Hyperparathyroidism Flashcards
Definition (primary)
Primary Hyperparathyroidism - increased secretion of PTH unrelated to the plasma calcium concentration
Definition (secondary)
Secondary Hyperparathyroidism - increased secretion of PTH secondary to hypocalcaemia
Definition (tertiary)
Tertiary Hyperparathyroidism - autonomous PTH secretion following chronic secondary hyperparathyroidism
Aetiology/Risk factors (primary)
o Parathyroid adenoma
o Parathyroid hyperplasia
o Parathyroid carcinoma
o MEN syndrome
Aetiology/Risk factors (secondary)
o Chronic renal failure
o Vitamin D deficiency
Presenting symptoms and signs on physical examination (primary)
· 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
Presenting symptoms and signs on physical examination (secondary)
· Secondary - may present with signs/symptoms of HYPOcalcaemia or of the underlying cause (e.g. renal failure, vitamin D deficiency)
Investigations
· 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
Management plan (acute hypercalcaemia)
o IV fluids
o Avoid factors that exacerbate hypercalcaemia (e.g. thiazide diuretics)
o Maintain adequate hydration
o Moderate calcium and vitamin D intake
Management plan (surgical)
o Subtotal parathyroidectomy
o Total parathyroidectomy
Management plan (secondary)
o Treat underlying cause (e.g. renal failure)
o Calcium and vitamin D supplements may be needed
Possible complications (primary)
o Increased bone resorption
o Increased tubular calcium reabsorption
o Increased 1a-hydroxylation of vitamin D
o All of these lead to hypercalcaemia
Possible complications (secondary)
o Increased stimulation of osteoclasts and increased bone turnover
o This leads to osteitis fibrosa cystica
Possible complications (surgery)
o Hypocalcaemia
o Recurrent laryngeal nerve palsy
Prognosis
· Primary - surgery is curative for benign disease in most cases
· Secondary or Tertiary - same prognosis as chronic renal failure