7/29/2019 Lecithinsphingomyelin ratio - Wikipedia, the free encyclopedia

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Sphingomyelin

Phosphatidylcholine, a type of

phospholipid in lecithin.

Lecithinsphingomyelin ratioFrom Wikipedia, the free encyclopedia

Thelecithinsphingomyelin ratio is a test of fetal amniotic fluid to assess for fetal lung immaturity.[1][2][3] Lungs require surfactant, asoap-like substance, to lower the surface pressure of the alveoli in the lungs. This is especially important for premature babies trying toexpand their lungs after birth. Surfactant is a mixture of lipids, proteins, and glycoproteins, lecithin and sphingomyelin being two of them.Lecithin makes the surfactant mixture more effective.

Contents

1 Evaluation2 Procedure3 See also4 References

Evaluation

The lecithinsphingomyelin ratio is a marker of fetal lung maturity. The outward flow of pulmonary secretions from the fetal lungs into theamniotic fluid maintains the level of lecithin and sphingomyelin equally until 3233 weeks gestation, when the lecithin concentration beginsto increase significantly while sphingomyelin remains nearly the same. As such, if a sample of amniotic fluid has a higher ratio, it indicatesthat there is more surfactant in the lungs and the baby will have less difficulty breathing at birth. An LS ratio of 2 or more indicates fetallung maturity and a relatively low risk of infant respiratory distress syndrome, and an L/S ratio of less than 1.5 is associated with a high riskof infant respiratory distress syndrome.

If preterm delivery is necessary (as evaluated by a biophysical profile or other tests) and the LS ratio is low, the mother may need to receive

steroids to hasten the fetus' surfactant production.

Procedure

An amniotic fluid sample is collected via amniocentesis and the sample is spun down in a centrifuge at 1000 rpm for 35 minutes. Thin layerchromatography (TLC) is performed on the supernatant, which separates out the components. Lecithin and sphingomyelin are relatively easy

to identify on TLC and the predictive value of the test is good.[4]

See also

Phosphatidol glycerol another amniotic fluid marker of fetal lung maturitySurfactant-albumin ratioLamellar body count

Foam stability index

References^Gluck L, Kulovich MV, Borer RC, Brenner PH, Anderson GG, Spellacy WN (1971). "Diagnosis of the respiratory distress syndrome by amniocentesis.". Amer. J . Obstet. Gynecol.109(3):44045. PMID 5107880 (//www.ncbi.nlm.nih.gov/pubmed/5107880) .

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^Whitfield CR, Chan WH, Sproule WB, Stewart AD (April 1972). "Amniotic fluid lecithin: sphingomyelin ratio and fetal lung development" (//www.ncbi.nlm.nih.gov/pmc/articles/PMC1787826/) . Br Med J 2(5805): 856. doi:10.1136/bmj.2.5805.85 (http://dx.doi.org/10.1136%2Fbmj.2.5805.85) . PMC 1787826 (//www.ncbi.nlm.nih.gov/pmc/articles/PMC1787826) .PMID 5018313 (//www.ncbi.nlm.nih.gov/pubmed/5018313) . //www.ncbi.nlm.nih.gov/pmc/articles/PMC1787826/.

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^Wijnberger LD, de Kleine M, Voorbij HA, et al. (April 2009). "Prediction of fetal lung immaturity using gestational age, patient characteristics and fetal lung maturity tests: a probabilisticapproach" (//www.ncbi.nlm.nih.gov/pmc/articles/PMC2780670/) . Arch. Gynecol. Obstet.281: 1521. doi:10.1007/s00404-009-1033-0 (http://dx.doi.org/10.1007%2Fs00404-009-1033-0) .PMC 2780670 (//www.ncbi.nlm.nih.gov/pmc/articles/PMC2780670) . PMID 19381669 (//www.ncbi.nlm.nih.gov/pubmed/19381669) . //www.ncbi.nlm.nih.gov/pmc/articles/PMC2780670/.

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^Spillman T, Cotton DB (1989). "Current perspectives in assessment of fetal pulmonary surfactant status with amniotic fluid" (http://informahealthcare.com/doi/abs/10.3109/10408368909105719) . Crit Rev Clin Lab Sci27(4): 34189. doi:10.3109/10408368909105719 (http://dx.doi.org/10.3109%2F10408368909105719) . PMID 2675912 (//www.ncbi.nlm.nih.gov/pubmed/2675912) . http://informahealthcare.com/doi/abs/10.3109/10408368909105719.

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Categories: Medical tests

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