Pseudo-hypertriglyceridaemia or hyperglycerolemia?

Handling of lipemic samples in the clinical laboratory

Interferences in the clinical laboratory may lead physicians misinterpret results for some biological analytes. The most common analytical interferences in the clinical laboratory include hemolysis, icterus and lipemia. Lipemia is defined as turbidity in a sample caused by the accumulation of lipoproteins, mainly very-low density lipoproteins (VLDL) and chylomicrons. Several methods are available for the detection of lipemic samples, including the lipemic index, or triglyceride quantification in serum or plasma samples, or mean corpuscular hemoglobin (MCHC) concentration in blood samples. According to the European Directive 98/79/CE, it is the responsibility of clinical laboratories to monitor the presence of interfering substances that may affect the measurement of an analyte. There is an urgent need to standardize interference studies and the way interferences are reported by manufacturers. Several methods are currently available to remove interference from lipemia and enable accurate measurement of biological quantities. The clinical laboratory should establish a protocol for the handling of lipemic samples according to the biological quantity to be tested.

Glycerol kinase deficiency in adults: Description of 4 novel cases, systematic review and development of a clinical diagnostic score

BACKGROUND AND AIMS

Glycerol kinase deficiency (GKD) is a rare genetic disorder characterized by hyperglycerolemia and glyceroluria, which could be misdiagnosed as a moderate to severe hypertriglyceridemia (HTG). We aimed to describe four novel cases of GKD, to complete a systematic review of all cases of isolated GKD published so far, and to develop a suspicion clinical diagnostic score for GKD.

METHODS

We reported four cases with suspicion of GKD and compared their phenotype with 584 males with triglycerides (TG) > 300 mg/dL, selected as control group (HTG non-GKD). The GK gene was sequenced in all cases. Lipoprotein particle concentrations were measured in all cases with GKD. The systematic review involved a PubMed, Cochrane and Scopus databases search to identify anthropometric and biochemical characteristics of all described cases with GKD.

RESULTS

The systematic review retrieved a total of 15 articles involving 39 subjects with GKD. GKD cases reported a history of high TG levels resistant to lipid-lowering therapy. Compared to GKD subjects (n = 43), HTG non-GKD subjects (n = 584) showed significantly higher BMI, total cholesterol, non-HDL cholesterol and gamma-glutamyltransferase, significantly lower HDL cholesterol and TG, and higher prevalence of diabetes. The proposed diagnostic score was significantly higher in GKD than in HTG non-GKD subjects.

CONCLUSIONS

This is the first systematic review that compiles all GKD cases reported to date including 4 novel cases, and examine the differential GKD phenotype compared to other types of HTG. The proposed score would have a broad utility in clinical practice to avoid unwarranted lipid lowering treatment in GKD patients.

Inherited metabolic disorders and dyslipidaemia

Monogenic dyslipidaemia is a diverse group of multisystem disorders. Patients may present to various specialities from early childhood to late in adult life, and it usually takes longer before the diagnosis is established. Increased awareness of these disorders among clinicians is imperative for early diagnosis. This best practice review provides an overview of primary dyslipidaemias, highlighting their clinical presentation, relevant biochemical and molecular tests. It also addresses the emerging role of genetics in the early diagnosis and prevention of these disorders.