What does an elevated folate (folic acid) level of 318 nanograms per milliliter indicate?

From the Guidelines

An elevated folate level of 318 nanograms per milliliter indicates a normal to high folate status, but the exact interpretation depends on the reference range used by the laboratory, with most recent guidelines suggesting a normal range for red blood cell folate to be around 340 nmol/L, which is roughly equivalent to 318 ng/mL when considering the conversion factors and units used in different studies 1.

Key Points to Consider

• The patient's folate level is within a range that suggests adequate folate status, considering the reference range provided in the most recent and highest quality study 1.
• Red blood cell folate is a reliable indicator of long-term folate status, reflecting tissue stores accumulated over the 120-day lifespan of red blood cells, rather than recent dietary intake.
• Folate is crucial for proper DNA synthesis, cell division, and prevention of megaloblastic anemia, as well as for preventing neural tube defects in the developing fetus during pregnancy.
• The measurement of folate status can be affected by various factors, including the method of analysis, with microbiological assays being considered the gold standard, and pre-analytical precautions being necessary to ensure reliable results 1.

Clinical Implications

• Given the patient's folate level, no intervention or supplementation is immediately needed, as the level falls within a range that suggests adequate folate status, according to the most recent guidelines 1.
• However, it is essential to consider the patient's overall clinical context, including dietary habits, pregnancy status, and presence of any conditions that may affect folate metabolism or increase the risk of folate deficiency.
• Healthcare providers should consult the most recent and reliable guidelines, such as those from the ESPEN micronutrient guideline 1, to ensure accurate interpretation of folate levels and to provide evidence-based recommendations for patient care.

From the FDA Drug Label

Normal erythrocyte folate levels have been reported to range from 175 to 316 ng/mL. An elevated folate level of 318 nanograms per milliliter indicates that the level is slightly above the normal range.

• The normal range is 175 to 316 ng/mL.
• A level of 318 ng/mL is only slightly elevated and may not be clinically significant. 2

From the Research

Folate Levels and Interpretation

• An elevated folate level of 318 nanograms per milliliter may indicate an excess of folate in the body, but the provided studies do not directly address the significance of this specific level 3, 4, 5, 6, 7.
• Folate deficiency is typically diagnosed using red blood cell folate levels, along with macrocytosis and/or megaloblastic anemia 3.
• Serum folate levels can be affected by various factors, including hemolysis, vitamin B12 deficiency, and dietary intake 4, 6, 7.
• Elevated homocysteine levels, which are associated with folate deficiency, can be reduced by folic acid administration 3.

Clinical Significance

• Folate plays a crucial role in preventing neural tube defects, and women of childbearing age are recommended to take 400 micrograms of folate per day 3.
• Folate deficiency can have significant consequences, including macrocytic anemia, megaloblastic anemia, and increased risk of cardiovascular disease 3, 5.
• The relationship between folate levels and gastrointestinal health is complex, and folate deficiency can produce gastrointestinal alterations 5.

Laboratory Testing

• Serum and red blood cell folate measurements are used to assess folate deficiency, but there is no consensus on the lower limit of serum folate reference values 7.
• Hemolysis can affect folate analysis in plasma, leading to biased results, and an evidence-based approach is needed to interpret folate concentrations in hemolytic samples 6.