Thesis (MTech (Medical Technology))--Cape Technikon, 1992. / As early as 1822 it was discovered that treating a patient, who had a macrocytic anaemia, with a diet containing liver, a rich source of folic acid (folacin), brought about an excellent haematological response. extract, a source of The same happened in 1851 when a yeast vitamin B12 (cobalamine), corrected a megaloblastic anaemia. It is well known that a lack of either one or both of these vitamins is responsible for a megaloblastic anemia which has been shown to be hematologically indistinguishable yet requires different treatment to correct. It is therefore important to make a correct diagnosis as to the cause of the illness in a megaloblastic anaemia by the measurement of vitamin B12 and folate levels. Various laboratory test methods were developed over the past 20 to 30 years and through constant improvement culminated in the current radio immune assay (RIA) technique used for the measurement of vitamin B12 and folate values. This method has many advantages over the microbiological method that preceeded it, but is still dependent on normal values or reference ranges. These reference ranges, supplied with each test kit, are obtained from a white American population and are probably only applicable to the white South African population.