Endocrine Diseases Flashcards
Phaeochromocytoma
A pheochromocytoma is a catecholamine-secreting tumor that originates in the adrenal medulla.
When a similar tumor arises in sympathetic nerve tissue elsewhere in the body, it is termed a paraganglioma.
1st line investigation:
- Plasma metanephrines testing followed by urinary metanephrines.
Hyperthyroidism/thyrotoxicosis
Hyperthyroidism: an overactive thyroid => excess thyroid hormones.
Thyrotoxicosis: The syndrome resulting from the presence of excessive thyroid hormones in the body, not always due to thyroid gland overactivity
Primary causes of Hyperthyroidism:
- Graves disease
- Toxic adenoma
- Toxic multinodular goitre
- Certain meds e.g. amiodarone
- Thyroiditis
Key signs:
- Increased basal metabolic rate
- Heat intolerance = too hot
- Tachycardia
- Weight loss
- Sleep disturbances
Management:
- Anti-thyroid drugs e.g. Carbimazole (preferred but has risk of agranulocytosis) or Propylthiouracil (PTU) (preferred in pregnancy women, women planning pregnancy)
- Beta-blockers - Propanolol
- Radio iodine
- Surgery - Thyroidectomy
NOTE: look out for thyroid storm = Medical emergency
Graves disease
Hyperthyroidism resulting from autoimmune stimulation of the thyroid gland by TSH receptor auto-antibodies
Specific Features to Graves:
- Exophthalmos/proptosis: Bulging eyes
- Lid lag: Upper eyelid remaining higher than normal during downward gaze
- Thyroid acropachy: Soft tissue swelling in extremities, nail clubbing, and periosteal new bone growth.
- Pretibial myxoedema: Mucopolysaccharide deposition in the dermis leading to oedema and skin thickening, predominantly in the shins.
Toxic adenoma
Adenoma that produces thyroid hormones
Toxic multinodular goitre
Multiple thyroid nodules that produce thyroid hormones, leading to goitre.
Thyroiditis
Inflammation of the thyroid gland, e.g., de Quervain’s thyroiditis.
Acromegaly
Excess GH typically caused by a GH secreting pituitary adenoma (GHRH independent). Assoc. w MEN I
Other causes:
- Primary pituitary hyperplasia (GHRH independent) - sporadic or typically assoc. w McCune-Albright Syndrome
- Excess GHRH from Hypothalamus => secondary pituitary hyperplasia (GHRH dependent)
- Ectopic GHRH release => Secondary pituitary hyperplasia (GHRH dependent)
Key signs/symptoms:
- abnormal enlargement of hands, feet, jaw, and head, headaches, erectile dysfunction, and fatigue
Pathophysiology of Acromegaly (& Gigantism)
- Excess growth hormone (be it GHRH dependent or independent) then increases production of insulin-like growth factor (IGF-1)
- Excess IGF-1 acts on its receptors in many tissues => excess growth of these tissues
- Excess GH also results in: increased Gluconeogenesis, lipolysis and insulin resistance
NOTE: IGF-1 is first line investigation, then diagnosis: failure of suppression of GH during oral glucose tolerance test
- Gigantism occurs before epiphyseal plate closure => linear growth
- Acromegaly occurs after plate closure => enlargement of bones and soft tissues
Adrenal insufficiency (& Addisons disease)
Adrenal insufficiency is a clinical syndrome that arises due to the insufficient production of glucocorticoids and mineralocorticoids from the adrenal cortex
Primary adrenal insufficiency: aka Addison’s disease, damage to adrenal glands themselves
Secondary adrenal insufficiency: Inadequate stimulation of the adrenal glands by the pituitary or hypothalamus is the culprit (More common)
Lack of cortisol disrupts feedback mechanisms => elevated adrenocorticotropic hormone (ACTH) levels
Clinical features:
- Hypotension
- Fatigue and weakness
- Gastrointestinal symptoms
- Syncope
- Skin pigmentation due to increased ACTH which stimulates production of alpha melanocyte stimulating hormone (MSH)
1st line investigation: U + E and serum cortisol:
- Hyponatraemia
- Hyperkalaemia
- Low serum cortisol
ACTH high in PAI, low or low-normal in SAI
Diagnosis: an ACTH (Short synacthen) test
Amiodarone-induced thyrotoxicosis
A recognized adverse effect of the anti-arrhythmic agent, amiodarone, which is rich in iodine, a component of thyroid hormone.
The condition manifests in two types:
- AIT type 1, a direct toxic effect of amiodarone due to the high content of iodine => excess thyroid hormone release
- AIT type 2, where amiodarone triggers underlying thyroid autoimmunity - destructive thyroiditis
Signs/symptoms:
- Weight loss
- Tremors
- Palpitations
- Nervousness
- Fatigue
NOTE: patients on amiodarone could exhibit minimal symptoms due to its anti-adrenergic effects
Cushing’s syndrome/disease
Cushing’s Syndrome: Excess glucocorticoids - either ACTH dependent or independent
Cushing’s disease:glucocorticoid excess caused by an adrenocorticotropic hormone (ACTH)-secreting pituitary tumour
Some of the many features:
- central obesity (+/- striae)
- Moon face
- Easy bruising
- osteoporosis & osteopenia
- DM
- Hypertension
- Hypokalaemia
Diagnosis:
- 24hr urinary free cortisol test
- Low-dose dexamethasone suppression test (then try high-dose if Cushing’s disease sus)
Results: - Not suppressed by low dose - Cushing’s syndrome (e.g. exogenous steroid use)
- Not suppressed by low dose but suppressed by high dose - Cushing’s disease (pituitary source)
- Not suppressed by low dose or by high dose dex – ectopic ACTH (not under axis control, likely ACTH-producing tumour)
what is Hertoghe sign/Queen Anne’s sign?
Loss of the lateral third of the eyebrow
- classically seen in hypothyroidism but can also be seen is other conditions such as atopic dermatitis and leprosy
Hypothyroidism
Insufficient production of thyroid hormones, which are crucial for metabolism and energy utilization in the body.
- Women>men
- No. 1 cause worldwide = iodine deficiency
- No.1 cause in UK = Hashimoto’s thyroiditis
Causes:
- Autoimmune causes e.g. Hashimoto’s thyroiditis
- Iatrogenic causes e.g. surgical removal of thyroid
- Congenital causes e.g. Thyroid aplasia, Pendred syndrome
- Iodine deficiency or excess
Key Sign/symptoms (not all):
- Dry, thick skin, brittle hair
- Cold
- Macroglossia, puffy face, loss of outer
- Bradycardia, cardiomegaly
- Carpal tunnel syndrome, slow relaxing reflexes, peripheral neuropathy
Investigations:
- TFT: low T3/4 and raised TSH
- Autoimmune disease: Anti-TPO, Anti-thyroglobulin, Anti-TSH receptor
- imaging and biopsy - congenital or infiltrative causes
- iodine levels: deficient or excess
Which type of thyroid cancer carries the worst prognosis?
Anaplastic Thyroid cancer
- least common
- unless found early = rapid death
rapid growth of a firm, hard, fixed tumour - 7% 5 year survival rate
What are the risk factors which are part of the criteria used to screen patients for Gestational Diabetes Mellitus (GDM)?
- BMI >30
- Previous macrosomic baby (>4.5kg)
- Previous GDM
- First Degree Relative with Diabetes
- Family origin with a high prevalence of diabetes (South Asia,Black Caribbean and Middle Eastern)
GDM occurs within 2-5% of pregnancies
