Dear List Members

 

Many Aeroset users may be aware of the interference by indoxyl sulphate (found in the serum of patients with severe renal disease) on the "new" Abbott total bilirubin (diazo) method. (6L45-20 or 6L45-40).

The method was designed to replace the oxidation method 7D60-02.

 

Abbott state in the pack insert that the addition of 0.25 mmol/L indoxyl sulphate to specimens increased the total bilirubin by a maximum of 1.5 mg/dL. Read casually, this may not seem important (even if you realize that 1.5 mg/dL is 25.7 mmol/L).  We are all used to adding a few hundred mg of cholesterol to steroid assays and the cross reactivity making no difference.

 

However after changing to the diazo method, our renal physician contacted us almost immediately to ask what had happened to the bilirubin method?

Patients on haemodialysis monitored regularly, suddenly showed an increase in bilirubin.

 

We have moved back to the oxidation method, pending a "fix" from Abbott for the diazo method. While we had both methods on our Aerosets, we did a very brief comparison, shown below (oxidation method in brackets) in umol/L:

 

Normal (non-renal unit) patients: 24 (20), 11 (10), 30 (27), 22 (20), 25 (24).

 

Renal Unit (haemodialysis): 19 (5), 30 (4), 34 (5), 23 (3), 15 (5), 36 (3), 21 (3)

 

Graham Ellis and Stephen McCombe

St. John's Hospital

Livingston

West Lothian