Zinc blood test: normal range and what low or high zinc levels mean
Zinc (serum or plasma zinc) (Zn) · Trace elements / nutritional assessment (ordered individually) · reported in µg/dL (SI: µmol/L; 1 µmol/L = 6.54 µg/dL)
A zinc blood test measures the concentration of zinc in serum or plasma, usually reported in micrograms per decilitre (µg/dL). Zinc is an essential trace mineral that more than 300 enzymes depend on, with roles in immune defence, wound healing, taste and smell, growth, fertility and the function of skin and gut lining. The typical adult reference range is about 60 to 120 µg/dL, and values below roughly 60 to 70 µg/dL (depending on sex and time of day) suggest deficiency. Laboratories differ, so use the range printed on your report.
The test has a well-known limitation: only about 0.1 percent of the body's zinc is in the blood, and the level is held fairly steady until stores are quite depleted. It also falls temporarily during any infection or inflammation, after a meal, in pregnancy and when albumin is low, and it rises if the sample hemolyses or is drawn into the wrong tube. So a low result is a reasonable signal of deficiency when it comes with the right story (poor intake, malabsorption, liver disease, alcohol use, chronic diarrhea or typical symptoms), while a normal result does not fully exclude mild deficiency.
True deficiency shows up as hair loss, a scaly rash around the mouth, eyes, hands and genital area, diarrhea, loss of taste and smell, slow wound healing, frequent infections and, in children, poor growth. It is most common in people with Crohn's disease, celiac disease, bariatric surgery, cirrhosis, chronic kidney disease, sickle cell disease and alcohol use disorder, in older adults eating little, and in vegans eating a lot of unrefined grains and legumes. High zinc is almost always from supplements and is a problem mainly because it drives copper deficiency.
Zn at a glance
- What it is: the amount of zinc circulating in serum or plasma, about 70 to 80 percent of it bound to albumin.
- Normal (adults): about 60–120 µg/dL (9–18 µmol/L); labs differ. Levels are highest in the morning after an overnight fast and fall 10 to 20 percent after eating.
- Low: below about 70 µg/dL fasting in men and 66 in women on a morning sample (IZiNCG cut-offs), or below 60 on an afternoon sample; under 40 is severe and usually symptomatic.
- Low zinc causes: not enough in the diet, malabsorption (Crohn's, celiac, bariatric surgery), cirrhosis, alcohol, kidney disease, sickle cell disease, chronic diarrhea, and any acute illness, which lowers the reading without true deficiency.
- High zinc (above about 120–150 µg/dL): nearly always supplements, zinc lozenges or zinc-containing denture cream, or a hemolysed or contaminated sample; long-term intake above 40 mg a day causes copper deficiency.
- Next step: repeat on a fasting morning sample when well, with albumin and CRP; if deficient, your clinician will look for the cause and usually suggest 15 to 40 mg of elemental zinc a day for a few months, then retest.
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What Zn measures
The adult body holds 2 to 3 grams of zinc, most of it in muscle and bone, and there is no dedicated store that can be released on demand the way iron is released from ferritin. Plasma zinc is a small, rapidly exchanging pool: about 70 to 80 percent travels bound to albumin, most of the rest to alpha-2-macroglobulin, and a tiny fraction to amino acids. The laboratory measures total zinc in serum or plasma by atomic absorption or mass spectrometry, so anything that lowers albumin lowers the result, and anything that breaks red cells (which contain about ten times more zinc than plasma) raises it.
Several things move the number without changing body stores. Infection and inflammation redistribute zinc into the liver within hours, so serum zinc can drop 10 to 20 percent with a modest rise in CRP and considerably more during serious illness. Eating lowers it for a few hours, which is why fasting morning samples are preferred and why reference cut-offs differ by time of day. Pregnancy lowers it by 15 to 35 percent by the third trimester, as do oral contraceptives and corticosteroids. Zinc supplements raise it within hours of a dose.
The sample matters. Blood should be drawn into a trace-element-free (usually royal-blue top) tube, because rubber stoppers and ordinary tubes can leak zinc, and a prolonged tourniquet or hemolysis inflates the result. Hair, urine and red-cell zinc are not reliable measures of status. A practical alternative when the blood test is equivocal is a supervised trial of zinc supplementation with symptoms reassessed after 1 to 3 months.
