Hyperparathyroidism

Question 1

Define primary:

Answer 1

increased secretion of PTH unrelated to the plasma calcium concentration

Question 2

Define secondary:

Answer 2

• increased secretion of PTH secondary to hypocalcaemia

Question 3

Define tertiary:

Answer 3

autonomous PTH secretion (despite high calcium) following chronic secondary hyperparathyroidism – glands undergo hyperplastic or adenomatous changes.

Question 4

Aetiology/risk factors of primary:

Answer 4

o Parathyroid adenoma 80%
o Parathyroid hyperplasia 20%
o Parathyroid carcinoma <0.5%
o MEN syndrome

Question 5

Aetiology/risk factors of secondary:

Answer 5

o Chronic renal failure

o Vitamin D deficiency – causes reduced calcium absorption in gut hence hypocalcaemia

Question 6

Epidemiology:

Answer 6

• Primary - incidence of 5/100,000
• Twice as common in FEMALES
• Peak incidence: 40-60 yrs

Question 7

Symptoms/signs of primary:

Answer 7

•	Primary - many patients have mild hypercalcaemia and may be asymptomatic 
•	Symptoms/Signs of hypercalcaemia:
o	Polyuria
o	Polydipsia
o	Renal calculi 
o	Bone pain 
o	Abdominal pain 
o	Nausea
o	Constipation 
o	Psychological depression 
o	Lethargy 
o	Pancreatitis
o	Duodenal ulcers

Question 8

Symptoms/signs of secondary:

Answer 8

CATS go numb:

Convulsions
Arrhythmias
Tetany
Paraesthesia in hands, mouth, feet and lips
Chvostek’s sign (tap facial nerve just below zygomatic arch and see twitching) and trousseau’s sign (inflation of BP cuff for several minutes induces carpopedal spasm)

Question 9

Investigations:

Answer 9

•	U&Es
•	Serum calcium (high in primary and tertiary, low/normal in secondary)
•	Serum phosphate (low in primary and tertiary, high in secondary)
•	Albumin
•	ALP
•	Vitamin D 
•	PTH - high
•	Primary Hyperparathyroidism
o	Hyperchloraemic acidosis 

• Renal ultrasound - can visualise renal calculi

Question 10

Management:

Answer 10

o IV fluids
o Avoid factors that exacerbate hypercalcaemia (e.g. thiazide diuretics)
o Maintain adequate hydration
o Moderate calcium and vitamin D intake

Surgical Management
o Subtotal parathyroidectomy
o Total parathyroidectomy

Secondary Hyperparathyroidism Management
o Treat underlying cause (e.g. renal failure)
o Calcium and vitamin D supplements may be needed

Question 11

Complications of primary:

Answer 11

o Increased bone resorption
o Increased tubular calcium reabsorption
o Increased 1-hydroxylation of vitamin D
o All of these lead to hypercalcaemia

Question 12

Complications of secondary:

Answer 12

o Increased stimulation of osteoclasts and increased bone turnover
o This leads to osteitis fibrosa cystica – seen on X-ray as subperiosteal erosions, cysts, brown tumours, pepper pot skull

Question 13

Complications of surgery:

Answer 13

o Hypocalcaemia
o HypoPTH
o Recurrent laryngeal nerve palsy

Question 14

Prognosis:

Answer 14

• Primary - surgery is curative for benign disease in most cases
• Secondary or Tertiary - same prognosis as chronic renal failure