Recommendations on the measurement and use of the alcohol consumption biomarker CDT. A position paper from the IFCC Working Group on CDT standardisation

BACKGROUND

Carbohydrate deficient transferrin (CDT) is a biomarker for excessive alcohol consumption utilized in clinical and forensic medicine and workplace testing. Previously, many different analytical methods for CDT were used and the measurand varied considerably, making direct comparison of test results difficult. To end this confusion, the IFCC established a working group on CDT standardisation (WG-CDT) which completed its tasks in 2017.

METHODS

This IFCC position paper by the WG-CDT summarizes state of the art information about the measurand and the analytical methods and gives concise recommendations for its utilization.

RESULTS

The results achieved by the CDT standardisation process led to accuracy improvements in national external quality assessment schemes over the years. A brief review of ROC based comparison studies with the traditional biomarkers (GGT, MCV, ALT and AST) discusses the bias resulting from inadequate study populations. In large groups of the general population the superior diagnostic performance of CDT is confirmed.

CONCLUSION

The relationship between alcohol intake versus resulting CDT is discussed as well as the cutoff and measurement uncertainty. Concerning the application in practice, potential pitfalls are considered and recommendations handling both analytical and preanalytical caveats are given. Finally, some examples of serious misunderstandings in publications about CDT are addressed.

Fatal hyperammonaemia due to late-onset ornithine transcarbamylase deficiency

In this case report we describe a 67-year-old male, admitted to the ICU with pneumonia who unexpectedly developed a fatal coma due to hyperammonaemia. At postmortem the diagnosis late-onset ornithine transcarbamylase deficiency was made. The non-specific clinical presentation, the rapid deterioration and incidentally the fatal outcome all underline the importance of recognition and knowledge of this genetic disorder. Several measures to treat and prevent potentially fatal episodes of hyperammonaemia are available, if only the disorder is recognised in time. In retrospect, several clues to the diagnosis were available in this fatal case, such as voluntary protein avoidance, as well as several male family members who died at a young age of an unknown cause. After his death, two daughters were discovered to be carriers of an OTC gene mutation, as well as his infant grandson. We emphasise the importance of obtaining ammonia levels in all patients with unexplained coma, seizures or cerebral oedema, irrespective of their age, especially in patients in the ICU or in an otherwise catabolic state.

Vitamin D status is not associated with inflammatory cytokine levels during experimental human endotoxaemia

Vitamin D has been shown to modulate innate immune responses in vitro and ex vivo; however, human in-vivo data are lacking. At high latitudes, seasonal vitamin D deficiency is common due to alternating ultraviolet (UV)-B radiation exposure. In the present study, we investigated whether levels of 25 hydroxyvitamin D(3) [25(OH)D(3) ] and its active metabolite 1,25 dihydroxyvitamin D(3) [1,25(OH)(2) D(3) ] are subject to seasonal variation and whether plasma levels of these vitamin D metabolites correlate with the in-vivo cytokine response during experimental human endotoxaemia [administration of lipopolysaccharide (LPS) in healthy volunteers]. Plasma levels of 25(OH)D(3) and 1,25(OH)(2) D(3) were determined in samples obtained just prior to administration of an intravenous bolus of 2 ng/kg LPS (derived from Escherichia coli O:113) in 112 healthy male volunteers. In the same subjects, plasma levels of the inflammatory cytokines tumour necrosis factor (TNF)-α, interleukin (IL)-6 and IL-10 were analysed serially after endotoxin administration. Plasma levels of 1,25(OH)(2) D(3) , but not 25(OH)D(3) , were subject to significant seasonal variation, with lower levels in autumn and winter. 25(OH)D(3) and 1,25(OH)(2) D(3) levels did not correlate with plasma cytokine responses. Furthermore, 25(OH)D(3) deficient subjects (< 50 nmol/l) displayed an identical cytokine response compared with sufficient subjects. In conclusion, plasma levels of vitamin D are not correlated with the LPS-induced TNF, IL-6 and IL-10 cytokine response in humans in vivo. These findings question the direct role of vitamin D in modulation of the innate immune response.

Seasonal variation of serum 25-hydroxyvitamin D levels in adult patients with inflammatory bowel disease

Patients with inflammatory bowel disease (IBD) are at risk of osteoporosis. Vitamin D (vitD) deficiency is known as a risk factor of osteoporosis. We observed low vitD blood levels in adult IBD patients both at the end of summer and winter. Furthermore, effects of oral vitD supplementation in (generally low) daily dosages were poor.

