Hyperparathyroidism

Question 1

def of hyperparathyroidism

Answer 1

primary: increased secretion of parathyroid hormone (PTH) unrelated to the plasma calcium concentration
secondary: increased secretion of PTH secondary to hypocalcaemia
tertiary: autonomous PTH secretion following chronic secondary hyperparathyroidism

Question 2

aetiology of hyperparathyroidism

Answer 2

primary
-parathyroid gland adenomas or hyperplasia
-80% single adenoma, 18% hyperplasia, 2% parathyroid carcinoma
secondary
-chronic renal failure
-vitamin D deficiency

Question 3

what is multiple endocrine neuroplasia

Answer 3

cause of primary hyperparathyroidism

Question 4

what is MEN type 1

Answer 4

mutation in menin gene on chromosome 11

• parathyroid adenoma/hyperplasia
• pancreatic endocrine tumours
• pituitary adenomas

Question 5

what is MEN type 2

Answer 5

mutation in RET gene on chromosome 10

• medullary thyroid carcinoma & phaeochromocytoma
• MEN-2A plus parathyroid hyperplasia
• MEN-2B plus mucosal neuromas on lips/tongue

Question 6

history & examination of hyperparathyroidism

Answer 6

primary
-mild hypercalcaemia
-present with polyuria, polydipsia, bone pain, abdominal pain, constipation
secondary
-symptoms & signs of hypocalcaemia
-symptoms & signs of underlying cause (chronic renal failure or vitamin D deficiency)

Question 7

investigations performed in suspected hyperparathyroidism

Answer 7

1 UEs
-serum calcium (high in primary/tertiary, low/normal in secondary)
-phosphate (low in primary/tertiary, high in secondary)
-high alkaline phosphatase
-low vitamin D in secondary
-hypercalcaemia & high PTH with parathyroid carcinoma
2 primary
-hyperchloraemic acidosis (normal anion gap) caused by PTH inhibition of renal tubular reabsorption of bicarbonate
3 urine
-ddx of primary hyperparathyroidism includes familial hypocalciuric hypercalcaemia (FHH)
-therefore in patients with high/inappropriately normal PTH, calcium: creatinine clearance ratio should be measured (24h urine collection)
-primary hyperparathyroidism (ratio>0.01), FHH (ratio<0.01)
4 renal ultrasound for renal calculi

Question 8

management of hyperparathyroidism

Answer 8

PRIMARY
acute hypercalcaemia
-IV fluids
conservative management
-for patients who do no meet surgical criteria
-avoid factors which can exacerbate hypercalcaemia (thiazide diuretics)
-maintain high hydration, moderate Ca & vit D
surgical
-partial/complete removal of parathyroid gland
-symptomatic patients
-asymptomatic patients with (Age <50yrs, Bone mineral density: Tscore <2.5, Calculi (renal stones), Creatinine clearance decreased by 30%, Difficult to do follow up regularly, Elevated serum calcium)
SECONDARY
-treat underlying cause
-calcium & vitamin D supplements

Question 9

complications of hyperparathyroidism

Answer 9

primary
-high PTH causes increased bone resorption, increased renal tubular calcium resorption, 1a-hydroxylation of vit D & intestinal calcium absorption
-causes hypercalcaemia
secondary
-increases stimulation of osteoclasts & bone turnover causing osteitis fibrosa cystica
complications of surgery
-hypocalcaemia

Question 10

prognosis of hyperparathyroidism

Answer 10

primary

-surgery is curative for benign disease