Hyperparathyroidism

Question 1

Definition of hyperparathyroidism

Answer 1

There are 3 different types:
◦ Primary Hyperparathyroidism: Occurs when there is an increased secretion of PTH UNRELATED to calcium concentration

						◦ Secondary hyperparathyroidism: Increased PTH secretion SECONDARY to low calcium (related to vitamin D deficiency)

						◦ Tertiary hyperparathyroidism: More rare, occurs due to chronic renal failure and chronically low calcium that results in autonomous PTH secretion; hence leading to hypercalcaemia

Question 2

Aetiology of the different types of hyperparathyroidism

Answer 2

Primary Hyperparathyroidism:
• Most common cause is a single benign parathyroid adenoma
• Another cause may be overstimulation of the parathyroid gland by Lithium therapy
• This would result in high PTH (not suppressed by the resultant high calcium)
• There would also be a low phosphate due to the high PTH inhibiting the sodium phosphate transporter in the kidneys

Secondary Hyperparathyroidism:
◦ Most common cause is Vitamin D deficiency. (Can be due to diet, reduced sunlight or renal failure)
◦ Other causes are chronic renal failure
◦ This would lead to low calcium and hence an increased PTH (normal physiological response to hypocalcaemia)

Question 3

Pathophysiology of hyperparathyroidism

Answer 3

Primary
• A high PTH can lead to an over-stimulation of bone resorption

Secondary:
• Any deficiency in vitamin D causes a decrease in the absorption of calcium from the intestines. This would lower the serum calcium levels; hence lead to an increased PTH secretion response

Question 4

History and Examination of different types of hyperparathyroidism

Answer 4

PRIMARY:
• Most are asymptomatic: diagnosed incidentally
• Can show signs of hypercalcaemia:
◦ Myalgia
◦ Depression
◦ Fatigue
◦ Renal stones
◦ Constipation
◦ Abdominal pain
• Bone pain: due to high PTH resulting in increased bone resorption. OSTEOPOROSIS or osteopenia is commonly seen

SECONDARY:
• Features of chronic kidney disease: discoloured skin, bruising, pruritus, fluid overload, increased blood pressure
• Malbsorption syndrome features: may be the reason to the decreased vitamin D and calcium absorption
• Tingling or paresthaesia: due to hypocalcaemia
• Chvostek’s sign or Trousseeau’s sign
• Osteomalacia bone pain: due to vitamin D deficiency

Question 5

Investigations for hyperparathyroidism

Answer 5

PRIMARY:
• Serum calcium: would be elevated
• PTH: would be elevated

• Phosphate: decreased
• ALP: increased due to bone resorption

SECONDARY:
• Serum calcium: would be elevated
• Serum PTH: would be elevated
• Serum 25-hydroxyvitamin D: would be decreased
• U&Es: would be raised due to likely kidney disease

Question 6

Treatment for the different types of hyperparathyroidism

Answer 6

HYPERCALCAEMIA TREATMENT:
1) IV fluids, avoid factors that exacerbate Hypercalcaemia (thiazide diuretics), hydration

PRIMARY:
1) Parathyroidectomy: For symptomatic hyperparathyroidism, this is 1st line

If ASYMPTOMATIC
1) Monitor

SECONDARY:
Can give VITAMIN D REPLACEMENT:
◦ If normal renal function, then give 25 hydroxy vitamin D (Can give Ergocalciferiol or Cholecaliferiol)
◦ If RENAL FAILURE, give Alfacalcidiol as they are unable to activate the 25 hydroxy vitamin D due to lack of 1 alpha hydroxylation

Treat underlying cause of Vitamin D deficiency (e.g increase UV exposure, or treat malabsorption)

If CKD may need phosphate restriction or phosphate binders

Question 7

Prevention of hyperparathyroidism

Answer 7

SECONDARY:
-Manage hypertension to help avoid CKD
-Early treatment of the CKD (with phosphate binders) and replacement of Vitamin D can reduce the effects of secondary Hyperparathyroidism

Question 8

Complications and prognosis of hyperparathyroidism

Answer 8

• Osteoporosis: due to high bone turnover due to high PTH
• Hypercalcaemia symptoms: stones, abdominal moans and psychic groans

Parathyroidectomy has a very high cure rate
Prognosis of secondary Hyperparathyroidism is dependent on underlying condition (usually chronic kidney disease)