Normal range for Zn
Reference ranges vary between labs and by age, sex and pregnancy. Use the range printed on your own report.
| Group | Typical range (µg/dL (SI: µmol/L; 1 µmol/L = 6.54 µg/dL)) | Notes |
|---|---|---|
| Adults, typical laboratory range | About 60–120 µg/dL (some labs 66–110 or 70–120) | Labs differ in cut-offs and in whether serum or plasma is used; plasma runs slightly lower. |
| Deficiency cut-offs, men (IZiNCG) | Below 74 µg/dL fasting morning; below 70 non-fasting morning; below 61 afternoon | International Zinc Nutrition Consultative Group thresholds for people aged 10 and over. |
| Deficiency cut-offs, women (IZiNCG) | Below 70 µg/dL fasting morning; below 66 non-fasting morning; below 59 afternoon | Non-pregnant women; oral contraceptives lower levels slightly. |
| Children under 10 | Below 65 µg/dL (morning) or 57 (afternoon) suggests deficiency | Typical reference range is otherwise similar to adults. |
| Pregnancy | Below about 56 µg/dL in the first trimester or 50 in the second and third suggests deficiency | Levels fall 15 to 35 percent by late pregnancy from plasma expansion and hormonal changes; standard adult cut-offs over-diagnose deficiency. |
| Mild to moderate deficiency | About 40–60 µg/dL | Often few or subtle symptoms (taste changes, slow healing, more infections). Confirm on a fasting morning sample when well. |
| Severe deficiency | Below 40 µg/dL | Usually with hair loss, dermatitis, diarrhea or poor growth; seen in acrodermatitis enteropathica, severe malabsorption and long-term intravenous nutrition without zinc. |
| High | Above about 120–150 µg/dL | Supplements, lozenges or denture cream in most cases, or a hemolysed or contaminated sample. Serum zinc is a poor measure of toxicity; intake history matters more. |
High zinc
A high serum zinc almost always comes from zinc going in, not from a disease. A supplement, multivitamin, cold lozenge or zinc-containing denture adhesive taken in the hours before the draw raises the level, and regular intake above the tolerable upper limit of 40 mg a day keeps it high. The other common explanation is the sample itself: red cells contain far more zinc than plasma, so hemolysis, a long tourniquet time or an ordinary tube with a zinc-leaching stopper can push a normal person into the high range. A repeat in a trace-element-free tube on a fasting morning sample with no supplement for 24 hours usually settles it.
The reason high zinc matters is copper. Zinc induces metallothionein in the gut lining, which traps copper and prevents its absorption, so months of zinc intake above about 50 mg a day can cause copper deficiency: anemia that does not respond to iron, a low neutrophil count, and a nerve and spinal cord disorder (myeloneuropathy) with numbness, unsteadiness and weakness that can be permanent. Zinc-containing denture creams used in large amounts were a well-documented cause before manufacturers removed zinc. Chronic high intake also lowers HDL cholesterol and, paradoxically, impairs immune function.
Acute zinc toxicity is a different picture: swallowing more than about 200 mg at once (or a dose of zinc sulfate on an empty stomach) causes nausea, vomiting, cramps and diarrhea within hours, and inhaling zinc oxide fumes when welding or galvanising causes metal fume fever, a flu-like illness 4 to 12 hours later. Rarely, a high serum zinc with high calprotectin is an inherited condition (hyperzincemia with hypercalprotectinemia); the zinc is bound to protein and not toxic.
Common causes
Zinc supplements and multivitamins
The most common cause. 50 mg tablets sold for immune support and skin contain more than four times the RDA; a dose taken that morning raises serum zinc for several hours, and daily intake over 40 mg keeps it high and starts to deplete copper.
Zinc lozenges and cold remedies
Lozenge regimens for colds deliver 75 to 100 mg a day; harmless for a few days but a problem if continued for weeks.
Zinc-containing denture adhesive
Heavy daily use of older zinc-based creams delivered tens of milligrams a day and caused copper deficiency with anemia and myeloneuropathy; most products are now zinc-free, but check the label.
Hemolysed or contaminated sample
Red cells hold about ten times the zinc concentration of plasma, so any hemolysis, a prolonged tourniquet, or blood drawn into a tube with a zinc-containing stopper gives a falsely high result.
