Endocrine Flashcards
What is hyperthyroidism?
- Hyperthyroidism is a common endocrine condition caused by an overactive thyroid gland causing an excess of thyroid hormone.
What is thyrotoxicosis?
- Thyrotoxicosis is an excess of thyroid hormone, having an overactive thyroid gland is not essential → can consume too much thyroid hormone.
What is the difference between primary and secondary hyperthyroidism?
- Primary hyperthyroidism: involves an excessive production of T3/T4 by the thyroid gland due to pathology affecting the thyroid gland itself.
- Secondary hyperthyroidism: occurs due to excessive stimulation of the thyroid gland by TSH, secondary to pituitary or hypothalamic pathology, or from an ectopic source such as a TSH-secreting tumour.
What are the risk factors for hyperthyroidism?
- 20-40 years old.
- Gender → Female > Male.
- Family history
- Auto-immune disease → Vitiligo, T1DM, Addison’s disease.
What are the key presentations of hyperthyroidism?
- THYROIDISM nmemonic.
- T - Thyroidism Tremor
- H - Heart rate increase
- Y - Yawning
- R - Restless
- O - Oligomenorrhoea
- I - Irritability
- D - Diarrhoea
- I - Intolerance to heat
- S - Sweating
- M - Muscle wasting (weight loss)
What are the signs of hyperthyroidism?
- Postural tremor
- Palmar erythema
- Hyperreflexia
- Sinus tachycardia / arrhythmia
- Goitre
- Lid lag and retraction
- Signs specific to Grave’s disease
What are the symptoms of hyperthyroidism?
- Weight loss
- Anxiety
- Fatigue
- Reduced libido
- Heat intolerance
- Palpitations
- Menstrual irregularity
What are the investigations for hyperthyroidism?
- Thyroid function test (TFTs)
- Anti-TSH receptor antibody test
*If there is serological confirmation no need for imaging
- Thyroid ultrasound
- Glucose levels
- ECG
What would the change be for TSH and T4 in Primary hyperthyroidism?
- Decreased TSH
- Increased T4
What would the change be for TSH and T4 in subclinical hyperthyroidism?
- Decreased TSH
- Normal T4
What would the change be for TSH and T4 in secondary hyperthyroidism?
- Increased TSH
- increased T4
What is the primary management for hyperthyroidism?
- Beta blocker e.g. propranolol for symptomatic relief
- Anti-thyroid in mild disease e.g. Carbimazole
- Radioiodine treatment:first line treatment in more than mild Graves’ or toxic multinodular goitre (contraindicated in pregnancy)
- Often require long-term levothyroxine after radioiodine therapy
What are other management strategies for hyperthyroidism?
- Second line antithyroid medication if Carbimazole not used =Propylthiouracil, but this is associated with hepatotoxicity. In pregnancy, propylthiouracil is used in the first trimester and this is switched to carbimazole thereafter as per NICE
- Surgery - total or hemithyroidectomy
What are the complications of hyperthyroidism?
- HF, AF
- Osteoporosis, proximal myopathy
- Thyrotoxic crisis, thyroid storm
What is Graves disease?
- The most common cause of hyperthyroidism (66% of cases).
- An autoimmune induced excess production of thyroid hormone.
What are the risk factors for Graves disease?
- Gender - Female > Male.
- Age - 40-60 years old.
- Autoimmune disease history.
- High iodine intake.
- Stress.
- Radiation.
- Tobacco use.
- Family history.
What are the signs of graves disease?
- Postural tremor
- Palmar erythema
- Hyperreflexia
- Sinus tachycardia / arrhythmia
- Goitre
- Lid lag and retraction
What are the symptoms of graves disease?
- Weight loss
- Anxiety
- Fatigue
- Reduced libido
- Heat intolerance
- Palpitations
- Menstrual irregularity
What are the clinical manifestations that are specific to Graves disease?
