Gestational age-related reference values for amniotic fluid organic acids.
BACKGROUND
Normative data for amniotic fluid (AF) levels of organic acids at different gestational ages are lacking. They can provide a useful framework to investigate the accuracy of prenatal diagnosis for organic acidemias.


METHODS
We report on the concentration of 21 organic acids in AF obtained by gas chromatography/mass spectrometry between the 12th and 34th weeks of gestation from 92 pregnancies that were not at risk for organic acidurias.


RESULTS
We infer normal reference values that can be compared with 134 pregnancies at risk for several metabolic conditions, that is, propionic acidemia, methylmalonic acidemia (methylmalonyl-CoA mutase deficiency or defects in cobalamin metabolism), 4-hydroxybutyric acidemia, glutaric acidemia and pyroglutamic acidemia.


CONCLUSIONS
Most of the metabolites tested did not show conspicuous variations across gestational ages in normal fetuses, with ranges that were consistently similar to available reference values from pooled samples in previous reports. With rare exceptions, knowledge of pathological versus normal values for relevant metabolites leads to clear-cut differentiation of affected versus unaffected fetuses. Nevertheless, it is strongly recommended that mutational analysis and/or additional biochemical approaches complement organic acid analysis for an adequate diagnostic workup.
Ottolenghi
C
C
Metabolic Biochemistry Unit, Hôpital Necker-Enfants Malades, Paris, France. chris.ottolenghi@nck.aphp.fr
Abermil
N
N
Lescoat
A
A
Aupetit
J
J
Beaugendre
O
O
Morichon-Delvallez
N
N
Ricquier
D
D
Chadefaux-Vekemans
B
B
Rabier
D
D
D000328:Adult; D000592:Amino Acid Metabolism, Inborn Errors / Q000175:diagnosis*; D000653:Amniotic Fluid / Q000737:chemistry*; D002264:Carboxylic Acids / Q000032:analysis*; D005260:Female; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods* / Q000706:statistics & numerical data; D012016:Reference Values
D002264:Carboxylic Acids