Endocrinology

Question 1

What are the clinical features of hypercalcaemia?

Answer 1

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

Question 2

Where are the parathyroid glands found?

Answer 2

• Two pairs of parathyroid glands
• Found in the superior and inferior poles of the thyroid

Question 3

What investigation is used to detect a suspected parathyroid adenoma?

Answer 3

• Technetium-99 m-sestamibi scintigraphy
• Nuclear medicine scan

Question 4

What are the physiological effects of excessive parathyroid hormone?

Answer 4

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

Question 5

What are the perioperative considerations in patients with hypercalcaemia?

Answer 5

• Lethargic or drowsy patients need less aanesthesia
  
  • Neuromuscular blockade may be potentiated by hypercalcaemia
  • Increased risk of cardiac arrhythmias

Question 6

What are the clinical features of acute hypocalcaemia?

Answer 6

• 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

Question 7

Which inherited endocrine conditions include hyperparathyroidism?

Answer 7

• Multiple endocrine neoplasia type 1 and 2A
  
  • Familial isolated hyperparathyroidism

Question 8

How much hydrocortisone is equivalent to 5mg prednisolone?

Answer 8

20mg

5mg of Prednisolone is equivalent to:

• 20mg Hydrocortisone
• 750mcg Dexamethasone
• 25mg Cortisone acetate
• 4mg Methylprednisolone

Question 9

How can you diagnose diabetes insipidus biochemically?

Answer 9

Urine osmolality <200mOsmol/kg
Urinary sodium 20-40mmol/L
Plasma osmolality >305mOsmol/kg
Serum sodium >145mmol/L
Urinary specific gravity <1.005

Question 10

How can you differentiate central diabetes insipidus from cerebral salt wasting syndrome?

Answer 10

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

Question 11

What are the characteristic tumour sites for Multiple Endocrine Neoplasia 2?

Answer 11

Phaeochromocytoma (adrenal)
Medullary cell thyroid
Parathyroid

Question 12

What are the characteristic tumour sites for Multiple Endocrine Neoplasia 1?

Answer 12

Three Ps

Pituitary
Parathyroid
Pancreas

Question 13

What are the biochemical findings associated with adrenal insufficiency?

Answer 13

Hyponatraemia
Hyperkalaemia
Hypoglycaemia
Acidosis

Question 14

What are the typical fluid and electrolyte deficits seen in DKA?

Answer 14

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.

Question 15

What are the diagnostic criteria for DKA

Answer 15

BM >11mmol/litre
Ketones >3mmol/litre
Bicarbonate <15mmol/litre

Question 16

What are the pathophysiological changes seen in DKA?

Answer 16

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

Question 17

What is the definition of resolution of DKA?

Answer 17

pH >7.3
Bicarbonate >15 mmol/litre
Ketones <0.6 mmol/litre

Question 18

What are the serious complications of DKA?

Answer 18

Hypokalaemia
Hypoglycaemia
Acute Kidney Injury
Cerebral oedema
Death

Question 19

What are the three endogenous ketone bodies?

Answer 19

3-beta-hydroxybutyrate*
Acetoacetate
Acetone
*This is the main one, and is usually the one measured in point of care testing

Question 20

What are the risk factors for cerebral oedema in children with DKA?

Answer 20

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