GESTATIONAL AGE-RELATED REFERENCE VALUES FOR AMNIOTIC FLUID AMINO ACIDS: A USEFUL TOOL FOR PRENATAL DIAGNOSIS OF AMINOACIDOPATHIES

Abstract We determined age-related reference values for urinary free amino acids (in mmol/mol creatinine) in first morning urine specimens from 360 control subjects who were divided into nine age groups: birth to 1 month, 1-6 months, 6-12 months, 1-2 years, 2-4 years, 4-7 years, 7-10 years, 10-13 years, and older than 13 years. Except for taurine and 3-methylhistidine, the concentration of all the amino acids decreased with increasing age. The use of these results to detect aminoacidopathies and tubulopathies is discussed.

Download Full-text

Age Related Reference Values for Urinary Free Amino Acids: A Simple Method of Evaluation

Clinical Chemistry and Laboratory Medicine (CCLM) ◽

10.1515/cclm.1979.17.4.205 ◽

1979 ◽

Vol 17 (4) ◽

Author(s):

Ph. Parvy ◽

Y. Huang ◽

P. Kamoun

Keyword(s):

Amino Acids ◽

Reference Values ◽

Free Amino Acids ◽

Free Amino ◽

Simple Method ◽

Age Related ◽

Method Of Evaluation

Download Full-text

Prenatal Megacystis – Is Prediction of Outcome and Renal Function Possible?

Ultraschall in der Medizin - European Journal of Ultrasound ◽

10.1055/s-0043-105263 ◽

2017 ◽

Vol 39 (04) ◽

pp. 407-412 ◽

Cited By ~ 1

Author(s):

Regina Tschannen ◽

Rita Gobet ◽

Josef Wisser

Keyword(s):

Renal Function ◽

Amniotic Fluid ◽

Gestational Age ◽

Fluid Volume ◽

Amniotic Fluid Volume ◽

Age Related ◽

Age Dependent ◽

Fetal Urine ◽

Beta 2 ◽

Beta 2 Microglobulin

Abstract Objective To assess prenatal prognostic criteria for fetuses with megacystis in order to counsel parents. Methods In a retrospective observational study at a single tertiary referral center, we assessed the clinical course of 53 fetuses with megacystis cared for at the Department of Obstetrics of the University Hospital Zurich between 1995 and 2008 and followed them up for 2 to 12 years. We determined fetal karyotype, amniotic fluid volume and fetal urinary biochemistry as prenatal prognostic factors. The renal function of survivors was grouped according to age-related creatinine values. Using logistic regression analysis, gestational age-dependent discrimination curves and corresponding ROC curves for fetal urine, beta-2 microglobulin, osmolarity and chloride were calculated. Results 43 out of 53 fetuses underwent vesicocentesis, and spontaneous remission occurred in 3 fetuses. 15 fetuses survived, termination of pregnancy was requested in 23 cases, and 12 neonatal and 3 intrauterine deaths were observed. Reduced amniotic fluid volume showed a significant (p = 0.0027) increase of impaired renal function or perinatal death. Discrimination between survivors and non-survivors was complete for fetal urine beta-2 microglobulin with an area under the curve (AUC) of 1.0. For fetal urine osmolarity and fetal urinary chloride, the AUC was 0.81 and 0.76, respectively. Conclusion The assessment of prognosis for fetal megacystis should include fetal k aryotyping, determination of amniotic fluid and assessment of fetal urine biochemistry. Gestational age-dependent regression lines disclose clinically relevant discrimination and can be used as selection criteria for fetal interventions and parental counselling.

Download Full-text

Year-Long Validation Study and Reference Values for Urinary Amino Acids Using a Reversed-Phase HPLC Method

Clinical Chemistry ◽

10.1093/clinchem/47.3.575 ◽

2001 ◽

Vol 47 (3) ◽

pp. 575-583 ◽

Cited By ~ 17

Author(s):

Rafael Venta

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Reference Values ◽

Amino Acid Analysis ◽

Reference Intervals ◽

Reversed Phase ◽

Hplc Method ◽

Rp Hplc ◽

Age Related

Abstract Background: Reversed-phase HPLC (RP-HPLC) has become an alternative to ion-exchange chromatography for amino acid analysis in biological fluids. However, validation studies for its urine application are limited, and the corresponding reference values have not been reported extensively. We studied the long-term performance of a commercial HPLC method for urine amino acid analysis and established specific age-related reference values for urine amino acid excretion. Methods: Method performance was continuously assessed by recovery and precision studies with urine samples and controls, respectively. Healthy individuals were prospectively analyzed throughout a 5-year period. Excretion of individual amino acids, expressed as mmol/mol of creatinine, was included in six age-related groups for random urine samples (0–1 month, 1–12 months, 1–3 years, 3–8 years, 8–16 years, and >16 years) and in two groups for 24-h urine collections (8–16 years and >16 years). Results: Over a 1-year period, CVs for retention times were <0.5% and 3.3% for within- and between-run imprecision, respectively. For amino acid concentrations, within-run CVs were 2.9–17% and between-run CVs were 7.1–46% for the same period. Amino acid recoveries were 78–122%. Reference intervals for 35 amino acids were calculated and compared with the concentrations observed in patients diagnosed with specific pathologies. A few statistically significant differences were found between the reference intervals derived using random and 24-h urine collections. Conclusions: Long-term reliability of the RP-HPLC method for urine amino acid analysis has been demonstrated. Representative age-related reference intervals for the RP-HPLC method in both random urine and 24-h urine collections have been established, and their feasibility for diagnosis of aminoaciduria has been shown. These intervals could serve as a guide for laboratories changing to HPLC methods.

Download Full-text