A mini review of the assessment of vitamin E status in patients with familial hypobetalipoproteinaemia

The secretory deficit (SD) subtypes of familial hypobetalipoproteinaemia (FHBL) are characterised by low circulating lipid concentrations. Driving some of the pathophysiology of these conditions are deficiencies in the fat-soluble vitamins, namely vitamins A, D, E and K, caused by reduced absorption from the intestinal tract. Management involves giving larger than usual doses of these vitamins to overcome the inefficient absorption. It is difficult to monitor response to supplementation of vitamin E, not least because vitamin E circulates within lipoproteins. Its blood concentration is therefore largely determined by concentrations of lipoproteins, which are invariably low in these FHBL subtypes, rather than by actual body stores. Thus, patients with these conditions may be over- or under-replaced on the usual blind replacement strategies. Deficiency of vitamin E in the SD subtypes of FHBL can lead to neuromuscular complications, which can be life-limiting as well as severely impact these patients’ quality of life. Vitamins A and D, conversely, have their ow transport particles in circulation and concentrations of these measured in serum or plasma do represent whole body stores well. Vitamin K has the advantage of being able to directly alter coagulation times which therefore serve as very useful markers of adequacy of supplementation. Measurement of metabolites of vitamin E as well as measurement in adipose tissue and in cellular components of blood are all alternative methods of assessment that have been postulated to bring improved accuracy, though only few studies in recent years have been carried out in this field and much of the work s over 3 decades old. In this mini review we explore the currently available literature on these methods of assessment. We believe that more work is needed soon to better serve this small but important issue in the management of patients with SD subtypes of FHBL.