bubble_chart Overview

Zinc is one of the essential trace elements in the body, involved in cellular metabolism, the composition and function of various enzymes, particularly in the breakdown and synthesis of proteins and nucleic acids, which require zinc. It is also closely related to the synthesis and function of DNA and RNA. Therefore, zinc is associated with children's growth and development, taste, appetite, immune function, wound healing, as well as the occurrence, progression, and treatment of certain diseases.

bubble_chart Etiology

1. Inadequate intake is a common cause, such as long-term reliance on cereals as the staple food, lack of animal-based foods, improper artificial feeding, overly refined foods, picky eating, anorexia, and prolonged use of high-energy intravenous nutrition therapy.
2. Malabsorption Chronic digestive system diseases like malabsorption syndrome, steatorrhea, and acrodermatitis enteropathica can reduce zinc absorption in the intestines. Phytic acid in plant-based foods can form insoluble complexes with zinc and calcium, while excessive fiber in the diet accelerates intestinal motility, speeding up zinc excretion and reducing absorption.
3. Excessive loss Large-area burns and trauma cause zinc loss through exudates; kidney diseases increase the glomerular filtration of zinc while reducing tubular reabsorption, leading to excessive zinc loss in urine; repeated blood loss and hemolysis result in zinc loss through red blood cells; prolonged profuse sweating causes excessive zinc loss through sweat; diuretics and skin diseases can also lead to excessive zinc loss.
4. Increased demand Rapidly growing infants and young children, malnourished individuals, and those in the convalescence stage after large-area burns have an increased need for zinc. If the diet does not provide enough zinc and zinc supplements are not administered, zinc deficiency can occur.
5. Congenital deficiency Pregnant women require 2–3 times the normal zinc intake. If the mother is zinc-deficient, the fetus may also become zinc-deficient.

bubble_chart Pathogenesis

Due to the multifaceted physiological functions of zinc, it has a close relationship with clinical conditions. When zinc is deficient, it can lead to various physiological changes in the body.

1. **Growth and Development Retardation**: Zinc is an essential component of DNA and RNA polymerases, directly involved in nucleic acid and protein synthesis, playing a critical role in metabolism. Zinc deficiency slows intracellular DNA replication, reduces RNA polymerase activity, and impairs protein synthesis, affecting children's growth and development. Zinc is a necessary trace element for children's growth and is closely related to overall development. It directly influences collagen formation, bone growth, and growth hormone synthesis. Thus, zinc significantly impacts height and weight. Zinc-deficient individuals may exhibit stunted growth, delayed sexual maturation, hypogonadism, underdeveloped or absent secondary sexual characteristics, and in severe cases, testicular atrophy, splenomegaly, rough skin, and zinc-deficiency anemia, leading to zinc-deficiency dwarfism. Zinc deficiency affects DNA synthesis in brain tissue more prominently than in other organs, thereby impairing intellectual development.
2. **Digestive Dysfunction**: When the body lacks zinc, the metabolism of nucleic acids and proteins, as well as the activity of various zinc-dependent enzymes required for digestion and metabolism, decreases. This initially leads to reduced taste sensitivity and loss of appetite. Zinc deficiency hinders nucleic acid and protein synthesis, making taste bud structures—which have a high cell turnover rate—more susceptible to damage. Oral mucosal epithelial hyperplasia and parakeratosis occur, shortening the half-life and increasing shedding, which blocks the taste bud pores on the tongue papillae. This prevents food from contacting taste buds, reducing taste stimulation and appetite. Additionally, zinc deficiency decreases salivary phosphatase levels, impairing taste bud function related to phosphatase. The decline in taste sensation affects oral mucosal nutrition, increasing susceptibility to recurrent stomatitis and further reducing appetite. Zinc is a key component of insulin (each insulin molecule binds two zinc atoms), so insulin activity is closely tied to zinc levels. Zinc deficiency lowers insulin activity, leading to glucose metabolism disorders. It also reduces the activity of carboxypeptidase A (a zinc-dependent enzyme), significantly impairing digestion. Recent studies suggest that infantile anorexia and infantile paroxia are linked to zinc deficiency.
3. **Impaired Immune Function**: Zinc binds to phosphate groups in membrane lipids and sulfur in proteins, forming stable complexes that maintain membrane stability, reduce toxin absorption, and mitigate tissue injury. Zinc deficiency causes immune dysfunction, atrophy of immune organs (thymus, lymph nodes, and spleen), weakened resistance, suppressed cellular immunity, reduced lymphocyte counts, decreased T-cell numbers and function, diminished immune responses, impaired leukocyte chemotaxis, and increased susceptibility to infections.

bubble_chart Clinical Manifestations

Zinc deficiency is not an independent disease, and its clinical manifestations are multifaceted. It may also be masked and inconspicuous due to the more severe symptoms of the primary disease.

