Zn/Fe deficiency

[cpl__0]

  Patient is 30y male with family history of autoimmune thyroid disease
  and NIDDM.  Symptoms include severe fatigue, hyperpigmentation, minor
  alopecia, loss of appetite, bilateral peripheral neuropathies, muscle
  weakness and joint pain, and cognitive dysfunction.
  Thyroid and adrenal function tests show no abnormalities.  B12 normal.
  Alkaline phosphatase, AST, ALT, and WBC are low to borderline low.
  AST/ALT ratio of 0.7.  
  Transferrin and Fe normal.  Ferritin at 19 (nl range of 30-233).
  Hematology panel shows no abnormalities other than borderline
  low WBC.  Plasma Zn at 52 (nl 75-291), and may explain low AlkP,
  a Zn dependent metalloenzyme.
  Diet is well balanced and includes red meat.  Suggestions?
  Possible malabsorption problem?  Does not look like Celiac/Sprue.
  Zn and Fe appear to compete for same transporter in gut.  Are
  there hereditary abnormalities associated with Zn/Fe transporter
  other than acrodermatitis enteropathica?
  Many thanks,
  cpl
Dear cpl,
Although a low serum zinc level and low alkaline phosphatase may indicate zinc depletion, plasma/serum Zn does not necessarily reflect reductions in dietary zinc intake or changes in whole-body Zn. Stress, infection, food intake, short-term fasting and the hormonal state all appear to influence the distribution of zinc among the tissues and thereby alter the amount in plasma. Low serum zinc levels have also been associated with a variety of high-risk clinical situations such as pregnancy, elderly, alcoholics, diabetes, sickle cell anemia, chronic infections, trauma, acquired immune deficiency syndrome and malabsorption (such as in inflammatory bowel disease). A number of medications contribute to secondary Zn deficiency as well (for example: diuretics, chemotherapy, anti-convulsants, chelating agents).
The clinical manifestations of severe zinc deficiency include: growth retardation, delayed sexual maturation, low sperm counts, alopecia, skin lesions, nail changes, immune deficiencies, delayed wound healing, behavior disturbances, night blindness, impaired taste, impaired appetite, lack of dark adaptation.
You mention several of these in your clinical description.
You also mentioned zinc's interaction with iron. Because both elements have a mutual affinity for a particular carrier protein, competition for binding to that protein can result. In fact, iron can interfere with zinc absorption when elemental Zn is given in solution but it has little effect on the utilization of Zn from a complex meal. Some human studies have suggested that supplemental iron can lower serum zinc levels during pregnancy but for the most part this is not a clinically important zinc-nutrient interaction. More important is zinc's effect on copper absorption. Large quantities of zinc can interfere with copper bioavailability because zinc induces the synthesis of metallothionein, a copper binding ligand. Increased metallothionein will bind to copper and sequester it making it unavailable for absorption. In fact, this is the basis for using high doses of zinc in the treatment of Wilson's disease (a liver disease characterized by copper overload).
Acrodermatitis enteropathica is a rare, inherited, autosomal recessive disease. The basic defect in acrodermatitis enteropathica is impaired intestinal uptake and transfer of Zn. Another syndrome of altered Zn metabolism is found in lactating women. The condition results from an inability of the mother's mammary gland to secrete normal quantities of zinc into her milk.
Recommended daily oral intake in adult males is 15mg/d and for adult females 12 mg/d. Good sources of zinc are meats, liver, eggs and seafood. I hope you find this information helpful.
This response is being provided for general informational purposes only and should not be considered medical advice or consultation. Always check with your personal physician when you have a question pertaining to your health.
If you want to be seen at our institution please call 1-800-653-6568, our Referring Physicians' Office and make an appointment to see Dr. Muszkat, one of our experts in Gastroenterology.
HFHSM.D.-ym
*Keywords: zinc