Endocrinology Flashcards
What are the clinical features of hypercalcaemia?
The old adage of “Stones, bones, abdominal groans and psychiatric overtones” is actually rarely seen, and many patients are asymptomatic.
Classically described symptoms:
- Bone pain
- Muscle weakness
- Reduced reflexes
- Fatigue
- Constipation
- Anorexia and nausea
- Polyuria caused by nephrogenic diabetes insipidus due to nephrocalcinosis
- Renal stones
- Depression
- Confusion
- Insomnia
Where are the parathyroid glands found?
- Two pairs of parathyroid glands
- Found in the superior and inferior poles of the thyroid
What investigation is used to detect a suspected parathyroid adenoma?
- Technetium-99 m-sestamibi scintigraphy
- Nuclear medicine scan
What are the physiological effects of excessive parathyroid hormone?
Renal
- Increased calcium reabsorption in loop of Henle, DCT and Collecting Duct
- Increased phosphate excretion in PCT
- Increased conversion of vitamin D3
Bone
- Increased release of calcium from bone
- Inhibition of osteoblasts, stimulation of osteoclasts
GI
- Increase in calcium absorption from GI tract
What are the perioperative considerations in patients with hypercalcaemia?
- Lethargic or drowsy patients need less aanesthesia
- Neuromuscular blockade may be potentiated by hypercalcaemia
- Increased risk of cardiac arrhythmias
What are the clinical features of acute hypocalcaemia?
- Peri-oral and peripheral paraesthesia
- Trousseau’s sign
- Chvostek’s sign
- Carpopedal spasm
- Laryngospasm
- Bradycardia and hypotension
- ECG
- QT prolongation
- Torsades
- CATS go numb
- Convulsions
- Arrhythmias
- Tetany
- Laryngospasm
- Paraesthesia
Which inherited endocrine conditions include hyperparathyroidism?
- Multiple endocrine neoplasia type 1 and 2A
- Familial isolated hyperparathyroidism
How much hydrocortisone is equivalent to 5mg prednisolone?
20mg
5mg of Prednisolone is equivalent to:
- 20mg Hydrocortisone
- 750mcg Dexamethasone
- 25mg Cortisone acetate
- 4mg Methylprednisolone
How can you diagnose diabetes insipidus biochemically?
Urine osmolality <200mOsmol/kg
Urinary sodium 20-40mmol/L
Plasma osmolality >305mOsmol/kg
Serum sodium >145mmol/L
Urinary specific gravity <1.005
How can you differentiate central diabetes insipidus from cerebral salt wasting syndrome?
Cerebral salt wasting syndrome also causes polyuria and dehydration as a result of loss of urinary sodium, but with hyponatraemia and a plasma osmolality of less than 280mOsmol/kg
What are the characteristic tumour sites for Multiple Endocrine Neoplasia 2?
Phaeochromocytoma (adrenal)
Medullary cell thyroid
Parathyroid
What are the characteristic tumour sites for Multiple Endocrine Neoplasia 1?
Three Ps
Pituitary
Parathyroid
Pancreas
What are the biochemical findings associated with adrenal insufficiency?
Hyponatraemia
Hyperkalaemia
Hypoglycaemia
Acidosis
What are the typical fluid and electrolyte deficits seen in DKA?
Sodium - 7-10 mmol/kg
Chloride - 3-5 mmol/kg
Potassium - 3-5 mmol/kg
Water - 100 ml/kg
So your 100kg patient can need up to 10 litres of water and 500 mmol of potassium replacement.
What are the diagnostic criteria for DKA
BM >11mmol/litre
Ketones >3mmol/litre
Bicarbonate <15mmol/litre
What are the pathophysiological changes seen in DKA?
Hyperglycaemia:
Increase in glucagon, cortisol and growth hormone
Increased gluconeogenesis
Increased glycogenolysis
Ketonaemia:
Increased lipolysis
Beta oxidation of fatty acids to keto acids
Acidosis:
Dissociation of keto acids
High anion gap metabolic acidosis
Glycosuria:
Proximal convoluted tubule cannot reabsorb glucose from tubular fluid
What is the definition of resolution of DKA?
pH >7.3
Bicarbonate >15 mmol/litre
Ketones <0.6 mmol/litre
What are the serious complications of DKA?
Hypokalaemia
Hypoglycaemia
Acute Kidney Injury
Cerebral oedema
Death
What are the three endogenous ketone bodies?
3-beta-hydroxybutyrate*
Acetoacetate
Acetone
*This is the main one, and is usually the one measured in point of care testing
What are the risk factors for cerebral oedema in children with DKA?
Young age
New diagnosis of diabetes
Hyperventilation (hypocapnoea) at presentation
Longer duration of symptoms
Increased urea
Lower pH
Bicarbonate required for acidosis management
Slower increase in sodium in response to treatment
Insulin administration within the first hour of fluid resuscitation
Higher volumes of fluid
