What is a child's vitamin D level? Understanding the benchmarks for healthy growth

January 10, 2026 •

4 min read

According to the National Institutes of Health, over 20% of the US population may have insufficient vitamin D levels, a concerning statistic that can include children. A child's vitamin D level, measured via a simple blood test, is a crucial indicator of their bone health and overall development. Ensuring your child maintains an adequate level is essential for preventing serious health issues.

Quick Summary

A child's vitamin D level is determined by a blood test that measures 25-hydroxyvitamin D (25[OH]D). Sufficient levels are typically considered above 20 ng/mL, while lower levels indicate insufficiency or deficiency, which can affect bone growth. Intake from sunlight, diet, and supplements helps children maintain proper levels.

Key Points

Blood Test: A child's vitamin D level is accurately measured by a blood test for 25-hydroxyvitamin D (25[OH]D).
Sufficient Range: A level of 20 ng/mL (50 nmol/L) or higher is generally considered sufficient for most children's bone health.
Deficiency Warning Signs: Low levels can manifest as bone pain, muscle weakness, fatigue, and in severe cases, rickets.
Combination Approach: Healthy vitamin D levels are maintained through a combination of safe sun exposure, consumption of fortified foods, and supplements.
Supplementation for Infants: Breastfed infants and some formula-fed infants often require vitamin D supplements to help prevent deficiency.
Expert Guidance: Always consult with a pediatrician to get tested and determine the correct supplementation plan for your child.

Measuring a Child's Vitamin D Status: The 25(OH)D Test

The most reliable way to assess a child's vitamin D status is through a blood test that measures serum 25-hydroxyvitamin D, often abbreviated as 25(OH)D. This is because 25(OH)D is the main circulating form of vitamin D in the bloodstream and is a good reflection of the body's total vitamin D reserves. The results are typically reported in nanograms per milliliter (ng/mL) or nanomoles per liter (nmol/L). Different health organizations use slightly varied benchmarks, but a general consensus on the ranges exists. It's important to have a healthcare professional interpret the results in the context of the child's overall health and growth.

Normal, Insufficient, and Deficient Ranges

For most children, a sufficient vitamin D level is considered to be 20 ng/mL (50 nmol/L) or higher. However, some experts suggest that optimal levels may be higher, around 30 ng/mL (75 nmol/L), to maximize benefits for bone health. The following benchmarks provide a helpful reference for parents discussing their child's results with a doctor:

Sufficient: Levels at or above 20 ng/mL (50 nmol/L). This range is considered adequate for bone and overall health for the majority of children.
Insufficient: Levels between 12-20 ng/mL (30-50 nmol/L). Children in this range are at risk of developing vitamin D deficiency-related issues.
Deficient: Levels below 12 ng/mL (30 nmol/L). This poses a significant risk to the child's bone health and can lead to conditions like rickets.

Symptoms and Risks of Low Vitamin D

While mild vitamin D insufficiency may not cause noticeable symptoms, a moderate to severe deficiency can present with a range of signs. Parents should be aware of these indicators, as prompt action can prevent more serious health complications.

Common signs of deficiency

Bone or muscle pain: Persistent aches, particularly in the lower limbs, can be a symptom in older children.
Muscle weakness: A noticeable lack of strength can indicate a problem with calcium regulation.
Fatigue and irritability: A general feeling of being tired or having a low mood can be non-specific but still related to vitamin D status.
Delayed developmental milestones: In infants, a severe deficiency can lead to delayed walking.
Frequent infections: Vitamin D plays a role in immune system function, and low levels can lead to more frequent respiratory infections.
Growth delays: A deficiency can slow overall growth.

The risk of rickets

Severe vitamin D deficiency can cause rickets, a condition where the bones soften and weaken due to defective mineralization. This can lead to bone deformities, bowed legs, and stunted growth. While less common in developed countries today, rickets is still a risk, especially for infants and toddlers who are exclusively breastfed without supplementation and have limited sun exposure. In adolescents, severe deficiency can lead to osteomalacia, a similar softening of the bones that occurs after growth plates have closed.

