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Calcium regulation in the human body. [6]The plasma ionized calcium concentration is regulated within narrow limits (1.3–1.5 mmol/L). This is achieved by both the parafollicular cells of the thyroid gland, and the parathyroid glands constantly sensing (i.e. measuring) the concentration of calcium ions in the blood flowing through them.
Calcium homeostasis. The plasma ionized calcium (Ca 2+) concentration is very tightly controlled by a pair of homeostatic mechanisms. [61] The sensor for the first one is situated in the parathyroid glands, where the chief cells sense the Ca 2+ level by means of specialized calcium receptors in their membranes.
The US Institute of Medicine (IOM) established Recommended Dietary Allowances (RDAs) for calcium in 1997 and updated those values in 2011. [6] See table. The European Food Safety Authority (EFSA) uses the term Population Reference Intake (PRIs) instead of RDAs and sets slightly different numbers: ages 4–10 800 mg, ages 11–17 1150 mg, ages 18–24 1000 mg, and >25 years 950 mg. [10]
Calcium-binding proteins have specific domains that bind to calcium and are known to be heterogeneous. One of the functions of calcium binding proteins is to regulate the amount of free (unbound) Ca 2+ in the cytosol of the cell. [1] The cellular regulation of calcium is known as calcium homeostasis.
Vitamin D increases absorption of calcium and phosphate in the intestinal tract, leading to elevated levels of plasma calcium, [4] and thus lower bone resorption. Calcitriol (1,25-dihydroxycholecalciferol) is the active form of vitamin D 3. [10] It has numerous functions involved in blood calcium levels.
Disorders of calcium metabolism occur when the body has too little or too much calcium. The serum level of calcium is closely regulated within a fairly limited range in the human body. In a healthy physiology, extracellular calcium levels are maintained within a tight range through the actions of parathyroid hormone , vitamin D and the calcium ...
Idiopathic hypercalcinuria (IH) is a condition including an excessive urinary calcium level with a normal blood calcium level resulting from no underlying cause. [1] IH has become the most common cause of hypercalciuria and is the most serious metabolic risk factor for developing nephrolithiasis . [ 1 ]
Familial hypocalciuric hypercalcemia (FHH) is an inherited condition that can cause hypercalcemia, a serum calcium level typically above 10.2 mg/dL; although uncommon. [1] It is also known as familial benign hypocalciuric hypercalcemia (FBHH) where there is usually a family history of hypercalcemia which is mild, a urine calcium to creatinine ratio <0.01, and urine calcium <200 mg/day ...