| Specimen requirement | Special EDTA tube (blue top) for
RBC Zinc
Minimum blood volume: 3 mL
|
| Authorisation code required | No |
| 24 Hr available service | No |
| Method | Inductively coupled plasma-mass spectrometry (ICP-MS) |
| Reference interval |
155 - 237 µmol/RBC (Source: Local population study published in Acta. Endo. 120: 1,989: 155 - 160) |
| Clinical indication | A useful tissue marker for established thyrotoxicosis. |
| Result interpretation |
Erythrocyte carbonic anhydrase I, the major zinc containing protein in red cells, is decreased in thyrotoxicosis. Erythrocyte zinc indirectly reflects the carbonic anhydrase I content. The response to a changing thyroid status is slow and therefore it cannot be used for monitoring treatment of thyrotoxicosis. |
| Measurement of uncertainty | See table. |
| Frequency of measurement | Monthly |