Hyperparathyroidism

Question 1

Definition (primary)

Answer 1

Primary Hyperparathyroidism - increased secretion of PTH unrelated to the plasma calcium concentration

Question 2

Definition (secondary)

Answer 2

Secondary Hyperparathyroidism - increased secretion of PTH secondary to hypocalcaemia

Question 3

Definition (tertiary)

Answer 3

Tertiary Hyperparathyroidism - autonomous PTH secretion following chronic secondary hyperparathyroidism

Question 4

Aetiology/Risk factors (primary)

Answer 4

o Parathyroid adenoma
o Parathyroid hyperplasia
o Parathyroid carcinoma
o MEN syndrome

Question 5

Aetiology/Risk factors (secondary)

Answer 5

o Chronic renal failure

o Vitamin D deficiency

Question 6

Presenting symptoms and signs on physical examination (primary)

Answer 6

· Primary - many patients have mild hypercalcaemia and may be asymptomatic

· Symptoms/Signs of hyperclacaemia:
o Polyuria
o Polydipsia
o Renal calculi
o Bone pain/Osteoporosis
o Abdominal pain
o Nausea
o Constipation
o Psychological depression
o Lethargy

Question 7

Presenting symptoms and signs on physical examination (secondary)

Answer 7

· Secondary - may present with signs/symptoms of HYPOcalcaemia or of the underlying cause (e.g. renal failure, vitamin D deficiency)

Question 8

Investigations

Answer 8

· U&Es

· Serum calcium (high in primary and tertiary, low/normal in secondary)
· Serum phosphate (low in primary and tertiary, high in secondary)
· Albumin (elevated)
· ALP
· Vitamin D
· PTH

· Primary Hyperparathyroidism
o Hyperchloraemic acidosis
o Normal anion gap
o Due to PTH inhibition of renal reabsorption of bicarbonate
o Urine - high PTH in the presence of high calcium can also be caused by familial hypocalciuric hypercalcaemia (FHH)
· Calcium: creatinine clearance ratio can help differentiate between primary hyperparathyroidism and FHH

· Renal ultrasound - can visualise renal calculi

Question 9

Management plan (acute hypercalcaemia)

Answer 9

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

Question 10

Management plan (surgical)

Answer 10

o Subtotal parathyroidectomy

o Total parathyroidectomy

Question 11

Management plan (secondary)

Answer 11

o Treat underlying cause (e.g. renal failure)

o Calcium and vitamin D supplements may be needed

Question 12

Possible complications (primary)

Answer 12

o Increased bone resorption

o Increased tubular calcium reabsorption

o Increased 1a-hydroxylation of vitamin D

o All of these lead to hypercalcaemia

Question 13

Possible complications (secondary)

Answer 13

o Increased stimulation of osteoclasts and increased bone turnover

o This leads to osteitis fibrosa cystica

Question 14

Possible complications (surgery)

Answer 14

o Hypocalcaemia

o Recurrent laryngeal nerve palsy

Question 15

Prognosis

Answer 15

· Primary - surgery is curative for benign disease in most cases

· Secondary or Tertiary - same prognosis as chronic renal failure