1. Due to damage to the taste buds, the tongue's perception of sour, sweet, bitter, and salty tastes may diminish or be lost, accompanied by flattened papillae, geographical tongue, and oral mucosal ulcers. The reduced taste sensation and impaired digestive function lead to loss of appetite and picky eating. In severe cases, anorexia and infantile pica may occur, such as eating dirt, coal cinders, cigarette butts, sand, or stones. The number of non-food items consumed can range from one to several.
2. Height and weight are lower than those of peers, with emaciation and varying degrees of anemia. There may also be hepatosplenomegaly, and in severe cases, signs of dwarfism.
3. Hair becomes dry, brittle, and prone to breakage, with alopecia areata, dermatitis, skin lesions, and delayed wound healing.
4. Symptoms include poor concentration, lack of self-control, hyperactivity, and poor academic performance.
5. The body's resistance weakens, increasing susceptibility to infectious diseases, such as recurrent upper respiratory infections, chronic diarrhea, and prolonged illness.
6. Delayed puberty, poor development of secondary sexual characteristics, and reduced sexual function may also occur.

bubble_chart Diagnosis

Based on a comprehensive analysis of the causes and clinical manifestations of zinc deficiency, diagnostic treatment can be administered to suspected patients. Improvement or recovery after oral zinc supplementation supports the diagnosis. If conditions permit, serum zinc or hair zinc tests can be conducted to confirm the diagnosis.

Reported normal zinc values vary and are influenced by multiple factors. Generally, the normal reference range for serum zinc is 11.99–19.28 μmol/L (78.3–126 μg/dL), and reduced serum zinc levels can serve as one diagnostic indicator for zinc deficiency. The reference value for hair zinc is 33.57 μmol/g (219.4 μg/g), but it fluctuates widely within the normal range, making it unsuitable as a sensitive indicator.

bubble_chart Treatment Measures

Adopt comprehensive treatment measures:

1. Disease cause treatment: Identify the disease cause and actively treat the primary condition.
2. Dietary therapeutics: First, determine whether there are factors in the diet that hinder zinc absorption, such as high levels of phytates, fiber, and calcium. At the same time, provide foods rich in zinc, such as peanuts, meat, legumes, and shellfish.
3. Infection control: Zinc deficiency increases susceptibility to infections, and infections in turn deplete zinc reserves. Therefore, preventing and treating infections is crucial. Effective antibiotics may be selected based on the condition for thorough treatment, and attention should be paid to local care of the skin and mucous membranes.
4. Supportive therapy: For patients with anemia or compromised immune function, administer small transfusions of fresh blood or plasma as appropriate. Immunostimulants such as levamisole or gamma globulin may also be given.
5. Provide multivitamins: Zinc deficiency is often accompanied by deficiencies in multiple vitamins. Therefore, appropriate supplementation of vitamins A, B, C, etc., is necessary.
6. Zinc therapy: This is highly effective for treating zinc deficiency.

bubble_chart Related Drugs

1. Types of Zinc Preparations:
   1. Zinc Sulfate: Widely used, dosage forms include solution (with varying concentrations, 0.1% to 1%) and tablets (each tablet contains 120mg, with 25mg of elemental zinc).
   2. Zinc Acetate: Causes less irritation to the gastric mucosa compared to zinc sulfate. Each tablet of zinc acetate contains 13mg, with 1mg of elemental zinc. Additionally, there are zinc gluconate, zinc citrate, licorice root zinc, N-acetylproline zinc, etc.
2. Dosage and Administration of Zinc: Generally, the dose is 1.0 to 2.5mg/kg/day of elemental zinc. For infants and children, an oral dose of 120mg/day of zinc sulfate is sufficient to meet therapeutic needs, with a recommended maximum of 150mg/day. In cases of severe zinc deficiency, intravenous administration may be used at a dose of 300 to 500μg/kg/day of elemental zinc. After improvement, the maintenance dose is 100 to 300μg/kg/day.
3. Treatment Course: Since the body's intake, absorption, utilization, and storage of zinc is a complex and slow process, zinc supplementation requires a period of time, typically 2 to 3 months per course.
4. Side Effects: About 5% to 10% of users may experience nausea, vomiting, and gastric discomfort. Very few may develop urticaria, which usually resolves within 3 to 5 days after discontinuation. Excessive doses may lead to zinc toxicity.

bubble_chart Prevention

Since zinc deficiency is relatively common in children, proactive preventive measures should be taken to prevent its occurrence.

1. Encourage timely breastfeeding after birth to promote colostrum secretion, as breastfed infants have a lower incidence of zinc deficiency.
2. For those fed with cow's milk, due to the low bioavailability of zinc in cow's milk, zinc-rich foods should be promptly added or an appropriate amount of zinc should be supplemented in the milk. Formula-fed infants should receive zinc supplementation even more promptly.
3. For low-birth-weight infants, children with chronic diarrhea, those on intravenous nutrition, patients treated with steroid hormones, surgical or burn patients, those with recurrent infections, and children experiencing rapid growth, zinc supplements should be administered in appropriate doses, with a dose of 0.25–0.5 mg/kg.
4. Provide zinc-rich foods, avoid frequent consumption of refined grains, and promptly correct children's picky eating habits.