Zinc level
Serum zinc cut points from the International Zinc Nutrition Consultative Group run from 57 to 74 µg/dL by age, sex, fasting and time of day. They were built to assess populations, and the group states the test may not reliably show one person's status. Meals, afternoon draws and infection lower the result. Links to pneumonia, depression and diabetes are observational.
- Status
- A blood test ordered by a clinician and also sold direct to consumers by some US laboratories. Blood is drawn with stainless steel needles into trace element-free tubes, because zinc from ordinary equipment can contaminate the sample [1][2].
- Measures
- The concentration of zinc in serum or plasma.
- Also called
- serum zinc, plasma zinc, zinc serum, zinc plasma, zinc blood test, Zn, Zn level
- Tested for
- zinc deficiency, frequent infections, hair loss, slow wound healing, loss of taste or smell, vegetarian or vegan diet, checking a zinc supplement
Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on
Linked in research4
- ModerateShown in trials: zinc supplements raised serum zinc and increased height and weight gain in prepubertal children by about a third of a standard deviation.
- ModerateLinked to depression: blood zinc was about 1.85 µmol/L (12 µg/dL) lower in depressed people than in controls across 17 pooled studies.
- ModerateLinked to more type 2 diabetes at higher serum or plasma zinc in pooled observational studies (odds ratio 1.64), while higher zinc intake from food went with less.
- LimitedLimited evidence: one study of Boston nursing home residents linked serum zinc of 70 µg/dL or above to fewer and shorter pneumonia episodes.
Reported risks0
No risks sourced yet.
Reference ranges
Each range is the one its source published, in µg/dL. Also reported in µmol/L. Where sources differ, each is shown.
International Zinc Nutrition Consultative Group (IZiNCG), 2004, women, morning fasting
Non-pregnant females aged 10 and older, blood drawn in the morning after at least 8 hours without food · [1], [2], [3]
| Range | What the source calls it |
|---|---|
| below 70 µg/dL | "below the relevant cutoff" |
| 70 or above µg/dL | No name given |
The cut-off is the 2.5th percentile of presumably healthy participants in a US national survey from 1976 to 1980, after excluding people with conditions that alter serum zinc [1][2]. The group built these cut-offs to assess populations: when more than 20% of a group falls below the relevant one, it considers the whole group at risk of zinc deficiency. It states that serum zinc may not be a reliable indicator of an individual's zinc status [2]. The morning fasting figure is based on participants aged 20 and older [1]. The group prints the conversion as µmol/L = µg/dL divided by 6.54 [1][2].
International Zinc Nutrition Consultative Group (IZiNCG), 2004, women, morning not fasting
Non-pregnant females aged 10 and older, blood drawn in the morning without fasting · [1], [2], [3]
| Range | What the source calls it |
|---|---|
| below 66 µg/dL | "below the relevant cutoff" |
| 66 or above µg/dL | No name given |
The cut-off is the 2.5th percentile of presumably healthy participants in a US national survey from 1976 to 1980, after excluding people with conditions that alter serum zinc [1][2]. It is lower than the morning fasting cut-off of 70, in line with the lower serum zinc the survey found in morning samples from people who had not fasted [1]. Built to assess populations, not individuals [2].
International Zinc Nutrition Consultative Group (IZiNCG), 2004, women, afternoon
Non-pregnant females aged 10 and older, blood drawn in the afternoon or evening · [1], [2], [3]
| Range | What the source calls it |
|---|---|
| below 59 µg/dL | "below the relevant cutoff" |
| 59 or above µg/dL | No name given |
The cut-off is the 2.5th percentile of presumably healthy participants in a US national survey from 1976 to 1980, after excluding people with conditions that alter serum zinc [1][2]. Afternoon and evening samples were combined. Built to assess populations, not individuals [1][2].
