Background: Sodium potassium ATPase (Na+-K+ ATPase) and Glucose 6 phosphate dehydrogenase (G 6 PD) activities in different tissues have been found to be stimulated by thyroid hormones. In erythrocytes, the activities of these enzymes were reported to vary. The aim of our study was to determine the sodium potassium AT-Pase and glucose 6 phosphate dehydrogenase ac-tivities in patients with hyperthyroidism and compare them with those of patients with euthy-roid goiter.
Materials and Methods: After approval from the Institutional Ethics Committee and obtaining in-formed consent from all patients, 40 hyperthyro-id patients (17 men, 23 women; mean age 44.75±2.6 years) and 50 patients with euthyroid goiter (13 men, 37 women; mean age 37.2±1.6 years) were included in the study. They were classified based on T3, T4, TSH measurements. Erythrocyte Na+-K+ ATPase and G 6 PD activity were measured using spectrophotometry.
Results: In hyperthyroid patients, Na+-K+ AT-Pase activity was significantly lower compared to euthyroid controls (134.98±3.78 vs. 164.34±3.85 nmol pi/hr.mg protein, p<0.001) and G 6 PD le-vels were significantly elevated when compared to euthyroid controls (19.19±0.438 U/g Hb vs. 11.505±0.385 U/g Hb, p<0.001).
Conclusion: Hyperthyroidism is associated with decrease in Na+-K+ ATPase activity and increase in G 6 PD levels when compared to patients with euthyroid goiter. The measurement of Na+-K+ ATPase activity could be used as an early marker for diagnosis of hyperthyroidism.
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