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Use of normal serum as a satisfactory binding protein in radioassay of Vitamin B12
322
HSA AND ASBT
Pathology (1980), 12, April
viable after storage as assessed by the above tests, and auto-transfusion of stored marrow cells is a feasible procedure in the treatment of patients with malignant diseases.
THE USE OF AN INDWELLING SUBCUTANEOUS CENTRAL VENOUS CATHETER FOR THE SUPPORT OF LEUKAEMIA PATIENTS
H. BLACKLOCK, M. PILLAI,R. HILL,J. R. D. MATTHEWS, T. CLARKE & J. WADE Departments qf Haematology, Surgery and Medical Physics, Auckland Hospital An indwelling subcutaneous central venous catheter modified from Broviacs hyperalimentation catheter was used for venous access in 25 patients with haematological malignancies, between February 1978 and January 1979. The catheter, inserted for a duration of 5-201 d (mean 77j, provided a suitablemeans for the infusion ofdrugs and blood products, as well as the drawing of frequent blood specimens. Ten septicaemia episodes occurred in the 25 patients, mainly during periods of neutropenia (1 x 109/l). The incidence of these and other infective processes seems consistent with such episodes in other neutropenic leukaemic patients undergoing remission induction therapy. The catheter and its mode of insertion will be briefly described. Despite its apparent advantages (support in situations of inadequate peripheral veins, reduced physical and psychological trauma secondary to frequent venepunctures and the infusion of irritating agents, etc.) its use, not previously described in this group of patients should be further evaluated before general recommendation.
THE VALUE OF RED CELL INDICES IN THE DIFFERENTIAL DIAGNOSIS OF THALASSAEMIA IN PREGNANCY
M. B. SMITH& M. N . CAUCHI Haematology Section. Department of Pathology, Royal Women’s Hospital, Melbourne The diagnosis of thalassaemia minor early in pregnancy has become increasingly important as prenatal diagnosis of homozygous beta-thalassaemia is now available. A low MCV is often the first abnormality detected by haematological studies on antenatal patients. A recent survey of 1169 pregnant patients of Mediterranean origin, at the Royal Women’s Hospital found that 7% of the group had a low MCV (less than 78 flj. The incidence of low MCV varied withethnicorigin, from 2% in Yugoslavs to 18%in Cypriots. H b A, and F levels weredetermined on all samples where the MCV was below 78 fl. On average, 48% of antenatal patients with low MCV had betathalassaemia. However, the discriminant value of MCV (defined as the number of patients with beta-thalassaemia divided by the total number of patients with low MCVj varies widely with ethnic origin, being 82u/,in Cypriots, 80% in Maltese, 73% in Italians, 59:4 in Greeks, 20% in Turks, 13% in Lebanese and 0% in Yugoslavs. It is suggested that the value of a low MCV in the diagnosis of thalassaemia depends on a number of factors, including ethnic origin and clinical condition.
USE OF NORMAL SERUM AS A SATISFACTORY BINDING PROTEIN IN RADIOASSAY OF VITAMIN 812
G. PALTRIDGE, Z. RUDZKI& R . RYALL Departments uf Haematology. The Queen Elizabeth Hospital, The Inslitute of Medical and Veterinary Science and Flinders Medical Centre. Adelaide Recent investigations of radioassay procedures for serum Vitamin B12 have shown a disturbing discrepancy between the clinical state of Vitamin B12 deficiency and the normal result produced for serum Vitamin B12 in a number of patients. It was estimated that this discrepancy occurred in more than 10% of Vitamin B12 deficient patients, a frequency which is unacceptably high. Investigation of the problem by Kolhouse et uI. revealed that serum contained Vitamin B12 analogues which are not biologically active in man but are measured as Vitamin B12 in many commercial assays because of the contamination of the intrinsic factor binder with ‘ R protein. The ‘R’ protein can bind the analogues whereas the intrinsic factor is specific for Vitamin B12. Kolhouse recommended that clinical laboratories and commercial manufacturers change their assays and use only purified intrinsic factor as binder, and this applied to laboratories which used human serum as the source of Vitamin 812 binding protein. The purpose of this report is to present evidence that normal human serum is a satisfactory source of Vitamin B 12
ABSTRACTS OF ANNUAL MEETING
1979 323
binding protein and that assays using serum did not suffer the same problems that occur with commercial kits. As in other laboratories, the awareness of the authors of the problem started with a clear discrepancy between serum Vitamin B12 results using a commercial kit (Quanta-Count BI 2 Radioassay. Bio Rad Laboratories) and the clinical diagnosis of 5 patients. However. instead of repeating the Vitamin B12 analyses by a microbiological method, the analyses were repeated by a radioassay using normal human serum as binder. Results consistent with the patient’s diagnoses were obtained in all cases. Subsequently 49 specimens with mainly low Vitamin B12 levels were assayed by the commercial radioassay kit, radioassay using serum binder and microbiological assay. Six samples gave normal levels by commercial kit but low levels by the serum binder radioassay and microbiological assay. The agreement between the serum binder radioassay and microbiological assay was good overall. Over a 12 mth period all serum radioassay results Tor Vitamin 8 1 2 below 350 pg/ml were checked by microbiological assay. A total of 264 samples were assayed in this way. The results showed good agreement between the 2 methods. with no major difference in classification evident. Thus it is concluded that normal human serum is a satisfactory binder for radioassay of Vitamin 812.