- Thyroid acropachy - clubbing, swollen fingers and periosteal bone formation
- Thyroid bruit - continuous sound heard over thyroid mass
- Pretibial myxoedema - raised, purple-red symmetrical skin lesions over the anterolateral aspects of the shin
- Eye signs
- Exophthalmos - protruding eye
- Ophthalmoplegia - paralysis or weakness of eye muscles
What are the investigations for Graves disease?
- Thyroid function test’s
- Raised T3
- Raised T4
- Reduced TSH
- Other investigations related to hyperthyroidism
What is a thyroid storm?
- Known as Thyroid storm or Thyrotoxic crisis, is a life-threatening complication of hyperthyroidism and is most commonly seen in patients with Grave’s disease or Toxic multi-nodular goitre.
- Often occurs secondary to infections or trauma in patients with known hyperthyroidism.
- Could also be the first manifestation of a person with undiagnosed hyperthyroidism.
What are the signs of a thyroid storm?
- Hyperpyrexia: often >40ºC.
- Tachycardia: often > 140 BPM, with or without atrial fibrillation
- Reduced GCS - consciousness
What are the symptoms of a thyroid storm?
- Nausea and vomiting
- Diarrhoea
- Abdominal pain
- Jaundice
- Confusion, delirium or coma
What are the investigations for a thyroid storm?
- TFTs: elevated T3 and T4 levels, suppressed TSH levels
- ECG: tachycardia; may demonstrate atrial fibrillation
- Blood glucose: perform in all patients with reduced consciousness
What is the management for a thyroid storm?
- Conservative: IV fluids, NG tube insertion (if vomiting), tepid sponging, paracetamol, ITU admission
- Antithyroid drugs: propylthiouracil is generally preferred, but carbimazole is an alternative
- Corticosteroid: IV hydrocortisone or methylprednisolone
- Beta-blocker: propranolol PO, or IV
- Oral iodine: Lugol’s iodine is offered > 1 hour after propylthiouracil
- Sedation: if required, use chlorpromazine
- Plasma exchange or thyroidectomy: in refractory patients
What is hypothyroidism?
- Hypothyroidism is a common endocrine condition caused by a deficiency in thyroid hormone: T3 and T4.
- Classified as either primary (95%), secondary or congenital.
What is primary hypothyroidism?
Primary hypothyroidism is due to pathology affecting the thyroid gland itself, such as an autoimmune disorder (e.g. Hashimoto’s thyroiditis) or iodine deficiency.
What is secondary hypothyroidism?
Secondary hypothyroidism is usually due to pathology affecting thepituitary gland (e.g. pituitary apoplexy) or a tumour compressing the pituitary gland. It may also be caused byhypothalamicdisorders and certain drugs
What is congenital hypothyroidism?
Congenital hypothyroidism occurs due to an absent or poorly developed thyroid gland (dysgenesis), or one that has properly developed but cannot produce thyroid hormone (dyshormonogenesis).
What are the risk factors for hypothyroidism?
- Gender → Female > Male
- Age → 30-50 years old
- Family history
- History of auto-immune disorders
- Genetic → Turner syndrome or Down syndrome
- Chest or Neck irradiation
- Thyroidectomy or Radioiodine
What are the signs of hypothyroidism?
- Dermatological: hair loss, loss of lateral aspect of the eyebrows (Queen Anne’s sign), dry and cold skin, coarse hair
- Bradycardia
- Goitre
- Decreased deep tendon reflexes
- Carpal tunnel syndrome
- Hoarse voice
What are the symptoms of hypothyroidism?
- Myxoedema - seen in autoimmune hypothyroidism
- Fluid retention - oedema, pleural effusions, ascites
- Weight gain
- Cold intolerance
- Lethargy
- Dry skin
- Constipation
- Menorrhagia: followed later by oligomenorrhoea and amenorrhoea
What are the investigations for hypothyroidism?
