Active B12 Case Studies

Where we become aware of case studies where the use of Active B12 has helped with diagnosis we will publish them here. If you would like to send us an example then please send to or use the contact us page.

Case Study – Low Total B12 caused by Haptocorrin deficiency

Patient H had a Total B12 level of 98pmol/L so appeared to be Vitamin-B12 deficient. However, the patient had no clinical symptoms (no anaemia, no macrocytosis, no neuropathy, normal Homocysteine and MMA). Active-B12 level was found to be 46pmol/L indicating that biologically-available B12 was replete..

Patient had a partial deficiency of Haptocorrin which appeared to be of no clinicalconcequence. The low Total B12 concentration mean the patient was sent for several follow-up tests incurring extra cost and added inconvenience. A single Active-B12 test would have given a conclusive result.

Low Total B12 during pregnancy

Patient DS was 38 weeks pregnant and complaining of numbness so was sent for a Vitamin B12 assessment.
Total B12 was 77pmol/L so the patient appeared to be severely B12 deficient and pernicious anaemia was suspected.
However, the Active-B12 level was 43 pmol/L indicating sufficiency.
It is known that during pregnancy the B12 level falls but the Active-B12 level remains high. (Haematologica 2007;92:1711).

Although the Total B12 level was very low, this was due to a recognised fall inHolohaptocorrin during pregnancy. The Active-B12 level showed that B12 status was normal and the numbness was not due to B12 deficiency.

Low Total B12 caused by Haptocorrin deficiency

Patient EE was an 89 year old woman who presented confused and with macrocytosis.
B12 deficiency was presumed with elevated MCV and borderline anaemia. Total B12level was only 114pmol/L, however, Active-B12 level was 99pmol/L indicating that B12status was normal.

This was attributed to a deficiency in Holohaptocorrin (Clin Chem 2003;49:8)

Patient was B12 replete and the low Total B12 level was caused by a Haptocorrindeficiency. Carmel (Clin Chem 2003;49:8) estimates that up to 15% of patients with low Total B12 levels may have low levels due to a mild Haptocorrin deficiency.

B12 deficiency caused by hypothyroidism?

Patient SE, an 87 year old man, presented with shortness of breath and anaemia.
Hb was low, MCV was normal and TSH was elevated indicating hypothyroidism.
Total B12 level was 170pmol/L indicating sufficiency.
Normal RBC folate and serum folate indicated that Iron status was normal and the anaemia was presumed to be due to the hypothyroidism.
However, the Active-B12 concentration was only 4pmol/L indicating severe B12 deficiency.

Although the Total B12 level was normal, the Active-B12 level was severely low showing that the patient was B12 deficienct. Hypothyroidism patients can have this discrepancy between Total and Active B12 levels.

B12 status confounded by haematological disorders

Patient CCM was an 87 year old female suffering from Non-Hodgkins lymphoma.
Patient was severely anaemic with high RDW and low MCV indicating microcytosis.
However the ferritin level was very high so there was no reason to be microcytic.
Total B12 was high at 373 pmol/L so patient appeared to be B12-replete. However, the Active-B12 was severely depressed at only 12 pmol/L.

Patient was severely B12-deficient, even with a high Total B12 level. Abnormalities in transport proteins are evident in many haematological disorders, in this case affecting B12 transport.