INTRODUCTION

Patients with IBD are at risk of osteoporosis. This study evaluates seasonal vitD status, determinants of vitD deficiency and effects of vitD supplementation in adult IBD patients.

METHODS

Patients were screened for vitD deficiency at the end of summer and winter using serum 25OHD(3) (cut-off point, <50 nmol/L) combined with routine laboratory tests. A standardized questionnaire was used for demographic/lifestyle data i.e. IBD activity, health behaviour and vitD intake through diet and ultraviolet light.

RESULTS

Late-summer, 39% of the included 316 patients were vitD deficient. Late-winter, 57% of the follow-up patients (n=281) were deficient. Independent protective determinants of vitD deficiency were oral vitD supplementation (summer/winter: odds ratio [OR], 0.52 [95% confidence interval [CI], 0.29-0.94]/OR, 0.44 [95% CI, 0.26-0.75]), recent sun holiday (summer: OR, 0.42 [95% CI, 0.24-0.74]) and regular solarium visits (summer/winter: OR, 0.28 [95% CI, 0.13-0.63]/OR, 0.17 [0.06-0.50]). IBD activity (p=0.031), red blood cell distribution width (RDW; p=0.04) and erythrocyte sedimentation rate (p=0.03) were associated with low vitD levels using univariate analyses of the extreme 25OHD quartiles. In a subgroup with vitD supplementation, still 30% (late-summer) and 44% (late-winter) were vitD deficient.

CONCLUSION

VitD deficiency is common in IBD patients, but prevalence might be comparable with the general population. Ultraviolet light is essential for adequate vitD levels. Effects of oral vitD supplementation in (generally low) daily dosages are poor. Determinants for low vitD levels were IBD activity and elevated inflammatory markers, suggesting that increased risk of osteoporosis in IBD might be more related to the inflammation than to vitD deficiency.

Serum 25-hydroxy-vitamin D3 concentrations increase during tuberculosis treatment in Tanzania

SETTING

Vitamin D deficiency is associated with susceptibility to active tuberculosis (TB) in many settings. In vitro studies and studies on human volunteers showed that two of the first-line anti-tuberculosis drugs, isoniazid and rifampicin, reduce 25-hydroxy vitamin D (25[OH]D) concentrations.

OBJECTIVE

To study changes in vitamin D status during treatment of Tanzanian hospitalised patients with pulmonary TB (PTB).

DESIGN

We compared serum 25[OH]D concentrations in 81 Tanzanian PTB patients before and after 2 months of treatment.

RESULTS

Median serum 25[OH]D concentrations increased from 91 nmol/l at baseline to 101 nmol/l after 2 months of TB treatment (median increase 6.0 nmol/l, IQR -0.7-25.0, P = 0.001). Median serum parathyroid hormone concentrations increased from 1.6 to 2.0 pmol/l (median increase 0.46, IQR -0.2-1.1, P < 0.001).

CONCLUSION

25[OH]D serum concentrations increased during the first 2 months of TB treatment in 81 PTB patients in northern Tanzania. Improved dietary intake and increased sunlight exposure may have contributed to the increased 25[OH]D concentrations.

[Severe vitamin-D deficiency in more than half of the immigrant pregnant women of non-western origin and their newborns]

OBJECTIVE

To determine the prevalence of vitamin-D deficiency in pregnant women and their newborns.

DESIGN

Descriptive.

METHOD

During the period of one year (April 2004-April 2005) 545 pregnant women of Dutch/European origin and 131 pregnant women of non-Western origin (mainly Turkish and Moroccan) were studied during their 10th and/or 30th week of pregnancy for calcidiol (vitamin-D) and calcium levels. The study took place in the Amersfoort region in the center of the Netherlands. In addition, cord blood samples were taken for vitamin-D and calcium levels from the 442 and 81 Dutch/European and non-Western newborns respectively.

RESULTS

A severe deficiency was found (calcidiol < 20 nmol/l) in 55% of non-European women compared to 5% of Dutch/West-European women. From the cord blood samples, a severe vitamin-D deficiency (calcidiol < 13 nmol/l) was found in 54% of the newborns of non-European origin compared to 6% of the Dutch/West-European newborns. Vitamin-D concentrations in pregnant women at term were strongly correlated to the concentrations in the newborns' cord blood (R = 0.84). The calcium levels of pregnant women and newborns did not differ significantly between both population groups.

