hypercalcaemia

see also calcium

• primary hyperparathyroidism
• hypercalcaemia of malignancy - bone metastases / SCC lung / Ca kidney / multiple myeloma / lymphoma
• sarcoidosis/vitamin D intoxication/milk-alkali synd./immobilisation
• thyrotoxicosis/thiazides/familial hypocalciuric hypercalcaemia

• “bones, stones, groans & psychic moans”
• abdominal pain, nausea, vomiting, constipation, anorexia, 
• polyuria, polydipsia, hypotension, weakness, clouding of consciousness
• depression, weight loss, tiredness, pyrexia, renal calculi, renal failure, corneal calcification
• shortened QTc, sudden cardiac arrest

• hyperparathyroidism supported by:
  • low plasma phosphate/raised plasma chloride/low-normal plasma bicarb.
  • raised PTH if renal function normal
  • raised urinary c-AMP if renal function normal (but also in malingant cause)
  • XR hands - subperiosteal erosions; bone cysts elsewhere;
• malignancy supported by:
  • low plasma albumin, lowish chloride, hypokalaemia, alkalosis, raised phosphate, raised alk. phosphatase
• if albumin raised:
  • consider dehydration (raised urea) or cuffed specimen
• if albumin normal or low:
  • if phosphate low or normal & urea normal
    • ⇒ primary or tertiary hyperparathyroidism likely
  • if phosphate high or normal:
    • if raised alkaline phosphatase:
      • bone metastases (most common primary: breast, kidney, lung, thyroid, prostate, ovary, colon)
      • sarcoidosis (serum ACE raised in hypercalcaemia due to sarcoidosis)
      • thyrotoxicosis
    • if normal alkaline phosphatase:
      • myeloma (plasma protein raised)
      • vit D excess (serum 25-OH vitD raised in Vit.D intoxication)
      • milk-alkali syndrome
      • (sarcoidosis, thyrotoxicosis, raised bicarb)
• CXR, bone scan for metastases
• AXR - renal/ureteric calculi or nephrocalcinosis - hyperPTH/sarcoidosis
• CT abdo to excl. renal carcinoma if microhaematuria present

• see also: hypercalcaemia of malignancy ¹⁾
• Rx underlying cause
• if Ca > 3.5mM or hypotensive, severe abdominal pain, vomiting, pyrexia, clouding of consciousness:
  • rehydrate with IV NSaline eg. 4-6L over 24h as needed
  • monitor Na, K, Mg & urea
  • correct hypokalaemia & hypomagnesaemia 
  • frusemide / furosemide / Lasix 125mg slow IV (< 4mg/min) up to every 3h, monitoring CVP, U&E
  • salmon calcitonin 8U/kg 8h IM to inhibit osteoclasts
  • plicamycin 
  • if hypercalcaemia of malignancy:
    • bisphosphonates eg. pamidronate is more effective than etidronate
  • if multiple myeloma, sarcoid, vit D overdose:
    • hydrocortisone 250mg/24h IVI may be effective
  • cinacalcet:
    • increases the sensitivity of a sensor that responds to serum calcium concentration & then secretes parathyroid hormone, thus it reduces parathyroid hormone secretion which in turn reduces serum calcium levels.
    • introduced in Australia in 2005 as oral tablets taken once daily for secondary hyperparathyroidism, but may need bd dosing for primary hyperparathyroidism or parathyroid carcinoma.
• if primary hyperparathyroidism ⇒ neck exploration by experienced neck surgeon, etc;