Specimen requirement

Adult patient:

  Heparin gel tube

Minimum blood volume: 5 mL

Paediatric patient:

Paediatric heparin gel tube

Number of vials: 1

Minimum blood volume: 1.3 mL

Authorisation code required

No

24 Hr available service

Yes

For suspected iron overdose cases, please call Duty Biochemist for 'Urgent' iron level testing.

Precaution

Please note the timing of blood collection and diurnal variation in serum iron concentration. Values are lower in the afternoon than in the morning and are very low in the evening. A fasting morning sample is preferred for optimal iron studies.

Method

Spectrophotometry

Reference interval

(Source: from manufacturer's kit insert)

Clinical indication

Investigation of suspected iron deficiency or iron overload.

Assessment of patients with acute iron poisoning

Result interpretation

This may be complicated by the presence of an acute phase response, which is associated with decreased iron and total iron binding capacity (with increased ferritin). Hepatocellular disease can have a similar effect.

When iron deficiency may co-exist with an acute phase response assay of serum soluble transferrin receptors may be helpful.

In acute iron poisoning, iron levels are often > 60 µmol/L, with transferrin saturation > 100%. Toxicity can occur with lower levels if absorption is continuing at the time of specimen collection.

Serum ferritin is the preferred method for assessing iron stores.

Measurement of uncertainty

See table.

Frequency of measurement

Daily