Pseudo-hypertriglyceridaemia: a measurement artefact due to glycerol kinase deficiency

Severe glycerol intoxication mimicking toxic alcohol ingestion following large volume consumption of vanilla essence

INTRODUCTION

Patients with ethanol dependence may consume vanilla extract for the high alcohol content.

CASE PRESENTATION

A 42-year-old male with ethanol dependence who developed status epilepticus, severe anion gap metabolic acidosis and a hyperosmolar non-ketotic coma after ingestion of 600 mL vanilla essence. He was found to have an osmolar gap of 151 with a marked pseudohypertriglyceridaemia of 96.4 mmol/L (8350 mg/dL), found to be secondary to significantly elevated glycerol levels. The patient required intubation for status epilepticus and dialysis to correct the severe acid-base disturbance and remove excess glycerol. The patient made a full recovery.

DISCUSSION

Glycerol is traditionally thought to be a nontoxic alcohol, but this represents a severe case of glycerol toxicity requiring treatment with dialysis. It may represent an emerging or underdiagnosed clinical presentation given availability of high-glycerol products. In the right clinical context, pseudohypertriglyceridaemia and altered mental state may be recognised as glycerol intoxication, avoiding the need for unnecessary investigations.

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.

Evaluating the need for free glycerol blanking for serum triglyceride measurements at Charlotte Maxeke Johannesburg Academic Hospital

Background The accurate and precise measurement of triglycerides is important due to the adverse effects associated with hypertriglyceridaemia. Most laboratory methods are based on enzymatic hydrolysis of triglycerides with measurement of the total glycerol. An elevated free glycerol concentration may result in overestimation of triglyceride concentrations. The removal of free glycerol by blanking may therefore be of clinical importance. The aim of this study was to compare the glycerol blanking and non-glycerol blanking triglyceride methods. Methods This was a method comparison study of 1518 samples from both in-patients and out-patients at Charlotte Maxeke Johannesburg Academic Hospital. Triglycerides were measured in each sample using both the blanking and the non-blanking methods. Analytical performance was assessed based on the National Cholesterol Education Program (NCEP) goals. Clinical impact was assessed according to the NCEP Adult Treatment Program III (ATP III) risk classification. Results The method median was significantly higher in the non-blanking compared to the blanking method (1.33 vs. 1.12 mmol/L, p < 0.0001) in all patients. The average bias was above the total allowable error of 15% across all groups. There was a significant change in NCEP ATP III risk classification, with fewer patients classified as normal (67.6% vs. 74.6%, p < 0.0001) with the non-blanking method compared to the blanking method. Conclusions There was a significant error when glycerol blanking for triglyceride determination was not performed. The non-blanking triglyceride method overestimates triglyceride concentrations. This does not only exceed analytical performance goals, but also impacts on patient categorisation and clinical decision making in all patients.

Pseudohypertriglyceridemia: two cases of probable glycerol kinase deficiency

The National Cholesterol Educational Program Adult Treatment Panel's third report define borderline-high, high, and very high triglycerides as serum levels of 150-199 mg/dL, 200-499 mg/dL, and ≥500 mg/dL, respectively. Hypertriglyceridemia (HTG) is generally very responsive to both therapeutic lifestyle changes (TLC), and drug therapy, with niacin, omega-3 fatty acids, fibrates, and statins, each reducing levels by ~10-50%. This paper presents two cases of patients who were aggressively treated for significant HTG with little response to therapy. Although most measured triglyceride (TG) values in these patients were markedly elevated, periodic concentrations were reported as normal. When this occurs, the clinician must immediately think of the diagnosis 'pseudohypertriglyceridemia' or as it is more aptly termed 'glycerolemia' secondary to glycerol kinase deficiency (GKD).

A young boy with diffuse hyperpigmentation and delayed puberty

An 18-year-old male patient had presented with diffuse hyperpigmentation after birth and with adrenal insufficiency syndrome since childhood. After puberty, no secondary sexual signs developed. Laboratory examination showed an extremely high concentration of serum triglycerides (9.14 mmol/L) and plasma adrenocorticotropic hormone (>275 pmol/L), however, a low concentration of plasma free cortisone (<25.1-67.6 nmol/L). Abdomen computed tomography detected atrophy of both adrenals glands.

Longitudinal genome-wide association of cardiovascular disease risk factors in the Bogalusa heart study

Cardiovascular disease (CVD) is the leading cause of death worldwide. Recent genome-wide association (GWA) studies have pinpointed many loci associated with CVD risk factors in adults. It is unclear, however, if these loci predict trait levels at all ages, if they are associated with how a trait develops over time, or if they could be used to screen individuals who are pre-symptomatic to provide the opportunity for preventive measures before disease onset. We completed a genome-wide association study on participants in the longitudinal Bogalusa Heart Study (BHS) and have characterized the association between genetic factors and the development of CVD risk factors from childhood to adulthood. We report 7 genome-wide significant associations involving CVD risk factors, two of which have been previously reported. Top regions were tested for replication in the Young Finns Study (YF) and two associations strongly replicated: rs247616 in CETP with HDL levels (combined P = 9.7×10⁻²⁴), and rs445925 at APOE with LDL levels (combined P = 8.7×10⁻¹⁹). We show that SNPs previously identified in adult cross-sectional studies tend to show age-independent effects in the BHS with effect sizes consistent with previous reports. Previously identified variants were associated with adult trait levels above and beyond those seen in childhood; however, variants with time-dependent effects were also promising predictors. This is the first GWA study to evaluate the role of common genetic variants in the development of CVD risk factors in children as they advance through adulthood and highlights the utility of using longitudinal studies to identify genetic predictors of adult traits in children.

We have studied the association between genetic factors on a whole genome level and cardiovascular disease (CVD) risk factors in a population of individuals studied from childhood through adulthood. The longitudinal study design has enabled the investigation of genetic variation influencing trait values over time. We have identified DNA variants that are associated with CVD trait values consistently over time, and a second set of variants that are associated with CVD trait values in a time-dependent manner. We also show that variants previously identified in adult populations have consistent effects within our population and that these effects are usually similar across childhood through adulthood. The discovery of time-dependent variants that influence CVD trait values over time can potentially be used to screen young individuals who are pre-symptomatic and provide the opportunity for preventive measures decades before disease onset.