Zinc test: what the blood result means (Zn)

Zinc is a trace element that the body does not make itself and has to get from food. According to the MedlinePlus encyclopedia, zinc takes part in the working of the immune system, in cell division and growth, in wound healing, in the breakdown of carbohydrates, and in the senses of smell and taste. It is especially important during pregnancy, infancy and childhood, when the body is growing and developing fast. The best sources of zinc are animal proteins: beef, pork, lamb and dark chicken meat; also nuts, wholegrain products, legumes and yeast. Zinc from plant foods is absorbed less well than from animal foods, so vegetarians and people who eat little protein may fall short of it. The blood test shows the amount of zinc circulating in the blood at that moment; it is most often ordered when a deficiency is suspected from symptoms or risk factors, rather than as a routine screening test.

• When infections keep coming back, or wounds heal unusually slowly
• When there is hair loss, a skin rash or skin sores of unclear cause
• When the sense of smell or taste is disturbed, or appetite drops with no clear reason
• In children, when growth is slower than expected
• When the diet is vegetarian or low in animal protein and a trace element deficiency is suspected
• To monitor the condition of people whose digestion or absorption of food is impaired

The normal interval for zinc in blood depends on the laboratory method, so you will find the exact limits on your own result sheet (see how to read blood test results). Separately from the blood test, MedlinePlus gives the recommended daily intake from food: about 11 mg a day for adult men, about 8 mg for women and about 11 mg for pregnant women. This is an intake amount, not a blood test range, so a blood result cannot be compared with it.

A raised zinc level

A raised amount of zinc in the blood is most often linked to taking too much in supplements, rather than to food. According to MedlinePlus, large amounts of zinc supplements can cause digestive upset, and taking high doses over a long time can cause a deficiency of copper, iron or magnesium. A conversation about the supplements being taken, and tests of the other trace elements, help to establish the cause.

What can raise zinc

• Taking too much zinc in supplements over a long period
• Nasal sprays or gels for the lining of the nose that contain zinc
• Rarely — occupational contact with zinc dust or fumes

Symptoms that can accompany a raised level

• Nausea, diarrhoea, abdominal pain
• Vomiting
• Disturbances of the sense of smell (especially from zinc products sprayed into the nose)

• Discuss with your doctor which supplements you take and at what doses
• Copper, iron and magnesium levels — a long-term excess of zinc can reduce how well they are absorbed
• Whether the symptoms (nausea, diarrhoea) coincide with the times the supplement is taken

A low zinc level

A reduced amount of zinc is most often linked to not getting or not absorbing enough of it from food. According to MedlinePlus, zinc from plants is absorbed less well than zinc from animal foods, so a vegetarian diet or one low in protein may not meet the need — especially during pregnancy, infancy or childhood, when the need is greater. A deficiency can show itself as frequent infections, hair loss or slow wound healing.

What can lower zinc

• A vegetarian diet, or one low in animal protein — zinc from plants is absorbed less well
• An increased need that the diet does not match — during pregnancy, infancy or childhood
• Not enough food overall, or too little variety in it

Signs that can accompany a low level

• Frequent infections
• Hair loss
• Poor appetite
• Disturbances of taste and smell
• Skin sores
• Slower growth in children
• Difficulty seeing in the dark
• Wounds that take a long time to heal

What is usually assessed alongside a low result

• An assessment of the diet — whether there is enough animal protein, nuts and wholegrain products
• Whether there are digestive or absorption problems that could reduce how much zinc is taken up
• When to repeat the test, so that a change is visible once the diet has been adjusted
• Discuss with your doctor whether a supplement is needed and in what form