Nihon Kohden MicroCC-20: PLT counts read low during calibration
What happened
As reported in the case, PLT values came out low — roughly 75% of the lower expected level — calibration would not let the value go any lower, and a blank run showed background around 5.
What was checked
- Run blank (zero) measurements to assess the counting background.
- Repeat the calibration with fresh human blood instead of the commercial calibrator.
- Rule out mains noise from a low-cost UPS and verify the grounding.
- Check that the sample-type calibration coefficients match the mode in use (capillary vs whole blood).
Cause
The engineers considered the most likely cause to be a calibrator whose assigned PLT values did not match its stated specifications; interference from the UPS remained a possible contributor. The conclusion was probable, not confirmed.
The cause is probable and was not fully confirmed.
What was done
Calibration was redone against fresh human blood, and the sample-type calibration coefficients were corrected. The coefficient adjustment was a procedure from the manufacturer's service documentation, done by authorised personnel. The outcome was reported as probable.
Safety
Fresh blood and the analyzer's fluid path are potentially infectious: work with gloves, contain any spills, and decontaminate the sampling area after calibration.
Lesson: When the counter will not reach the calibration target, suspect the calibrator's assigned values and mains noise before blaming the counting channel.
Covered in the course: Lab Analyser Service — Level 2: Fault-Finding →
Written from an anonymised case shared by service engineers. It is not a manufacturer instruction and grants no authorisation. Independent note; names are trademarks of their owners.