What vitamins should be checked in laboratory (lab) work?

From the Guidelines

When checking vitamin levels in lab work, I recommend focusing on vitamins D, B12, folate, and iron studies as these are most commonly deficient and clinically significant, as supported by the most recent study 1. A comprehensive panel should include vitamin D (25-hydroxyvitamin D), vitamin B12, folate, and iron studies (including ferritin, iron, total iron binding capacity, and transferrin saturation). Additional vitamins worth checking in specific situations include:

• vitamin A,
• vitamin E,
• vitamin K, and
• other B vitamins like B1 (thiamine) and B6 (pyridoxine), as indicated in the study 1. These tests are particularly important for patients with:
• malabsorption disorders,
• restrictive diets,
• pregnancy,
• certain medications, or
• chronic diseases, as highlighted in the study 1. Vitamin deficiencies can cause various symptoms ranging from fatigue and neurological problems to bone health issues and anemia. Regular monitoring is especially important for at-risk populations such as:
• the elderly,
• pregnant women,
• those with gastrointestinal disorders, and
• individuals on certain medications that may deplete vitamin levels, as emphasized in the study 1. The frequency of testing should be determined based on individual risk factors and previous results. It is also essential to consider the patient's specific condition, such as short bowel syndrome, and adjust the supplementation and monitoring accordingly, as recommended in the study 1. Furthermore, in patients planning to become pregnant after bariatric surgery, it is crucial to monitor and supplement vitamins and minerals, including folic acid, vitamin B12, iron, and vitamin D, to prevent deficiencies and ensure a healthy pregnancy, as advised in the study 1.

From the FDA Drug Label

Hematocrit, reticulocyte count, vitamin B12, folate and iron levels should be obtained prior to treatment. The vitamins that should be checked in laboratory work are:

• Vitamin B12
• Folate 2

From the Research

Laboratory Tests for Vitamin Deficiency

The following vitamins should be checked in laboratory work:

• Vitamin D:
  • 25-hydroxyvitamin D (25(OH)D) testing is recommended for certain risk groups 3, 4, 5
  • Serum 25-hydroxyvitamin D level measurement is suggested as the initial diagnostic test in patients at risk for deficiency 5
  • Target concentrations of 30 to 50 ng/mL (75 to 125 nmol/L) are recommended 3
• Other vitamins:
  • No specific recommendations are provided in the studies for laboratory tests on vitamins other than Vitamin D

Risk Groups for Vitamin D Deficiency

Certain risk groups should be screened for vitamin D deficiency, including:

• Patients with malabsorption syndromes 3
• Individuals with limited sun exposure, limited oral intake, and impaired intestinal absorption 4
• Middle-aged adults with characteristics such as female sex, overweight, low physical activity, winter season, moderate sun exposure, and very fair or dark skin 6

Diagnosis and Treatment of Vitamin D Deficiency

• Diagnosis: Measurement of serum 25-hydroxyvitamin D level by a reliable assay is recommended as the initial diagnostic test in patients at risk for deficiency 5
• Treatment: Treatment with either vitamin D(2) or vitamin D(3) is recommended for deficient patients, with a supplementation dose of 800 to 2000 international units (IU) per day 3, 5