### Abstract

Background: An improved understanding of copper metabolism is needed to derive more precise estimates of dietary requirements.

Objectives: The objectives were to validate a method for estimating endogenous losses of copper, test whether a simple model can predict true absorption from the plasma appearance of labeled copper, and develop a compartmental model for copper metabolism by using stable isotopes.

Design: A stable isotope of copper was intravenously administered to 6 men, and fecal samples were collected for 14 d. Four weeks later the study was repeated, but with an oral dose, and blood samples were collected for 7 d and fecal samples for 14 d.

Results: There was no significant difference (P = 0.48) in the estimated endogenous loss of copper calculated by using either the excreted intravenous dose ((x) over bar +/- SD: 32 +/- 5%) or the absorbed and excreted oral dose (35 +/- 2%). A simple mathematical model fitted to plasma isotope appearance data estimated true absorption to be 8 +/- 2% compared with 48-49% measured by fecal monitoring. A more complicated compartmental model predicted that, when newly absorbed copper first enters the blood, 74% is removed by the liver and 99% is bound to ceruloplasmin in the plasma. The exchangeable pool of copper was estimated to be 43 +/- 30 mg. Daily endogenous losses were predicted to be 2.4 mg.

Conclusions: The results showed that fecal monitoring is the only method that can reliably measure labeled copper absorption, and it is not necessary to administer an intravenous dose of copper to estimate endogenous losses. The compartmental model provides new insights into human copper metabolism.

Original language | English |
---|---|

Pages (from-to) | 807-813 |

Number of pages | 7 |

Journal | The American Journal of Clinical Nutrition |

Volume | 81 |

Issue number | 4 |

Publication status | Published - Apr 2005 |

### Keywords

- copper
- stable isotopes
- men
- compartmental modeling
- endogenous losses
- true absorption
- exchangeable copper
- mass spectrometry
- iron absorption
- isotope CU-65
- blood plasma
- zinc
- kinetics
- calcium
- tracer

### Cite this

*The American Journal of Clinical Nutrition*,

*81*(4), 807-813.

**Use of mathematical modeling to study copper metabolism in humans.** / Harvey, L J ; Dainty, J R ; Hollands, W J ; Bull, V J ; Beattie, J H ; Venelinov, T I ; Hoogewerff, J A ; Davies, I M ; Fairweather-Tait, S J .

Research output: Contribution to journal › Article

*The American Journal of Clinical Nutrition*, vol. 81, no. 4, pp. 807-813.

}

TY - JOUR

T1 - Use of mathematical modeling to study copper metabolism in humans

AU - Harvey, L J

AU - Dainty, J R

AU - Hollands, W J

AU - Bull, V J

AU - Beattie, J H

AU - Venelinov, T I

AU - Hoogewerff, J A

AU - Davies, I M

AU - Fairweather-Tait, S J

PY - 2005/4

Y1 - 2005/4

N2 - Background: An improved understanding of copper metabolism is needed to derive more precise estimates of dietary requirements. Objectives: The objectives were to validate a method for estimating endogenous losses of copper, test whether a simple model can predict true absorption from the plasma appearance of labeled copper, and develop a compartmental model for copper metabolism by using stable isotopes. Design: A stable isotope of copper was intravenously administered to 6 men, and fecal samples were collected for 14 d. Four weeks later the study was repeated, but with an oral dose, and blood samples were collected for 7 d and fecal samples for 14 d. Results: There was no significant difference (P = 0.48) in the estimated endogenous loss of copper calculated by using either the excreted intravenous dose ((x) over bar +/- SD: 32 +/- 5%) or the absorbed and excreted oral dose (35 +/- 2%). A simple mathematical model fitted to plasma isotope appearance data estimated true absorption to be 8 +/- 2% compared with 48-49% measured by fecal monitoring. A more complicated compartmental model predicted that, when newly absorbed copper first enters the blood, 74% is removed by the liver and 99% is bound to ceruloplasmin in the plasma. The exchangeable pool of copper was estimated to be 43 +/- 30 mg. Daily endogenous losses were predicted to be 2.4 mg. Conclusions: The results showed that fecal monitoring is the only method that can reliably measure labeled copper absorption, and it is not necessary to administer an intravenous dose of copper to estimate endogenous losses. The compartmental model provides new insights into human copper metabolism.

AB - Background: An improved understanding of copper metabolism is needed to derive more precise estimates of dietary requirements. Objectives: The objectives were to validate a method for estimating endogenous losses of copper, test whether a simple model can predict true absorption from the plasma appearance of labeled copper, and develop a compartmental model for copper metabolism by using stable isotopes. Design: A stable isotope of copper was intravenously administered to 6 men, and fecal samples were collected for 14 d. Four weeks later the study was repeated, but with an oral dose, and blood samples were collected for 7 d and fecal samples for 14 d. Results: There was no significant difference (P = 0.48) in the estimated endogenous loss of copper calculated by using either the excreted intravenous dose ((x) over bar +/- SD: 32 +/- 5%) or the absorbed and excreted oral dose (35 +/- 2%). A simple mathematical model fitted to plasma isotope appearance data estimated true absorption to be 8 +/- 2% compared with 48-49% measured by fecal monitoring. A more complicated compartmental model predicted that, when newly absorbed copper first enters the blood, 74% is removed by the liver and 99% is bound to ceruloplasmin in the plasma. The exchangeable pool of copper was estimated to be 43 +/- 30 mg. Daily endogenous losses were predicted to be 2.4 mg. Conclusions: The results showed that fecal monitoring is the only method that can reliably measure labeled copper absorption, and it is not necessary to administer an intravenous dose of copper to estimate endogenous losses. The compartmental model provides new insights into human copper metabolism.

KW - copper

KW - stable isotopes

KW - men

KW - compartmental modeling

KW - endogenous losses

KW - true absorption

KW - exchangeable copper

KW - mass spectrometry

KW - iron absorption

KW - isotope CU-65

KW - blood plasma

KW - zinc

KW - kinetics

KW - calcium

KW - tracer

M3 - Article

VL - 81

SP - 807

EP - 813

JO - The American Journal of Clinical Nutrition

JF - The American Journal of Clinical Nutrition

SN - 0002-9165

IS - 4

ER -