IN UK THE ESTIMATED AVERAGE REQUIREMENT FOR ADULTS IS 525 MG (13.1 MMOL) DAILY AND THE REFERENCE NUTRIENT INTAKE (RNI) FOR ADULTS IS 700 MG (17.5 MMOL) DAILY. IN THE USA IT IS 800 MG DAILY FOR ADULTS AGED OVER 25 YEARS & FOR ADULTS AGED UP TO 50 YEARS THE ADEQUATE INTAKE IS 1 G DAILY, AND FOR THOSE 51 YEARS OR OLDER, IT IS 1.2 G DAILY.
SIMPLE DEFICIENCY STATES:
CALCIUM SALTS MAY BE GIVEN BY MOUTH, USUALLY IN DOSES OF 10 TO 50MMOL (I400 MG TO 2 G) OF CALCIUM DAILY ADJUSTED TO THE INDIVIDUAL PATIENT'S REQUIREMENTS.
SEVERE ACUTE HYPOCALCAEMIA OR HYPOCALCAEMIC TETANY:
PARENTERAL ADMINISTRATION IS NECESSARY, GENERALLY BY SLOW INTRAVENOUS INJECTION OR CONTINUOUS INFUSION OF CALCIUM CHLORIDE OR CALCIUM GLUCONATE. A TYPICAL DOSE IS 2.25 MMOL OF CALCIUM BY SLOW INTRAVENOUS INJECTION, EITHER REPEATED AS REQUIRED, OR FOLLOWED BY CONTINUOUS INTRAVENOUS INFUSION OF ABOUT 9 MMOL DAILY. 2.25 MMOL OF CALCIUM IS PROVIDED BY 10 ML OF CALCIUM GLUCONATE 10%.
SEVERE HYPERKALAEMIA:
INTRAVENOUS CALCIUM SALTS ARE USED TO REVERSE THE TOXIC CARDIAC EFFECTS OF POTASSIUM IN THE EMERGENCY TREATMENT OF SEVERE HYPERKALAEMIA.
SEVERE HYPENNAGNESAEMIA :
AS AN ANTIDOTE TO MAGNESIUM IN SEVERE HYPENNAGNESAEMIA 2.25 TO 4.5 MMOL OF CALCIUM (10 TO 20 ML OF CALCIUM GLUCONATE 10%) IS USED.
HYPERPHOSPHATAEMIA OR IN PATIENTS WITH CHRONIC RENAL FAILURE:
CALCIUM CARBONATE OR ACETATE ARE EFFECTIVE PHOSPHATE BINDERS AND ARE GIVEN BY MOUTH TO REDUCE PHOSPHATE ABSORPTION FROM THE GUT IN PATIENTS WITH HYPERPHOSPHATAEMIA; THIS IS PARTICULARLY RELEVANT TO PATIENTS WITH CHRONIC RENAL FAILURE IN ORDER TO PREVENT THE DEVELOPMENT OF RENAL OSTEODYSTROPHY. THE INITIAL DOSE OF CALCIUM CARBONATE IS 2.5 G DAILY TITRATED TO A MAXIMUM OF 17 G DAILY.
BONE DISEASE:
DOSES OF I TO 3 G OF CALCIUM DAILY ARE USED IN
OSTEOMALACIA & RICKETS & AS AN ADJUNCT IN THE MANAGEMENT OF OSTEOPOROSIS.
CALCIUM CARBONATE, ADMINISTERED BY MOUTH, IS ALSO WIDELY USED FOR ITS ANTACID PROPERTIES.