HYPERLIPIDEMIA AND CARDIOVASCULAR DISEASE: Edited by Paul N. DurringtonNon-HDL or LDL cholesterol in heterozygous familial hypercholesterolaemia: findings of the Simon Broome RegisterSoran, Handreana,b; Cooper, Jackie A.c; Durrington, Paul N.a; Capps, Nigeld; McDowell, Ian F.W.e; Humphries, Steve E.c,∗; Neil, Andrewf,∗; on behalf of the Simon Broome Familial Hyperlipidaemia Register GroupAuthor Information aCardiovascular Research Group, School of Clinical and Laboratory Sciences, University of Manchester bDepartment of Diabetes, Endocrinology and Metabolism, Manchester University NHS Foundation Trust, Manchester cCentre for Cardiovascular Genetics, Institute Cardiovascular Science, University College London, London dDepartment of Clinical Biochemistry, The Shrewsbury and Telford Hospital NHS Trust, Princess Royal Hospital, Telford eDepartment of Medical Biochemistry and Immunology, University Hospital of Wales, Cardiff fWolfson College, University of Oxford, Oxford, UK Correspondence to Handrean Soran, MSc, MD, FRCP, Consultant Physician and Endocrinologist, Department of Diabetes, Endocrinology and Metabolism, Manchester University NHS Foundation Trust, Manchester, United Kingdom. Tel: +44 161 276 4066; fax: +44 161 276 3630; e-mails: firstname.lastname@example.org; email@example.com Current Opinion in Lipidology: August 2020 - Volume 31 - Issue 4 - p 167-175 doi: 10.1097/MOL.0000000000000692 Buy Metrics Abstract Purpose of review The role of non-HDL-C in the identification and management of lipid disorders is not clearly defined, although UK guidelines recommend its wider use in assessing the need for lipid-lowering therapy and as a treatment target. Recent findings We examined the implications of the use of non-HDL-C as opposed to LDL-C in 253 people with hypercholesterolaemia before treatment and 573 after treatment in whom fasting total serum cholesterol, HDL-C and LDL-C had been recorded and the diagnosis of heterozygous familial hypercholesterolemia (heFH) was investigated by genetic testing. The difference and the limits of agreement between non-HDL-C and LDL-C calculated using the Friedewald formula were assessed in those with and without heFH-causing mutations. Summary There were 147 mutation-positive and 106 mutation-negative pretreatment participants and 395 mutation-positive and 178 mutation-negative patients receiving treatment. The difference between non-HDL-C and LDL-C pretreatment in mutation-positive people (mean LDL-C 7.73 mmol/l) was 0.67 mmol/l (95% CI 0.62–0.73) and posttreatment (mean LDL-C 4.71 mmol/l) was 0.62 mmol/l (95% CI 0.59–0.65) with wide limits of agreement of −0.02 to 1.37 and 0.07–1.18 mmol/l, respectively. Among patients with heterozygous familial hypercholesterolaemia, use of estimated LDL-C derived from non-HDL-C in place of calculated LDL-C may result in diagnostic misclassification and difficulty in assessing the true reduction in LDL-C with treatment, because of the wide inter-individual limits of agreement around the mean difference between non-HDL-C and LDL-C. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.