Variants
- Pseudopseudohypoparathyroidism
Showing posts with label endocrinology. Show all posts
Showing posts with label endocrinology. Show all posts
Friday, 19 July 2019
Friday, 12 July 2019
Tuesday, 2 July 2019
[Endocrinology] Introduction
This field specialises in diseases of the endocrine system.
Ancient Greek κρίνω (krínō) = to separate
In endocrine, crine (krínō) means "to secrete."
Ancient Greek λογία (logia) = study
Endocrinology = the study of internal secretions.
Etymology
Ancient Greek ἔνδον (éndon) = inner; internalAncient Greek κρίνω (krínō) = to separate
In endocrine, crine (krínō) means "to secrete."
Ancient Greek λογία (logia) = study
Endocrinology = the study of internal secretions.
Subspecialties
- Paediatric endocrinology
History taking
Physical examination
- Examination of suspected thyroid disease
- Examination of diabetic patients
Common problems:
- Hyperglycaemia
- Hypoglycaemia
- Hyperthyroidism
- Hypothyroidism
- Hyperparathyroidism
- Hypoparathyroidism
- Sex hormone disorders
- Thyroiditis
- Paraneoplastic syndromes
Endocrine system diseases
Diseases:
- Diabetes mellitus
- Type 1 diabetes
- Type 2 diabetes
- Cushing's syndrome (Hypercortisolism)
- Cushing's disease (Hypercortisolism)
- Addison's disease (Hypocortisolism)
- Grave's disease
- Hashimoto's thyroiditis
- Syndrome of inappropriate antidiuretic hormone secretion (excessive ADH)
- Diabetes insipidus (insufficient ADH)
- Thyroid cancer
- Pancreatic cancer
- Carcinoid syndrome
- Phaeochromocytoma
Thursday, 13 June 2019
Developmental bone diseases
Disease class: Bone diseases
Types
- Acro-osteolysis
- Basal cell nevus syndrome
- Dwarfism
- Dysostoses
- Funnel chest
- Gigantism
- Leg length inequality
- Marfan syndrome
- Osteochondrodysplasias
- osteolysis, Essential
- Pectus carinatum
- Platybasia
- Proteus syndrome
Noonan syndrome
Disease class: Connective tissue diseases
Features
Failure to thrive
Congenital heart defects
Bleeding disorders
Usually normal intelligence
Genetics
Caused by a mutation in one of several genes
Usually autosomal dominant inheritance
Pathophysiology
In 70% of cases, the affected genes play a role in the Ras/mitogen activated protein kinase signaling pathways.
Complications
Leukaemia
Management
Growth hormone may help children to reach
Saturday, 27 April 2019
Friday, 19 April 2019
Thursday, 18 April 2019
Hyponatraemia
Disease class: Water-electrolyte imbalance
This refers to sodium (natrium) levels in the blood below the reference range.
Management
Beware: rapid reversal of hyponatraemia with aggressive treatment can cause a severe disease: central pontine myelinolysis. Sodium restoration must be very slow and gradual. Specialist advice should be sought.See also
Hypokalaemia
Disease class: Water-electrolyte imbalance
This refers to potassium (kalium) levels in the blood below the reference range.
Management
See also
Hypocalcaemia
This refers to calcium levels in the blood below the reference range.
Aetiology / Causes
Low PTH (hypoparathyroidism)
- Genetic disorders
- Abnormal parathyroid gland development
- Abnormal PTH synthesis
- Activating mutations of calcium-sensing receptor (autosomal dominant hypocalcaemia or sporadic isolated hypoparathyroidism)
- Postsurgical
- Thyroidectomy
- Parathyroidectomy
- Radical neck dissection
- Autoimmune
- Autoimmune polyglandular syndrome (associated with chronic mucocutaneous candidiasis and primary adrenal insufficiency)
- Isolated hypoparathyroidism due to activating antibodies to calcium-sensing receptor
- Infiltration of the parathyroid gland (granulomatous, iron overload, metastases)
- Radiation-induced destruction parathyroid glands
- Hungry bone syndrome (post-parathyroidectomy)
- HIV infection
High PTH (secondary hyperparathyroidism in response to hypocalcaemia)
- Vitamin D deficiency or resistance
- Multiple causes
- PTH resistance
- Missense mutation in PTH
- Pseudohypoparathyroidism
- Hypomagnesaemia
- Kidney diseases
- Loss of calcium from the circulation
- Hyperphosphataemia
- Tumor lysis
- Acute pancreatitis
- Osteoblastic metastases
- Acute respiratory alkalosis
- Sepsis or acute severe illness
Drugs
- Inhibitors of bone resorption (bisphosphonates, calcitonin, denosumab), especially in vitamin D deficiency
- Cinacalcet
- Calcium chelators (EDTA, citrate, phosphate)
- Foscarnet (due to intravascular complexing with calcium)
- Phenytoin (due to conversion of vitamin D to inactive metabolites)
- Fluoride poisoning
Disorders of magnesium metabolism
- Hypomagnesaemia can reduce PTH secretion or cause PTH resistance and is therefore associated with normal, low, or high PTH levels.
