1. Department of Medical Biochemistry and Immunology; University Hospital of Wales; Cardiff; UK
2. Quality Laboratory; WEQAS; Cardiff; UK
3. Biochemistry Department; Royal Gwent Hospital; Newport; UK
4. Biochemistry Department; Prince Charles Hospital; Merthyr Tydfil; UK
5. Biochemistry Department; Bristol Royal Infirmary; Bristol; UK
6. Biochemistry Department; Southampton General Hospital; Southampton; UK
7. Centre for Endocrine and Diabetes Sciences; Institute for Molecular and Experimental Medicine; School of Medicine; Cardiff University; Cardiff; UK