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What percentage of total body calcium is ionized?
A. 10%
B. 20%
C. 40%
D. 60%
E. 80%
The answer is C. Plasma Ca2+ is maintained at a concentration of 9 to 10.5 g/dL (2.2 to 2.4 mmol/L) as total calcium, with approximately 40% of this value comprising the protein-bound nonfiltratable fraction, and 10% is chelated. Ionized calcium accounts for 47% of the total circulating Ca2+ and ranges from 4 to 5 mg/dL (1.0 to 1.25 mmol/L)
[1]
. The extent of protein binding per deciliter of plasma is approximately 0.8 mg of Ca2+ for every 1 g of albumin and 0.16 mg for each 1 g of globulin. Furthermore, a threefold increase in serum phosphate or sulfate concentration results in a 10% decrease in serum Ca2+ concentration. In addition, the binding of Ca2+ to albumin is pH-dependent between pH 7 and 9. An acute increase or decrease in the pH by 0.1 units results in an increase or a decrease, respectively, of proteinbound Ca2+ of 0.2 mg/dL (0.05 mmol/L).[2]
Notes
Keywords
- Water, volume, and blood composition
- Homeostasis functions (Renal/Urinary)
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This is a paragraph with several references that I would like to practice using.
According to scientists, the Sun is pretty big.[1] The Moon, however, is not so big.[2]
Notes
This is an example of multiple references to the same footnote.[1]
Such references are particularly useful when citing sources, if different statements come from the same source.[1]
A concise way to make multiple references is to use empty ref tags, which have a slash at the end. Although this may reduce redundant work, please be aware that if a future editor removes the first reference, this will result in the loss of all references using the empty ref tags. <ref name="multiple" />
Notes
The text above gives the following result in the article (see also section below):
Note: name= identifiers require alphabetic characters; solely relying on numerals will generate an error message