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Radioactive vitamin B12 absorption studies: Results of direct measurement of radioactivity in the blood
126
Report of meeting
false negative as well as false positive tests may be encountered with both methods. In this series the Heinle test gave overlapping of results in the pernicious-anemia and nonpernicious-anemia groups in 9 out of 97 tests, while no overlapping was found with the Schilling test. However, a false positive Schilling test was encountered in one instance. Although the Schilling test on rare occasions may be falsely positive, it appears to be a reliable test in the diagnosis of pernicious anemia. Radioactive Vitamin B12 Absorption Studies: Results of Direct Measurement of Radioactivity in the Blood: ALFRED M. DOSCHERI-IOLMEN and PAUL S. HAGEN, Minneapolis, Minnesota.
The absorption of vitamin Blz was determined by measurement of radioactivity of blood or plasma samples collected after the oral administration of radioactive vitamin B12. Radioactivity measurements were made with a 20-ml well-type scintillation counter. Test doses consisted of 0.46 #g and 0.92 /zg of vitamin BI~ containing 0.5/~c and 1-0 #c of C o 6°. respectively. Definite radioactivity usually first appeared at 4 hours. Then the activity increased until a peak was reached in the 8-12 hour interval. The plasma clearance of radioactivity was slow and slight activity was usually present after 1 week. Thirty nonpernicious-anemia patients had peak net counts ranging from 17 to 54 per minute in plasma after the smaller test dose, and 3 had 56 to 108 counts per minute after the bigger test dose. Seven patients with pernicious anemia showed either no radioactivity or only traces in the plasma. However, when potent intrinsic-factor concentrate was administered simultaneously with the test dose of vitamin B~, plasma radioactivity was within the range found in control subjects. A fairly good correlation was found between the plasma levels of radioactivity and the urinary excretion of radioactivity after a flushing dose of unlabeled
vitamin Ba~. Smaller scintillation counters have been found practical in further applications of the direct plasma-measurement technique. This method appears valuable in the diagnosis of pernicious anemia and other vitamin-B12 malabsorptive states, in the evaluation of intrinsic factor activity, and in studies of various aspects of the metabolism of vitamin B12. Experience with the Radioactive Vitamin B12 Urinary-Excretion Test of Schilling: MARTHA E. SMITH and TYRA HUTCHENS, Portland, Oregon.
Because the Schilling test is one which any routine laboratory equipped for clinical isotope studies can easily handle, and because this test is felt to have practical usefulness, this procedure has been set up in our laboratory on a trial basis. This report covers our practical experience with the first 100 tests performed, using an oral dose of 0.5 #c of vitamin B12 Co 6° with specific activity 758 #c/rag o r 1035-1082 /tc/mg. 56 patients with a diagnosis of pernicious anemia, who came to the Out-patient Clinic for treatment, and 3 normals were tested-without using intrinsic factor. Except for 3 cases, the vitamin B12 Co 6° excretion per 24 hour urine was 0-3.3% of the oral dose. The results of 4 tests on 3 normal individuals were 11.5-26.1%. Outpatients who have had gastric analyses for various reasons and who did not have a diagnosis of pernicious anemia were tested as further controls. They had excretions of 8"9-26"5% of the oral dose per 24 hour urine. Recently, patients with diagnostic problems have been studied on a consultation basis and a few intrinsic factor studies have been done as seemed indicated. These 19 cases included 9 cases previously diagnosed as pernicious anemia in which there was some question about the diagnosis or which were first seen in remission. In addition, there were 4 cases of nutritional macrocytic anemia, 2 macrocytic anemias of unknown etiology, 1 macrocytic anemia associated
Report of meeting
false negative as well as false positive tests may be encountered with both methods. In this series the Heinle test gave overlapping of results in the pernicious-anemia and nonpernicious-anemia groups in 9 out of 97 tests, while no overlapping was found with the Schilling test. However, a false positive Schilling test was encountered in one instance. Although the Schilling test on rare occasions may be falsely positive, it appears to be a reliable test in the diagnosis of pernicious anemia. Radioactive Vitamin B12 Absorption Studies: Results of Direct Measurement of Radioactivity in the Blood: ALFRED M. DOSCHERI-IOLMEN and PAUL S. HAGEN, Minneapolis, Minnesota.
The absorption of vitamin Blz was determined by measurement of radioactivity of blood or plasma samples collected after the oral administration of radioactive vitamin B12. Radioactivity measurements were made with a 20-ml well-type scintillation counter. Test doses consisted of 0.46 #g and 0.92 /zg of vitamin BI~ containing 0.5/~c and 1-0 #c of C o 6°. respectively. Definite radioactivity usually first appeared at 4 hours. Then the activity increased until a peak was reached in the 8-12 hour interval. The plasma clearance of radioactivity was slow and slight activity was usually present after 1 week. Thirty nonpernicious-anemia patients had peak net counts ranging from 17 to 54 per minute in plasma after the smaller test dose, and 3 had 56 to 108 counts per minute after the bigger test dose. Seven patients with pernicious anemia showed either no radioactivity or only traces in the plasma. However, when potent intrinsic-factor concentrate was administered simultaneously with the test dose of vitamin B~, plasma radioactivity was within the range found in control subjects. A fairly good correlation was found between the plasma levels of radioactivity and the urinary excretion of radioactivity after a flushing dose of unlabeled
vitamin Ba~. Smaller scintillation counters have been found practical in further applications of the direct plasma-measurement technique. This method appears valuable in the diagnosis of pernicious anemia and other vitamin-B12 malabsorptive states, in the evaluation of intrinsic factor activity, and in studies of various aspects of the metabolism of vitamin B12. Experience with the Radioactive Vitamin B12 Urinary-Excretion Test of Schilling: MARTHA E. SMITH and TYRA HUTCHENS, Portland, Oregon.
Because the Schilling test is one which any routine laboratory equipped for clinical isotope studies can easily handle, and because this test is felt to have practical usefulness, this procedure has been set up in our laboratory on a trial basis. This report covers our practical experience with the first 100 tests performed, using an oral dose of 0.5 #c of vitamin B12 Co 6° with specific activity 758 #c/rag o r 1035-1082 /tc/mg. 56 patients with a diagnosis of pernicious anemia, who came to the Out-patient Clinic for treatment, and 3 normals were tested-without using intrinsic factor. Except for 3 cases, the vitamin B12 Co 6° excretion per 24 hour urine was 0-3.3% of the oral dose. The results of 4 tests on 3 normal individuals were 11.5-26.1%. Outpatients who have had gastric analyses for various reasons and who did not have a diagnosis of pernicious anemia were tested as further controls. They had excretions of 8"9-26"5% of the oral dose per 24 hour urine. Recently, patients with diagnostic problems have been studied on a consultation basis and a few intrinsic factor studies have been done as seemed indicated. These 19 cases included 9 cases previously diagnosed as pernicious anemia in which there was some question about the diagnosis or which were first seen in remission. In addition, there were 4 cases of nutritional macrocytic anemia, 2 macrocytic anemias of unknown etiology, 1 macrocytic anemia associated