II. Iron Metabolism 1. The serum iron: The serum iron was estimated by the method of Umemoto and Yamamoto (by means of o-nitroso resorcinmonomethylether) The average serum iron level of 33 cases with rheumatoid arthritis was 47γ/100 ml., and in 27 of 33 cases (82%) the serum iron levels were shown to be below the lower limit of the normal range (5% rejection limit: 54-141γ/100 ml. ), but the concentrations of serum iron of neuralgias (degenerative Spondylosis, sciatica and painful shoulder) were mostly within the normal range. 2. Iron absorption: To investigate the possible role of poor absorption in preventing a response to
oral iron therapy, the changes in serum iron were followed after a test of iron by mouth in 16 caseS with rheumatoid arthritis. The test dose was 1 gm. of reduced iron given with 30 mI. of lemonade-pepsin solution to preserve the iron in the ferrous state and obviate the effects of possible achlorhydria in rheumatoid patients. The results may be grouped under three headings: a) Large rise in serum iron: good adsorption. Three caseS (19%) showed a very large rise in serum iron after the test dose, which is similar to simple iron-deficiency anemia. b) Slight rise in serum iron: presumed poor absorption. Six cases (38%) showed a very small or negligible rise after the test dose, so that at its peak the serum iron was below the normal range. c) In the remaining 7 cases, a maximal rise in serum iron after the test dose was within the normal range. 3. The iron-binding capacity of the serum: The iron-binding capacity of the serum was estimated by means of intravenous injection of Gluferricon (Fe content: 10 mg.). The mean total iron-binding capacity of the serum in the present 13 cases with rheumatoid arthritis was 273γ/100ml., virtually the same as the normal figure
(287γ /100 ml.). The degree of saturation of the iron-binding protein with iron was found to lie between 18 and 45% (average: 34%) in control sUbjects and between 7 and 24% (average: 16%) in rheumatoid patients. 4. The serum copper: The serum copper was estimated by means of diethyldithiocarbamate in rheumatoid arthritis with the following results. Healthy subjects: men (15 cases): mean 89.9±14.8γ /l00 ml., women (15 cases): mean 99.9± 12.6γ/100 ml. There is no significant difference between the two. In 10 of 17 cases (57%) with rheumatoid arthritis, the serum copper levels were shown to be above the upper limit of the normal range (57-138γ/100 ml. ・・・5% rejection limit), neuralgias were mostly (92%) within the normal range. The results of investigations upon alternations in iron metabolism of rheumatoid anemia are reported. 1. The serum iron concentration was usually reduced. 2. The intestinal absorption of iron after a single dose of 1 gm. of reduced iron was variable. Strong presumptive evidence of impaired absorption waS recognised in many cases, but some cases gave the excellent absorption. From these results, it seems that simple iron deficiency exist in some anemic caseS of rheumatoid arthritis. 3. The total iron-binding capacity of the serum was slightly reduced. 4. The degree of Saturation of iron-binding protein with iron was below nornal. 5. The serum copper concentration waS usually elevated.