- Thyroid function test’s
- Anti-TPO antibody test
- Serum glucose and Hb1Ac
- FBC and serum B12
What would the change be for TSH and T4 in primary hypothyroidism?
- Increased TSH
- Decreased T4
What would the change be for TSH and T4 in subclinical hypothyroidism?
- Increased TSH
- Normal T4
What would the change be for TSH and T4 in secondary hypothyroidism?
- Decreased or normal TSH
- Decreased T4
What is the management for hypothyroidism?
- Levothyroxine (T4) - review every 3 months
- Dose will need to be higher in pregnant women
What are the complications of hypothyroidism?
- Ischaemic heart disease
- Carpal tunnel syndrome, Peripheral neuropathy, Proximal myopathy
- Myxoedema coma
- Thyroid lymphoma
- Side effects of medication
In what conditions would you see anti-TSH receptor?
- Graves’ disease - 90-100%
- Hashimoto thyroiditis - 0-5%
In what conditions would you see anti-TPO receptor?
- Grave’s disease - 70-80%
- Hashimoto’s thyroiditis - 90-95%
In what conditions would you see anti-thyroglobulin?
- Graves’ disease - 20-40%
- Hasimoto’s thyroiditis - 30-50%
What is Hashimoto thyroiditis?
- A hypothyroid condition caused by anti-thyroid antibodies.
- Most common cause of hypothyroidism in the western world.
What are the risk factors for Hashimoto thyroiditis?
- Gender → Female > Male.
- Age
- Associated with auto-immune disease e.g. T1DM
- Genetic disorders → Turner and Down syndrome.
What is subacute granulomatous thyroiditis?
- Sub-acute → Between acute and chronic disease, typically develops after a viral infection of the upper respiratory system.
- A granulomatous disease → aggregation of immune cells (macrophages) forming nodules on the thyroid gland.
What is post-partum thyroiditis?
Inflammation of the thyroid gland that women experience after giving birth.
What is a pituitary adenoma?
- Tumours of the pituitary gland
- They can be either non-functional (causing compressive symptoms) or functional (prolactinoma, acromegaly, Cushing’s disease etc)
- Can either be microadenoma or macroadenoma
What are the risk factors for a pituitary adenoma?
- MEN-1 gene
- Carney complex
- Familial isolated pituitary adenomas - rare
- Age → peak incidence at 30-60 years old
What are the differential diagnosis for pituitary adenoma?
- Rathke’s cleft cyst
- Craniopharyngioma
- Meningioma
- Hypophysitis
- Infection
What are the complications of a pituitary adenoma?
- Hyperpituitarism
- Hypopituitarism - may be due to compressive effects or iatrogenic
- Conditions related to hypopituitarism e.g. hypothyroidism
- Surgery related complications - such as mortality, meningitis, cerebrospinal fluid rhinorrhoea
What is a prolactinoma?
A benign tumour of the pituitary gland which secretes prolactin.
What are the risk factors for a prolactinoma?
- Gender → Females > Males
- MEN-1 → causes tumours in hormone producing glands.
What are the signs of a prolactinoma?
- Infertility in both males and females.
- Bones fractures.
What are the symptoms of a prolactinoma?
- Micro-prolactinomas → often no symptoms.
- Bi-temporal hemianopia.
- Headaches.
- Decreased libido.
- Galactorrhoea - milky nipple discharge (women).
- Amenorrhea - missed menses (women).
- Vaginal dryness (women).
- Brittle bones (women).
- Gynecomastia (males)
- Erectile dysfunction (males).
What are the investigations for a prolactinoma?
- Prolactin test → Raised prolactin.
- Thyrotropin releasing hormone can also be raised.
- MRI → can visualise the prolactinoma and classify it on size.
- PET-CT or CT can also be used to do this.
- DNA testing → MEN-1 mutation.
- First and second degree relatives of those with a known family history may be screened annually.
What is the management for a prolactinoma?
- Dopamine agonist such as bromocriptine or cabergoline which will inhibit prolactin release from the prolactinoma.
