Fetal Beta2-Microglobulin as a Biomarker of Kidney Disease

Ultrasound diagnosis of fetal kidney and urinary tract anomalies is generally performed at 18–20 WG, showing renal agenesis, cystic kidneys, and urinary tract enlargement. Prognosis of the renal function and its postnatal outcome relies on the US follow-up of the amniotic fluid volume and renal parenchyma. In case of lower urinary tract obstruction, bilateral hydronephrosis, and nephropathies, fetal puncture may be useful to analyze β2-microglobulin. It is a small protein which circulates in a free and stable soluble form in biological fluids and can be G. Grange • V. Tsatsaris CHU Cochin, AP-HP, Maternite Port Royal, Paris, France e-mail: gilles.grange@cch.aphp.fr; vassilis.tsatsaris@cch.aphp.fr M.C. Leguy CHU Cochin, AP-HP, Biologie hormonale, Paris, France e-mail: marie-clemence.leguy@cch.aphp.fr J. Guibourdenche (*) CHU Cochin, AP-HP, Biologie hormonale, INSERM U1139, Physiologie, Faculte de Pharmacie, Universite Paris Descartes, Paris, France e-mail: jean.guibourdenche@cch.aphp.fr; jean.guibourdenche@parisdescartes.fr # Springer Science+Business Media Dordrecht 2015 V.B. Patel, V.R. Preedy (eds.), Biomarkers in Kidney Disease, DOI 10.1007/978-94-007-7743-9_21-1 1 measured using different immunoassay. As β2-microglobulin is entirely filtered and reabsorbed and degraded by the nephron, serum levels rise when glomerular filtration is impaired, while urinary levels increase when tubular reabsorption is affected. Viral fetal infections may also increase serum levels, activating the lymphocyte turnover and thus β2-microglobulin release. An increase in β2microglobulin in serum (above 5–6 mg/L) and to some extent in urine (above 4–5) constitutes an accurate marker to predict a postnatal renal failure in case of urinary tract obstruction and bilateral hydronephrosis. In urines, measurement of Na and Ca if possible has to be associated. In contrast to uropathies, measurement of β2-microglobulin is poorly informative in nephropathies. However, discrepancies remain due to the difficulty in defining a good postnatal outcome and choosing of a reliable cutoff value and to the fact that nephrogenesis is a dynamic complex process in which injury is not entirely reflected by β2-microglobulin.