Reference range of B vitamins are:
- Vitamin B1 (thiamine) Normal conditions: serum 0.0-75.4nmol/L, total blood 41.5-108.9nmol/L.
- Normal for vitamin B6:14.6-72.8nmol/L.
- Normal conditions of vitamin B12 (cyanocobalamin): 118-959pmol/L in neonates and 162-694pmol/L in adults.
A low value of B vitamins may indicate:
- B1: Wet beriberi – severe deficiency associated with cardiovascular failure
Dry beriberi – associated with nervous system, peripheral neuropathy
Wernicke's encephalopathy, Wernicke-Korsakoff syndrome – mental changes.
- B2: Called ariboflavinosis, usually seen along with other vitamin deficiencies in those with alcoholism, malabsorption, liver disease, and in the elderly.
- B3: Severe deficiency in conjunction with a low-protein diet causes: Pellagra - classic symptoms are dermatitis, diarrhea, and dementia; may also cause a rash in areas exposed to the sun.
- B6: B6 deficiency is rare by itself; adequate B2 is required for the formation of active PLP; may be seen with chronic alcoholism, malabsorption, smoking, and in asthmatics who take theophylline; can cause convulsions and decreased immunity. Both deficiency and toxicity can cause peripheral neuropathy.
- B7: Very rare; may occur in those receiving total parenteral nutrition and with some inborn errors of metabolism; can cause weakness, delayed development, rash, hair loss, weakness.