Validation of serum free light chain reference ranges in primary care.

Background: The demand for measurement of serum immunoglobulin free kappa (κ) and lambda (λ) light chains has increased. The κ:λ ratio is used to assist in diagnosis/monitoring of plasma cell disorders. The binding site reference range for serum-free light chain κ:λ ratios of 0.

Patient-reported fasting status for glucose-tolerance testing compared with fasting status identified by total bile-acid concentrations.

Aim: To investigate whether patients follow advice regarding the duration of a fast, prior to blood tests which require an overnight fast for their correct interpretation.

Method: Patients referred for a glucose-tolerance test gave informed consent. They were asked to complete a questionnaire regarding the duration of their fast, and an additional blood sample was collected for fasting total bile-acid measurement.