Liliana Zago

The molar ratio of retinol-binding protein to transthyretin in the assessment of vitamin A status in adults. Proposal of a cut-off point.

Abstract 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 ≥0.7 μmol/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 μmol/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 ≤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.

Vitamin A and zinc levels in gastroenterological surgical patients: Relation with inflammation and postoperative complications

INTRODUCTION It is accepted that even mild nutrient depletion may affect the evolution of the surgical patient. OBJECTIVE To evaluate the influence of preoperative levels of plasma retinol and zinc on postoperative evolution of surgical patients; to evaluate the influence of inflammation on both level markers. METHODS Plasma retinol and zinc were determined in 50 patients before programmed gastroenterological surgeries. To detect global malnutrition BMI and weight loss percentage (WL%) were included. C-reactive protein (CRP) was included as inflammation marker. During follow up postoperative complications were recorded. The present analysis was carried out in 43 patients with complete information. RESULTS Low retinol values (< 20 μg/dl) were founded in 3 cases and low Zn values (< 85 μg/dl) in 20 cases, being 9 of them indicative of severe deficiency (< 70 μg/dl). Postoperative complications were recorded in 17 patients; patients with complications presented lower values of plasma Zn (78.4 ± 25.8 vs. 87.8 ± 25.7 μg/dl) and retinol (36.9 ± 14.5 vs. 49.7 ± 20.6; P = 0.0318) than those with no complications; the number of patients with complications decreased when retinol and Zn ranges increased. No relation between BMI or WL% and appearance of complications was founded; patients with higher WL% were those with higher usual weight. Inflammation affected both markers: retinol dropped from 50.1 ± 17.2 to 44.0 ±20.8 and to 23.7 ± 4.0 μg/dl for CRP ranges of < 0.5, 0.5-3.9 and ≥ 4 mg/dl, respectively (p = 0.0193); levels of zinc fell from 90.1 ± 17.8 to 85.2 ± 29.9 and to 55.0 ± 25.9 μg/dl for the same CRP ranges (P = 0.0195). Zn level influenced retinol level, dropping to 33.1 ± 11.7 μg/dl of retinol in the Zn severe deficiency group (P = 0.0386). CONCLUSIONS The obtained results confirm the influence of vitamin A and zinc on postoperative evolution of the surgical patient, while alert about the interrelationships among vitamin A, zinc and inflammation, which lead to difficulty to establish the real source of deficiencies. Beyond these difficulties, retinol and zinc plasma levels determine the nutrient availability for the body and appear as promissory markers of surgical risk.

Apolipoproteins A-I and B as Predictors of Complications in Gallbladder Lithiasis Surgical Patients

Specific serum proteins have been traditionally used in the assessment of protein-energy malnutrition. Some short half-life serum proteins have been related to the appearance of postoperative complications in surgical patients with low-risk pathologies that, far from undernutrition, showed a trend toward overweight and obesity. Apolipoproteins have been proposed as potential tools to assess protein status and nutritional recovery, so we investigated apolipoproteins A-I and B as new tools with prognostic value to detect postoperative complications. We analyzed the interrelation between apolipoproteins level and the appearance of complications after programed surgical procedures of gallbladder lithiasis. Assessment was performed, and postoperative complications were recorded in 52 patients (39 women and 13 men, age range = 21-69 y). Assessment included measurements of weight and height and determinations of apolipoprotein A-I and B by quantitative radial immunodiffusion on gel layers. Apolipoproteins levels showed no statistical differences between complicated and uncomplicated patients. The apolipoproteins included in this study did not predict surgical complications because abnormal values were not associated with the presence of complications in this kind of patient.