HSA AND ASBT
Pathology (1980), 12, April
viable after storage as assessed by the above tests, and auto-transfusion of stored marrow cells is a feasible procedure in the treatment of patients with malignant diseases.
THE USE OF AN INDWELLING SUBCUTANEOUS CENTRAL VENOUS CATHETER FOR THE SUPPORT OF LEUKAEMIA PATIENTS
H. BLACKLOCK, M. PILLAI,R. HILL,J. R. D. MATTHEWS, T. CLARKE & J. WADE Departments qf Haematology, Surgery and Medical Physics, Auckland Hospital An indwelling subcutaneous central venous catheter modified from Broviacs hyperalimentation catheter was used for venous access in 25 patients with haematological malignancies, between February 1978 and January 1979. The catheter, inserted for a duration of 5-201 d (mean 77j, provided a suitablemeans for the infusion ofdrugs and blood products, as well as the drawing of frequent blood specimens. Ten septicaemia episodes occurred in the 25 patients, mainly during periods of neutropenia (1 x 109/l). The incidence of these and other infective processes seems consistent with such episodes in other neutropenic leukaemic patients undergoing remission induction therapy. The catheter and its mode of insertion will be briefly described. Despite its apparent advantages (support in situations of inadequate peripheral veins, reduced physical and psychological trauma secondary to frequent venepunctures and the infusion of irritating agents, etc.) its use, not previously described in this group of patients should be further evaluated before general recommendation.
THE VALUE OF RED CELL INDICES IN THE DIFFERENTIAL DIAGNOSIS OF THALASSAEMIA IN PREGNANCY
M. B. SMITH& M. N . CAUCHI Haematology Section. Department of Pathology, Royal Women’s Hospital, Melbourne The diagnosis of thalassaemia minor early in pregnancy has become increasingly important as prenatal diagnosis of homozygous beta-thalassaemia is now available. A low MCV is often the first abnormality detected by haematological studies on antenatal patients. A recent survey of 1169 pregnant patients of Mediterranean origin, at the Royal Women’s Hospital found that 7% of the group had a low MCV (less than 78 flj. The incidence of low MCV varied withethnicorigin, from 2% in Yugoslavs to 18%in Cypriots. H b A, and F levels weredetermined on all samples where the MCV was below 78 fl. On average, 48% of antenatal patients with low MCV had betathalassaemia. However, the discriminant value of MCV (defined as the number of patients with beta-thalassaemia divided by the total number of patients with low MCVj varies widely with ethnic origin, being 82u/,in Cypriots, 80% in Maltese, 73% in Italians, 59:4 in Greeks, 20% in Turks, 13% in Lebanese and 0% in Yugoslavs. It is suggested that the value of a low MCV in the diagnosis of thalassaemia depends on a number of factors, including ethnic origin and clinical condition.
USE OF NORMAL SERUM AS A SATISFACTORY BINDING PROTEIN IN RADIOASSAY OF VITAMIN 812
G. PALTRIDGE, Z. RUDZKI& R . RYALL Departments uf Haematology. The Queen Elizabeth Hospital, The Inslitute of Medical and Veterinary Science and Flinders Medical Centre. Adelaide Recent investigations of radioassay procedures for serum Vitamin B12 have shown a disturbing discrepancy between the clinical state of Vitamin B12 deficiency and the normal result produced for serum Vitamin B12 in a number of patients. It was estimated that this discrepancy occurred in more than 10% of Vitamin B12 deficient patients, a frequency which is unacceptably high. Investigation of the problem by Kolhouse et uI. revealed that serum contained Vitamin B12 analogues which are not biologically active in man but are measured as Vitamin B12 in many commercial assays because of the contamination of the intrinsic factor binder with ‘ R protein. The ‘R’ protein can bind the analogues whereas the intrinsic factor is specific for Vitamin B12. Kolhouse recommended that clinical laboratories and commercial manufacturers change their assays and use only purified intrinsic factor as binder, and this applied to laboratories which used human serum as the source of Vitamin 812 binding protein. The purpose of this report is to present evidence that normal human serum is a satisfactory source of Vitamin B 12
ABSTRACTS OF ANNUAL MEETING
1979 323
binding protein and that assays using serum did not suffer the same problems that occur with commercial kits. As in other laboratories, the awareness of the authors of the problem started with a clear discrepancy between serum Vitamin B12 results using a commercial kit (Quanta-Count BI 2 Radioassay. Bio Rad Laboratories) and the clinical diagnosis of 5 patients. However. instead of repeating the Vitamin B12 analyses by a microbiological method, the analyses were repeated by a radioassay using normal human serum as binder. Results consistent with the patient’s diagnoses were obtained in all cases. Subsequently 49 specimens with mainly low Vitamin B12 levels were assayed by the commercial radioassay kit, radioassay using serum binder and microbiological assay. Six samples gave normal levels by commercial kit but low levels by the serum binder radioassay and microbiological assay. The agreement between the serum binder radioassay and microbiological assay was good overall. Over a 12 mth period all serum radioassay results Tor Vitamin 8 1 2 below 350 pg/ml were checked by microbiological assay. A total of 264 samples were assayed in this way. The results showed good agreement between the 2 methods. with no major difference in classification evident. Thus it is concluded that normal human serum is a satisfactory binder for radioassay of Vitamin 812.