Ca+2
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Introduction
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
- extracellular Ca+2
- 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
- free or ionized Ca+2 is biologically active
- 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
- a Ca+2 sensing receptor is expressed on parathyroid cells, renal tubular cells & others & serves to monitor ionized Ca+2 concentrations
- intracellular Ca+2
- 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
- intraneuronal Ca+2 is typically 100 nM (0.1 mM)
- dietary Ca+2 & Ca+2 balance:
- normal dietary Ca+2 varies between 400-1500 mg/day
- 150-200 mg is excreted in the urine
- ~500 mg is deposited in & released from bone each day from bone remodeling
- bone serves as a reservoir for extracellular Ca+2 in the face of diminished dietary supply
- 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
- excess absorbed Ca+2 is excreted in the urine as a result of diminished levels of PTH
- 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
More general terms
More specific terms
Additional terms
- 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)
Component of
- ca+2/gamma hydroxybutyrate/k+/mg+2/na+
- ca+2/vitamin d
- ca+2/iodine/isoproterenol
- ca+2/calcium phosphate/magnesium carbonate/potassium chloride
- ascorbate/ca+2/cobalamin/folic acid/iron/polysaccharide iron complex
- calcium salt (Ca+2 salt)
- sevelamer (Renagel, Genzyme, Renvela)
References
- ↑ Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998
- ↑ Prescriber's Letter 14(3): 2007 Calcium and Vitamin D Supplementation: Who Needs It? Detail-Document#: http://prescribersletter.com/(5bhgn1a4ni4cyp2tvybwfh55)/pl/ArticleDD.aspx?li=1&st=1&cs=&s=PRL&pt=3&fpt=25&dd=230304&pb=PRL (subscription needed) http://www.prescribersletter.com
- ↑ National Cancer Institute: Calcium and Cancer Prevention https://www.cancer.gov/about-cancer/causes-prevention/risk/diet/calcium-fact-sheet
- ↑ 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