Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background:
The CH50 and AP100 assays are ran conjunctively and test complement function. The use of these assays should be limited to the investigation of suspected complement deficiency or the monitoring of complement blocking medications. Any patient with recurrent pyogenic infections or meningococcal disease should be screened, as there is a possibility of a complement deficiency. Patients with atypical lupus may rarely show a defect in CH50 and complement components C1 or C2.
Specimen container paediatric:
Serum-Plain tube
Specimen container adult:
Serum-SST
Minimum volume paediatric:
2 ml
Minimum volume adult:
2 ml
Special requirements:
Samples MUST be separated within 4 hours of venesection. Please ensure that the sample arrives in the laboratory as soon as possible after being taken.
Availability:
CH50 and AP100 are run together on a fortnightly basis.
Freq analysis:
Fortnightly
Add on test:
All urgent add ons via telephone on 0191 282 4766, and must be confirmed via email to the appropriate email address [email protected]
Interpretation:
Serial monitoring of the CH50 in SLE provides no additional information that cannot be obtained from C3 and C4 measurement and is therefore not recommended.
Reference ranges:
AP100: Reported as either Normal or Absent.
CH50: 41.68-95.06 U/ml
Other info:
The AP100 assay is a lytic plate assay which is dependent on 100% haemolysis. The CH50 assay is a liposomal assay which uses a change in absorbance to determine complement activitySerial monitoring of the CH50 in SLE provides no additional information that cannot be obtained from C3 and C4 measurement and is therefore not recommended.