Sources of Vitamin D

A child's vitamin D comes from three main sources: sunlight, food, and supplements. For many, a combination of these is necessary to maintain adequate levels, especially during winter months or in northern latitudes where sun exposure is limited.

Sunlight: The skin produces vitamin D when exposed to ultraviolet B (UVB) rays. About 10-15 minutes of sun exposure in the midday with hands and face uncovered can be sufficient for many, but sun protection measures should always be prioritized.
Foods: Few foods naturally contain significant amounts of vitamin D. The best sources include fatty fish like salmon, mackerel, and sardines, as well as cod liver oil.
Fortified Foods: Many dairy products like milk and yogurt, as well as some cereals and orange juice, are fortified with vitamin D. This is a common and important source for many children.
Supplements: Pediatricians often recommend supplements, especially for breastfed infants and for children who don't get enough dietary intake or sun exposure.

Comparison of Vitamin D Considerations by Age Group


Age Group	Key Considerations
0–12 months	Breastfed infants need supplements; some formula-fed infants also need supplementation if they don't consume enough formula.
1–3 years	Focus on fortified foods and consider supplements, especially in winter or with low dietary intake.
4–8 years	Continue with a mix of sun exposure, diet, and supplements as needed.
9–18 years	Teens have a higher risk of insufficiency due to rapid growth and lifestyle factors like limited outdoor time.

How to Address a Child's Vitamin D Level

If a child has been diagnosed with insufficient or deficient vitamin D levels, a healthcare provider will recommend a treatment plan, which may include:

Supplementation: This is the most direct method to correct low levels. Pediatricians will advise on the appropriate supplementation plan to restore levels.
Dietary Changes: Incorporating more vitamin D-rich or fortified foods into the child's diet can help support healthy levels. This includes fatty fish, fortified milk, cereals, and orange juice.
Controlled Sun Exposure: Encouraging safe outdoor time is beneficial. However, parents should avoid prolonged, unprotected sun exposure and use sunscreen to prevent skin damage.

Conclusion

Understanding what is a child's vitamin D level is a critical component of proactive pediatric healthcare. By monitoring for symptoms, discussing testing with a pediatrician, and ensuring a balanced approach to diet, sun exposure, and supplementation, parents can help their children maintain healthy vitamin D levels. Adequate vitamin D is not just about bone health; it supports a wide range of bodily functions vital for proper growth and development. Always consult a healthcare professional for personalized guidance regarding your child's specific vitamin D needs and treatment. For more information, visit the National Institutes of Health Office of Dietary Supplements website.

Frequently Asked Questions

A normal or sufficient vitamin D level for a child is typically considered 20 ng/mL (50 nmol/L) or higher. Many experts also consider levels above 30 ng/mL (75 nmol/L) to be optimal for supporting bone and overall health.

The initial signs can be subtle, such as fatigue, irritability, and muscle aches. In infants, slowed growth or delayed developmental milestones, like walking, may be observed.

A child's vitamin D level is tested with a blood draw to measure the concentration of 25-hydroxyvitamin D (25[OH]D). This test is the most accurate way to determine vitamin D status.

It is often difficult for children to get enough vitamin D from food alone, as it's naturally present in only a few foods like fatty fish. This is why many foods are fortified, and why supplements are frequently recommended.

A moderate amount of direct sun exposure, about 10-15 minutes on hands and face during midday, can stimulate vitamin D production. However, this varies by skin tone and location, and sun safety measures are crucial to prevent skin damage.

Yes, vitamin D supplements are safe and often necessary for children, especially infants and those with low dietary intake or sun exposure. High doses should only be administered under the guidance of a healthcare professional to avoid toxicity.

Rickets is a disease caused by severe vitamin D deficiency in children. It leads to the softening and weakening of bones due to insufficient calcium absorption, which can result in bone deformities and impaired growth.

Vitamin D2 is typically from plant sources and fortified foods, while Vitamin D3 is produced by the skin in response to sunlight and is found in some animal products. D3 is generally considered more effective at raising and maintaining vitamin D levels in the blood.