Endocrine and Metabolic Flashcards
What is Addison’s Disease?
Autoimmune destruction of adrenal glands (primary hypoadrenalism) which leads to reduced cortisol and aldosterone
What are the symptoms and key diagnostic factors of Addison’s Disease?
- Fatigue
- Anorexia
- Weight loss
- Hyperpigmentation
- Acute adrenal crisis = hypotension and tachycardia leading to collapse
- Salt craving
- Muscle weakness
- N + V
- Postural hypotension
- Axillary + Pubic hair loss in women
What is the NICE guidelines investigation for Addison’s?
- 9am serum cortisol
- > 500 nmol/L = unlikely
- > 100-500 nmol/L = ACTH stimulation test or repeat test
- ACTH stimulation test (short SynACTHen test)
- Serum electrolytes for hyponatremia and hyperkalaemia
- Serum aldosterone (suppressed)
What is the NICE guidelines management for Addison’s?
Glucocorticoid = Hydrocortisone total daily dose 15 mg to 25 mg orally in 2 to 4 divided doses.
Mineralocorticoid = Fludrocortisone total daily dose initially 50 micrograms and adjusted according to response up to 300 micrograms orally. Consider a higher daily dose orally for young and physically active people.
If under physical or psychological stress, apply sick day rules (double dose of corticosteroid to mimic usual increase during stress)
What is Cushing’s Syndrome?
Cushing’s syndrome is a collection of symptoms that develop as the result of very high levels of cortisol in the body.
What are the ACTH dependent causes of Cushing’s?
- Cushing’s Disease (80%) : pituitary tumour secreting ACTH producing adrenal hyperplasia
- Ectopic ACTH production (5-10%) : e.g. small cell lung cancer is the most common cause of
What are the ACTH independent causes of Cushing’s?
- Iatrogenic : steroids
- Adrenal adenoma (5-10%)
- Adrenal carcinoma
- Carney complex : syndrome including cardiac myxoma
- Micronodular adrenal dysplasia (very rare)
What is Pseudo-Cushing’s?
Mimics Cushing’s, often due to alcohol excess or severe depression.
Causes false positive dexamethasone suppression test or 24h urinary free cortisol
Insulin stress test may be used to differentiate
Symptoms and key diagnostic factors of Cushing’s
- Facial plethora
- Supraclavicular fullness
- Violaceous Striae + easy bruising
- Menstrual irregularities
- Linear growth deceleration in children
- Hypertension
- DM
- Premature osteoporosis
- Weight gain + central obesity
- Acne
- Low libido
Investigations for Cushing’s
- Overnight 1mg dexamethasone suppression test : morning cortisol is not suppressed
- 24h urinary free cortisol (unless kidney failure)
- If ACTH is suppressed night = likely non-ACTH dependent
- High dose dexamethasone suppression test
- Cortisol unsuppressed and ACTH suppressed = non ACTH
- Cortisol suppressed and ACTH suppressed = Cushing’s Disease
- Cortisol and ACTH unsuppressed = Ectopic ACTH
What are other investigations to consider for Cushing’s?
- Serum Glucose
- ABG for hypokalaemic metabolic alkalosis
- Pituitary MRI if ACTH dependent
- Adrenal CT if ACTH independent
- Insulin stress test to differentiate with pseudo-Cushing’s
Management for Cushing’s
Cushing’s disease - Transsphenoidal pituitary adenomectomy
Ectopic ACTH or CRH syndrome - Surgical resection or ablation of tumour + metastasis
Unilateral adrenal carcinoma or adenoma - unilateral adrenalectomy or resection
Bilateral adrenal hyperplasia or adenoma - Bilateral adrenalectomy + corticosteroid replacement therapy
What is Hypothyroidism and the types?
Conditions that result in low thyroxine levels in the body.
Primary - there is a problem with the gland itself
Secondary - there is a problem outside the thyroid gland, usually the pituitary gland
Congenital - due to a problem with the thyroid dysgenesis or thyroid dyshormonogenesis
What are the causes of primary Hypothyroidism?
Hashimoto’s Thyroiditis: An autoimmune condition and MC in developed countries. It involves immune-mediated destruction of thyroid tissue, increases risk of MALT lymphoma
Subacute (De Quervain’s) Thyroiditis: Often follows a viral infection, leads to temporary thyroid inflammation and initial hyperthyroidism, followed by hypothyroidism.
Riedel Thyroiditis: A rare form of thyroiditis where fibrous tissue replaces thyroid tissue, potentially leading to primary hypothyroidism.
Postpartum Thyroiditis: An autoimmune inflammation that occurs within a year after childbirth, sometimes resulting in temporary hypothyroidism.
Drug-Induced Hypothyroidism: Medications like lithium and amiodarone can interfere with thyroid hormone synthesis or release, leading to primary hypothyroidism.
Iodine Deficiency: Inadequate iodine intake impairs thyroid hormone synthesis, causing primary hypothyroidism. It is a common cause in areas with low dietary iodine
What are causes of secondary Hypothyroidism?
Pituitary Tumors: Tumors in the pituitary gland can impair TSH production, leading to reduced thyroid function. Adenomas are the most common type of benign tumor affecting pituitary function
Hypothalamic Dysfunction: Lesions, trauma, or diseases decrease the release of thyrotropin-releasing hormone (TRH), reducing TSH production
Pituitary Surgery or Radiation: Treatment for pituitary tumors or other brain conditions may damage pituitary tissue
Sheehan’s Syndrome: Occurs after significant postpartum hemorrhage, leading to pituitary infarction and decreased TSH production due to pituitary damage