International Zinc Nutrition Consultative Group (IZiNCG), 2004, men, morning fasting
Males aged 10 and older, blood drawn in the morning after at least 8 hours without food · [1], [2], [3]
| Range | What the source calls it |
|---|---|
| below 74 µg/dL | "below the relevant cutoff" |
| 74 or above µg/dL | No name given |
The cut-off is the 2.5th percentile of presumably healthy participants in a US national survey from 1976 to 1980, after excluding people with conditions that alter serum zinc [1][2]. The morning fasting figure is based on participants aged 20 and older. The group applies the same cut-off to men over 65, although their 2.5th percentile was lower [1]. Built to assess populations, not individuals [2].
International Zinc Nutrition Consultative Group (IZiNCG), 2004, men, morning not fasting
Males aged 10 and older, blood drawn in the morning without fasting · [1], [2], [3]
| Range | What the source calls it |
|---|---|
| below 70 µg/dL | "below the relevant cutoff" |
| 70 or above µg/dL | No name given |
The cut-off is the 2.5th percentile of presumably healthy participants in a US national survey from 1976 to 1980, after excluding people with conditions that alter serum zinc [1][2]. Built to assess populations, not individuals [2].
International Zinc Nutrition Consultative Group (IZiNCG), 2004, men, afternoon
Males aged 10 and older, blood drawn in the afternoon or evening · [1], [2], [3]
| Range | What the source calls it |
|---|---|
| below 61 µg/dL | "below the relevant cutoff" |
| 61 or above µg/dL | No name given |
The cut-off is the 2.5th percentile of presumably healthy participants in a US national survey from 1976 to 1980, after excluding people with conditions that alter serum zinc [1][2]. Afternoon and evening samples were combined. Built to assess populations, not individuals [1][2].
International Zinc Nutrition Consultative Group (IZiNCG), 2004, children under 10, morning not fasting
Children under 10, boys and girls, blood drawn in the morning without fasting · [1], [2], [3]
| Range | What the source calls it |
|---|---|
| below 65 µg/dL | "below the relevant cutoff" |
| 65 or above µg/dL | No name given |
The cut-off is the 2.5th percentile of presumably healthy participants in a US national survey from 1976 to 1980, after excluding people with conditions that alter serum zinc [1][2]. The survey measured children from age 3, and the group applies the same cut-off to younger children until reference data exist. It gives no morning fasting cut-off for children [1][2].
International Zinc Nutrition Consultative Group (IZiNCG), 2004, children under 10, afternoon
Children under 10, boys and girls, blood drawn in the afternoon or evening · [1], [2], [3]
| Range | What the source calls it |
|---|---|
| below 57 µg/dL | "below the relevant cutoff" |
| 57 or above µg/dL | No name given |
The cut-off is the 2.5th percentile of presumably healthy participants in a US national survey from 1976 to 1980, after excluding people with conditions that alter serum zinc [1][2]. The survey measured children from age 3 [1]. Built to assess populations, not individuals [2].
International Zinc Nutrition Consultative Group (IZiNCG), 2004, first trimester of pregnancy
Pregnant women in the first trimester · [1], [2], [3]
| Range | What the source calls it |
|---|---|
| below 56 µg/dL | "below the relevant cutoff" |
| 56 or above µg/dL | No name given |
The 2.5th percentile for the first trimester in the same US survey, controlling for time of day and fasting. Only 61 pregnant women were in the survey, so the group could not set separate cut-offs by time of day [1]. The reanalysis that produced these figures calls its pregnancy cut-offs tentative [3].
International Zinc Nutrition Consultative Group (IZiNCG), 2004, second and third trimesters of pregnancy
Pregnant women in the second or third trimester · [1], [2], [3]
| Range | What the source calls it |
|---|---|
| below 50 µg/dL | "below the relevant cutoff" |
| 50 or above µg/dL | No name given |
The second and third trimesters did not differ significantly, so one pooled 2.5th percentile is given for both. It rests on 61 pregnant women across all trimesters [1]. The group reports that serum zinc declines through pregnancy and attributes lower values partly to the dilution of blood [1].
