Zinc Flashcards
Why is gastric acidity important to the absorption of Zinc?
Zinc is hydrolyzed from a.a and nucleic acids via the actions of gastric HCL and other enzymes making it available for intestinal absorption (mostly in duodenum and jejunum). Therefore, a decreased in gastric acidity results in lower zinc availability.
How is Zn transported in the blood?
By albumin (70%) or alphamacroglobulins (20-40%). So diseases or physiological conditions characterized by hypoalbuminemia can impair hepatic release of Zn.
How does acute infections affect plasma Zn levels?
During infections, Zn is redistributed and results in hypozincemia. The extent and type of injury determine the duration and magnitude of the reduction (10-69%). In the acute phase responses, the secretion of cytokines like interleukin 1 and 6 act to increase the hepatic zinc uptake.
What factors can decreased zinc absorption?
1.Metallothionein (MT), protein responsible for the regulation of Zn. Synthesis is stimulated during inflammation, which utilizes Zn and reduced it’s absorption.
2. Phytic acid in grain fibers, and Ca supplements decreases Zn absorption by as much as 50%.
NB: large amounts of Zn can compete with Cu and Fe for absorption.
Certain milk proteins may have a negative impact on absorption as well.
What are the biochemical functions of Zn?
Zn biochemical function includes: catalytic. Zn is imp as a catalyst for enzymes in all 6 classes.
b) Structural: Zn has imp role in metalloenzymes.
c) Regulatory: It is involves in gene expression.
d) Involves in lipid peroxidation, apoptosis, cellular proliferation and differentiation, and immune function.
What are good sources of Zn? What is the DRI?
- Seafood, meats, greens and whole grains.
2. 11/9mg/day for 14-18 M/F, and 11/8 for M/F for all other groups.
Why diagnose of Zn deficiency is difficult?
it Is difficult because of the Zn redistribution during the acute phase response to infection, inadequate bio markers of Zn status and the diversity of clinical symptoms.
True/False: Zinc deficiency can cause glucose intolerance?
True although the underlying mechanism has not been identified.
Since Zn an Cu can compete for absorption, what levels of Zn supplementation could affect Cu deficiency?
25 to 150mg/day can induce a Cu deficiency.
What conditions indicate additional zinc supplementation because of additional losses?
Thermal injury and hypermetabolic states like traumatic brain injury (TBI)
2. Because of excessive GI losses like diarrhea, decubitus ulcers, and high fistula outputs.
What is the standard Zn treatment in Traumatic brain injury (TBI)?
220mg/daily.
What is the recommended daily parenteral supplementation for Zn?
2.5 - 5mg with additional 2mg/d for hypermetabolic pts (total of 6 -12mg/day) and extra 12mg/L of small bowel losses and 17mcg/kg of stool or ileostomy losses.
During systematic inflammatory response syndrome (SIRS), serum Zn will fall to about 1/2 normal and remain at that level until SIRS is resolved. What is indicated in this situation to differentiate between a declining plasma Zn due to acute phase rxt and declining levels associated with increased requirements.
By evaluating serum C-reactive protein, an acute phase protein, we could differentiate between the 2 conditions because elevated CRP levels are consistent with APR.
What are the typical recommendation for zinc for wound healing?
40mg ( 176mg zinc sulfate) for 10 days. The standard oral adult replacement dose is 220mg daily (50 mg elemental zinc).
