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The molar ratio of retinol-binding protein to transthyretin (RBP:TTR) has been proposed as an indirect method to assess vitamin A status in children with inflammation. Neither reference values nor appropriate cut-off point are available for adults. RBP, TTR and retinol were determined in plasma from 100 healthy adults and 31 low-risk surgical patients with no inflammatory response. RBP:TTR percentile distribution from 99 healthy adults with plasma retinol > or = 0.7 micromol/l was: 2.5th = 0.24; 5th = 0.31; 10th = 0.32; 25th = 0.41; 50th = 0.47; 75th = 0.54; 90th = 0.67; 95th = 0.78 and 97.5th = 0.81. In order to define a cut-off point, receiver operating characteristic (ROC) curve was constructed, using plasma retinol as gold standard. ROC curve was based on data from the 131 studied subjects, 11 of whom (8.4%) were classified as deficient on the basis of plasma retinol < 0.7 pmol/l. According to ROC curve criteria, RBP:TTR ratio was considered a good test, the area under the curve being 0.822, p < 0.001. A cut-off-point of < or = 0.37 is proposed to detect vitamin A deficiency in adults, since it allows reaching high sensitivity (81.8%), specificity (79.2%) and predictive value (79.4%). The proposed cut-off point falls between 13th and 14th percentiles.

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The bone marker α‐CTX is significantly affected by calcium nutritional status (CNS) during the phase of growth in children in the pre puberty ages whereas β‐CTX seems not to be related to that variable. This situation appears as a promissory secondary index to assess bone maturation through the ratio between both (α/β) at ranges of CNS as nutritional reference. Here, changes in bone maturity were related to three CNS in 180 both sex children 6 to 9 years old with paired data for the three determinations performed in basal urine samples: both CTX (NB‐Denmark) and the ratio between Ca to creatinine (Ca/Cr). Reference values for CNS were: Ca/Cr: <0,07, deficient (D); 0,07–0,15, adequate (A) y > 0,15, high (H). ANOVA test with GraphPad was used. When plotted versus age according CNSα/β ratio data adjusted to a binomial equation for D (y=−0,055x2 0,0798x+1,5666; R2=0,9936) and H (y=−0,0657x2 +0,2707x +1,2768 R2 = 0,8339) curves whereas for the A group the best fitting is the lineal one: (y= 0,1952x + 1,8416; R2=0,9174 being significantly different from D and H. Calcium nutritional status can modulate interrelationships between bone markers associated to maturity progress. Supported by UBACyT B/060.2.HD. Doctoral Fellowship from UBCyT

The influence of Calcium nutritional status (CaS) on biomarkers (BM) of normal bone development became recently recognized as a vacancy area in paediatric research. In this study a comparative analysis of the influence of CaS on the age‐linked changes of two different types of CTX markers was afforded. Basal urine samples of 160, both sex, healthy children 6 to 9 years old, normal according to body mass index (BMI by NCHS), were collected. CTXs α and βwere determined by ELISA (Nordic Bioscience Diagnostic, Denmark); calcium/creatinine ratio (Ca/C) was measured as estimator of Ca status: <0, 07 deficient (D); 0,07–0,15, adequate (A); >0,15 high (H). Analyzed as a function of age, and grouping data according CaS, neither significant influence of age nor of CaS was detected over βCTX along the frame of ages of the study. However, CaS modified α CTX evolution so that the although changes linked to age were not founded in D, the decreasing in values with age was similar in A and H groups. The slope of the curves αCTX vs. age was very similar for both (y= −1,6071x + 50,214) but the correlation coefficients(R2) were 0,5432 and 0,9643 respectively. Both CTX molecules,αα‐CTX and ββ‐CTX‐, reflect bone metabolic activity and bone remodelling but only the new biomarker &[alpha&[alpha]‐CTX responds to Ca status and appears appropriate for studies related to bone problems due to calcium inadequacy in paediatric patients.

Grow process is a state of high bone turnover and an inadequate calcium nutritional status can lead to suboptimal peak bone mass and predispose to osteoporosis in adulthood. Previously, we have found that the a‐CTX marker of bone growth was highly affected by body Ca status. A similar study was carried out in relation to bone densitometry. For that, urine basal samples were obtained from 120 healthy girls, aged 5.8 to 9.2 years, attending public schools of Vicente Lopez (Bs. As) and over them Ca (AAS) and creatinine (Cr) (Wiener Lab®. Argentina) were determined to calculate Ca/ Cr ratio as marker of Ca status. Bone densitometry was assessed by ultrasound (Sahara Olohi. USA) and expressed as Quantitative Ultrasonic Index (QUI). The relation: QUI vs Ca/Cr divided in five ranges between < 0,10 and >0,15, fits a quadratic function so that QUI=92,828e0,3426x; R2=0,78; p<0,01. Results show a quite good no linear correlation presenting a flat area between Ca/Cr <0,07‐0.01 and then ahead a significant positive slope. As in the case of the evolution of the CTX bone marker previously studied, a Ca/Cc >0,01 was mandatory during bone growth to allow the age dependent increase in bone mineralization. Supported by UBCyT US.B/735. HD PhD Thesis. Fellow from UBA

Serum retinol (R) is the most reliable marker to evaluate vitamin A nutritional status. It is accepted that inflammation result in a serum level decrease that may conduce to a deficiency that current knowledge does not even define as functional or as apparent. In order to evaluate the influence of inflammation on R levels in surgical patients with no infection, 45 patients from programmed gastroenterological surgeries were studied. R was determined by HPLC and C‐Reactive Protein (CRP) by commercial kits as a marker of inflammation (CRP positive when >0.6 mg/dl; I+) in fasting samples taken before surgical procedure. Patients with no inflammation (I−; n=28) presented a X±SD of 49.5±19.1 μg/dl; distribution of values showed none patient with values <20 μg/dl indicatives of deficiency, 7% of values <30, considered sub‐optimal, and 3.5% of values <25, founded as associated with increased risk of complications in a previous work. Patients with inflammation (I+; n=17) presented a X±SD of 35.6±16.1μg/dl, significantly lower than that of I− (P=0.0162); 18% of values were <20, 53% <30 and 23% <25μg/dl. We conclude that chronic inflammation with no infection expose the patient to a higher chance of deficiency, that if traduced in low utilization by peripheral tissues, may compromise evolution by increasing the risk of complications. Supported by UBACyT B077.