World Health Organization and Food and Agriculture Organization fortification guidelines, 2006
All population groups, as a cut-off for assessing zinc status at the population level · [4]
| Range | What the source calls it |
|---|---|
| below 70 µg/dL | "deficiency" |
| 70 or above µg/dL | No name given |
The same table states that there are no universally agreed cut-offs, that plasma zinc is homeostatically regulated and so may not detect marginal deficiency, that values change through the day, and that plasma zinc is decreased by pregnancy, low albumin and infection. It makes no allowance for age, sex, fasting or time of day [4].
How it compares with the reference method
Mixed results2
Effect of infection and inflammation on the result
Mixed results: in pooled surveys, low zinc became more common as inflammation markers rose in half of the preschool child surveys, and the relation in women was weak and inconsistent.
The numbers and sources
- Compared with
- Zinc in people in the same surveys with lower inflammation markers
- Effect
- A technical document reports that serum zinc is reduced during acute infection and inflammation, likely because zinc moves from plasma to the liver, and that low albumin also lowers it [1]. In pooled survey data, the estimated prevalence of zinc deficiency rose with increasing C-reactive protein in 6 of 12 surveys of preschool children. In women of reproductive age the association with inflammation markers was weak and inconsistent. Where an adjustment was applied in children, it lowered the estimated prevalence of deficiency by a median of 11 percentage points (range 4 to 18) [11]. In a US survey, low albumin raised the odds of falling below the serum zinc cut-off (OR 11.2, 99% CI 3.4 to 37.3) [9].
- Population
- 18,859 preschool children and 22,695 non-pregnant women aged 15 to 49 in 13 nationally representative surveys [11]. 4,347 people in a US survey [9].
- Sources
- [1], [11], [9]
- Caveats
- The survey authors found the relations inconsistent and advise checking for an association before any adjustment. They found too little evidence to warrant adjusting results in women [11].
How well serum zinc tracks zinc intake
Mixed results: a systematic review found plasma zinc moved with zinc intake in controlled studies, while a US survey found no relation to dietary or supplemental zinc.
The numbers and sources
- Compared with
- Zinc intake from diet and supplements
- Effect
- In a systematic review of 46 publications, plasma zinc responded in a dose-dependent manner to dietary manipulation in adults, pregnant and lactating women, the elderly and people at low and moderate baseline zinc status. Zinc in red cells, platelets and white cells did not appear to be a useful biomarker [12]. In the 2011 to 2014 US survey, zinc from diet or supplements did not affect serum zinc, while sex, age and time of draw did [9]. An expert panel reports that plasma zinc responds to severe dietary restriction and to supplements, responds less to zinc added to food, and varies considerably between individuals for the same change in intake [10]. The group that publishes the most used cut-offs states that serum zinc may not be a reliable indicator of an individual's status, and that hemolyzed samples and contamination from zinc in tubes, needles, air or water alter the result [1][2].
- Population
- 46 publications covering 32 candidate biomarkers [12]. 4,347 people aged 6 and older [9].
- Sources
- [12], [9], [10], [1], [2]
- Caveats
- The review covered healthy people in controlled studies and found few data for infants and adolescents [12]. The survey related a single blood draw to reported intake [9].
Did not match the reference method1
Time of day and fasting
Shown to read lower later in the day: in US survey data, afternoon and evening draws ran about 10 and 15 µg/dL below morning draws.
The numbers and sources
- Compared with
- A morning blood sample
- Effect
- In the 2011 to 2014 US national survey, afternoon and evening blood draws were associated with lower serum zinc, with regression coefficients of -9.7 and -15.3 on serum zinc measured in µg/dL (P < 0.0001 for both) [9]. In the 1976 to 1980 survey, the 2.5th percentile for non-pregnant females aged 10 and older was 70 µg/dL in morning fasting samples, 66 in other morning samples and 59 in afternoon samples. A technical document reports that serum zinc fluctuates by as much as 20% over 24 hours, largely from eating: it rises just after a meal, declines for the next 4 hours, then rises until food is eaten again [1]. An expert panel review lists recent meals, time of day, inflammation and certain drugs and hormones as influences on plasma zinc [10].