Management
See also
Hypercalcaemia
Definition
- This refers to calcium levels in the blood above the reference range.
Causes
- Hyperparathyroidism
- Neoplasms
- Lymphoma
- Sarcoidosis
- Tuberculosis
- Vitamin D poisoning
- Multiple myeloma
- Vitamin A poisoning
- Hyperthyroidism
Management
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| Diagram created by uptodate.com |
Investigations
- Serum calcium
- Total corrected calcium
- Intact parathyroid hormone (PTH)
- PTHrP
- Chest radiograph
- CT-thorax scan
- 1,25-dihydroxyvitamin D
- Lymph node biopsy
- 25-hydroxyvitamin D
- SPEP
- UPEP
- Serum free light chain assay
See also
Hypernatraemia
Disease class: Water-electrolyte imbalance
This refers to sodium (natrium) levels in the blood above the reference range.
Management
See also
Hyperkalaemia
Disease class: Water-electrolyte imbalance
This refers to potassium (kalium) levels in the blood above the reference range.
Management
Wednesday, 17 April 2019
Tuesday, 9 April 2019
Aldosterone antagonists
Also known as
- Mineralocorticoid antagonists
- MRAs, MRCAs
Key examples
- Spironolactone
- Eplerenone
Common indications
- Ascites and oedema due to liver cirrhosis: spironolactone is the first-line diuretic.
- Chronic heart failure: of at least moderate severity or arising within 1 month of a myocardial infarction, usually as an addition to a β-blocker and an ACE inhibitor/angiotensin receptor blocker.
- Primary hyperaldosteronism: for patients awaiting surgery or for whom surgery is not an option.
Mechanisms of action
- Aldosterone is a mineralocorticoid that is produced in the adrenal cortex. It acts on mineralocorticoid receptors in the distal tubules of the kidney to increase the activity of luminal epithelial sodium channels (ENaC). This increases the reabsorption of sodium and water (which elevates blood pressure) with the by-product of increased potassium excretion.
- Aldosterone antagonists inhibit the effect of aldosterone by competitively binding to the aldosterone receptor. This increases sodium and water excretion and potassium retention. Their effect is greatest in primary hyperaldosteronism or when circulating aldosterone is increased, e.g. in cirrhosis.
Important adverse effects
- An important adverse effect of aldosterone antagonists is hyperkalaemia, which can lead to muscle weakness, arrhythmias and even cardiac arrest.
- Spironolactone causes gynaecomastia, which can have a significant impact on patient adherence.
- Aldosterone antagonists can cause liver impairment and jaundice and are a cause of Stevens–Johnson syndrome (a T cell-mediated hypersensitivity reaction) that causes a bullous skin eruption.
Warnings
- Aldosterone antagonists are contraindicated in patients with severe renal impairment, hyperkalaemia and Addison’s disease (who are aldosterone deficient).
- Aldosterone antagonists can cross the placenta during pregnancy and appear in breast milk so should be avoided where possible in pregnant or lactating women.
Important interactions
- The combination of an aldosterone antagonist with other potassium-elevating drugs, including ACE inhibitors and angiotensin receptor blockers, increases the risk of hyperkalaemia.
- Nevertheless, when supported by appropriate monitoring, this may be a beneficial combination in the context of heart failure.
- Aldosterone antagonists should not be combined with potassium supplements except in specialist practice.
Sunday, 7 April 2019
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