- Surgery → those who have failed medical therapy or have macro-prolactinomas.
- Radiation therapy may be given to patients whom have had surgical treatment; however, prolactin levels are still raised.
What are the complications of prolactinoma?
- Infertility
- Osteoporosis
- Pregnancy complications
- Vision loss
What is acromegaly?
Acromegaly is a condition caused by an excess of growth hormone (GH) most commonly related to a pituitary adenoma.
What is gigantism?
Gigantism refers to excess GH production before fusion of the epiphyses of the long bones.
What are the risk factors for either acromegaly or gigantism?
- MEN-1: pituitary adenomas, primary hyperparathyroidism, and pancreatic neuroendocrine tumours; MEN-1 is present in 6% of cases.
- McCune-Albright syndrome
What are the signs for acromegaly/gigantism?
- Bitemporal hemianopia: due to compression of optic chiasm by pituitary tumour
- Facial features:
- Prominent jaw and supra-orbital ridge
- Coarse facial appearance
- Prognathism: protrusion of the lower jaw
- Splaying of teeth
- Macroglossia: large tongue
- Spade like hands
- Sweaty palms and oily skin
- Hypertension
- Organomegaly
What are the symptoms for acromegaly/gigantism?
- Visual disturbance
- Headaches
- Obstructive sleep apnoea
- Rings and shoes are tight
- Polyuria and polydipsia due to T2DM
- Tingling in hands: carpal tunnel syndrome
- Hyperprolactinaemia (20%)
What are the investigations for acromegaly/gigantism?
- GH levels - note. not diagnostic of acromegaly as levels will vary throughout the day, as well as episodic bursts throughout growth.
- Serum IGF-1 - elevated
- Oral glucose tolerance test
- Pituitary MRI
- Visual perimetry
- Pituitary hormone screen
What are the differential diagnoses for acromegaly/gigantism?
Acromegaloidism or pseudo-acromegaly
What is the primary management for acromegaly/gigantism?
Surgery:trans-sphenoidal resection of the pituitary. Surgery isfirst-lineas acromegaly can have significant systemic complications
What is the second line management for acromegaly/gigantism?
- Medical:for patients unsuitable for surgeryor if there are persistent symptoms after surgery
- Mild - Dopamine agonist e.g. cabergoline is FIRST-LINE, bromocriptine is an alternative.
- Moderate - Somatostatin analogues e.g. octreotide
- Severe - GH antagonist pegvisomant - usually avoided due to cost.
What is the third line management for acromegaly/gigantism?
Radiotherapy:reserved for patients who have failed medical and surgical treatment, or in elderly patients unsuitable for surgery
What are the complications of acromegaly/gigantism?
- Cardiomyopathy, HF, hypertension
- Sleep apnoea
- Carpal tunnel syndrome, proximal myopathy
- T2DM, panhypopituitarism
- CRC
- Organ dysfunction
- Arthritis
What are the differences between acromegaly and gigantism?
- Acromegaly is over secretion of growth hormone AFTER fusion of growth plates, gigantism is over secretion of growth hormone BEFORE fusion of growth plates.
- Acromegaly has onset in adulthood, gigantism had onset in childhood.
- Acromegaly facial features - large lips, tongue and protruding jaw.
- Gigantism facial features - prominent forehead and jaw.
What is diabetes insipidus?
- Diabetes insipidus (DI) is a metabolic disorder characterised by an absolute or relative inability to concentrate urine, resulting in the production of large quantities of dilute urine.
- It is due to the patient’s inability to make ADH or respond to ADH. This leads to polydipsia, polyuria, and hypotonic urine.
What is cranial diabetes insipidus?
No ADH produced or secreted.
What nephrogenic diabetes insipidus?
Pathology affecting the kidney.
What are the risk factors for diabetes insipidus?
- Pituitary surgery.
