Red Blood Cell Zn Research Articles

Erythrocyte zinc concentration as an indicator to distinguish painless thyroiditis-associated transient hypothyroidism from permanent hypothyroidism

Red blood cell (RBC) zinc (Zn) concentration reflects a patient's mean thyroid hormone level over the preceding several months. The aim of this study was to examine whether RBC Zn level can be used as an indicator to distinguish painless thyroiditis-associated transient hypothyroidism (TH) from permanent hypothyroidism (PH). RBC Zn level was measured in 30 untreated PH patients with Hashimoto's thyroiditis and 7 untreated TH patients with painless thyroiditis in whom preceding transient thyrotoxicosis had been confirmed. RBC Zn concentration was significantly lower in TH patients than that in PH patients. There was a positive correlation between RBC Zn and serum TSH, and the latter was clearly lower in TH patients than that in PH patients. However, RBC Zn level was again significantly lower in TH patients than PH patients despite of the comparable serum TSH levels in both groups when RBC Zn was evaluated in patients with serum TSH levels of less than 50 mU/L. Thus TH patients could be identified with RBC Zn measurement, allowing us avoidance of unnecessarily prolonged T4 administration to them.

Clinical utility of red blood cell carbonic anhydrase I and zinc concentrations in patients with thyroid diseases

We have recently reported that, in patients with hyperthyroidism, the red blood cell (RBC) carbonic anhydrase I (CAI) and zinc (Zn) concentrations both reflect the patient's integrated thyroid hormone level over the preceding few months. In this study, we evaluated the clinical usefulness of determining the RBC CAI and Zn concentrations in patients with various types of thyroid disease. Six patients with painless thyroiditis (PT) had normal RBC CAI concentrations and the two patients tested had normal RBC Zn levels. In four patients with syndromes of inappropriate thyrotropin (TSH) secretion (SITSH) two euthyroid patients had normal RBC CAI and two hyperthyroid patients had subnormal RBC CAI and Zn. In a patient with Graves' disease whose plasma thyroxine (T 4) and triiodothyronine (T 3) concentrations changed remarkably because of poor compliance with the regimen, the change in plasma thyroid hormone levels preceded the change in the RBC CAI and Zn concentrations by 2 to 3 months. These observations suggest that the measurement of RBC CAI and Zn concentrations may be useful clinically as follows: (1) in differentiating hyperthyroid Graves' disease from transient hyperthyroidism due to destructive thyroiditis; and (2) in obtaining an accurate estimate of the extent of elevated thyroid hormone levels in hyperthyroid patients over time.

Erythrocyte Carbonic Anhydrase-I Concentrations in Patients with Graves’ Disease and Subacute Thyroiditis Reflect Integrated Thyroid Hormone Levels over the Previous Few Months*

We have recently reported that in patients with hyperthyroidism, red blood cell (RBC) zinc (Zn), most of which is present as the metal of carbonic anhydrase-I isozyme (CAI), reflects a patient's integrated thyroid hormone level over the previous few months. In the present report the RBC CAI concentration was measured by RIA in 26 healthy controls, 25 patients with hyperthyroid Graves' disease, 5 patients with primary hypothyroidism, and 10 subjects with subacute thyroiditis with elevated thyroid hormone levels. The mean (+/- SD) RBC CAI concentration in euthyroid controls was 380 +/- 70 nmol/g hemoglobin (Hb), and the normal range defined as the mean +/- 2 SD, was 240-520 nmol/g Hb. The mean RBC CAI in Graves' disease was decreased (180 +/- 53 nmol/g Hb), and 22 patients (88%) had subnormal values. The mean RBC CAI concentrations in hypothyroidism and subacute thyroiditis were not different from the control values. After treatment with antithyroid drugs, both mean the plasma T4 and T3 levels in 11 Graves' patients became normal within 4 weeks, but the normalization of RBC CAI lagged behind by about 2 months. Furthermore, the highest correlation was observed between the RBC CAI and plasma T4 and T3 levels measured 8 weeks earlier. During prednisolone therapy the RBC CAI in patients with subacute thyroiditis remained at a normal level. These results suggest that 1) not only RBC Zn but also the RBC CAI concentration in patients with Graves' disease reflect the patient's mean thyroid hormone level over the preceding several months; and 2) in patients with subacute thyroiditis, elevation of plasma thyroid hormone concentrations is transient and causes little change in the RBC CAI concentration.

