Arrows to the pathology and then the haematology department lead you down a long, white corridor. Heavy doors swing open and there they are: the medical laboratory technicians, working away in the background, heads down, backs bent, eyes scanning minute slides and test tubes. What do they do all day in their white coats sitting in front of microscopes and other complicated equipment?

"It's amazing how little the public knows about our work," says Helena Reynolds, who works in the haematology department of St Vincent's General Hospital, Dublin. "It's kind of in the back room, it doesn't seem to be seen very much but it's such a huge and a very important part of medicine."

The work is absolutely vital in the running of a hospital, she say. "Without the lab, there would not be diagnosis, patients could not be treated. It's crucial especially where patients are extremely ill, where they are in intensive care or post-operative care. They need constant monitoring. The lab plays a huge role in that."

Reynolds loves her work. "You feel like you are making a difference, that you have a role to play."

There on one counter ESR (Erythrocyte Sedimentation Rate) tests are carried out. In another section, she points to the ACL 1,000 (Automated Coagulation Laboratory) analyser - "this is a huge section of haematology."

The range of tests carried out in the lab include blood coagulation, full blood counts, diabetic monitoring and the study of blood under the microscope. "It takes a long time to be familiar with all the different cell morphology types . . . cell size, colour, cell shape and the various granulations. Anything that looks abnormal has to be examined. A blood film has to be fixed and stained in order to be examined under the microcope. Looking at blood film is probably the most skilled part of the job - it's something that requires a lot of expertise."

Reynolds had no idea what a med lab technician did until she visited the general hospital in Naas, Co Kildare, as a student at St Mary's College in the town. "Pat Flynn, the chief medical laboratory technologist, took me through every section and showed me the main procedures in each section. It really opened my eyes to what goes on." She saw the five different disciplines of haematology, blood transfusion, histology, clinical chemistry and microbiology.

The visit awakened her interest and, as a result, she applied to DIT Kevin Street. "You have to have honours chemistry for the (certificate in medical laboratory sciences) course and I had that. I was eligible. It was 415 points at the time. First year was a year to bring everybody up to the same level. We did the three science subjects, maths and a language. I did German."

After three years, students, on successful completion of their exams, go on to study for a diploma in biomedical sciences at DIT and a B Sc (applied sciences) degree from TCD. In her final year Reynolds majored in haematology/ blood transfusion. She also spent six months researching her final year project at the University of Uppsala, Sweden.

Reynolds graduated at the top of her class earlier this year. "It's a very, very tough course. It's hard going. There are long hours as well as the practicals. Most practicals are three hours long. It's definitely not an easy trip to get through but at the same time it's rewarding when you get to the end, when you have your qualification.

"The more familiar you become with technology and the tests you carry out, the better you are. You have to have your wits about you. You're dealing with people. What you say means you have a huge impact on the treatment that person receives. You see samples all day - you have to remember that what you say is extremely important."