Occupational exposure
Welding, galvanising, smelting and brass foundry work expose people to zinc oxide fumes; metal fume fever is the acute effect, and chronic exposure raises serum levels.
High-dose zinc prescribed for Wilson's disease
Zinc acetate 150 mg a day is a standard treatment to block copper absorption; a high serum zinc here is expected and copper is monitored deliberately.
Accidental or deliberate ingestion
Swallowed zinc coins (US pennies minted after 1982 are mostly zinc) and zinc chloride products cause acute toxicity, mainly in children.
Symptoms that can go with it
- Usually none when the level is only modestly raised by a supplement
- Nausea, vomiting, stomach cramps and diarrhea within hours of a large dose, especially on an empty stomach
- Metallic taste and loss of appetite
- Numbness or tingling in the feet and hands, unsteady walking and weakness from copper deficiency after months of excess
- Tiredness and pallor from copper-deficiency anemia, and frequent infections from a low neutrophil count
- Fever, chills, muscle aches and cough 4 to 12 hours after inhaling zinc fumes (metal fume fever)
- Loss of smell after using intranasal zinc gels, which the FDA warned against in 2009
Low zinc
A low zinc level means either that your body's zinc is genuinely depleted or that the level has been temporarily pushed down by illness, a recent meal, low albumin or pregnancy. The first question is whether the sample was drawn fasting in the morning while you were well; if not, a repeat with CRP and albumin is the usual move. A level under about 60 to 70 µg/dL on a clean sample, with poor intake, a gut or liver condition, or typical symptoms, is enough for most clinicians to diagnose deficiency and treat.
Mild deficiency is common and quiet. Roughly 15 percent of Americans, and a higher share of older adults, consume less zinc than the estimated average requirement, and absorption from plant-heavy diets is reduced by phytate in whole grains, legumes and seeds. The consequences at this level are subtle: slower wound healing, more frequent or prolonged respiratory infections, dulled taste and appetite, thinning hair and mild dermatitis. Children fail to grow as expected and adolescents may have delayed puberty.
Severe deficiency is unmistakable. The classic triad is a scaly, red, sometimes blistering rash around the mouth, eyes, anus and on the hands and feet, chronic diarrhea and hair loss, often with mood changes, night blindness and recurrent infections. It occurs in the rare inherited absorption defect acrodermatitis enteropathica, after bariatric surgery or extensive bowel resection, with long-term intravenous nutrition lacking zinc, in advanced cirrhosis and in severe malabsorption. Zinc replacement reverses the skin and gut changes within one to two weeks.
Common causes
Low dietary intake
Older adults eating small amounts, people on restrictive diets, and vegans and vegetarians relying on unrefined grains and legumes (high in phytate, which binds zinc) are at most risk. Oysters, red meat, shellfish, poultry and dairy are the richest, best-absorbed sources.
Malabsorption
Crohn's disease, celiac disease, short bowel, pancreatic insufficiency, cystic fibrosis, SIBO and gastric bypass or sleeve surgery all reduce absorption; zinc deficiency is found in 20 to 40 percent of people after bariatric surgery without supplements.
Liver disease and alcohol
Cirrhosis lowers albumin and zinc absorption and increases urinary loss; alcohol itself increases zinc excretion. Low zinc in cirrhosis is linked to muscle cramps, taste changes and hepatic encephalopathy.
Chronic kidney disease and dialysis
Reduced intake, protein restriction, urinary losses in nephrotic syndrome and dialysis losses combine; zinc deficiency is common in advanced CKD.
Sickle cell disease
Chronic hemolysis and increased urinary losses make deficiency common (40 to 60 percent in some series); it contributes to growth delay and infections in children with the condition.
Chronic diarrhea and high gut losses
Zinc is secreted into the gut and lost in stool; prolonged diarrhea from any cause, ileostomy output and fistulas deplete it quickly.
Acute illness, infection and inflammation
Cytokines drive zinc into the liver within hours, so serum zinc falls during pneumonia, surgery, sepsis and flares of inflammatory disease. This is redistribution, not deficiency, and the level recovers as CRP falls.
