ZINC DEFICIENCY

ZINC DEFICIENCY - Jeremy Golding, MD
BASICS
DESCRIPTION
• Condition whose manifestations may involve growth retardation, hypogonadism, cell-mediated immune dysfunction, and skin changes related to decreased zinc levels
• System(s) Affected: Endocrine/metabolic; Nervous; Skin/exocrine
ALERT
Geriatric Considerations
• Zinc deficiency may cause poor night vision, leading to falls; poor wound healing or chronic ulcer; or loss of smell and taste, which may cause worsening nutrition.
• Elderly persons living in institutions may have low zinc intake.
Pediatric Considerations
Zinc deficiency may cause failure to thrive, and impair growth and development of secondary sexual characteristics.
Pregnancy Considerations
Requirements increase; deficiency may cause spontaneous abortion, inadequate weight gain.
GENERAL PREVENTION
• Adequate diet
• Supplementation when indicated (see "Medication")
EPIDEMIOLOGY
• Predominate age: All ages
• Predominant sex: Male = Female
Prevalence
In the US: Unknown
RISK FACTORS
• High milk consumption
• Low socioeconomic status
• Malabsorption syndromes
• Living in developing nations
• Strict vegetarian diet
Genetics
Usually acquired, but rarely caused by acrodermatitis enteropathica (autosomal recessive) and associated with sickle cell anemia (autosomal recessive).
ETIOLOGY
• Increased requirements
- Pregnancy
- Lactation
- Rapid growth phase in childhood
- Burns
- Major trauma
• Increased losses
- Diabetes
- Cirrhosis
- Renal disease
- Malabsorption states (e.g., inflammatory bowel diseases)
- Sickle cell anemia
• Decreased absorption
- Acrodermatitis enteropathica, an autosomal recessive deficiency in the enzyme required for intestinal absorption
- Geophagia
- Chelating agents
- Parasitism
- Diet high in phytates (plant fiber)
• Insufficient dietary intake
- Vegetarianism
- Parenteral hyperalimentation without supplementation
- Breast-feeding
- Suboptimal zinc conditions in diet (rare)
- Alcoholism
ASSOCIATED CONDITIONS
• Sickle cell anemia
• Malabsorption
• Parenteral hyperalimentation
• In the older patient, diabetes, cirrhosis, those taking diuretics


DIAGNOSIS
SIGNS AND SYMPTOMS
• Mild deficiency
- Hypogeusia
- Decreased dark adaptation
- Decreased lean body mass
• Moderate deficiency
- All the above
- Diarrhea
- Growth retardation
- Hypogonadism (especially male)
- Mental lethargy
- Anergy
- Rough skin
- Delayed wound healing
- Glucose intolerance
- Impaired cell-mediated immunity
• Severe deficiency
- All the above
- Bullous pustular dermatitis
- Weight loss
- Dwarfism
- Emotional instability
- Tremors
- Ataxia
- Alopecia
- Death
TESTS
Lab
• Plasma zinc levels decreased (in moderate to severe zinc deficiency). Levels 60 ug/L are strongly suggestive, but correction may be needed for low albumin, because most serum zinc is bound to albumin.
• Erythrocyte or leukocyte zinc levels more adequately assess tissue stores, but these are more costly and not widely available.
• Hair and fingernail levels are not useful.
DIFFERENTIAL DIAGNOSIS
• Congenital dwarfism
• Failure to thrive in infants
• Multiple micronutrient deficiencies
• Primary hypogonadism
• Mental retardation
TREATMENT
GENERAL MEASURES
Diet
• Balanced omnivorous diet, or vegetarian diet with supplementation
• Avoid excessive intake of foods with high phytate content (e.g., raw cereals, but ready-to-eat cereal may be the richest source of zinc from a plant product).
• Meat, seafood, milk, eggs, grains, legumes, nuts, and seeds are rich in zinc.
Activity
Full activity
MEDICATION (DRUGS)
• Zinc gluconate or zinc sulfate 25-50 mg PO q.i.d. for 6-9 months
• In adult patient, 4-6 mg of elemental zinc daily added to hyperalimentation, may increase to 12 mg q.i.d. if suspect ongoing heavy zinc losses (e.g., burns or major trauma)
• In pediatric patients, 0.02-0.04 mg zinc/kg/d in hyperalimentation
• Prenatal vitamins with minerals during pregnancy and lactation to prevent deficiency
• Precautions: Avoid large (>20 mg elemental zinc) parenteral doses
• Recommended daily intake is 15 mg, assuming no excessive losses
FOLLOW-UP
PROGNOSIS
Immediate improvement in clinical status with treatment. Full resolution in signs and symptoms
PATIENT MONITORING
Clinical status such as improved energy, weight gain, resolution of symptoms
REFERENCES
1. Abrams S. zinc deficiency and supplementation in children and adolescents. UpToDate; 2006.
2. Ronaghy H. The role of zinc in human nutrition. World Rev Nutr Diet. 1987;54:237-254.
3. Tasman-Jones C. Disturbances of trace mineral metabolism. In: Wyngaarden JB, Smith LH Jr, Bennet JC, eds. Cecil Textbook of Medicine, 19th ed. Philadelphia: WB Saunders, 1992.
MISCELLANEOUS
See also: Alcohol use disorders; Anemia, sickle cell; Failure to thrive (FTT)