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Ca+2

The average adult body contains 1 kg of Ca+2, 99% of which is deposited in bone in the form of hydroxyapatite. The remainder is found in soft tissues & the extracellular space. Physiology: 1) extracellular Ca+2 a) normal serum concentration of Ca+2 is 9.0-10.5 mg/dL (2.2-2.6 mmol/L) with 50-60% bound to serum protein or complexed with citrate or phosphate b) free or ionized Ca+2 is biologically active c) plasma ionized Ca+2 (~ 1 mmol/L) is regulated under tight control by PTH, 1,25-(OH)2 vit D3, & to a lesser extent calcitonin, varying < 0.1 mg/dL under normal conditions d) a Ca+2 sensing receptor is expressed on parathyroid cells, renal tubular cells & others & serves to monitor ionized Ca+2 concentrations 2) intracellular Ca+2 a) intracellular Ca+2 is present in much lower concentrations than extracellular Ca+2 (2-4 orders of magnitude lower), except for intracellular compartmentalized stores of Ca+2 in the endoplasmic reticulum & mitochondria b) intraneuronal Ca+2 is typically 100 nM (0.1 mM) 3) dietary Ca+2 & Ca+2 balance: a) normal dietary Ca+2 varies between 400-1500 mg/day b) 150-200 mg is excreted in the urine c) ~500 mg is deposited in & released from bone each day from bone remodeling d) bone serves as a reservoir for extracellular Ca+2 in the face of diminished dietary supply e) diminished intake of Ca+2 stimulates production of PTH by the parathyroid thus enhancing bone resorption, renal tubular reabsorption of Ca+2, & 1,25-(OH)2 vit D3 production by the kidney which in turn stimulates Ca+2 absorption from the intestine f) excess absorbed Ca+2 is excreted in the urine as a result of diminished levels of PTH g) see calcium carbonate for calcium supplementation Laboratory: - calcium measurement - calcium in stone - calcium in hair - calcium in erythrocytes - calcium in parenteral nutrition - calcium in water - calcium in body fluid - calcium in amniotic fluid - calcium in blood - calcium in CSF - calcium in dialysis fluid - calcium in peritoneal dialysis fluid - calcium in gastric fluid - calcium in peritoneal fluid - calcium in pleural fluid - calcium in saliva - calcium in semen - calcium in serum/plasma - calcium in stool - calcium in synovial fluid - calcium in urine - ionized Ca+2 in body fluid - ionized Ca+2 in blood - ionized Ca+2 in serum/plasma

Related

Ca+2 sensor or Ca+2 sensing receptor calcinosis calcitriol; 1,25-dihydroxycholcalciferol; 1,25-dihydroxyvitamin D3 calcium (Ca+2) in 24 hour urine calcium (Ca+2) in serum/plasma calcium [Ca] dietary calcium hydroxyapatite ionized Ca+2 in serum/plasma/blood parathyroid hormone; parathormone; parathyrin (PTH)

Specific

calcium acetate (PhosLo) calcium supplement

General

divalent cation bioagent

Properties

Database Correlations

PUBCHEM correlations Kegg hsa/hsa04210

References

  1. Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998
  2. Prescriber's Letter 14(3): 2007 Calcium and Vitamin D Supplementation: Who Needs It? Detail-Document#: 230304 (subscription needed) http://www.prescribersletter.com
  3. National Cancer Institute: Calcium and Cancer Prevention https://www.cancer.gov/about-cancer/causes-prevention/risk/diet/calcium-fact-sheet
  4. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) Eating, Diet, & Nutrition for Kidney Stones https://www.niddk.nih.gov/health-information/urologic-diseases/kidney-stones/eating-diet-nutrition

Component-of

ascorbate/ca+2/cobalamin/folic acid/iron/polysaccharide iron complex ca+2/calcium phosphate/magnesium carbonate/potassium chloride ca+2/gamma hydroxybutyrate/k+/mg+2/na+ ca+2/iodine/isoproterenol ca+2/vitamin d calcium salt (Ca+2 salt) sevelamer (Renagel, Genzyme, Renvela)