- Population
- 4,347 people aged 6 and older in the 2011 to 2014 US National Health and Nutrition Examination Survey [9]. 11,857 participants aged 3 to 74 in the 1976 to 1980 survey [1].
- Sources
- [9], [1], [10]
- Caveats
- Both analyses compare different people sampled at different times, not the same people tested twice. A laboratory report does not usually adjust its range for the time of the draw.
What studies tie it to
Linked in research4
Growth in children, in trials of zinc supplements
Shown in trials: zinc supplements raised serum zinc and increased height and weight gain in prepubertal children by about a third of a standard deviation.
The numbers and sources
- Effect
- In a meta-analysis of randomized controlled trials, zinc supplementation increased height gain (effect size 0.350, 95% CI 0.189 to 0.511) and weight gain (0.309, 95% CI 0.178 to 0.439), with no significant effect on weight-for-height. Serum zinc rose by an effect size of 0.820 (95% CI 0.499 to 1.14). Growth responses were greater in children with low initial weight-for-age, and in those older than 6 months with low initial height-for-age [5]. A technical document from a zinc expert group reports that in an earlier version of the analysis, lower starting serum zinc went with a larger growth response, a relationship that was not statistically significant once severely malnourished children were excluded [1].
- Population
- Prepubertal children in 33 studies [5].
- Sources
- [5], [1]
- Caveats
- Effect sizes are in standard deviation units across trials in different countries. The trials show the effect of giving zinc and do not show that a child's own serum zinc predicts the response [1][5].
Pneumonia in older adults in nursing homes
Limited evidence: one study of Boston nursing home residents linked serum zinc of 70 µg/dL or above to fewer and shorter pneumonia episodes.
The numbers and sources
- Effect
- Compared with residents whose serum zinc was below 70 µg/dL, those with final concentrations of 70 µg/dL or above had a lower incidence of pneumonia, almost 50% fewer new antibiotic prescriptions, a shorter duration of pneumonia and fewer days of antibiotic use (2.6 against 3.9 days), with P at or below 0.004 for all. Baseline serum zinc of 70 µg/dL or above was associated with lower all-cause mortality (P = 0.049) [6].
- Population
- Residents of 33 nursing homes in Boston who took part in a 1-year vitamin E trial, 578 with baseline and 420 with final serum zinc. All received daily essential vitamins and minerals, including zinc, at 50% of the US dietary allowance (RDA) [6].
- Sources
- [6]
- Caveats
- An observational analysis within a trial of another nutrient. Infection itself lowers serum zinc [1], so low zinc may mark illness and need not cause it.
Depression
Linked to depression: blood zinc was about 1.85 µmol/L (12 µg/dL) lower in depressed people than in controls across 17 pooled studies.
The numbers and sources
- Effect
- In a meta-analysis, peripheral blood zinc was 1.85 µmol/L lower in depressed than in control subjects (95% CI -2.51 to -1.19), about 12 µg/dL. The gap was larger in studies of inpatients (-2.54 µmol/L) than in community samples (-0.94 µmol/L), and greater depression severity went with a larger gap [7].
- Population
- 1,643 depressed and 804 control subjects in 17 studies [7].
- Sources
- [7]
- Caveats
- Comparisons of people with and without depression at one point in time, so they cannot show which came first. Results differed widely between studies (I² 88%) [7]. The µg/dL figure is converted here.
Type 2 diabetes
Linked to more type 2 diabetes at higher serum or plasma zinc in pooled observational studies (odds ratio 1.64), while higher zinc intake from food went with less.