Pregnancy, low albumin and estrogen
Plasma expansion, hormonal changes and lower albumin reduce measured zinc in pregnancy and with oral contraceptives; nephrotic syndrome and liver failure lower albumin and, with it, bound zinc.
Medications
Thiazide and loop diuretics increase urinary zinc loss, penicillamine and other chelators bind it, long-term ACE inhibitors and valproate have been linked to lower levels, and high-dose iron taken at the same time competes for absorption.
Acrodermatitis enteropathica
A rare inherited defect in the intestinal zinc transporter (SLC39A4) that presents in infancy with rash, diarrhea and failure to thrive and needs lifelong zinc.
Symptoms that can go with it
- Hair thinning or patchy hair loss
- Red, scaly or crusted rash around the mouth, eyes, nose, anus and on the hands and feet
- Diarrhea, poor appetite and weight loss
- Loss or dulling of taste and smell
- Slow healing of cuts, mouth ulcers and skin that cracks easily
- Frequent or lingering colds, chest and skin infections
- Night blindness and, in men, low testosterone or reduced fertility
- Poor growth and delayed puberty in children and teenagers
Read it alongside
- Albumin — binds most plasma zinc; a low albumin lowers the zinc reading without true deficiency, and a corrected interpretation or repeat is needed.
- CRP — any rise means the zinc result is pushed down by inflammation; a zinc drawn with a CRP above 5 to 10 mg/L is best repeated when well.
- Copper and ceruloplasmin — ordered whenever zinc is high or supplements have been taken for months, because zinc excess causes copper deficiency.
- Alkaline phosphatase — a zinc-dependent enzyme; an unexpectedly low ALP supports real zinc deficiency, and a rise with treatment confirms response.
- Hemoglobin and CBC — anemia and a low neutrophil count point toward copper deficiency from zinc excess; anemia with low zinc suggests a shared cause such as malabsorption.
- Ferritin and iron saturation — iron and zinc deficiency travel together in malabsorption, heavy menstrual loss and poor diets; high-dose iron supplements also impair zinc absorption.
- Vitamin D, vitamin B12 and folate — other nutrients commonly low after bariatric surgery, in celiac disease and in alcohol-related liver disease.
- Testosterone — low in severe zinc deficiency in men and improves with repletion.
What usually happens next
- If the level is low and the sample was not a fasting morning draw, or you were unwell, expect a repeat with albumin and CRP before anything is concluded.
- If deficiency is confirmed, your clinician will look for the cause: a dietary review, questions about alcohol and gut symptoms, and sometimes celiac testing, stool studies or liver tests.
- Treatment is usually 15 to 40 mg of elemental zinc a day (zinc gluconate, citrate, picolinate or sulfate) for 1 to 3 months, taken away from iron and calcium supplements and from meals high in phytate; higher doses for longer need copper monitoring.
- Retest after about 3 months of treatment on a fasting sample at least 24 hours after the last dose; symptoms such as taste changes and skin healing usually improve within 2 to 4 weeks.
- If the level is high, stop supplements and lozenges, check denture adhesive labels, and ask for a repeat in a trace-element-free tube along with copper and a CBC.
Diet, lifestyle and natural levers with evidence
What can move Zn once the cause is known. Nothing here replaces finding the cause.
A systematic review of supplementation and depletion studies confirmed that plasma zinc responds reliably to intake, rising within weeks of 10 to 30 mg a day in people who start low, with larger responses the lower the baseline. Trials in older adults with low zinc found 15 to 30 mg a day raised plasma zinc into the normal range within 3 months. The RDA is 11 mg for men and 8 mg for women, the tolerable upper limit is 40 mg a day, and zinc gluconate, citrate, picolinate and sulfate are all well absorbed; zinc oxide is poorly absorbed.
Doses above 40 mg a day for more than a few months deplete copper; pair high doses with 1 to 2 mg of copper and recheck both. Zinc reduces absorption of quinolone and tetracycline antibiotics and penicillamine, so separate doses by at least 2 hours. Avoid intranasal zinc products, which have caused permanent loss of smell.
