causes of polyuria.
- Hypokalaemia.
- Hypercalcaemia.
- Hyperglycaemia.
- Diabetes insipidus.
causes of cranial diabetes insipidus vs nephrogenic DI
Cranial DI =
1. Tumours.
2. Trauma.
- Infections.
- Idiopathic. (<50%)
- Genetic - AR.
nephrogenic diabetes insipidus =
1. Osmotic diuresis - diabetes mellitus.
2. Drugs. (lithium, demeclocycline )
- CKD.
- Metabolic e.g. hypercalcaemia and hypokalaemia.
Give 3 potential consequences of a pituitary adenoma
and give eg of diseases
- Pressure on local structures e.g. optic chiasm. -> eg Bitemporal hemianopia
- Pressure on normal pituitary
-> hypopituitarism. - Functioning tumour e.g. Cushing’s, gigantism/acromegaly, prolactinoma.
Cushing’s syndrome: definition
A set of signs/symptoms/ a clinical state
resulting from chronic glucocorticoid excess with a
- loss of normal feedback mechanisms.
- and loss of circadian rhythm of cortisol secretion (normally highest on waking).
Cushing’s syndrome: aetiology?
- Adrenal Tumour (adenoma or carcinoma).(tumor on the adrenal gland itself makes too much cortisol)
- Pituitary adenoma/tumour (would secrete too much ACTH) - (Cushing’s disease).
- Exogenous steroids.
- Ectopic ACTH syndrome.(tumors that develop outside the pituitary gland)
Cushing’s syndrome:
signs/symptoms
- Central obesity.
- Moon face.
- Hypertension.
- Skin thinning.
- Abdominal striae.
- Mood change.
- Osteoporosis.
- Muscle thinning.
- Weight gain.
Cushing’s syndrome:
investigations?
- Overnight dexamethasone suppression test
In Cushing’s syndrome there will be no suppression - Late night salivary cortisol - loss of circadian rhythm.
- Urinary free cortisol is raised.
- Loss of circadian rhythm.
Cushing’s syndrome:
treatment?
- Surgical removal of pituitary tumours.
(eg Bilateral adrenalectomy (remove both adrenal glands)) or Surgical selective removal of pituitary adenoma trans-sphenoidal approach - Drugs to inhibit cortisol synthesis e.g. metyrapone, ketoconazole.
Acromegaly:
Aetiology?
A benign pituitary adenoma producing excess GH.
(In rare cases is due to hyperplasia e.g. ectopic GH-releasing hormone from a carcinoid tumour)
Symptoms vs signs of acromegaly?
Symptoms:
1. Change in appearance.
2. Increase in size of hands and feet.
3. Excessive sweating.
4. Headache.
5. Tiredness.
6. Weight gain.
7. Amenorrhoea.
8. Deep voice.
9. Goitre.
Signs:
1. Prognathism - jaw protrusion.
2. Interdental separation.
3. Large tongue.
4. Spade like hands and feet.
5. Tight rings.
6. Bi-temporal hemianopia.
What co-morbidities are associated with acromegaly?
- Arthritis.
- Cerebrovascular events.
- Hypertension and heart disease.
- Sleep apnea. (due to excess soft tissue in larynx - pauses in breathing whilst sleeping)
- T2 DM.
- Impaired glucose tolerance (40%)
Colon Cancer
Acromegaly: investigations?
- Plasma GH levels can exclude acromegaly - not diagnostic!
- Serum IGF-1 levels raised.
- Oral glucose tolerance test - diagnostic! - (Oral glucose tolerance test - failure of glucose to suppress serum GH.)
- MRI of pituitary.
What test is diagnostic for acromegaly?
Oral glucose tolerance test - failure of glucose to suppress serum GH.
Acromegaly: treatment?
Also name 2 drugs that can be used to treat acromegaly. What class of drugs do they belong to?
- Trans-sphenoidal surgical resection.
- Radiotherapy.
- Medical therapy: somatostatin analogues, dopamine agonists e.g. cabergoline.
Cabergoline - dopamine agonist.
Octreotide - somatostatin analogue.
Prolactinoma: Aetiology?
- Pituitary adenoma.
- Anti-dopaminergic drugs.
- Physiological - pregnancy, breast feeding, stress
Prolactinoma: signs and symptoms?
- Infertility.
- Golactorrhoea.
- Amenorrhoea.
- Loss of libido.
- Visual field defects and headaches due to local effect of tumour.
- Erectile dysfunction and reduced facial hair in men
What investigation would you do on someone presenting with difficulty getting pregnant, golactorrhoea, amenorrhoea, loss of libido and headaches?
You would measure serum prolactin.
These are symptoms of prolactinoma.