[New service for laboratory investigation of problematic cases. Four patients illustrate the value of EQUALIS].

In 1996, the Endocrinology Group in EQUALIS, in collaboration with The Thyroid Unit at The Section of Endocrinology at Sahlgrenska University Hospital, introduced a "patient-related" quality assurance program. Serum samples from patients with established or suspected thyroid disorder and/or results from thyroid-related biochemical measurements which were at variance with the clinical presentation, were analyzed by the participants of an external quality assurance program in endocrinology. The results from this program were informative as regards capacity, in the individual laboratories, for the evaluation of analytical and/or biological factors causing unexpected results from the measurement of thyroid-related serum components.