Laboratory facilities for investigating lipid disorders in the United Kingdom: results of the British Hyperlipidaemia Association survey

Performance criteria of the post-analytical phase

Quality in healthcare is ideally at an optimal benchmark, but must be at least above the minimal standards for care. While laboratory quality is ideally judged in clinical terms, laboratory medicine has also used biological variations and state-of-the-art criteria when, as is often the case, clinical outcome studies or clinical consensus are not available. The post-analytical phase involves taking quality technical results and providing the means for clinical interpretation in the report. Reference intervals are commonly used as a basis for data interpretation; however, laboratories vary in the reference intervals they use, even when analysis is similar. Reference intervals may have greater clinical value if they are both optimised to account for physiological individuality, as well as if they are harmonised through professional consensus. Clinical decision limits are generally superior to reference intervals as a basis for interpretation because they address the specific clinical concern in any patient. As well as providing quality data and interpretation, the knowledge of laboratory experts can be used to provide targeted procedural knowledge in a patient report. Most profoundly critically abnormal results should to be acted upon to minimise the risk of mortality. The three steps in quality report interpretation, (i) describing the abnormal data, (ii) interpreting the clinical information within that data and (iii) providing knowledge for clinical follow-up, highlight that the quality of all laboratory testing is reflected in its impact on clinical management and improving patient outcomes.

Precipitation procedures used to isolate high density lipoprotein with particular reference to effects on apo A-I-only particles and lipoprotein(a)

Analysis of high density lipoprotein (HDL) isolated from serum without major hypertriglyceridaemia and by five different precipitation methods showed that there were no significant differences in total cholesterol and triglyceride concentrations in the HDL supernatants prepared by the different methods but that free cholesterol, phospholipid, apolipoprotein (apo) A-I and HDL particles containing apo A-I but not apo A-II (LpAI) concentrations were significantly lower for heparin-manganese chloride method 2 (final manganese chloride concentration 92 mmol/l) compared with the other methods. Modest differences in HDL cholesterol, apo A-I and LpAI were observed between heparin-manganese chloride method 1 (final magnesium concentration 46 mmol/l) and the dextran sulphate, phosphotungstate and polyethylene glycol 6000 methods. Lipoprotein(a) (Lp(a)) and apo B were undetectable in the HDL supernatants, indicating that apo B-containing lipoproteins including Lp(a) were essentially completely removed by all the precipitation procedures.

Management of hyperlipidaemia: guidelines of the British Hyperlipidaemia Association

There is considerable evidence to suggest that the identification and treatment of dyslipidaemia will reduce the risk of premature CHD, i.e. before the age of 65. Diagnosis of the cause of raised plasma lipid levels will enable appropriate decisions to be taken with regard to management. The cornerstone of treatment is nutritional counselling and attention to other major risk factors for CHD, particularly smoking and hypertension. For a small percentage of patients with severe hyperlipidaemia drug therapy is indicated. Appropriate drug choices need to be made based on the particular lipid abnormality to be treated. In general those patients with clinical vascular disease are treated more aggressively than those where the aim is primary prevention. More research is needed to determine individual risk more precisely and to allow proper targeting of therapy. Genetic factors, qualitative changes in lipoproteins, lipoprotein (a), fibrinogen, and other coagulation and thrombotic factors are likely to be important in individual risk assessment. There is no doubt that more information is needed from prospective studies of lipid-lowering therapy in terms of risk benefit for affected individuals. Hopefully the major studies currently underway will fill some of the gaps in our knowledge. Until then aggressive therapy with drugs should be reserved for those at highest risk where the benefit is likely to be greatest.