in the sample obtained. In that moment the clinician realized that in all the previous laboratory reports, there was a commentary on the platelet count remarking the presence of plentiful platelet aggre- gates. The hemogram and the blood smear was repeated, and a platelet count was made in a sample with sodium citrate, obtaining a normal count (160 . 10^3/μL). Results According to the WHO, patient safety is the absence of preventable harm to a patient during the process of health care and reduction of risk of unnecessary harm associated with health care to an aceptable minimum. The clinic laboratory works an importan role over patient safety, not only in the analytical and preanalytical phase, but also in the -sometimes forgotten- post-analytical phase. Likewise, we should make sure our laboratory reports are understood by clinicians and consider offering complementary tests if necessary. Conclusions From the laboratory, we should enhance our relationship with clinicians trying to avoid misunderstandings as the reflected in the case report. It should be remainded them that in those cases with EDTA-dependent pseudothrombocytopenia, a blood smear is man- datory to confirm platelet aggregates and that the evolution of the platelet count requires a sample with sodium citrate. doi:10.1016/j.cca.2019.03.1527 M407 Demand modulation`s of procalcitonin from electronic request S. De Las Heras Florez, M. Carretero Perez, C.T. Sanz Diaz, E. Mateos Rodriguez Servicio de Análisis Clínicos, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain Background-aim During the last years the assistance activity and the demand for laboratory tests have increased, without being associated with an increase in economic resources. That makes it necessary to use management tools, especially in expensive tests such as pro- calcitonin, a useful biomarker in the diagnosis of sepsis and infections in other locations. In our laboratory, procalcitonin was introduced in April-2013, restricted to Paediatrics, Intensive and Resuscitation. It was possible to apply for any clinician, increasing their demand and generalizing in practically all areas, with 8,793 requests in 2017, more than a half from services not agreed at the beginning. After this increase, a preanalytic demand modulation protocol was established. Methods A request filter was made. In the computer system procalcitonin is an open test. Upon request, a pop-up window opens: “The determination of procalcitonin is useful for the diagnosis and monitoring of the septic patient. Do you want to continue the application? “, Once accepted, a drop-down will appear to choose a reason for request:” suspicion of sepsis, treatment control in septic patients, fever and leukocytosis without focus, others “ Results After the implementation of this filter, half of determinations are made. The majority of Intensive, Resuscitation, Internal Medicine and Geriatrics, Pediatrics, Urgencies and Hematology, although there are of all areas. The most requested request motive was “septic patient control”, followed by “suspicion of sepsis” Conclusions In recent years, the need to assume has arisen the responsibility of reviewing and evaluating analytical determinations by laboratory professionals. A more unnecessary requests, higher risk and more chances of error. The best strategies for the control of the demand of testing are the act when the requesting doctor makes the request. After detecting the high demand for procalcitonin, the need arises for its modulation without impairing the attention to patients and clinicians. A modulation of the preanalytic demand is decided, which allows the application with clinical justification, since it is handled by most of the units. doi:10.1016/j.cca.2019.03.1528 M408 Hemolysis index interfered by high bilirubin: A patient safety problem N. Del Amo, R. Ramos, M.B. Alvarez, E. Marquez, M.J. Ruiz, R. Guillen, F. Cava Laboratorio Central de la Comunidad de Madrid- BRSalud, Spain Background-aim Nowadays serum indices (HIL), hemoglobin (H-index), icterus (I- index) and lipemia (L-index), have been automatized in many laboratories for evaluating the sample quality. Data of HIL indices measures condition the rejection or acceptance of laboratory test results. However, HIL indices are susceptible to interference and the laboratory must ensure the results accuracy so that patient safety won’t be compromised. Methods A specific protocol was computerized in the laboratory informa- tion system according to the results of an internal interference study performed following CLSI recommendations in a Dimension EXL system (Siemens Healthcare SLU). For the indices estimation, the analyzer adds water to 20 ⎧L of sample and the indices measure- ment wavelengths are 405 nm (hemoglobin), 452 (bilirubin) and 700 (lipemia/turbidity). Results After protocol implementation, direct observation detected icteric samples (I index N or=3, equivalent to a bilirubin concentration from 5 to 20 mg/dl) leaded to a hemolytic index N or = 3 (equivalent to a hemoglobin concentration from 50 to 200 mg/dl) without hemolysis. Lactate dehydrogenase, aspartate aminotransferase, po- tassium, sodium and creatinine were incorrectly rejected or flagged with a possible hemolysis interference comment. The algorithm was modified and a flag is now displayed with a recommendation for Abstracts / Clinica Chimica Acta 493 (2019) S673–S710