RBC zinc optimal range and reference range

The reason to measure it: serum zinc falls during any acute-phase response independently of status, so a low serum zinc with a raised CRP says more about inflammation than about zinc. The red cell compartment reflects weeks to months and is far less disturbed. Intervals are markedly laboratory-specific: two large US laboratories publish 794 to 1470 µg/dL and, for adults over 40, 1005 to 1559 µg/dL, so a result between 794 and 1005 is low at one and normal at the other. Sera's band of 900 to 1500 sits between them; read the result against the reporting laboratory's own interval first. Some laboratories report per gram of haemoglobin rather than per volume — a different scale, not a different unit. No guideline defines a deficiency threshold for red cell zinc, and a sample that was haemolysed or slow to be separated can read falsely low.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Erythrocyte zinc, the intracellular fraction, which runs roughly an order of magnitude above serum.

Reflects zinc status over weeks to months rather than the last few days, and — the reason it exists — it is far less disturbed by inflammation than serum zinc is. Worth measuring when the serum value is borderline, or when deficiency is suspected despite a normal serum result. Reference intervals are markedly laboratory-specific.