- Craniopharyngioma
- Brain injury
- Congenital pituitary abnormalities
- Medication e.g. lithium
- Autoimmune disease - some cases linked to antibodies against ADH secreting cells
- Family history
- CNS infections
- Pregnancy
What are the signs of diabetes insipidus?
- Postural hypotension
- Hypernatremia
What are the symptoms of diabetes insipidus?
- Polyuria
- Polydipsia
- Dehydration
What are the differential diagnoses for diabetes insipidus?
- Primary polydipsia
- Diabetes mellitus
- Hypercalcaemia
What are the investigations for diabetes insipidus?
- Water deprivation test (desmopressin suppression test) - GOLD STANDARD
- U&E
- Serum glucose
- Urine osmolarity
- Serum osmolarity
- MRI for cranial DI
What is the management for cranial DI?
- Correct underlying cause
- Mild cases can be managed conservatively e.g. low sodium diet
- Synthetic ADH analogue - oral desmopressin
What is the management for nephrogenic DI?
- Treat the cause - most likely renal disease
- Thiazide diuretic e.g. Bendroflumethiazide
- NSAIDS e.g. ibuprofen
What is SIADH?
- The syndrome of inappropriate anti-diuretic hormone (SIADH) results from excess ADH secretion.
- ADH excess, as the name suggests, results in reduced diuresis - water excretion and urinary output are reduced. This leads to an increase in total body water and hyponatraemia.
What are the risk factors for SIADH?
- Age >50
- Pulmonary conditions
- Malignancy
- Medicine associated SIADH induction
- CNS disorder
What are the clinical manifestations of SIADH?
- Mild(130-135 mmol/L):
- Nausea, vomiting, headache, lethargy, anorexia
- Moderate(125-129 mmol/L):
- Weakness, muscle aches, confusion, ataxia, asterixis
- Severe (< 125 mmol/L):
- Reduced consciousness, seizures, myoclonus, respiratory arrest
- NOTE - A large proportion of cases will be asymptomatic → clinical features developing during chronic disease.
What are the investigations for SIADH?
- There is no single test that conclusively diagnoses SIADH. Instead, diagnosis relies upon suggestive biochemistry results and the clinical context.
- Renal function
- Serum osmolarity
- Urine osmolarity
- Urine sodium
- Patient will be euvolemic
- U&Es
What is the acute management for SIADH?
Acute hyponatraemia (<48 hours) must be treated urgently due to the risk of cerebral oedemaand herniation
- Hypertonic (3%) salineis preferred - slow infusion to avoid complications
- Furosemide (diuretic) -in patients who have fluid overload. Causes an increase in water, Na+, Ka+ and Cl- excretion. (Note: KCl should be replaced)
What is the chronic management for SIADH?
- Correction should not occur too quickly and aim for amaximum increase in 10 mmol/L per day
- Mild to moderate asymptomatic cases: fluid restriction to increase Na+ concentration
- Severe or symptomatic cases: guidelines differ but demeclocycline or tolvaptan may be considered
What are the complications of SIADH?
- Cerebral oedema
- Central pontine myelinolysis
- ‘locked in syndrome’
What is primary adrenal insufficiency?
- Addison’s disease (primary adrenal insufficiency) is caused by destruction or dysfunction of the adrenal cortex.
- Results in mineralocorticoid (aldosterone), glucocorticoid (cortisol) and gonadocorticoid (androgens) deficiency
What are the risk factors for Addison’s disease?
- Gender → Female > Male
- Autoimmune conditions
- Autoimmune polyendocrinopathy syndrome
- Adrenal haemorrhage
- Warfarin which may predispose to adrenal haemorrhage
- TB
- HIV
What are the signs of Addison’s disease?
- Hyperpigmentation (caused by increased levels of ACTH) - especially in palmar creases and buccal mucosa
- Vitiligo - due to loss of androgens
- Loss of pubic hair in women
- Hypotension and postural drop
- Associated autoimmune conditions
- Tachycardia