Eat the foods zinc is actually absorbed from
Strong evidenceAnimal foods supply zinc in a form absorbed at 30 to 50 percent, versus 10 to 20 percent from grains and legumes. Three ounces of cooked oysters provide about 32 mg, beef chuck roast about 7 mg, crab 6 mg, pork or dark-meat chicken 2 to 3 mg, and a cup of yogurt or milk 1 to 2 mg. Among plant foods, pumpkin seeds (2.2 mg per ounce), cashews, chickpeas, lentils and fortified cereals contribute most, and because phytate limits absorption, vegetarians are advised to aim for about 50 percent more than the RDA.
Reduce phytate and separate competing minerals
Moderate evidencePhytate in whole grains, legumes, nuts and seeds binds zinc in the gut; absorption studies show that soaking, sprouting and fermenting (for example sourdough rather than yeast-leavened whole-grain bread) break phytate down and can increase zinc absorption by 30 to 50 percent. Taking 60 mg or more of iron at the same time as a zinc supplement reduces zinc absorption, and large calcium doses may do the same, so supplements are better taken at different times of day. Protein in a meal improves zinc absorption, which partly explains why animal-protein meals score well.
Address alcohol, diarrhea and malabsorption
Moderate evidenceAlcohol increases urinary zinc loss and damages the gut lining, and zinc deficiency is found in 30 to 60 percent of people with alcohol-related liver disease; levels improve with abstinence and supplementation, and small trials in cirrhosis report fewer muscle cramps and better encephalopathy scores with 50 mg a day. In chronic diarrhea, treating the cause is what restores zinc; the WHO recommends 10 to 20 mg a day for 10 to 14 days during diarrheal illness in children because it shortens episodes by about 10 to 15 percent. After bariatric surgery, lifelong supplementation of 8 to 22 mg a day is standard, with annual levels.
Cirrhosis and kidney disease change zinc handling; doses here should be set and monitored by your clinician rather than self-prescribed.
Balance zinc with copper if you take it long term
Moderate evidenceZinc above about 50 mg a day induces intestinal metallothionein and blocks copper absorption; case series show copper deficiency anemia and myeloneuropathy after months of 100 mg or more, and recovery of the anemia but often only partial recovery of the nerve damage. The AREDS formula used in macular degeneration trials pairs 80 mg of zinc with 2 mg of copper for this reason, and the usual advice for anyone on more than 40 mg a day is 1 to 2 mg of copper and a copper and CBC check every 6 to 12 months.
Copper supplements above 10 mg a day are themselves toxic; the aim is balance, not high doses of both.
When to see a clinician promptly
- Numbness, tingling, weakness or unsteady walking in anyone taking zinc supplements for months: possible copper-deficiency myeloneuropathy, which can become permanent and needs prompt assessment.
- Persistent vomiting, severe abdominal pain or bloody diarrhea after swallowing a large zinc dose or a zinc-containing object (such as pennies in a child): same-day emergency care.
- Fever, chills, cough and chest tightness within hours of welding, galvanising or working with zinc fumes.
- A spreading rash around the mouth, eyes or genitals with diarrhea and hair loss, especially in an infant, after bowel surgery, or on long-term intravenous nutrition.
- Recurrent infections, slow-healing wounds, or poor growth or delayed puberty in a child, where zinc is one of several deficiencies that need checking.
- A low zinc level with weight loss, chronic diarrhea, jaundice or heavy alcohol use, which points to an underlying condition rather than diet alone.
Frequently asked questions
What is a normal zinc level in blood?
Most laboratories quote about 60 to 120 µg/dL (9 to 18 µmol/L) for adults, with the exact range varying by lab and by whether serum or plasma is measured. Levels are highest in the morning after fasting and fall 10 to 20 percent after a meal, so research cut-offs for deficiency are about 70 to 74 µg/dL on a fasting morning sample and about 60 on an afternoon one. Pregnant women run lower, with deficiency defined below about 50 to 56 µg/dL.
What are the symptoms of low zinc?
Mild deficiency causes slow wound healing, more frequent colds and skin infections, dulled taste and smell, poor appetite, thinning hair and mild eczema-like rashes. Severe deficiency causes a red, scaly or blistering rash around the mouth, eyes, anus, hands and feet, chronic diarrhea, hair loss, night blindness and, in children, poor growth and delayed puberty. Most of these improve within a few weeks of zinc replacement.
Is a zinc blood test accurate?
