1973 Volume 49 Issue 1 Pages 11-16,1
It has been confirmed by many reports that glucose-6-phosphate dehydrogenase (G-6-PD) activity of the erythrocytes increased in hyperthyroidism. However, the comparison of this activity with the results of thyroid function tests used commonly at present, that is, serum protein-bound iodine (PBI), resin sponge uptake of 131I-T3 (Triosorb test), basal metabolic rate (BMR) and thyroid 131I uptake have not been explored adequately.
To clarify this problem, erythrocyte G-6-PD activity and the various thyroid functions were measured simultaneously in patients with hyperthyroidism, hypothyroidism and struma nodosa.
The series comprised inpatients with hyperthyroidism (15), with hypothyroidism (4), with struma nodosa (2) and 10 healthy control subjects. G-6-PD activity of the erythrocytes was determined by the method of Konberg and Horecker in which the amount of NADPH2 newly produced in vitro was determined. The procedures of the determination were performed at 25°C. The effect of hemoglobin concentration in samples was excluded. The enzyme activity was expressed as the change rate ΔOD/min./gHb.
1. The mean value for G-6-PD activity of the erythrocytes obtained in patients with hyperthyroidism was 10.8±1.38 ΔOD/min./gHb (M±SD), whereas in healthy control subjects, it was 7.26±0.58 ΔOD/min./gHb (M±SD). The difference between these values was statistically significant (p<0.001).
2. A positive correlation between G-6-PD activity of the erythrocytes and Triosorb test, PBI, BMR and thyroid 131I uptake (24 hours value), respectively, was observed in the patients with hyperthyroidism, hypothyroidism and struma nodosa, an individual correlation coefficient “r” between G-6-PD activity and each one of the other tests was 0.844 (p<0.01, N=21), 0.726 (p<0.01, N=19), 0.880 (p<0.01, N=16) and 0.673 (p<0.01, N=18), respectively.
3. From the above results, it is suggested that the determination of G-6-PD activity of the erythrocytes can be used as one of the useful thyroid function tests.