CONCLUSION

More than half of the non-European pregnant women and their newborns had a severe vitamin-D deficiency. Screening for vitamin D deficiency and adequate suppletion for this risk group appears to be necessary. The causes and consequences of vitamin-D deficiency in pregnancy are discussed.

[A pilot study of vitamin D in psychogeriatric patients: 82% is (severely) deficient]

In a group of 34 psychogeriatric patients (mean age 79 years) the prevalence of hypovitaminosis D was found to be 82%, taking 30 nmol/l as cut-off for calcidiol. We found 47% of the whole group to be severely deficient having values lower than 20 nmol/l. Results of related test are presented and discussed. Patient were treated with oral calcium and vitamin D3 medication. Origin, presentation and risks of hypovitaminosis D, including muscle weakness and the aggravating role of low calcium intake, are discussed with special attention to psychogeriatric patients. Suppletion of vitamin D and calcium is suggested for this patient group.

Determinants of insulin sensitivity in chronic heart failure

OBJECTIVE

To describe the determinants of insulin sensitivity (IS) in chronic heart failure (CHF), we created a model in which the influence of lifestyle factors and etiology of heart failure on IS were incorporated concomitantly with age, left ventricular ejection fraction (LVEF) and parameters of body composition.

DESIGN

Observational cohort study.

SETTING

Outpatient clinic for chronic heart failure.

PATIENTS

Fifty-seven male CHF patients [NYHA class II-III, age 61+/-9 years, body mass index (BMI) 26.9+/-3.3 kg/m2 (mean+/-S.D.)].

INTERVENTIONS

Euglycemic hyperinsulinemic clamp, cycle ergometry, anthropometric measurements, LVEF and a physical activity questionnaire.

MAIN OUTCOME MEASURES

A model explaining the variance of IS in CHF.

RESULTS

IS was 18.2+/-8.6 microg.kg(-1).min(-1).mU(-1).l(-1), fasting insulin level was 15.9+/-11.0 mU/l and fasting glucose level was 5.5+/-0.6 mmol/l. Peak VO2 was 19.1+/-4.9 ml.kg(-1).min(-1) and LVEF 26.2+/-7.1%. IS was inversely associated with fasting insulin concentration (r=-0.50, P<0.001) and BMI (r=-0.54, P<0.001). After controlling for BMI, IS also revealed a correlation with age (r=-0.36, P<0.01). The model explained 60% of variance in IS: BMI contributed 20%, smoking 17%, age 17% and physical activity in daily life (DPA) 16% (all P<0.05) to the variance of IS, whereas LVEF (9%) and etiology of heart failure (8%) contributed moderately.

CONCLUSIONS

In CHF patients, IS is for a major part predicted by BMI, smoking, age, daily physical activity, LVEF and etiology of heart failure.

[A pilot study of hypovitaminosis D in apparently healthy, veiled, Turkish women: severe vitamin D deficiency in 82%]

A pilot study was performed in March 2001 in order to estimate the prevalence of hypovitaminosis D in veiled women in the Netherlands. In a group of 51 Turkish women aged 14-63 years, 42 (82%) were severely deficient (25-hydroxyvitamin D (25-(OH)D) < 20 nmol/l), and 4 (8%) were moderately deficient (25(OH)D: 20-30 nmol/l). About half of the deficient women complained of muscle pain, muscle weakness or fatigue. These results confirm the presence of a serious public health problem with regard to vitamin D amongst veiled women.

[Zinc deficiency in geriatric patients. A study on a geriatric department's wheeling and dealing]

We studied the prevalence of zinc deficiency in patients who were hospitalised in a geriatric ward and its association with risk factors for this deficiency and the possible symptoms. The serum zinc level was measured from 45 consecutive admissions to a geriatric ward and patient characteristics were collected. A peer group of healthy subjects originating from a population survey was used as a control group. The serum zinc measured in the admitted patients was significantly lower than the reference value for adults (65.8% had a lowered zinc level) and the serum zinc for healthy elderly. There was no association found with possible causes of zinc deficiency. In an univariate analysis lethargy was the only significant association to zinc deficiency. There was a reverse relationship between the sum of the number of present symptoms and the zinc proportion A lower zinc level is associated with symptoms of zinc deficiency. As more symptoms appear the probability of zinc deficiency is greater. The importance for the clinical practice based on present knowledge is discussed.