It is useful but imperfect. Only about 0.1 percent of body zinc is in blood, and the level falls during infection, inflammation, pregnancy and after meals, and with low albumin, so a single low value can be misleading and a normal value does not exclude mild deficiency. It is most reliable as a fasting morning sample drawn in a trace-element-free tube when you are well, interpreted alongside CRP and albumin. Hair and urine zinc tests are not recommended.
What causes high zinc levels?
Almost always zinc coming in from supplements, multivitamins, cold lozenges or zinc-containing denture creams, or a sample problem such as hemolysis or the wrong tube. Occupational exposure to zinc fumes and the high-dose zinc used to treat Wilson's disease are other causes. The main harm of sustained high intake (over 40 to 50 mg a day) is copper deficiency, which causes anemia, low white cells and nerve damage.
How much zinc should I take if my level is low?
Most clinicians use 15 to 40 mg of elemental zinc a day for one to three months, then retest. The RDA is 8 mg for women and 11 mg for men and the safe upper limit for long-term intake is 40 mg a day. Doses above that, or any dose for more than a few months, should be paired with 1 to 2 mg of copper and monitored. Take zinc apart from iron and calcium supplements and from quinolone or tetracycline antibiotics, and discuss the dose with your clinician if you have kidney or liver disease.
Do I need to fast for a zinc blood test?
Ideally yes: a morning sample after an overnight fast gives the most reliable result, because eating lowers plasma zinc for several hours. Do not take a zinc supplement, multivitamin or lozenge for at least 24 hours before the draw unless told otherwise, and mention any recent illness, since infection lowers the level. The blood should be collected in a trace-element-free tube.
Can too much zinc be harmful?
Yes. A single dose above about 200 mg causes nausea, vomiting and cramps, and intake above 40 mg a day for months causes copper deficiency with anemia, low neutrophils and nerve damage that can be permanent. Chronic excess also lowers HDL cholesterol and weakens rather than strengthens immune function. Intranasal zinc products have caused lasting loss of smell. Keep long-term intake at or below 40 mg a day unless a clinician is monitoring you.
Does zinc help with colds?
Modestly, and only as lozenges started within 24 hours of symptoms. A 2024 Cochrane review found zinc lozenges may shorten a cold by about two days, with low-certainty evidence and frequent side effects (bad taste, nausea), and no benefit for preventing colds in people with normal zinc levels. People who are genuinely deficient do get more and longer infections, and correcting the deficiency helps; taking extra zinc when you are already replete does not.
References
- Zinc: fact sheet for health professionals. Office of Dietary Supplements, National Institutes of Health (2022)View source
- Zinc deficiency. Merck Manual Professional Version (2024)
- Zinc toxicity. Merck Manual Professional Version (2024)
- Zinc. Mayo Clinic (2023)View source
- King JC, Brown KH, Gibson RS, et al.. Biomarkers of Nutrition for Development (BOND): zinc review. Journal of Nutrition (2016)
- Lowe NM, Fekete K, Decsi T. Methods of assessment of zinc status in humans: a systematic review. American Journal of Clinical Nutrition (2009)
- Hotz C, Brown KH, eds.. International Zinc Nutrition Consultative Group (IZiNCG) technical document #1. Assessment of the risk of zinc deficiency in populations and options for its control. Food and Nutrition Bulletin (2004)
- Duncan A, Talwar D, McMillan DC, Stefanowicz F, O'Reilly DS. Quantitative data on the magnitude of the systemic inflammatory response and its effect on micronutrient status based on plasma measurements. American Journal of Clinical Nutrition (2012)
- Nault D, Machingo TA, Shipper AG, et al.. Zinc for prevention and treatment of the common cold. Cochrane Database of Systematic Reviews (2024)
- Nations SP, Boyer PJ, Love LA, et al.. Denture cream: an unusual source of excess zinc, leading to hypocupremia and neurologic disease. Neurology (2008)
- Prasad AS. Discovery of human zinc deficiency: its impact on human health and disease. Advances in Nutrition (2013)
- Maret W, Sandstead HH. Zinc requirements and the risks and benefits of zinc supplementation. Journal of Trace Elements in Medicine and Biology (2006)
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Ask about my ZnThis page is educational and is not medical advice or a diagnosis. Lab results have to be interpreted together with your history, symptoms and other results by a clinician who knows you. Do not start or stop a supplement to change a lab value before the cause is known.