ABSTRACT
Mounting evidence indicates that marginal biotin deficiency is not rare, contrary to previous assumptions. Accordingly, robust indicators of biotin status would be useful. In a study of 10 healthy adults, we recently provided evidence that abnormally increased plasma concentration of 3-hydroxyisovaleryl carnitine (3HIA-carnitine) is a sensitive indicator of marginal biotin deficiency. We sought to determine whether urinary excretion of 3HIA-carnitine (expressed as the ratio to urinary creatinine) significantly increases in marginal biotin deficiency. Marginal, asymptomatic biotin deficiency was induced experimentally in the same 10 healthy adults (8 women) by feeding undenatured egg white with meals for 28 d. Biotin status was repleted by a mixed general diet plus biotin supplementation. Urinary excretion of 3HIA-carnitine was determined by liquid chromatography-tandem MS on d 0, 14, and 28 (depletion) and on d 35 and 50 (repletion). Mean urinary 3HIA-carnitine concentration increased with depletion (P < 0.0001; d 0 vs. 28) and decreased with repletion (P = 0.0002; d 28 vs. 50). Urinary 3HIA-carnitine excretion was greater than the upper limit of normal in 9 of 10 participants by d 14 and decreased to within normal limits by d 50 in all participants. This study provides evidence that urinary excretion of 3HIA-carnitine is an early and sensitive indicator of marginal biotin deficiency. The ease of collection of untimed urine samples and application of a new analytical method with simplified sample preparation suggest that urinary 3HIA-carnitine is likely to be a useful indicator for large population studies.
Subject(s)
Biotin/deficiency , Carnitine/analogs & derivatives , Nutritional Status , Vitamin B Deficiency/diagnosis , Vitamin B Deficiency/urine , Adult , Biomarkers/blood , Biomarkers/urine , Biotin/therapeutic use , Carnitine/urine , Egg White , Female , Humans , Lymphocytes/enzymology , Male , Methylmalonyl-CoA Decarboxylase/blood , Reference Values , Time Factors , Vitamin B Deficiency/blood , Vitamin B Deficiency/drug therapyABSTRACT
OBJECTIVE: Calculogenic potential of refined sugars galactose and fructose was examined in vitamin B6 deficient and control rats in terms of their capacity to increase urinary excretion of lithogens. METHODS: Male albino rats were fed vitamin B6 deficient diet with 51.7% sucrose+ starch or galactose or fructose as the source of carbohydrate. Pair-fed controls were maintained for all the groups for a period of four weeks. Twenty-four hour urine samples obtained at weekly intervals were analyzed for creatinine, calcium, oxalate, phosphate and uric acid. Microscopic urinalysis was performed at the end of the study. RESULTS: Urinary calcium excretion increased with respect to baseline in all groups except vitamin B6 control group. On day 28, galactose and fructose-fed rats demonstrated significant hypercalciuria as compared to the sucrose + starch fed group. Vitamin B6 deficient rats (irrespective of the sugar fed) excreted significantly greater urinary calcium compared to pair-fed controls. Oxalate excretion was significantly increased in rats fed galactose compared to those fed fructose or sucrose + starch. Vitamin B6 deficiency further increased oxalate excretion by 1.5, 1.9 and 1.7 fold in sucrose + starch, fructose or galactose fed animals, respectively. Urinary uric acid excretion was enhanced only in fructose-fed rats. There was no change in urinary excretion of creatinine and phosphate in different experimental and control groups. Increased urinary saturation with lithogens caused pronounced crystalluria in all the vitamin B6 deficient groups as well as galactose control group. CONCLUSION: The results suggest galactose ingestion is associated with a greater propensity to form calcium oxalate kidney stones than fructose. Calculogenic potential of galactose and fructose is further enhanced in vitamin B6 deficiency.
