Editorial Note
Zinc is an essential trace element that functions as a cofactor for certain enzymes involved in metabolism and cell growth;[2,3] zinc supports immune function, protein metabolism, development of the gastrointestinal tract, and genetic processes.[3] Acute zinc deficiency disorder is characterized by dermatitis around the limbs and body orifices, diarrhea, and impaired immune function, whereas chronic zinc deficiency disorder can lead to liver or kidney failure.[2] A rare genetic disorder, acrodermatitis enteropathica, shares the same clinical manifestations as acute zinc deficiency disorder but is a metabolic disorder of zinc absorption. Zinc is a standard component in PN. Premature infants administered PN require 400 μg/kg/body weight/day of zinc to maintain serum levels and promote growth, whereas 200 μg/kg/body weight/day of zinc is sufficient for full-term infants on PN.[4] Additionally, PN might be needed for prolonged periods for very low birth weight infants (<1,500 g) and infants with chronic gastrointestinal dysfunction.
Studies have reported progressively decreasing serum zinc levels among infants on zinc-deficient PN, particularly premature infants and low birth weight infants.[3,5] Although zinc deficiency disorder can have serious health implications among all age groups, infants are particularly vulnerable because their systemic zinc reserves are not fully developed and they are totally dependent on breast milk or formula. Therefore, the American Society for Clinical Nutrition recommends adding injectable zinc to PN for all infants and children, with priority for those who are premature, have low birth weight, or have chronic gastrointestinal dysfunction.[4]
Zinc deficiencies among infants are difficult to identify for multiple reasons, including nonspecific signs and symptoms. The most common signs of zinc deficiency disorder include dermatitis and growth impairment, which can be attributed to multiple causes. Zinc deficiency disorder–associated dermatitis, which is a physical manifestation, is present in only the most severe cases. For premature infants, withdrawl of the amount of blood required to measure the serum zinc level might compromise the health of the infant; therefore, routine testing is not performed, which might explain, in part, why no other cases were reported.
Physicians who prescribe PN should recognize the potential risks for micronutrient deficiency, including zinc deficiency, among premature infants who require increased amounts or are unable to receive adequate doses. During shortages, clinicians might need to reserve micronutrients for the most vulnerable populations. According to FDA, shortages also are ongoing for other PN micronutrient components (e.g., selenium, chromium, and copper); FDA is working with manufacturers to prioritize which micronutrients to produce and to identify other sources for the micronutrients. Until the manufacture of these micronutrients increases, shortages will continue. Hospitals with limited stocks of injectable zinc should consider reserving available supplies for infants with the highest risk for deficiency. Whenever PN without the standard micronutrients is administered to patients, either as a result of shortages or other considerations, monitoring for signs and symptoms of micronutrient deficiencies is recommended. Health-care providers should always consider the specific clinical situation when applying these guidelines for individual clinical care.
Acknowledgments
Billie Lou Short, MD, Dept of Neonatology, Children's National Medical Center, Washington, DC. Valerie Jensen, Susan Lance, PhD, Andrei Perlloni, PhD, Food and Drug Administration. Jim Couto, MA, American Academy of Pediatrics. Diana Bensyl, PhD, Scientific Education and Professional Development Office, CDC.
Morbidity and Mortality Weekly Report. 2014;63(2):35-37. © 2014 Centers for Disease Control and Prevention (CDC)
