Estimation of vitamin B1 excretion in 24-hr urine by assay of first-morning urine.

Urinary B1 (vitamin B1) excretion is commonly determined in 24-hr urine specimens to obtain an estimate of nutritional status. The aim of our study was to investigate whether B1 in random urine specimens, corrected for the urine creatinine (Cr), can be substituted for B1 in 24-hr urines. Collection of such hour urines is often fraught with errors; an alternative method is described here. All urine specimens voided over 24 hr were collected from 32 healthy adults as were the first-morning urines from 30 healthy Japanese women. The B1 excretion was expressed as the ratio of B1 to Cr. Although the B1 excretion was expressed as the B1/Cr ratio, the B1 excretion varied with the urine volume and the time of urine collection. The B1/Cr ratio in random urine specimens not collected at a fixed time may mislead the evaluation of the nutritional status. We found that the B1/Cr ratio in the first-morning urine correlated significantly with the ratio in 24-hr urines (r=0.970, P<0.001) and also with the concentration of total B1 (B1 plus its phosphate esters) in whole blood (r=0.733, P<0.001). We conclude that the B1/Cr ratio in 24-hr urines could be estimated by measuring the ratio in the first-morning urine.

Assay values for thiamine or thiamine phosphate esters in whole blood do not depend on the anticoagulant used.

We compared the whole blood, plasma, and erythrocyte (red blood cell (RBC)) concentrations of thiamine and thiamine phosphate esters in the presence of heparin or EDTA as anticoagulants. Three blood specimens were collected from each of 24 healthy volunteers into evacuated collection tubes containing the following anticoagulants: heparin, Na2EDTA, or K2EDTA. The concentrations of nonphosphorylated free thiamine (T), thiamine monophosphate (TMP), thiamine diphosphate (TDP), and thiamine triphosphate (TTP) were determined by the NH2-column HPLC method. The anticoagulant used had no effect on the concentrations obtained in whole blood and plasma of thiamine or any of the above thiamine compounds (P>0.05). RBCs were isolated by centrifugation and washed with isotonic saline, and the cell counts of the washed cells were adjusted to their whole blood values. In the washed RBCs with any anticoagulant, the concentrations of T, TMP, and TDP expressed either as nmol/L of whole blood or a ratio to hemoglobin were significantly lower (P<0.05) than those in whole blood.

Recommended dietary allowance for vitamin C in the United States is also applicable to a population of young Japanese women.

The recommended dietary allowance (RDA) for ascorbic acid (AA) in Canada and the United States has been set for several years at 75 mg/day for women 19-30 years old. Recently this level was questioned, and an increase to 90 mg/day was suggested. For Japanese women in the same age group, we found that the RDA for AA is currently 100 mg/day. Our goal was to determine which RDA is sufficient for maintaining a serum concentration of AA in young Japanese women above the lower reference limit of 7.0 mg/L. We measured serum AA concentrations by an ascorbate oxidase method in 176 healthy Japanese women (19-26 years old). We also performed an ROC analysis to estimate the optimal cutoff value for oral dosage to distinguish individuals with hypovitaminosis-C (<7.0 mg/L) from those with a normal serum AA. We evaluated the Japanese RDA using the 75 or 90 mg/day U.S. RDA and the weight ratio between Japanese and U.S. women, and discovered that the RDA value ranged between 66 and 79 mg/day. From the ROC analysis, we found that the optimal daily dosage of AA is approximately 75 mg/day. This value gave the highest efficiency, sensitivity, negative predictive value, and positive likelihood ratio, and the lowest negative likelihood ratio. Therefore, an RDA of 100 mg/day may be unnecessarily high for young Japanese women.

The assay of ascorbic acid in serum is not affected by physiological concentrations of transferrin and hemoglobin.

Transferrin and hemoglobin have been reported to oxidize L-ascorbic acid (AA) in vitro. The aim of this study was to determine whether or not physiological concentrations of serum transferrin (reference range 22-45 micromol/L) and hemoglobin (reference range 0-3.0 micromol/L) interfer with the measurement of AA in the serum. Transferrin (33 to 41 micromol/L) and hemoglobin (1.9 micromol/L) added to freshly pooled serum significantly decreased measured AA in the serum (p < 0.05). However, we found that the magnitude of the decrease in AA due to transferrin at concentrations within the reference range or up to 80 micromol/L was inconsequential, and had no clinical importance in diagnosing a low AA concentration. Hemoglobin at concentrations within the reference range had little affect on the serum AA measurement. However, when serum specimens were stored at 4 degrees C for more than 1.5 h, the magnitude of the decrease in AA due to hemoglobin at physiological concentrations may cause a misleading clinical diagnostic evaluation of low AA concentration.

Removal of protein-bound and unbound unconjugated bilirubin by perfusion of plasma through an anion-exchange resin in a case of Crigler-Najjar syndrome type I.

BACKGROUND: Patients with Crigler-Najjar syndrome, type I (CNS-I) have an inherited absence of hepatocellular bilirubin uridine diphosphate-glucuronosyltransferase activity, which results in severe unconjugated hyperbilirubinaemia, often causing kernicterus and death in infancy or childhood. METHODS: Our patient is a 19-year-old Japanese man with CNS-I diagnosed by the complete absence of the hepatocellular enzyme in a liver biopsy and genotyping. The efficacies of the removal of protein-bound (PBB) and unbound (UB) unconjugated bilirubin by phototherapy, plasma perfusion and liver transplantation were compared in the patient. RESULTS: At the age of 5 years, phototherapy treatment reduced the patient's PBB by 21% and UB by 34%, and 98% of the bilirubin produced daily was removed. At the age of 16 years, plasma perfusion combined with nightly phototherapy completely removed the daily production of bilirubin; however, by 24 h post-treatment, the PBB and UB were again increased. Apparently, these treatments were effective in reducing PBB and UB, but the effect was only temporary. Following liver transplantation, PBB and UB decreased to normal concentrations. CONCLUSIONS: Liver transplantation as a potential cure should be performed at a younger age, particularly in confirmed CNS-I cases for which reliable effects of phototherapy cannot be guaranteed.

Selective use of transthyretin and retinol-binding protein as markers in the postoperative assessment of protein nutritional status.

We evaluated several markers to judge the postoperative state of protein nutriture in eight patients following surgery for cancer. Seven patients had a good prognosis and had no evidence of infections or other complications. Following surgery, all of the patients showed a shift toward abnormal values for the serum concentrations of albumin, transthyretin (TT), retinol-binding protein (RBP), and the amino acid (AA) ratio of nonessential to essential amino acids. In patients without complications, the AA ratio returned to normal first. When blood specimens were collected at 7-day intervals, concentrations of RBP and TT were revealed to be decreased and recovered at the same time, or TT was recovered after RBP was normalized. RBP and TT were usually abnormal until the AA ratio became normal. Although albumin moved toward normal concentrations after RBP and TT, the albumin concentrations in some patients were slightly above the lower reference value, whereas RBP and TT were significantly below their lower reference limits. In these patients, assessments over the next 7-14 days showed persistently low values for albumin, TT, and RBP. We recommend the selective use of TT and RBP for the postoperative assessment of protein nutriture in surgical patients.