Hyperparathyroidism Flashcards
Define primary:
increased secretion of PTH unrelated to the plasma calcium concentration
Define secondary:
- increased secretion of PTH secondary to hypocalcaemia
Define tertiary:
autonomous PTH secretion (despite high calcium) following chronic secondary hyperparathyroidism – glands undergo hyperplastic or adenomatous changes.
Aetiology/risk factors of primary:
o Parathyroid adenoma 80%
o Parathyroid hyperplasia 20%
o Parathyroid carcinoma <0.5%
o MEN syndrome
Aetiology/risk factors of secondary:
o Chronic renal failure
o Vitamin D deficiency – causes reduced calcium absorption in gut hence hypocalcaemia
Epidemiology:
- Primary - incidence of 5/100,000
- Twice as common in FEMALES
- Peak incidence: 40-60 yrs
Symptoms/signs of primary:
• 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
Symptoms/signs of secondary:
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)
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 • ALP • Vitamin D • PTH - high • Primary Hyperparathyroidism o Hyperchloraemic acidosis
• Renal ultrasound - can visualise renal calculi
Management:
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
Complications of primary:
o Increased bone resorption
o Increased tubular calcium reabsorption
o Increased 1-hydroxylation of vitamin D
o All of these lead to hypercalcaemia
Complications of secondary:
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
Complications of surgery:
o Hypocalcaemia
o HypoPTH
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