Dietitian Blog, MNT Guidelines | Dec 18 2020

Detecting and treating common vitamin and mineral deficiencies

Vitamins and minerals_Dietitians On Demand

Vitamins and minerals are utilized by the body for growth, development, and the prevention of diseases. They are considered essential because they cannot be synthesized by the body therefore, they need to be consumed through the diet. Vitamin and mineral deficiencies can be detected by clinical and physical symptoms and then confirmed by a blood test. For mild deficiencies, dietitians can counsel clients on focusing on certain foods to replete nutrient stores. For more severe nutritional deficiencies, a supplement may be prescribed. Read on for guidelines for some of the most common nutritional deficiencies according to The 2020-2025 Dietary Guidelines for Americans.


Clinical indicators

Physical symptoms of an iron deficiency include brittle or spooning of the nails, cracks at the side of the mouth, pale skin, or a swollen or sore tongue. Headaches, fatigue, dizziness, or weakness can also indicate an iron deficiency. More severe symptoms such as shortness of breath, irregular heartbeat, and pica can also occur.

Biochemical indicators

For a complete laboratory evaluation, order a complete blood cell count, reticulocyte count, stool sample, urine sample, serum bilirubin, and a peripheral blood smear. Serum ferritin reflects total iron stores, and a low level indicates iron deficiency. Other biological indicators include a low serum iron, elevated total iron binding capacity, low mean corpuscular hemoglobin concentration, elevated transferrin receptor level, or a low reticulocyte hemoglobin content.

Repletion guidelines

Counsel clients to improve their iron intake by combining dietary sources of iron with high vitamin C foods. Oral supplementation of ferrous sulfate is also recommended. The dosing of iron supplementation is based on age and severity of anemia. If oral iron repletion has failed or rapid iron replacement is indicated, then parenteral iron infusions may be utilized.

Vitamin D

Clinical indicators

In children, vitamin D deficiency results in rickets or poor bone mineralization. In older children and adults, vitamin D deficiency can lead to osteomalacia, the demineralization of bone. Severe cases of vitamin D deficiency can result in dental abnormalities, poor growth, developmental delays, hypocalcemic seizures, and cardiomyopathy.

Biochemical indicators

The main indicator of vitamin D status is the measurement of serum 25(OH)D levels in the blood. This is an approximate measurement of the body’s storage of vitamin D. A blood level less than 15 ng/ml is considered a deficiency, whereas a blood level of 15 to 20 ng/ml is an insufficiency. The optimal level for 25(OH)D is greater than 20 to 30 ng/ml.

Repletion guidelines

Vitamin D can be produced endogenously when combined with sunlight by the body. Encouraging more time outside can improve vitamin D status. Increase vitamin D intake in the diet by recommending foods high in vitamin D. Dietary supplements that contain vitamin D2 or D3 is an effective way to replete vitamin D stores. Supplementation dosage is based on age and severity of deficiency.


Clinical indicators

Hypocalcemia can cause tingling in the fingers, muscle cramps, convulsions, lethargy, poor appetite, altered mental status, irregular heart rhythms, and death. Inadequate calcium intake causes osteopenia in adults and rickets in children.

Biochemical indicators

Serum levels of total and ionized calcium should be measured, along with albumin. Severe hypoalbuminemia may create “false” hypocalcemia. If true hypocalcemia is present, clinicians may consider checking liver and kidney function tests to evaluate for organ dysfunction.

Repletion guidelines

For severe deficiencies, IV replacement is provided to correct hypocalcemia. However, calcium supplements and increased dietary sources of calcium are more commonly utilized for repletion and treatment of chronic hypocalcemia. Oral supplements can be in the form of calcium carbonate or calcium citrate, although calcium carbonate is most commonly used. Calcium citrate is typically utilized for people with limited gut absorption and inflammatory bowel disorders.

Vitamin C

Clinical indicators

Vitamin C deficiency is diagnosed as scurvy. Symptoms include fatigue, inflamed or bleeding gums, and loss of teeth. Without vitamin C, collagen synthesis is impaired, weakening tissue formation. This will cause changes in an individual’s skin and hair. For example, corkscrew hair, poor wound healing, bruising, petechiae, and joint pain are common in severe deficiencies. Physical signs are the best indicator of vitamin C deficiency.

Biochemical indicators

Serum testing for plasma vitamin C can be utilized to detect scurvy, however, recent intake or supplementation can elevate plasma levels. Scurvy, or vitamin C deficiency, is indicated with a serum level of less than 0.2 mg/dL can indicate scurvy. Leukocyte levels of vitamin C are the most accurate diagnosis for body stores of vitamin C.

Repletion guidelines

Dietary supplements come in the form of ascorbic acid. Vitamin C replacement requires a standard dose of 300 mg daily for children and 500 mg to 1,000 mg per day for adults.

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Baird-Gunning, J., & Bromley, J. (2016). Correcting iron deficiency. Australian prescriber39(6), 193–199.
Iron-Deficiency Anemia. (n.d.). Updated March 24, 2022. Accessed June 5, 2023, from
Kleinman, K., & McDaniel, L. (2021). The Harriet Lane Handbook: A manual for pediatric house officers. Philadelphia, PA: Elsevier.
Micronutrient Facts. (2020, March 09). Updated February 1, 2022. Accessed June 5, 2023, from
Office of Dietary Supplements – Calcium. (n.d.). Updated October 6, 2022. Accessed June 5, 2023, from
Office of Dietary Supplements – Vitamin C. (n.d.). Updated March 26, 2021. Accessed June 5, 2023, from
Office of Dietary Supplements – Vitamin D. (n.d.). Updated August 12, 2022. Accessed June 5, 2023, from
U.S. Department of Health and Human Services and U.S. Department of Agriculture. 2020 – 2025 Dietary Guidelines for Americans. 9th Edition. December 2020. Available at
Sara O'Brien, MS, RDN

About Sara O’Brien

Sara O'Brien, MS, RDN, is the Regional Access Manager for Nutricia North America. Previously she worked as a pediatric dietitian and clinical nutrition manager in both outpatient and acute care settings. She completed a combined bachelor's degree and dietetic internship at the University of Connecticut and a Master’s Degree in Dietetics at the University of Rhode Island. Sara is a specialist in pediatric nutrition and believes in an individualized patient-focused approach to nutrition

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