Homocystein (Hcy) är en aminosyra som är starkt bunden till kroppens metabolism av metionin. När hcy tillbakabildas till metionin krävs närvaro av vitamin B12 och folat. Analys av hcy i plasma (P-hcy) används vid misstanke om brist av någon av dessa vitaminer. Analysen kan utföras med ett antal olika metoder. I denna studie analyseras P-hcy immunologiskt med analysinstrumentet Immulite 2000 XPi (Siemens Healthcare Diagnostics Inc, Erlangen, Germany) och enzymatiskt med analysinstrumentet Cobas 6000 (Roche Diagnostics Scandinavia AB, Bromma, Sweden) med syfte att jämföra analysresultaten från de båda metoderna. Immulite 2000 XPi användes som referensmetod då denna validerats för klinisk analys av P-hcy. Studien genomfördes på 51 st slumpvis utvalda plasmaprover (24 kvinnor och 27 män) mellan 25 och 95 år.Utöver metodjämförelse genomfördes precisionsstudie med Cobas 6000 (20 replikat i två nivåer). Den enzymatiska metoden visade en hög precision. Vid låg nivå beräknades variationskoefficienten (CV) till 1,71 % (medelvärde: 8,32 ❍mol/L) och vid hög nivå till 2,54 % (medelvärde: 29,45 ❍mol/L). Korrelationen mellan de båda metoderna var r = 0,994, (y=0,977x + 1,4 och R2 = 0,989). Ingen statistisk signifikant skillnad påvisades. Resultaten av P-hcy vid analys med Cobas 6000 låg dock 0,9 ❍mol/L (medelvärde) högre än resultat från Immulite 2000 XPi. Denna systematiska avvikelse bör inte vara av klinisk betydelse vid analys av P-hcy för utredning av eventuell sjukdom. Skillnaden kan dock vara relevant om analysen används för uppföljning av tidigare analysresultat. Resultat visar att båda metoderna kan användas för analys av P-hcy och att de kan användas som ett tillfredsställande diagnostiskt verktyg.

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The complement components C3 and C4 are part of the complement system. The complement system has many tasks to perform in the body and consists of several proteins that all have unique tasks. C3 and C4 are examined, for example, if a deficiency is suspected, in the presence of autoimmune diseases or in the case of recurring bacterial infections. When verifying the analysis and after analyzing of external controls, it has been shown that the reference range is falsely high, especially for C3. The study therefore aimed to verify the analysis of C3 and C4 on Atellica NEPH 630 and establish a correct reference range for respective analysis. The method was verified by evaluating the precision of the method and by comparing the concentration of C3 and C4 measured on Cobas 6000 module C500 with the concentration measured on Atellica NEP 630. In addition, the reference intervals provided by Siemens were evaluated using samples from blood donors and from other healthy individuals. The verification began by performing quality controls on three different levels before analysis of samples. The coefficient of variation was less than 5 % for all control levels for both complement analysis. Reference values ​​for C3 were not in alliance with the reference values ​​provided by Siemens. A new proposed range for C3 is 0.48- 1.37 g/L, while the recommended range can be used for C4.

The pre-analytical phase is known for being the most important step in the laboratory process to reach reliable test results. If handling, transport or preparation of the sample is performed incorrectly the results can deviate from the true value. Today, sampling tubes contains various additives to stabilize concentration levels. The aim of this study was to test a new sampling tube containing fluoride/citrate for glucose, lactate and homocysteine. It was also of interest to evaluate the stability of those three analytes in lithium-heparin, sodium-fluoride/potassium oxalate and fluoride/citrate tubes. To perform the sustainability study, a method verification was done for homocysteine in plasma. The study was performed in a hospital laboratory on the routine instrument Roche Cobas 6000 analyzer. Blood was drawn from 20 patients and was analyzed at the hospital laboratory in Gävle. The blood samples were transported frozen to the laboratory in Hudiksvall and were used in the method verification. For the sustainability study, blood was drawn from 10 healthy volunteers in lithium-heparin, sodium-fluoride/potassium oxalate and fluoride/citrate tubes. The method verification was approved. The results showed that glucose was stable for up to 72 hours in Vacuette Glycaemia tube with fluoride/citrate and this tube also gave more accurate results. Lactate and homocysteine were also stable in fluoride/citrate, but needs further studies. All three analytes were more stable if the sample tubes were centrifuged as soon as possible after blood collection. Fluoride/citrate tubes were stable without centrifugation directly.