The numbers and sources
- Effect
- In a meta-analysis of observational studies, higher serum or plasma zinc was associated with type 2 diabetes (OR 1.64, 95% CI 1.25 to 2.14). Comparing the highest with the lowest zinc intake from diet, the odds ratio was 0.87 (95% CI 0.78 to 0.98), and no association was seen for supplemental or total zinc intake. The authors read the raised blood level as a sign of disturbed zinc handling in diabetes [8].
- Population
- 16 observational studies of incident diabetes or of people with type 2 diabetes compared with healthy subjects [8].
- Sources
- [8]
- Caveats
- Observational, and some of the studies measured zinc in people who already had diabetes, so the direction of the link is not established [8].
Sources
- Brown KH, Rivera JA, Bhutta Z, et al. International Zinc Nutrition Consultative Group (IZiNCG) technical document #1. Assessment of the risk of zinc deficiency in populations and options for its control. Chapter 2, Assessment of the risk of zinc deficiency in populations. Food and Nutrition Bulletin. 2004, vol. 25, no. 1, supplement 2. https://www.izincg.org/s/Volume-25-Chapter-2.pdf
- International Zinc Nutrition Consultative Group. Assessing population zinc status with serum zinc concentration. IZiNCG Technical Brief No. 2, 2nd edition, 2012. https://www.izincg.org/s/IZiNCG_TechBrief2_2012-3-njge.pdf
- Hotz C, Peerson JM, Brown KH. Suggested lower cutoffs of serum zinc concentrations for assessing zinc status: reanalysis of the second National Health and Nutrition Examination Survey data (1976-1980). The American Journal of Clinical Nutrition. 2003. https://doi.org/10.1093/ajcn/78.4.756
- Allen L, de Benoist B, Dary O, Hurrell R, eds. Guidelines on food fortification with micronutrients. Geneva: World Health Organization and Food and Agriculture Organization of the United Nations, 2006. ISBN 92-4-159401-2. https://iris.who.int/handle/10665/43412
- Brown KH, Peerson JM, Rivera J, Allen LH. Effect of supplemental zinc on the growth and serum zinc concentrations of prepubertal children: a meta-analysis of randomized controlled trials. The American Journal of Clinical Nutrition. 2002. https://doi.org/10.1093/ajcn/75.6.1062
- Meydani SN, Barnett JB, Dallal GE, et al. Serum zinc and pneumonia in nursing home elderly. The American Journal of Clinical Nutrition. 2007. https://doi.org/10.1093/ajcn/86.4.1167
- Swardfager W, Herrmann N, Mazereeuw G, et al. Zinc in Depression: A Meta-Analysis. Biological Psychiatry. 2013. https://doi.org/10.1016/j.biopsych.2013.05.008
- Fernández-Cao JC, Warthon-Medina M, Moran VH, et al. Zinc Intake and Status and Risk of Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis. Nutrients. 2019. https://doi.org/10.3390/nu11051027
- Hennigar SR, Lieberman HR, Fulgoni VL, McClung JP. Serum Zinc Concentrations in the US Population Are Related to Sex, Age, and Time of Blood Draw but Not Dietary or Supplemental Zinc. The Journal of Nutrition. 2018. https://doi.org/10.1093/jn/nxy105
- King JC, Brown KH, Gibson RS, et al. Biomarkers of Nutrition for Development (BOND): Zinc Review. The Journal of Nutrition. 2016. https://doi.org/10.3945/jn.115.220079
- McDonald CM, Suchdev PS, Krebs NF, et al. Adjusting plasma or serum zinc concentrations for inflammation: Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project. The American Journal of Clinical Nutrition. 2020. https://doi.org/10.1093/ajcn/nqz304
- Lowe NM, Fekete K, Decsi T. Methods of assessment of zinc status in humans: a systematic review. The American Journal of Clinical Nutrition. 2009. https://doi.org/10.3945/ajcn.2009.27230G