Erythrocyte Zinc Concentration in Patients with Subacute Thyroiditis

We have recently reported that red blood cell (RBC) zinc (Zn) in patients with hyperthyroidism reflects a patient's integrated thyroid hormone level over the previous few months. In the present paper RBC Zn concentrations were measured in 10 patients with subacute thyroiditis whose total plasma T4 and T3 levels were elevated. The values were compared with those obtained in 10 patients with untreated Graves' disease, whose plasma T4 concentrations were elevated to the same level as in the former group. The RBC Zn concentration was normal in 9 of 10 patients with subacute thyroiditis, but was depressed in all patients with Graves' disease. The mean (+/- SE) RBC Zn in patients with subacute thyroiditis was 162 +/- 9 mumol/L, significantly (P less than 0.001) higher than that in Graves' disease (87 +/- 5 mumol/L). During prednisolone treatment the RBC Zn in patients with subacute thyroiditis remained at the normal level and did not change significantly, although it was slightly decreased at 2 and 4 weeks of treatment. On the other hand, the RBC Zn in patients with Graves' disease was significantly increased at 8 weeks of treatment and reached the normal range in 12 weeks. These results suggest that elevation of plasma thyroid hormone concentrations in patients with subacute thyroiditis is transient and does not cause any significant change in the RBC Zn concentration.

Erythrocyte zinc in hyperthyroidism: Reflection of integrated thyroid hormone levels over the previous few months

Red blood cell (RBC) zinc (Zn) concentration was measured by atomic absorption spectrophotometry in 28 healthy volunteers, in 46 patients with hyperthyroidism, and in 6 patients with hypothyroidism. The mean (±SD) RBC Zn concentration in euthyroid controls was 11.4 ± 1.5 mg/L RBC, and the normal range defined as the mean ± 2 SD was 8.5 to 14.3 mg/L RBC. The mean RBC Zn in patients with hyperthyroidism was decreased to 6.4 ± 1.6 mg/L RBC, and 43 (93%) had low values. The mean RBC Zn in patients with hypothyroidism was not different from that in the controls. There was a significant negative correlation between the concentrations of RBC Zn and those of both plasma thyroxine (T 4; r = −0.73) and plasma 3,5,3′-triiodothyronine (T 3; r = −0.70). After the treatment of 17 hyperthyroid patients with antithyroid drugs, both mean plasma T 4 and T 3 levels became normal within 4 weeks, but the normalization of RBC Zn lagged about 2 months behind them. The RBC Zn levels significantly correlated with both the plasma T 4 and T 3 levels obtained 0, 4, 8, and 12 weeks prior to the RBC sampling, and the highest correlation was observed between the RBC Zn levels and plasma T 4 and T 3 levels measured 8 weeks previously. These data suggest that RBC Zn concentration in hyperthyroid patients reflects a patient's mean thyroid hormone level over the preceding several months as glycosylated hemoglobin level does in diabetic patients.

Alterations in magnesium and zinc metabolism in thyroid disease

Magnesium (Mg) and zinc (Zn) status was assessed in subjects to evaluate the effects of thyroid diseases on Mg and Zn metabolism. Plasma and red blood cell (RBC) concentration and peripheral blood mononuclear cell (MNC) content of Mg and Zn, and 24-hour urinary excretion of Mg, Zn, creatinine (Cr), calcium (Ca), sodium (Na), and potassium (K) were measured in 11 thyrotoxic, 29 hypothyroid, and 25 euthyroid control subjects. Serum albumin, α 2-macroglobulin, and the binding of Zn to albumin were also determined. Plasma and RBC Mg concentrations were low in half of the hyperthyroid subjects, but mean values were not significantly different from controls. Urinary excretion and clearance of Mg were lower in hypothyroid subjects, but differences were removed when expressed relative to Cr excretion and clearance. Similar patterns were noted for urinary Ca, Na, and K, suggesting that their reduced excretion reflects alterations in renal hemodynamics. Plasma Zn was lower in hypothyroid subjects and correlated with serum albumin; MNC Zn and urinary Zn were also low. Plasma Zn concentration was normal and serum albumin significantly lower in the hyperthyroid group than in the control group. Further, RBC Zn content was significantly lower in hyperthyroid subjects, and inversely related to plasma thyroxine concentration. The hyperthyroid group also excreted significantly greater amounts of Zn than controls, indicative of a catabolic process. This increased urinary loss may reflect a shift in the distribution of plasma Zn between ultrafilterable and Zn-albumin complexes. In summary, this study provides evidence for marked alterations in Zn homeostasis in persons with thyroid disease. Whether the observations indicate deficiency states and have clinical implications will require further investigation.