ABSTRACT
Laboratory investigations are very rarely needed more than once daily, except in some patients receiving intensive therapy. Laboratories often use large analysers capable of assaying hundreds of samples per day. They usually have ‘panic limits’, when highly abnormal test results indicate a potentially life-threatening condition that necessitates contacting the relevant medical staff immediately. Laboratory investigations are used: to help diagnosis or, when indicated, to screen for metabolic disease; to monitor treatment or detect complications; and occasionally for medicolegal reasons or, with due permission from the patient, for research. Close liaison with laboratory staff is essential; they may be able to help determine the best and quickest procedure for investigation, interpret results and discover reasons for anomalous findings. Agreement between laboratories is close for many constituents partly due to improved standardization procedures and because many laboratories belong to external quality control schemes.
