Macrocytosis with Normal B12 and Iron Studies

Laboratory Values and Interpretation

The European Society of Gastroenterology recommends that ferritin levels within the normal range, such as 195, indicate adequate iron stores 1, 2
The American Society of Hematology suggests that transferrin levels within the normal range, such as 188, are indicative of adequate iron binding capacity 1
The normal total iron level of 76 and TIBC of 229, as well as the % saturation of 33%, suggest adequate iron availability for erythropoiesis 1, 2
The elevated MCV of 102.8 is indicative of macrocytosis, with the American College of Physicians recommending further investigation to determine the underlying cause 1, 3
The normal B12 level of 476 rules out vitamin B12 deficiency as the cause of macrocytosis, according to the National Institute of Diabetes and Digestive and Kidney Diseases 2, 3

Folate deficiency is the most likely nutritional cause of macrocytosis with normal B12 levels, as suggested by the European Journal of Haematology 2, 3
Medication effects, particularly thiopurines, anticonvulsants, and methotrexate, can cause macrocytosis, as reported by the American Society of Clinical Oncology 3, 4
Chronic alcohol consumption can cause macrocytosis independent of nutritional deficiencies, according to the National Institute on Alcohol Abuse and Alcoholism 3, 4
Hypothyroidism can cause macrocytosis without anemia, as suggested by the American Thyroid Association 3, 4

The Centers for Disease Control and Prevention recommend measuring serum folate and erythrocyte folate levels to establish a definitive diagnosis of folate deficiency 3, 5
Assessing for medication use, alcohol consumption, and thyroid function is crucial in determining the underlying cause of macrocytosis, as suggested by the American Medical Association 3, 4
Evaluating reticulocyte count can help determine if increased erythropoiesis is contributing to macrocytosis, according to the International Society of Hematology 2, 3
Measuring homocysteine levels can provide additional information on tissue deficiency, as recommended by the National Institutes of Health 5